├── .gitignore ├── CONTRIBUTORS.md ├── LICENSE ├── README.md ├── fs ├── 1.mmap_write_performance │ ├── Makefile │ ├── README.txt │ └── mmap_write_performance.c ├── 2.mmap_read_performance │ ├── Makefile │ ├── README.txt │ └── mmap_read_performance.c ├── 3.mmap_write_sync_nocache │ ├── Makefile │ └── mmap_write_sync_nocache.c ├── 4.mmap_read_sync_nocache │ ├── Makefile │ └── mmap_read_sync_nocache.c ├── 5.multi_thread_write_file │ ├── Makefile │ └── multi_thread_write_file.c └── README.md ├── ipc ├── 1.mkfifo_with_unblock │ ├── Makefile │ └── mkfifo_with_nonblock.c ├── 2.unix_sock_recv_peer │ ├── Makefile │ └── unix_sock_recv_peer.c └── README.md ├── kernel ├── 1.rwlock_spinlock_performance │ ├── Makefile │ └── lock_test.c ├── 2.sleep_test │ ├── Makefile │ └── sleep_test.c └── README.md ├── mem ├── 1.vsz_and_rss │ ├── Makefile │ └── vsz_and_rss.cpp └── README.md ├── networks ├── 1.tcp_close_with_data │ ├── Makefile │ ├── README.md │ └── tcp_close_with_data.c ├── 10.udp_listen_unexpected_port │ ├── Makefile │ └── udp_listen_unexpected_port.c ├── 2.tcp_push_packet │ ├── Makefile │ ├── README.md │ └── tcp_force_push.c ├── 3.tcp_unread_hit_rst │ ├── Makefile │ ├── README.md │ └── tcp_unread_rst.c ├── 4.reuse_addr_option │ ├── Makefile │ └── reuse_addr_option.c ├── 5.no_listen_tcp_conn │ ├── Makefile │ └── no_listen_tcp_conn.c ├── 6.tcp_keepalive_reporter │ ├── Makefile │ └── tcp_keepalive_report.c ├── 7.tcp_send_rst │ ├── Makefile │ └── tcp_send_rst.c ├── 8.connect_until_fail │ ├── accpet_util_fail.py │ └── connect_until_fail.py ├── 9.tcp_unread_shutdown │ ├── Makefile │ ├── README.md │ └── tcp_unread_shutdown.c └── README.md ├── process ├── 1.child_inherit_flock │ ├── Makefile │ ├── README.md │ └── child_inherit_flock.c ├── 2.child_share_flock │ ├── Makefile │ ├── README.md │ └── child_share_flock.c ├── 3.fork_and_print │ ├── Makefile │ ├── README.md │ └── fork_and_print.c ├── 4.fork_with_fd │ ├── Makefile │ ├── README.md │ └── fork_with_fd.c └── README.md └── signal ├── 1.waitpid_sigchld_ignore ├── Makefile ├── README.md └── waitpid_sigchld_ignore.c ├── 2.waitanypid_sigchld_ignore ├── Makefile ├── README.md └── waitanypid_sigchld_ignore.c └── README.md /.gitignore: -------------------------------------------------------------------------------- 1 | # Object files 2 | *.o 3 | *.ko 4 | *.obj 5 | *.elf 6 | 7 | # Precompiled Headers 8 | *.gch 9 | *.pch 10 | 11 | # Libraries 12 | *.lib 13 | *.a 14 | *.la 15 | *.lo 16 | 17 | # Shared objects (inc. Windows DLLs) 18 | *.dll 19 | *.so 20 | *.so.* 21 | *.dylib 22 | 23 | # Executables 24 | *.exe 25 | *.out 26 | *.app 27 | *.i*86 28 | *.x86_64 29 | *.hex 30 | 31 | # Debug files 32 | *.dSYM/ 33 | *.su 34 | 35 | # Tmp files 36 | *.txt 37 | *.d 38 | *.ko* 39 | *.cmd 40 | 41 | -------------------------------------------------------------------------------- /CONTRIBUTORS.md: -------------------------------------------------------------------------------- 1 | This file contains a list of people who made some contribution. 2 | 3 | 4 | # Share the codes and knowledge 5 | 6 | 7 | gfree.wind@gmail.com: The founder and maintainer 8 | 9 | 10 | # Raise the problem 11 | 12 | ly(2270597823@qq.com): Close the TCP socket with pending data 13 | 14 | 15 | 16 | ## Note 17 | 18 | 19 | Welcome every to join QQ group 4367710! 20 | Share your knowledges or raise one problem. 21 | 22 | 23 | 24 | 25 | 26 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Such new versions will 567 | be similar in spirit to the present version, but may differ in detail to 568 | address new problems or concerns. 569 | 570 | Each version is given a distinguishing version number. If the 571 | Program specifies that a certain numbered version of the GNU General 572 | Public License "or any later version" applies to it, you have the 573 | option of following the terms and conditions either of that numbered 574 | version or of any later version published by the Free Software 575 | Foundation. If the Program does not specify a version number of the 576 | GNU General Public License, you may choose any version ever published 577 | by the Free Software Foundation. 578 | 579 | If the Program specifies that a proxy can decide which future 580 | versions of the GNU General Public License can be used, that proxy's 581 | public statement of acceptance of a version permanently authorizes you 582 | to choose that version for the Program. 583 | 584 | Later license versions may give you additional or different 585 | permissions. However, no additional obligations are imposed on any 586 | author or copyright holder as a result of your choosing to follow a 587 | later version. 588 | 589 | 15. Disclaimer of Warranty. 590 | 591 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 592 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 593 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY 594 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, 595 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 596 | PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM 597 | IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF 598 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 599 | 600 | 16. Limitation of Liability. 601 | 602 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 603 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 604 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 605 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 606 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 607 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 608 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 609 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 610 | SUCH DAMAGES. 611 | 612 | 17. Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | {one line to give the program's name and a brief idea of what it does.} 635 | Copyright (C) {year} {name of author} 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | {project} Copyright (C) {year} {fullname} 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # 简介 2 | 3 | 这个工程是用于研究Linux环境编程的一些细节。 4 | 其中每个目录聚焦于一个主题，每个主题目录下面，每个问题又有自己的单独目录。 5 | 6 | 因为这些是测试代码，所以没有细致的进行错误处理。就直接退出进程了事:)) 7 | 后面为了方便，干脆都没有检查函数的返回值:))在工作中，可不能这样哦~~~ 8 | 9 | 每一个子目录都验证Linux编程的一个问题。 10 | 要了解细节的话，可以进入具体的目录得到详细的解答。 11 | 12 | 每个目录下面都有一个README.md文件，用于介绍该目录或者分析具体的问题。 13 | 14 | # General 15 | This project is used to investigate on the details of Linux programming. 16 | Every directory focuses on one topic. 17 | Every topic dir contains different dir which investigates on different problems. 18 | 19 | Becasue they are test codes, so I don't perform the delicated error handler. 20 | Just exit the process :)) 21 | I don't check the return value of function in the latter codes. 22 | But you could not do it in real product:)) 23 | 24 | Every directory focuses on one Linux topic. For example, the signal dir focuses 25 | on the signal details of Linux Programming. 26 | 27 | There is one README.md file in every directory. It is used to introduce the dir 28 | or analyze the details of one problem. 29 | 30 | 31 | 32 | -------------------------------------------------------------------------------- /fs/1.mmap_write_performance/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -Werror -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := mmap_write_performance 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /fs/1.mmap_write_performance/README.txt: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | Firstly, we use mmap to write one file with 1024, 2048, 4096, 4 | and 5120 bytes for 1000000 times. 5 | Then we write another file with 1024, 2048, 4096 and 5120 bytes 6 | for 1000000 times too. 7 | 8 | # Conclusion 9 | 10 | The performane of mmap write is worser than direct write. 11 | 12 | 13 | -------------------------------------------------------------------------------- /fs/1.mmap_write_performance/mmap_write_performance.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: mmap_write_performance.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 10/06/2016 12:20:48 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng (gfree.wind@gmail.com) 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | 19 | #include 20 | #include 21 | 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | 31 | #define TEST_LOOPS (1000000) 32 | 33 | int main(void) 34 | { 35 | int cost, i, fd; 36 | time_t start, end; 37 | char buf[5120] = {"Hello world!\n"}; 38 | 39 | start = time(NULL); 40 | fd = open("./mmap_write.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 41 | ftruncate(fd, 1024); 42 | for (i = 0; i < TEST_LOOPS; ++i) { 43 | char *addr = mmap(NULL, 1024, PROT_WRITE, MAP_SHARED, fd, 0); 44 | memcpy(addr, buf, 1024); 45 | munmap(addr, 1024); 46 | } 47 | close(fd); 48 | end = time(NULL); 49 | cost = end - start; 50 | printf("mmap write 1024 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 51 | 52 | start = time(NULL); 53 | fd = open("./mmap_write.txt", O_CREAT|O_RDWR|O_TRUNC); 54 | ftruncate(fd, 2048); 55 | for (i = 0; i < TEST_LOOPS; ++i) { 56 | char *addr = mmap(NULL, 2048, PROT_WRITE, MAP_SHARED, fd, 0); 57 | memcpy(addr, buf, 2048); 58 | munmap(addr, 2048); 59 | } 60 | close(fd); 61 | end = time(NULL); 62 | cost = end - start; 63 | printf("mmap write 2048 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 64 | 65 | start = time(NULL); 66 | fd = open("./mmap_write.txt", O_CREAT|O_RDWR|O_TRUNC); 67 | ftruncate(fd, 4096); 68 | for (i = 0; i < TEST_LOOPS; ++i) { 69 | char *addr = mmap(NULL, 4096, PROT_WRITE, MAP_SHARED, fd, 0); 70 | memcpy(addr, buf, 4096); 71 | munmap(addr, 4096); 72 | } 73 | close(fd); 74 | end = time(NULL); 75 | cost = end - start; 76 | printf("mmap write 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 77 | 78 | start = time(NULL); 79 | fd = open("./mmap_write.txt", O_CREAT|O_RDWR|O_TRUNC); 80 | ftruncate(fd, 5120); 81 | for (i = 0; i < TEST_LOOPS; ++i) { 82 | char *addr = mmap(NULL, 5120, PROT_WRITE, MAP_SHARED, fd, 0); 83 | memcpy(addr, buf, 5120); 84 | munmap(addr, 5120); 85 | } 86 | close(fd); 87 | end = time(NULL); 88 | cost = end - start; 89 | printf("mmap write 5120 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 90 | 91 | 92 | start = time(NULL); 93 | fd = open("./direct_write.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 94 | for (i = 0; i < TEST_LOOPS; ++i) { 95 | pwrite(fd, buf, 1024, 0); 96 | } 97 | close(fd); 98 | end = time(NULL); 99 | cost = end - start; 100 | printf("direct write 1024 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 101 | 102 | start = time(NULL); 103 | fd = open("./direct_write.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 104 | for (i = 0; i < TEST_LOOPS; ++i) { 105 | pwrite(fd, buf, 2048, 0); 106 | } 107 | close(fd); 108 | end = time(NULL); 109 | cost = end - start; 110 | printf("direct write 2048 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 111 | 112 | start = time(NULL); 113 | fd = open("./direct_write.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 114 | for (i = 0; i < TEST_LOOPS; ++i) { 115 | pwrite(fd, buf, 4096, 0); 116 | } 117 | close(fd); 118 | end = time(NULL); 119 | cost = end - start; 120 | printf("direct write 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 121 | 122 | start = time(NULL); 123 | fd = open("./direct_write.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 124 | for (i = 0; i < TEST_LOOPS; ++i) { 125 | pwrite(fd, buf, 5120, 0); 126 | } 127 | close(fd); 128 | end = time(NULL); 129 | cost = end - start; 130 | printf("direct write 5120 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 131 | 132 | 133 | 134 | return 0; 135 | } 136 | 137 | -------------------------------------------------------------------------------- /fs/2.mmap_read_performance/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -Werror -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := mmap_read_performance 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /fs/2.mmap_read_performance/README.txt: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | Firstly, we use mmap to read one file with 1024, 2048, 4096, 4 | and 5120 bytes for 1000000 times. 5 | Then we read another file with 1024, 2048, 4096 and 5120 bytes 6 | for 1000000 times too. 7 | 8 | # Conclusion 9 | 10 | The performane of mmap read is worser than direct read. 11 | 12 | 13 | -------------------------------------------------------------------------------- /fs/2.mmap_read_performance/mmap_read_performance.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: mmap_write_performance.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 10/06/2016 12:20:48 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng (gfree.wind@gmail.com) 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | 19 | #include 20 | #include 21 | 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | 31 | #define TEST_LOOPS (1000000) 32 | 33 | int main(void) 34 | { 35 | int cost, i, fd; 36 | time_t start, end; 37 | char buf[5120]; 38 | 39 | start = time(NULL); 40 | fd = open("./mmap_read.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 41 | ftruncate(fd, 1024); 42 | for (i = 0; i < TEST_LOOPS; ++i) { 43 | char *addr = mmap(NULL, 1024, PROT_READ, MAP_SHARED, fd, 0); 44 | memcpy(buf, addr, 1024); 45 | munmap(addr, 1024); 46 | } 47 | close(fd); 48 | end = time(NULL); 49 | cost = end - start; 50 | printf("mmap read 1024 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 51 | 52 | start = time(NULL); 53 | fd = open("./mmap_read.txt", O_CREAT|O_RDWR|O_TRUNC); 54 | ftruncate(fd, 2048); 55 | for (i = 0; i < TEST_LOOPS; ++i) { 56 | char *addr = mmap(NULL, 2048, PROT_READ, MAP_SHARED, fd, 0); 57 | memcpy(buf, addr, 2048); 58 | munmap(addr, 2048); 59 | } 60 | close(fd); 61 | end = time(NULL); 62 | cost = end - start; 63 | printf("mmap read 2048 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 64 | 65 | start = time(NULL); 66 | fd = open("./mmap_read.txt", O_CREAT|O_RDWR|O_TRUNC); 67 | ftruncate(fd, 4096); 68 | for (i = 0; i < TEST_LOOPS; ++i) { 69 | char *addr = mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd, 0); 70 | memcpy(buf, addr, 4096); 71 | munmap(addr, 4096); 72 | } 73 | close(fd); 74 | end = time(NULL); 75 | cost = end - start; 76 | printf("mmap read 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 77 | 78 | start = time(NULL); 79 | fd = open("./mmap_read.txt", O_CREAT|O_RDWR|O_TRUNC); 80 | ftruncate(fd, 5120); 81 | for (i = 0; i < TEST_LOOPS; ++i) { 82 | char *addr = mmap(NULL, 5120, PROT_READ, MAP_SHARED, fd, 0); 83 | memcpy(buf, addr, 5120); 84 | munmap(addr, 5120); 85 | } 86 | close(fd); 87 | end = time(NULL); 88 | cost = end - start; 89 | printf("mmap read 5120 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 90 | 91 | 92 | start = time(NULL); 93 | fd = open("./direct_read.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 94 | ftruncate(fd, 1024); 95 | for (i = 0; i < TEST_LOOPS; ++i) { 96 | pread(fd, buf, 1024, 0); 97 | } 98 | close(fd); 99 | end = time(NULL); 100 | cost = end - start; 101 | printf("direct read 1024 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 102 | 103 | start = time(NULL); 104 | fd = open("./direct_read.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 105 | ftruncate(fd, 2048); 106 | for (i = 0; i < TEST_LOOPS; ++i) { 107 | pread(fd, buf, 2048, 0); 108 | } 109 | close(fd); 110 | end = time(NULL); 111 | cost = end - start; 112 | printf("direct read 2048 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 113 | 114 | start = time(NULL); 115 | fd = open("./direct_read.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 116 | ftruncate(fd, 4096); 117 | for (i = 0; i < TEST_LOOPS; ++i) { 118 | pread(fd, buf, 4096, 0); 119 | } 120 | close(fd); 121 | end = time(NULL); 122 | cost = end - start; 123 | printf("direct read 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 124 | 125 | start = time(NULL); 126 | fd = open("./direct_read.txt", O_CREAT|O_RDWR|O_TRUNC, 0644); 127 | ftruncate(fd, 5120); 128 | for (i = 0; i < TEST_LOOPS; ++i) { 129 | pread(fd, buf, 5120, 0); 130 | } 131 | close(fd); 132 | end = time(NULL); 133 | cost = end - start; 134 | printf("direct read 5120 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 135 | 136 | 137 | return 0; 138 | } 139 | 140 | -------------------------------------------------------------------------------- /fs/3.mmap_write_sync_nocache/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -Werror -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := mmap_write_sync_nocache 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /fs/3.mmap_write_sync_nocache/mmap_write_sync_nocache.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: mmap_write_performance.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 10/06/2016 12:20:48 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng (gfree.wind@gmail.com) 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | 19 | #define _GNU_SOURCE 20 | 21 | #include 22 | #include 23 | 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | #include 31 | #include 32 | 33 | #define TEST_LOOPS (10000000) 34 | 35 | int main(void) 36 | { 37 | int cost, i, fd; 38 | time_t start, end; 39 | char buf[20480] = {"Hello world!\n"}; 40 | 41 | start = time(NULL); 42 | fd = open("./mmap_write.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 43 | ftruncate(fd, 4096); 44 | for (i = 0; i < TEST_LOOPS; ++i) { 45 | char *addr = mmap(NULL, 4096, PROT_WRITE, MAP_SHARED, fd, 0); 46 | memcpy(addr, buf, 4096); 47 | munmap(addr, 4096); 48 | } 49 | close(fd); 50 | end = time(NULL); 51 | cost = end - start; 52 | printf("mmap write 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 53 | 54 | start = time(NULL); 55 | fd = open("./mmap_write.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC); 56 | ftruncate(fd, 8192); 57 | for (i = 0; i < TEST_LOOPS; ++i) { 58 | char *addr = mmap(NULL, 8192, PROT_WRITE, MAP_SHARED, fd, 0); 59 | memcpy(addr, buf, 8192); 60 | munmap(addr, 8192); 61 | } 62 | close(fd); 63 | end = time(NULL); 64 | cost = end - start; 65 | printf("mmap write 8192 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 66 | 67 | start = time(NULL); 68 | fd = open("./mmap_write.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC); 69 | ftruncate(fd, 12288); 70 | for (i = 0; i < TEST_LOOPS; ++i) { 71 | char *addr = mmap(NULL, 12288, PROT_WRITE, MAP_SHARED, fd, 0); 72 | memcpy(addr, buf, 12288); 73 | munmap(addr, 12288); 74 | } 75 | close(fd); 76 | end = time(NULL); 77 | cost = end - start; 78 | printf("mmap write 12288 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 79 | 80 | 81 | start = time(NULL); 82 | fd = open("./direct_write.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 83 | for (i = 0; i < TEST_LOOPS; ++i) { 84 | pwrite(fd, buf, 4096, 0); 85 | } 86 | close(fd); 87 | end = time(NULL); 88 | cost = end - start; 89 | printf("direct write 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 90 | 91 | start = time(NULL); 92 | fd = open("./direct_write.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 93 | for (i = 0; i < TEST_LOOPS; ++i) { 94 | pwrite(fd, buf, 8192, 0); 95 | } 96 | close(fd); 97 | end = time(NULL); 98 | cost = end - start; 99 | printf("direct write 8192 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 100 | 101 | start = time(NULL); 102 | fd = open("./direct_write.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 103 | for (i = 0; i < TEST_LOOPS; ++i) { 104 | pwrite(fd, buf, 12288, 0); 105 | } 106 | close(fd); 107 | end = time(NULL); 108 | cost = end - start; 109 | printf("direct write 12288 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 110 | 111 | 112 | return 0; 113 | } 114 | 115 | -------------------------------------------------------------------------------- /fs/4.mmap_read_sync_nocache/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -Werror -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := mmap_read_sync_nocache 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /fs/4.mmap_read_sync_nocache/mmap_read_sync_nocache.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: mmap_write_performance.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 10/06/2016 12:20:48 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng (gfree.wind@gmail.com) 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #define _GNU_SOURCE 19 | #include 20 | #include 21 | 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | 31 | #define TEST_LOOPS (5000000) 32 | 33 | int main(void) 34 | { 35 | int cost, i, fd; 36 | time_t start, end; 37 | char buf[20480]; 38 | 39 | start = time(NULL); 40 | fd = open("./mmap_read.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 41 | ftruncate(fd, 4096); 42 | for (i = 0; i < TEST_LOOPS; ++i) { 43 | char *addr = mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd, 0); 44 | memcpy(buf, addr, 4096); 45 | munmap(addr, 4096); 46 | } 47 | close(fd); 48 | end = time(NULL); 49 | cost = end - start; 50 | printf("mmap read 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 51 | 52 | start = time(NULL); 53 | fd = open("./mmap_read.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC); 54 | ftruncate(fd, 8196); 55 | for (i = 0; i < TEST_LOOPS; ++i) { 56 | char *addr = mmap(NULL, 8196, PROT_READ, MAP_SHARED, fd, 0); 57 | memcpy(buf, addr, 8196); 58 | munmap(addr, 8196); 59 | } 60 | close(fd); 61 | end = time(NULL); 62 | cost = end - start; 63 | printf("mmap read 8196 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 64 | 65 | start = time(NULL); 66 | fd = open("./mmap_read.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC); 67 | ftruncate(fd, 12288); 68 | for (i = 0; i < TEST_LOOPS; ++i) { 69 | char *addr = mmap(NULL, 12288, PROT_READ, MAP_SHARED, fd, 0); 70 | memcpy(buf, addr, 12288); 71 | munmap(addr, 12288); 72 | } 73 | close(fd); 74 | end = time(NULL); 75 | cost = end - start; 76 | printf("mmap read 12288 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 77 | 78 | 79 | start = time(NULL); 80 | fd = open("./direct_read.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 81 | ftruncate(fd, 4096); 82 | for (i = 0; i < TEST_LOOPS; ++i) { 83 | pread(fd, buf, 4096, 0); 84 | } 85 | close(fd); 86 | end = time(NULL); 87 | cost = end - start; 88 | printf("direct read 4096 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 89 | 90 | start = time(NULL); 91 | fd = open("./direct_read.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 92 | ftruncate(fd, 8192); 93 | for (i = 0; i < TEST_LOOPS; ++i) { 94 | pread(fd, buf, 8192, 0); 95 | } 96 | close(fd); 97 | end = time(NULL); 98 | cost = end - start; 99 | printf("direct read 8192 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 100 | 101 | start = time(NULL); 102 | fd = open("./direct_read.txt", O_CREAT|O_RDWR|O_TRUNC|O_DIRECT|O_SYNC, 0644); 103 | ftruncate(fd, 12288); 104 | for (i = 0; i < TEST_LOOPS; ++i) { 105 | pread(fd, buf, 12288, 0); 106 | } 107 | close(fd); 108 | end = time(NULL); 109 | cost = end - start; 110 | printf("direct read 12288 bytes %u times costs %d secs\n", TEST_LOOPS, cost); 111 | 112 | 113 | return 0; 114 | } 115 | 116 | -------------------------------------------------------------------------------- /fs/5.multi_thread_write_file/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -Werror -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := multi_thread_write_file 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /fs/5.multi_thread_write_file/multi_thread_write_file.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include 5 | #include 6 | #include 7 | #include 8 | #include 9 | 10 | //#define USE_CLIB 11 | 12 | #define TEST_FILE "./tmp.txt" 13 | 14 | #define LOOPS (1000000) 15 | 16 | 17 | #ifdef USE_CLIB 18 | struct thr_data { 19 | FILE *fp; 20 | const char *data; 21 | }; 22 | 23 | static void * write_data(void *data) 24 | { 25 | struct thr_data *d; 26 | size_t len; 27 | int i; 28 | 29 | d = data; 30 | len = strlen(d->data); 31 | for (i = 0; i < LOOPS; ++i) { 32 | fwrite(d->data, len, 1, d->fp); 33 | } 34 | 35 | return NULL; 36 | } 37 | 38 | #else 39 | struct thr_data { 40 | int fd; 41 | const char *data; 42 | }; 43 | 44 | static void *write_data(void *data) 45 | { 46 | struct thr_data *d; 47 | int i; 48 | size_t len; 49 | 50 | d = data; 51 | len = strlen(d->data); 52 | for (i = 0; i < LOOPS; ++i) { 53 | write(d->fd, d->data, len); 54 | } 55 | 56 | return NULL; 57 | } 58 | #endif 59 | 60 | 61 | 62 | int main(void) 63 | { 64 | pthread_t t1, t2, t3; 65 | struct thr_data d1, d2, d3; 66 | 67 | #ifdef USE_CLIB 68 | FILE *fp = fopen(TEST_FILE, "w"); 69 | d1.fp = d2.fp = d3.fp = fp; 70 | #else 71 | //int fd = open(TEST_FILE, O_WRONLY|O_TRUNC); 72 | int fd = open(TEST_FILE, O_WRONLY|O_TRUNC|O_APPEND); 73 | d1.fd = d2.fd = d3.fd = fd; 74 | #endif 75 | 76 | d1.data = "aaaaaa\n"; 77 | d2.data = "bbbbbb\n"; 78 | d3.data = "cccccc\n"; 79 | 80 | pthread_create(&t1, NULL, write_data, &d1); 81 | pthread_create(&t2, NULL, write_data, &d2); 82 | pthread_create(&t3, NULL, write_data, &d3); 83 | 84 | pthread_join(t1, NULL); 85 | pthread_join(t2, NULL); 86 | pthread_join(t3, NULL); 87 | 88 | #ifdef USE_CLIB 89 | fclose(fp); 90 | #else 91 | close(fd); 92 | #endif 93 | 94 | return 0; 95 | } 96 | -------------------------------------------------------------------------------- /fs/README.md: -------------------------------------------------------------------------------- 1 | # 1.mmap_write_performance 2 | 3 | ## 问题 4 | 5 | 对比mmap和write的性能，哪个性能更好？ 6 | 7 | ## 结论 8 | 9 | 利用mmap写文件的性能不如直接写文件。 10 | 11 | ## Question 12 | 13 | Compare the performance of mmap and write, which is better? 14 | 15 | ## Answer 16 | 17 | The performance of mmap write is worser than direct write. 18 | 19 | # 2.mmap_read_performance 20 | 21 | ## 问题 22 | 23 | 对比mmap和read的性能，哪个性能更好？ 24 | 25 | ## 结论 26 | 27 | 利用mmap读文件的性能不如直接读文件。 28 | 29 | ## Question 30 | 31 | Compare the performance of mmap and read, which is better? 32 | 33 | ## Answer 34 | 35 | The performance of mmap read is worse than direct read. 36 | 37 | # 3.mmap_write_sync_nocache 38 | 39 | ## 问题 40 | 41 | 一般情况下，write都会使用cache，本例中禁止了cache，再次比较mmap和write的性能 42 | 43 | ## 结论 44 | 随着写入字节的增加，mmap消耗的时间也越来越多。 45 | 但是write消耗的时间并没有明显增加。 46 | 47 | ## Question 48 | 49 | When disable the write cache, how about the performance of mmap write and write? 50 | 51 | ## Answer 52 | 53 | The cost increases with bytes increasing when use mmap. 54 | But the cost of write does not increase. 55 | 56 | # 4.mmap_read_sync_nocache 57 | 58 | ## 问题 59 | 60 | 同上。本例中禁止了cache，再次比较mmap和read的性能 61 | 62 | ## 性能 63 | 随着读入字节的增加，mmap消耗的时间也在增加。 64 | 但是read消耗的时间增加的非常少 65 | 66 | 67 | # 5. multi_thread_write_file 68 | 69 | ## 问题 70 | 71 | 多线程同时对相同的文件进行写操作时，会有问题吗？ 72 | 1）同时对相同的FILE*文件流进行写操作。   73 | 2）同时对相同的文件描述符进行写操作。   74 | 75 | ## 结论 76 | 1）当使用C库fwrite的时候，多线程同时写入文件没有问题。   77 | 2）当使用系统调用write时，多线程同时写入文件是非预期的行为可以使用O_APPEND标志避免这个问题。 78 | 79 | -------------------------------------------------------------------------------- /ipc/1.mkfifo_with_unblock/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -Werror -shared -fPIC 9 | LDFLAGS := 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := mkfifo_with_nonblock 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /ipc/1.mkfifo_with_unblock/mkfifo_with_nonblock.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: mkfifo_with_nonblock.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 09/25/2016 09:33:08 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng, gfree.wind@gmail.com 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | #include 21 | #include 22 | 23 | #include 24 | #include 25 | #include 26 | #include 27 | 28 | #define TEST_PIPE_FILE "./test.pipe" 29 | 30 | int main(void) 31 | { 32 | remove(TEST_PIPE_FILE); 33 | if (mkfifo(TEST_PIPE_FILE, 0644)) { 34 | printf("mkfifo failed, %s(%d)\n", strerror(errno), errno); 35 | return -1; 36 | } 37 | 38 | int fd = open(TEST_PIPE_FILE, O_WRONLY|O_NONBLOCK); 39 | if (fd == -1) { 40 | printf("open with O_WRONLY|O_NONBLOCK failed, %s(%d)\n", 41 | strerror(errno), errno); 42 | } else { 43 | printf("open with O_WRONLY|O_NONBLOCK is successful, return fd(%d)\n", fd); 44 | close(fd); 45 | } 46 | 47 | fd = open(TEST_PIPE_FILE, O_RDONLY|O_NONBLOCK); 48 | if (fd == -1) { 49 | printf("open with O_RDONLY|O_NONBLOCK failed, %s(%d)\n", 50 | strerror(errno), errno); 51 | } else { 52 | printf("open with O_RDONLY|O_NONBLOCK is successful, return fd(%d)\n", fd); 53 | close(fd); 54 | } 55 | 56 | return 0; 57 | } 58 | -------------------------------------------------------------------------------- /ipc/2.unix_sock_recv_peer/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -g -Wall -Werror -shared -fPIC 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := unix_sock_recv_peer 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /ipc/2.unix_sock_recv_peer/unix_sock_recv_peer.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: tcp_close_with_data.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 08/31/2016 09:29:46 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng gfree.wind@gmail.com 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | 30 | #define SERVER_PATH "./unix_server" 31 | #define CLIENT_PATH "./unix_client" 32 | 33 | #define BIND_UNIX_CLIENT 34 | 35 | static void* client_thread(void *data) 36 | { 37 | int fd = socket(AF_UNIX, SOCK_DGRAM, 0); 38 | 39 | #ifdef BIND_UNIX_CLIENT 40 | struct sockaddr_un cli_addr; 41 | memset(&cli_addr, 0, sizeof(cli_addr)); 42 | cli_addr.sun_family = AF_UNIX; 43 | strcpy(cli_addr.sun_path, CLIENT_PATH); 44 | unlink(CLIENT_PATH); 45 | if (bind(fd, (struct sockaddr*)&cli_addr, sizeof(cli_addr))) { 46 | printf("Fail to bind client\n"); 47 | exit(1); 48 | } 49 | #endif 50 | 51 | struct sockaddr_un serv_addr; 52 | memset(&serv_addr, 0, sizeof(serv_addr)); 53 | serv_addr.sun_family = AF_UNIX; 54 | strcpy(serv_addr.sun_path, SERVER_PATH); 55 | 56 | sendto(fd, "123", 3, 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 57 | 58 | close(fd); 59 | 60 | return NULL; 61 | 62 | } 63 | 64 | int main(void) 65 | { 66 | pthread_t tid; 67 | 68 | signal(SIGPIPE, SIG_IGN); 69 | 70 | int server_fd = socket(AF_UNIX, SOCK_DGRAM, 0); 71 | struct sockaddr_un serv_addr; 72 | 73 | memset(&serv_addr, 0, sizeof(serv_addr)); 74 | serv_addr.sun_family = AF_UNIX; 75 | strcpy(serv_addr.sun_path, SERVER_PATH); 76 | unlink(SERVER_PATH); 77 | if (bind(server_fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr))) { 78 | printf("Fail to bind\n"); 79 | exit(-1); 80 | } 81 | 82 | pthread_create(&tid, NULL, client_thread, NULL); 83 | 84 | char buf[32] = {0}; 85 | struct sockaddr_un peer_addr; 86 | socklen_t sock_len; 87 | 88 | memset(&peer_addr, 0, sizeof(peer_addr)); 89 | sock_len = sizeof(peer_addr); 90 | recvfrom(server_fd, buf, sizeof(buf), 0, (struct sockaddr*)&peer_addr, &sock_len); 91 | 92 | printf("buf: %s\n", buf); 93 | printf("peer sun_path: %s\n", peer_addr.sun_path); 94 | 95 | close(server_fd); 96 | pthread_join(tid, NULL); 97 | 98 | return 0; 99 | } 100 | -------------------------------------------------------------------------------- /ipc/README.md: -------------------------------------------------------------------------------- 1 | # 1.mkfifo_with_unblock 2 | 3 | ## 问题 4 | 5 | 调用mkfifo时，如果是只读打开且没有其它进程写入打开时，这个调用会阻塞。 6 | 同理，如果是写模式打开且没有其它进程读取打开时，这个调用也会阻塞。 7 | 那么当调用设置了非阻塞的标志时，会有什么现象呢？ 8 | 9 | ## Question 10 | 11 | When invokes mkfifo with O_RDONLY and there is no process which opened 12 | the fifo with O_WRONLY already, this call would be blocked. 13 | It is blocked too that when invokes mkfifo with O_WRONLY and there is no 14 | process which opened the fifo with O_RDONLY. 15 | 16 | Then how about invokes mkfifo with O_NONBLOCK. 17 | 18 | ## 答案 19 | 如果在没有读取者时，非阻塞写模式打开管道文件会返回错误； 20 | 如果在没有写入者时，非阻塞读模式打开管道文件会成功打开. 21 | 22 | ## Answer 23 | mkfifo returns OK with O_RDONLY|O_NONBLOCK eventhough no O_WRONLY process, while 24 | it faied with O_WRONLY|O_NONBLOCK when no O_RDONLY process. 25 | 26 | 27 | # 2.unix_sock_recv_peer 28 | 29 | ## 问题 30 | 对于UNIX域套接字来说，如果调用recvfrom，得到的对端地址是什么呢？ 31 | 32 | ## Question 33 | When UNIX socket invokes recvfrom, what peer info we could get? 34 | 35 | ## 答案   36 | 当Unix域套接字的客户端，也bind了一个文件，则服务端可以得到unix域的peer信息，就是客户端bind的地址，如sun_path就是bind的文件。 37 | 当Unix域套接字的客户端，没有bind，服务端得不到unix域的peer信息。 38 | -------------------------------------------------------------------------------- /kernel/1.rwlock_spinlock_performance/Makefile: -------------------------------------------------------------------------------- 1 | obj-m := lock_test.o 2 | 3 | KDIR := /lib/modules/`uname -r`/build 4 | 5 | modules: 6 | make -C $(KDIR) M=$(PWD) modules 7 | 8 | clean: 9 | rm -f *.ko *.o *.mod.o *.mod.c *.order *.symvers 10 | 11 | -------------------------------------------------------------------------------- /kernel/1.rwlock_spinlock_performance/lock_test.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include 5 | #include 6 | 7 | #define TEST_TIMES (100000000) 8 | #define ONE_SEC_NS (1000000000) 9 | 10 | static void time_cost(struct timespec *start, struct timespec *end, 11 | struct timespec *cost) 12 | { 13 | unsigned long long startns; 14 | unsigned long long endns; 15 | 16 | startns = start->tv_sec * ONE_SEC_NS + start->tv_nsec; 17 | endns = end->tv_sec * ONE_SEC_NS + end->tv_nsec; 18 | cost->tv_sec = end->tv_sec - start->tv_sec; 19 | if (end->tv_nsec >= start->tv_nsec) { 20 | cost->tv_nsec = end->tv_nsec - start->tv_nsec; 21 | } else { 22 | --cost->tv_sec; 23 | cost->tv_nsec = end->tv_nsec + ONE_SEC_NS - start->tv_nsec; 24 | } 25 | 26 | return; 27 | } 28 | 29 | static void lock_test(void) 30 | { 31 | DEFINE_RWLOCK(rwlock); 32 | spinlock_t spinlock; 33 | DEFINE_MUTEX(mutex); 34 | struct timespec start; 35 | struct timespec end; 36 | struct timespec cost; 37 | int i; 38 | 39 | preempt_disable(); 40 | local_bh_disable(); 41 | local_irq_disable(); 42 | 43 | spin_lock_init(&spinlock); 44 | 45 | /* rwlock case */ 46 | getnstimeofday(&start); 47 | for (i = 0; i < TEST_TIMES; ++i) { 48 | read_lock(&rwlock); 49 | read_unlock(&rwlock); 50 | } 51 | getnstimeofday(&end); 52 | 53 | time_cost(&start, &end, &cost); 54 | 55 | printk(KERN_INFO "wrlock start: %ld s, %ld ns\n", 56 | start.tv_sec, start.tv_nsec); 57 | printk(KERN_INFO "wrlock end: %ld s, %ld ns\n", 58 | end.tv_sec, end.tv_nsec); 59 | printk(KERN_INFO "wrlock costs %ld s, %ld ns\n", 60 | cost.tv_sec, cost.tv_nsec); 61 | 62 | /* spinlock case */ 63 | getnstimeofday(&start); 64 | for (i = 0; i < TEST_TIMES; ++i) { 65 | spin_lock(&spinlock); 66 | spin_unlock(&spinlock); 67 | } 68 | getnstimeofday(&end); 69 | 70 | time_cost(&start, &end, &cost); 71 | 72 | printk(KERN_INFO "spinlock start: %ld s, %ld ns\n", 73 | start.tv_sec, start.tv_nsec); 74 | printk(KERN_INFO "spinlock end: %ld s, %ld ns\n", 75 | end.tv_sec, end.tv_nsec); 76 | printk(KERN_INFO "spinlock costs %ld s, %lu ns\n", 77 | cost.tv_sec, cost.tv_nsec); 78 | 79 | /* rcu case */ 80 | getnstimeofday(&start); 81 | for (i = 0; i < TEST_TIMES; ++i) { 82 | rcu_read_lock(); 83 | rcu_read_unlock(); 84 | } 85 | getnstimeofday(&end); 86 | 87 | time_cost(&start, &end, &cost); 88 | 89 | printk(KERN_INFO "rculock start: %ld s, %ld ns\n", 90 | start.tv_sec, start.tv_nsec); 91 | printk(KERN_INFO "rculock end: %ld s, %ld ns\n", 92 | end.tv_sec, end.tv_nsec); 93 | printk(KERN_INFO "rculock costs %ld s, %lu ns\n", 94 | cost.tv_sec, cost.tv_nsec); 95 | 96 | /* mutex case */ 97 | getnstimeofday(&start); 98 | for (i = 0; i < TEST_TIMES; ++i) { 99 | mutex_lock(&mutex); 100 | mutex_unlock(&mutex); 101 | } 102 | getnstimeofday(&end); 103 | 104 | time_cost(&start, &end, &cost); 105 | 106 | printk(KERN_INFO "mutex start: %ld s, %ld ns\n", 107 | start.tv_sec, start.tv_nsec); 108 | printk(KERN_INFO "mutex end: %ld s, %ld ns\n", 109 | end.tv_sec, end.tv_nsec); 110 | printk(KERN_INFO "mutex costs %ld s, %lu ns\n", 111 | cost.tv_sec, cost.tv_nsec); 112 | 113 | local_irq_enable(); 114 | local_bh_enable(); 115 | preempt_enable(); 116 | } 117 | 118 | static int lock_test_init(void) 119 | { 120 | 121 | printk(KERN_INFO "Lock test init\n"); 122 | 123 | lock_test(); 124 | 125 | printk(KERN_INFO "Lock test exit\n"); 126 | 127 | /* Return -1 so that we needn't use rmmod to uninstall module */ 128 | return -1; 129 | } 130 | 131 | static void lock_test_exit(void) 132 | { 133 | printk(KERN_INFO "Lock test exit\n"); 134 | } 135 | 136 | module_init(lock_test_init); 137 | module_exit(lock_test_exit); 138 | 139 | -------------------------------------------------------------------------------- /kernel/2.sleep_test/Makefile: -------------------------------------------------------------------------------- 1 | obj-m := sleep_test.o 2 | 3 | KDIR := /lib/modules/`uname -r`/build 4 | 5 | modules: 6 | make -C $(KDIR) M=$(PWD) modules 7 | 8 | clean: 9 | rm -f *.ko *.o *.mod.o *.mod.c *.order *.symvers 10 | 11 | -------------------------------------------------------------------------------- /kernel/2.sleep_test/sleep_test.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include 5 | #include 6 | 7 | 8 | #define USE_UNINTERRUPTIBLE 9 | 10 | static struct task_struct *sleep_task = NULL; 11 | 12 | static int thread_func(void *data) 13 | { 14 | while (1) { 15 | if (kthread_should_stop()) { 16 | break; 17 | } 18 | 19 | #ifdef USE_UNINTERRUPTIBLE 20 | //ssleep(1); 21 | schedule_timeout_uninterruptible(HZ); 22 | #else 23 | 24 | schedule_timeout_interruptible(HZ); 25 | #endif 26 | } 27 | 28 | return 0; 29 | } 30 | 31 | static int __init sleep_task_init(void) 32 | { 33 | sleep_task = kthread_create(thread_func, NULL, "sleep_task"); 34 | if (IS_ERR(sleep_task)) { 35 | printk(KERN_ERR "sleep_task: kthread_create failed\n"); 36 | sleep_task = NULL; 37 | return -1; 38 | } 39 | 40 | wake_up_process(sleep_task); 41 | 42 | printk(KERN_INFO "sleep_task: init successfully\n"); 43 | 44 | return 0; 45 | } 46 | 47 | static void __exit sleep_task_exit(void) 48 | { 49 | if (sleep_task) { 50 | kthread_stop(sleep_task); 51 | sleep_task = NULL; 52 | } 53 | 54 | printk(KERN_INFO "sleep_task: exit successfully\n"); 55 | } 56 | 57 | MODULE_LICENSE("GPL"); 58 | 59 | module_init(sleep_task_init); 60 | module_exit(sleep_task_exit); 61 | -------------------------------------------------------------------------------- /kernel/README.md: -------------------------------------------------------------------------------- 1 | # 1.rwlock_spinlock_performance 2 | 3 | ## 问题 4 | 5 | rwlock与spinlock的性能对比，哪个性能更优？ 6 | 7 | ## Question 8 | 9 | How about the performance of rwlock and spinlock? 10 | 11 | ## Answer 12 | 13 | In the old kernel, the performance of rwlock is worse than spinlock. 14 | But it is better than spinlock in latest kernel. 15 | 16 | You could test it in your environment. 17 | 18 | 19 | # 2.sleep_test 20 | 21 | ## 问题 22 | 23 | 当线程sleep时，其状态为TASK_UNINTERRUPTIBLE和TASK_INTERRUPTIBLE有什么区别？ 24 | 25 | ## Question 26 | 27 | What's the difference when task's state is sleep with TASK_UNINTERRUPTIBLE or TASK_INTERRUPTIBLE? 28 | 29 | 30 | ## Answer 31 | 32 | When task state is TASK_UNINTERRUPTIBLE, it is counted into the CPU load. 33 | You would find the CPU load is increasing always when enable the macro USE_UNINTERRUPTIBLE. 34 | BTW, the ssleep would set the task state as TASK_UNINTERRUPTIBLE. 35 | 36 | The following link is my old blog about this topic. 37 | http://www.linxh.blog.chinaunix.net/uid-23629988-id-3242488.html 38 | -------------------------------------------------------------------------------- /mem/1.vsz_and_rss/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CXXFLAGS := -Wall -shared -std=c++11 -fPIC 9 | LDFLAGS := 10 | CXX := g++ 11 | 12 | SRCS := $(wildcard *.cpp) 13 | DEPS := $(patsubst %.cpp,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.cpp,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := vsz_and_rss 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CXX) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.cpp 25 | $(CXX) -M $(CXXFLAGS) $< > $@ 26 | 27 | %.o:%.cpp 28 | $(CXX) -c $(CXXFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /mem/1.vsz_and_rss/vsz_and_rss.cpp: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: vsz_and_rss.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 09/25/2016 09:33:08 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng, gfree.wind@gmail.com 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | #include 21 | 22 | using namespace std; 23 | 24 | vector mems; 25 | 26 | static void alloc_mem(bool fill) 27 | { 28 | int i; 29 | 30 | for (i = 0; i < 512; ++i) { 31 | void *p = malloc(1024*1024); 32 | if (fill) { 33 | memset(p, 0, 1024*1024); 34 | } 35 | mems.push_back(p); 36 | } 37 | 38 | printf("Mem is allocated\n"); 39 | } 40 | 41 | int main(int argc, const char **argv) 42 | { 43 | alloc_mem(argc >= 2); 44 | getchar(); 45 | return 0; 46 | } 47 | 48 | -------------------------------------------------------------------------------- /mem/README.md: -------------------------------------------------------------------------------- 1 | # 1.vsz_and_rss 2 | 3 | ## 问题 4 | 5 | 对比VSZ和RSS，当申请内存时，只会增加VSZ。 6 | 只有真正使用这块内存时，RSS才会增加。 7 | 也就是说，应用层分配内存时，内核仅仅是分配了地址空间，并没有建立与物理内存的 8 | 映射关系。 9 | 10 | ## Question 11 | 12 | Comparing with the VSZ and RSS. 13 | Only VSZ is increased when just allocate memory. 14 | The RSS is increased only when app uses the mem. 15 | In other words, when app allocates memories, kernel just allocates the virtual 16 | memory address without corresponding physical page. 17 | 18 | 19 | 20 | -------------------------------------------------------------------------------- /networks/1.tcp_close_with_data/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -Werror -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := tcp_close_with_data 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/1.tcp_close_with_data/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | There are one TCP server thread and one TCP client thread. 4 | At the first time, the server close fd after read all bytes from client. 5 | At the second time, the server close fd after accept. 6 | 7 | # Conclusion 8 | 9 | When close TCP socket, it sends the RST if there are some bytes which are 10 | not received by app. 11 | This behaviro is defined in the section 2.17 of RFC 2525. 12 | 13 | The following codes are from the kernel codes, tcp_close 14 | 15 | /* As outlined in RFC 2525, section 2.17, we send a RST here because 16 | * data was lost. To witness the awful effects of the old behavior of 17 | * always doing a FIN, run an older 2.1.x kernel or 2.0.x, start a bulk 18 | * GET in an FTP client, suspend the process, wait for the client to 19 | * advertise a zero window, then kill -9 the FTP client, wheee... 20 | * Note: timeout is always zero in such a case. 21 | */ 22 | if (data_was_unread) { 23 | /* Unread data was tossed, zap the connection. */ 24 | NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE); 25 | tcp_set_state(sk, TCP_CLOSE); 26 | tcp_send_active_reset(sk, sk->sk_allocation); 27 | } else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) { 28 | 29 | 30 | server: receive 6 bytes: First 31 | server: close fd at the first time 32 | client: ret is 0 33 | server: close fd at the second time 34 | client: ret is -1: Connection reset by peer 35 | 36 | But the first close never cause RST is sent. 37 | 38 | 39 | -------------------------------------------------------------------------------- /networks/1.tcp_close_with_data/tcp_close_with_data.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: tcp_close_with_data.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 08/31/2016 09:29:46 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng gfree.wind@gmail.com 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | 31 | typedef int bool; 32 | 33 | #define true 1 34 | #define false 0 35 | 36 | static volatile bool g_server_listen = false; 37 | 38 | static void* client_thread(void *data) 39 | { 40 | int fd = socket(AF_INET, SOCK_STREAM, 0); 41 | int ret; 42 | 43 | // wait parent listen 44 | while (!g_server_listen) { 45 | sleep(1); 46 | } 47 | 48 | struct sockaddr_in serv_addr; 49 | memset(&serv_addr, 0, sizeof(serv_addr)); 50 | serv_addr.sin_family = AF_INET; 51 | serv_addr.sin_addr.s_addr = 0x010007f; 52 | serv_addr.sin_port = htons(6000); 53 | 54 | // Fist time 55 | connect(fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 56 | 57 | send(fd, "First", sizeof("First"), 0); 58 | 59 | // parent close already 60 | char buf[2048]; 61 | ret = read(fd, buf, 32); 62 | printf("client: ret is %d\n", ret); 63 | close(fd); 64 | 65 | fd = socket(AF_INET, SOCK_STREAM, 0); 66 | ret = connect(fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 67 | if (ret) { 68 | printf("connect failed: %s\n", strerror(errno)); 69 | return 0; 70 | } 71 | send(fd, buf, 2048, 0); 72 | 73 | // parent close already 74 | ret = read(fd, buf, 32); 75 | printf("client: ret is %d: %s\n", ret, strerror(errno)); 76 | close(fd); 77 | 78 | return NULL; 79 | 80 | } 81 | 82 | int main(void) 83 | { 84 | pthread_t tid; 85 | int ret; 86 | 87 | signal(SIGPIPE, SIG_IGN); 88 | 89 | pthread_create(&tid, NULL, client_thread, NULL); 90 | 91 | int listen_fd = socket(AF_INET, SOCK_STREAM, 0); 92 | if (listen_fd == -1) { 93 | printf("socket failed\n"); 94 | goto err1; 95 | } 96 | 97 | int opt = 1; 98 | setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); 99 | 100 | struct sockaddr_in serv_addr; 101 | 102 | memset(&serv_addr, 0, sizeof(serv_addr)); 103 | serv_addr.sin_family = AF_INET; 104 | serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); 105 | serv_addr.sin_port = htons(6000); 106 | 107 | if (bind(listen_fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr))) { 108 | printf("bind failed\n"); 109 | goto err2; 110 | } 111 | 112 | if (listen(listen_fd, 5)) { 113 | printf("listen failed\n"); 114 | goto err2; 115 | } 116 | g_server_listen = true; 117 | 118 | int client = accept(listen_fd, NULL, 0); 119 | if (client == -1) { 120 | printf("accept failed\n"); 121 | goto err2; 122 | } 123 | 124 | /* 125 | First time: 126 | Server close the fd after receive all data 127 | */ 128 | char buf[32] = {0}; 129 | ret = read(client, buf, 32); 130 | printf("server: receive %d bytes: %s\n", ret, buf); 131 | 132 | close(client); 133 | printf("server: close fd at the first time\n"); 134 | 135 | client = accept(listen_fd, NULL, 0); 136 | 137 | /* 138 | Second time: 139 | Server close the fd without reading data 140 | */ 141 | /*We sleep 30 second here so we have time to observe the output of "tcpdump -i lo" and "ss", 142 | These commands will show the interactive between server and client, and where the data hold on 143 | */ 144 | 145 | sleep(30); 146 | close(client); 147 | printf("server: close fd at the second time\n"); 148 | 149 | err2: 150 | close(listen_fd); 151 | err1: 152 | pthread_join(tid, NULL); 153 | 154 | return 0; 155 | } 156 | -------------------------------------------------------------------------------- /networks/10.udp_listen_unexpected_port/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := udp_listen_unexpected_port 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/10.udp_listen_unexpected_port/udp_listen_unexpected_port.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include /* See NOTES */ 5 | #include 6 | #include 7 | #include 8 | #include 9 | #include 10 | #include 11 | #include 12 | 13 | #include 14 | 15 | int main(void) 16 | { 17 | int sock; 18 | 19 | if((sock = socket(PF_INET, SOCK_DGRAM, 0)) < 0) { 20 | exit(1); 21 | } 22 | 23 | int flags = fcntl(sock, F_GETFL, 0); 24 | fcntl(sock, F_SETFL, flags | O_NONBLOCK | O_CLOEXEC); 25 | 26 | struct sockaddr_in serv_addr; 27 | 28 | bzero(&serv_addr, sizeof(serv_addr)); 29 | serv_addr.sin_family = AF_INET; 30 | serv_addr.sin_addr.s_addr=inet_addr("127.0.0.1"); 31 | serv_addr.sin_port = htons(50505); 32 | 33 | char msg[4]; 34 | sendto(sock, (char*)&msg, sizeof(msg), 0, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr)); 35 | 36 | return 0; 37 | 38 | } 39 | -------------------------------------------------------------------------------- /networks/2.tcp_push_packet/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := tcp_force_push 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/2.tcp_push_packet/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | How to make sure kernel send one packet when call send every time 4 | 5 | # Conclusion 6 | 7 | TCP_NODELAY option: 8 | Enable TCP_NODELAY, it could send one TCP packet with PUSH every send call. 9 | 10 | int opt = 1; 11 | setsockopt(fd, SOL_TCP, TCP_NODELAY, &opt, sizeof(opt)); 12 | 13 | 14 | Packet Trace: 15 | tcpdump: verbose output suppressed, use -v or -vv for full protocol decode 16 | listening on lo, link-type EN10MB (Ethernet), capture size 65535 bytes 17 | 22:22:20.926263 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [S], seq 2443224076, win 43690, options [mss 65495,sackOK,TS val 398752434 ecr 0,nop,wscale 7], length 0 18 | 22:22:20.926305 IP 127.0.16.0.6000 > 127.0.0.1.46806: Flags [S.], seq 2966002025, ack 2443224077, win 43690, options [mss 65495,sackOK,TS val 398752434 ecr 398752434,nop,wscale 7], length 0 19 | 22:22:20.926331 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [.], ack 1, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 20 | 22:22:20.926371 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [P.], seq 1:2, ack 1, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 1 21 | 22:22:20.926404 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [P.], seq 2:3, ack 1, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 1 22 | 22:22:20.926426 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [P.], seq 3:4, ack 1, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 1 23 | 22:22:20.926428 IP 127.0.16.0.6000 > 127.0.0.1.46806: Flags [.], ack 2, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 24 | 22:22:20.926442 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [P.], seq 4:5, ack 1, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 1 25 | 22:22:20.926458 IP 127.0.16.0.6000 > 127.0.0.1.46806: Flags [.], ack 3, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 26 | 22:22:20.926463 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [P.], seq 5:6, ack 1, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 1 27 | 22:22:20.926474 IP 127.0.16.0.6000 > 127.0.0.1.46806: Flags [.], ack 4, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 28 | 22:22:20.926494 IP 127.0.16.0.6000 > 127.0.0.1.46806: Flags [.], ack 5, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 29 | 22:22:20.926493 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [F.], seq 6, ack 1, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 30 | 22:22:20.926509 IP 127.0.16.0.6000 > 127.0.0.1.46806: Flags [.], ack 6, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 31 | 22:22:20.927565 IP 127.0.16.0.6000 > 127.0.0.1.46806: Flags [F.], seq 1, ack 7, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 32 | 22:22:20.927613 IP 127.0.0.1.46806 > 127.0.16.0.6000: Flags [.], ack 2, win 342, options [nop,nop,TS val 398752434 ecr 398752434], length 0 33 | -------------------------------------------------------------------------------- /networks/2.tcp_push_packet/tcp_force_push.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: tcp_close_with_data.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 08/31/2016 09:29:46 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng gfree.wind@gmail.com 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | #include 31 | 32 | 33 | #define ENABLE_NODELAY_TEST 34 | typedef int bool; 35 | 36 | #define true 1 37 | #define false 0 38 | 39 | #define PACKET_CNT 5 40 | 41 | static volatile bool g_server_listen = false; 42 | 43 | static void* client_thread(void *data) 44 | { 45 | int fd = socket(AF_INET, SOCK_STREAM, 0); 46 | int i; 47 | int opt; 48 | 49 | // wait parent listen 50 | while (!g_server_listen) { 51 | sleep(1); 52 | } 53 | 54 | struct sockaddr_in serv_addr; 55 | memset(&serv_addr, 0, sizeof(serv_addr)); 56 | serv_addr.sin_family = AF_INET; 57 | serv_addr.sin_addr.s_addr = 0x010007f; 58 | serv_addr.sin_port = htons(6000); 59 | 60 | connect(fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 61 | #ifdef ENABLE_NODELAY_TEST 62 | /* Enable TCP_NODELAY, it could force PUSH */ 63 | opt = 1; 64 | setsockopt(fd, SOL_TCP, TCP_NODELAY, &opt, sizeof(opt)); 65 | #else 66 | /* Disable TCP_CORK, it dosn't make sure force PUSH */ 67 | opt = 0; 68 | setsockopt(fd, SOL_TCP, TCP_CORK, &opt, sizeof(opt)); 69 | #endif 70 | 71 | for (i = 0; i < PACKET_CNT; ++i) { 72 | send(fd, "1", 1, 0); 73 | #ifndef ENABLE_NODELAY_TEST 74 | opt = 0; 75 | setsockopt(fd, SOL_TCP, TCP_CORK, &opt, sizeof(opt)); 76 | #endif 77 | } 78 | close(fd); 79 | 80 | return NULL; 81 | 82 | } 83 | 84 | int main(void) 85 | { 86 | pthread_t tid; 87 | int ret; 88 | int i; 89 | 90 | signal(SIGPIPE, SIG_IGN); 91 | 92 | pthread_create(&tid, NULL, client_thread, NULL); 93 | 94 | int listen_fd = socket(AF_INET, SOCK_STREAM, 0); 95 | if (listen_fd == -1) { 96 | printf("socket failed\n"); 97 | goto err1; 98 | } 99 | 100 | int opt = 1; 101 | setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); 102 | 103 | struct sockaddr_in serv_addr; 104 | 105 | memset(&serv_addr, 0, sizeof(serv_addr)); 106 | serv_addr.sin_family = AF_INET; 107 | serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); 108 | serv_addr.sin_port = htons(6000); 109 | 110 | if (bind(listen_fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr))) { 111 | printf("bind failed\n"); 112 | goto err2; 113 | } 114 | 115 | if (listen(listen_fd, 5)) { 116 | printf("listen failed\n"); 117 | goto err2; 118 | } 119 | g_server_listen = true; 120 | 121 | int client = accept(listen_fd, NULL, 0); 122 | if (client == -1) { 123 | printf("accept failed\n"); 124 | goto err2; 125 | } 126 | 127 | char buf[32]; 128 | for (i = 0; i < PACKET_CNT; ++i) { 129 | memset(buf, 0, sizeof(buf)); 130 | ret = read(client, buf, 32); 131 | printf("server: recive %d bytes: %s\n", ret, buf); 132 | } 133 | 134 | close(client); 135 | printf("server: close fd at the first time\n"); 136 | 137 | err2: 138 | close(listen_fd); 139 | err1: 140 | pthread_join(tid, NULL); 141 | 142 | return 0; 143 | } 144 | -------------------------------------------------------------------------------- /networks/3.tcp_unread_hit_rst/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := tcp_unread_rst 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/3.tcp_unread_hit_rst/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | How about the return value of tcp read when receive one TCP RST? 4 | There are two threads. 5 | The server closes the socket after receives the client packet and left the packet in the socket. 6 | So it would trigger one TCP RST to client from server. 7 | 8 | # Conclusion 9 | 10 | The read returns "-1", and errno is set as "ECONNRESET"，"Connection reset by peer". 11 | -------------------------------------------------------------------------------- /networks/3.tcp_unread_hit_rst/tcp_unread_rst.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: tcp_close_with_data.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 08/31/2016 09:29:46 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng gfree.wind@gmail.com 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | #include 31 | #include 32 | 33 | typedef int bool; 34 | 35 | #define true 1 36 | #define false 0 37 | 38 | #define PACKET_CNT 5 39 | 40 | static volatile bool g_server_listen = false; 41 | static volatile bool g_client_send = false; 42 | static volatile bool g_server_close = false; 43 | 44 | static void* client_thread(void *data) 45 | { 46 | int fd = socket(AF_INET, SOCK_STREAM, 0); 47 | int i; 48 | int opt; 49 | 50 | // wait parent listen 51 | while (!g_server_listen) { 52 | sleep(1); 53 | } 54 | 55 | struct sockaddr_in serv_addr; 56 | memset(&serv_addr, 0, sizeof(serv_addr)); 57 | serv_addr.sin_family = AF_INET; 58 | serv_addr.sin_addr.s_addr = 0x010007f; 59 | serv_addr.sin_port = htons(6000); 60 | 61 | connect(fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 62 | /* Enable TCP_NODELAY, it could force PUSH */ 63 | opt = 1; 64 | setsockopt(fd, SOL_TCP, TCP_NODELAY, &opt, sizeof(opt)); 65 | 66 | for (i = 0; i < PACKET_CNT; ++i) { 67 | send(fd, "1", 1, 0); 68 | } 69 | g_client_send = true; 70 | 71 | while (!g_server_close) { 72 | sleep(1); 73 | } 74 | 75 | char buf[32]; 76 | int ret = read(fd, buf, sizeof(buf)); 77 | 78 | printf("ret: %d. error: %s(%d)\n", ret, strerror(errno), errno); 79 | 80 | close(fd); 81 | 82 | return NULL; 83 | 84 | } 85 | 86 | int main(void) 87 | { 88 | pthread_t tid; 89 | 90 | signal(SIGPIPE, SIG_IGN); 91 | 92 | pthread_create(&tid, NULL, client_thread, NULL); 93 | 94 | int listen_fd = socket(AF_INET, SOCK_STREAM, 0); 95 | if (listen_fd == -1) { 96 | printf("socket failed\n"); 97 | goto err1; 98 | } 99 | 100 | int opt = 1; 101 | setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); 102 | 103 | struct sockaddr_in serv_addr; 104 | 105 | memset(&serv_addr, 0, sizeof(serv_addr)); 106 | serv_addr.sin_family = AF_INET; 107 | serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); 108 | serv_addr.sin_port = htons(6000); 109 | 110 | if (bind(listen_fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr))) { 111 | printf("bind failed\n"); 112 | goto err2; 113 | } 114 | 115 | if (listen(listen_fd, 5)) { 116 | printf("listen failed\n"); 117 | goto err2; 118 | } 119 | g_server_listen = true; 120 | 121 | int client = accept(listen_fd, NULL, 0); 122 | if (client == -1) { 123 | printf("accept failed\n"); 124 | goto err2; 125 | } 126 | 127 | if (!g_client_send) { 128 | sleep(1); 129 | } 130 | 131 | close(client); 132 | printf("server: close fd\n"); 133 | g_server_close = true; 134 | 135 | err2: 136 | close(listen_fd); 137 | err1: 138 | pthread_join(tid, NULL); 139 | 140 | return 0; 141 | } 142 | -------------------------------------------------------------------------------- /networks/4.reuse_addr_option/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := reuse_addr_option 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/4.reuse_addr_option/reuse_addr_option.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | 5 | #include /* See NOTES */ 6 | #include 7 | #include 8 | #include 9 | #include 10 | 11 | #define LOCAL_PORT (12345) 12 | 13 | static void test_udp_any_addr_same_port_diff_ifs(void) 14 | { 15 | int udp_fd1 = socket(AF_INET, SOCK_DGRAM, 0); 16 | int udp_fd2 = socket(AF_INET, SOCK_DGRAM, 0); 17 | 18 | struct sockaddr_in addr_in; 19 | memset(&addr_in, 0, sizeof(addr_in)); 20 | addr_in.sin_family = AF_INET; 21 | addr_in.sin_port = htons(LOCAL_PORT); 22 | addr_in.sin_addr.s_addr = INADDR_ANY; 23 | 24 | char *opt = "eth0"; 25 | if (setsockopt(udp_fd1, SOL_SOCKET, SO_BINDTODEVICE, opt, strlen(opt))) { 26 | printf("UDP1 fail to bind eth0. %s:%d\n", strerror(errno), errno); 27 | } 28 | opt = "eth1"; 29 | if (setsockopt(udp_fd2, SOL_SOCKET, SO_BINDTODEVICE, opt, strlen(opt))) { 30 | printf("UDP2 fail to bind eth1. %s:%d\n", strerror(errno), errno); 31 | } 32 | 33 | if (bind(udp_fd1, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 34 | printf("UDP1 fail to bind any addr and port(%d) on eth0\n", LOCAL_PORT); 35 | } 36 | 37 | if (bind(udp_fd2, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 38 | printf("UDP2 fail to bind any addr and port(%d) on eth1 \n", LOCAL_PORT); 39 | } 40 | 41 | close(udp_fd1); 42 | close(udp_fd2); 43 | 44 | printf("UDP could bind two any addrs with same port and diff ifs without SO_REUSEADDR\n"); 45 | } 46 | 47 | 48 | static void test_udp_diff_addr_same_port(struct in_addr *addr) 49 | { 50 | int udp_fd1 = socket(AF_INET, SOCK_DGRAM, 0); 51 | int udp_fd2 = socket(AF_INET, SOCK_DGRAM, 0); 52 | 53 | struct sockaddr_in addr_in; 54 | memset(&addr_in, 0, sizeof(addr_in)); 55 | addr_in.sin_family = AF_INET; 56 | addr_in.sin_port = htons(LOCAL_PORT); 57 | addr_in.sin_addr = *addr; 58 | 59 | if (bind(udp_fd1, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 60 | printf("UDP1 fail to bind local addr and port(%d)\n", LOCAL_PORT); 61 | } 62 | 63 | addr_in.sin_addr.s_addr = 0x0100007f; 64 | if (bind(udp_fd2, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 65 | printf("UDP2 fail to bind any addr and port(%d)\n", LOCAL_PORT); 66 | } 67 | 68 | close(udp_fd1); 69 | close(udp_fd2); 70 | 71 | printf("UDP could bind two different addr with same port without SO_REUSEADDR\n"); 72 | } 73 | 74 | static void test_udp_any_addr_same_port(void) 75 | { 76 | int udp_fd1 = socket(AF_INET, SOCK_DGRAM, 0); 77 | int udp_fd2 = socket(AF_INET, SOCK_DGRAM, 0); 78 | 79 | struct sockaddr_in addr_in; 80 | memset(&addr_in, 0, sizeof(addr_in)); 81 | addr_in.sin_family = AF_INET; 82 | addr_in.sin_port = htons(LOCAL_PORT); 83 | addr_in.sin_addr.s_addr = INADDR_ANY; 84 | 85 | int enable = 1; 86 | setsockopt(udp_fd1, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 87 | setsockopt(udp_fd2, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 88 | 89 | if (bind(udp_fd1, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 90 | printf("UDP1 fail to bind any addr and port(%d)\n", LOCAL_PORT); 91 | } 92 | 93 | if (bind(udp_fd2, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 94 | printf("UDP2 fail to bind any addr and port(%d)\n", LOCAL_PORT); 95 | } 96 | 97 | close(udp_fd1); 98 | close(udp_fd2); 99 | 100 | printf("UDP could bind two any addrs with same port with SO_REUSEADDR\n"); 101 | } 102 | 103 | static void test_udp_any_and_local_addr_same_port(struct in_addr *addr) 104 | { 105 | int udp_fd1 = socket(AF_INET, SOCK_DGRAM, 0); 106 | int udp_fd2 = socket(AF_INET, SOCK_DGRAM, 0); 107 | 108 | struct sockaddr_in addr_in; 109 | memset(&addr_in, 0, sizeof(addr_in)); 110 | addr_in.sin_family = AF_INET; 111 | addr_in.sin_port = htons(LOCAL_PORT); 112 | addr_in.sin_addr.s_addr = INADDR_ANY; 113 | 114 | int enable = 1; 115 | setsockopt(udp_fd1, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 116 | setsockopt(udp_fd2, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 117 | 118 | if (bind(udp_fd1, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 119 | printf("UDP1 fail to bind any addr and port(%d)\n", LOCAL_PORT); 120 | } 121 | 122 | addr_in.sin_addr= *addr; 123 | 124 | if (bind(udp_fd2, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 125 | printf("UDP2 fail to bind local addr and port(%d)\n", LOCAL_PORT); 126 | } 127 | 128 | close(udp_fd1); 129 | close(udp_fd2); 130 | 131 | printf("UDP could bind any addr and one local addr with same port with SO_REUSEADDR\n"); 132 | } 133 | 134 | static void test_udp_local_and_any_addr_same_port(struct in_addr *addr) 135 | { 136 | int udp_fd1 = socket(AF_INET, SOCK_DGRAM, 0); 137 | int udp_fd2 = socket(AF_INET, SOCK_DGRAM, 0); 138 | 139 | struct sockaddr_in addr_in; 140 | memset(&addr_in, 0, sizeof(addr_in)); 141 | addr_in.sin_family = AF_INET; 142 | addr_in.sin_port = htons(LOCAL_PORT); 143 | addr_in.sin_addr = *addr; 144 | 145 | int enable = 1; 146 | setsockopt(udp_fd1, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 147 | setsockopt(udp_fd2, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 148 | 149 | if (bind(udp_fd1, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 150 | printf("UDP1 fail to bind local addr and port(%d)\n", LOCAL_PORT); 151 | } 152 | 153 | addr_in.sin_addr.s_addr = INADDR_ANY; 154 | 155 | if (bind(udp_fd2, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 156 | printf("UDP2 fail to bind any addr and port(%d)\n", LOCAL_PORT); 157 | } 158 | 159 | close(udp_fd1); 160 | close(udp_fd2); 161 | printf("UDP could bind one local addr and one any addr with same port with SO_REUSEADDR\n"); 162 | } 163 | 164 | static void test_udp_local_addr_same_port(struct in_addr *addr) 165 | { 166 | int udp_fd1 = socket(AF_INET, SOCK_DGRAM, 0); 167 | int udp_fd2 = socket(AF_INET, SOCK_DGRAM, 0); 168 | 169 | struct sockaddr_in addr_in; 170 | memset(&addr_in, 0, sizeof(addr_in)); 171 | addr_in.sin_family = AF_INET; 172 | addr_in.sin_port = htons(LOCAL_PORT); 173 | addr_in.sin_addr = *addr; 174 | 175 | int enable = 1; 176 | setsockopt(udp_fd1, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 177 | setsockopt(udp_fd2, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)); 178 | 179 | if (bind(udp_fd1, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 180 | printf("UDP1 fail to bind port(%d)\n", LOCAL_PORT); 181 | } 182 | 183 | if (bind(udp_fd2, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 184 | printf("UDP2 fail to bind port(%d)\n", LOCAL_PORT); 185 | } 186 | 187 | close(udp_fd1); 188 | close(udp_fd2); 189 | 190 | printf("UDP could bind two local addrs and port with SO_REUSEADDR\n"); 191 | } 192 | 193 | static void test_tcp_udp_same_port(struct in_addr *addr) 194 | { 195 | int tcp_fd = socket(AF_INET, SOCK_STREAM, 0); 196 | if (tcp_fd == -1) { 197 | printf("Fail to create tcp fd\n"); 198 | exit(1); 199 | } 200 | int udp_fd = socket(AF_INET, SOCK_DGRAM, 0); 201 | if (udp_fd == -1) { 202 | printf("Fail to creat udp fd\n"); 203 | exit(1); 204 | } 205 | 206 | struct sockaddr_in addr_in; 207 | memset(&addr_in, 0, sizeof(addr_in)); 208 | addr_in.sin_family = AF_INET; 209 | addr_in.sin_port = htons(LOCAL_PORT); 210 | addr_in.sin_addr = *addr; 211 | 212 | if (bind(tcp_fd, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 213 | printf("TCP fail to bind port(%d)\n", LOCAL_PORT); 214 | } 215 | 216 | if (bind(udp_fd, (const struct sockaddr *)&addr_in, sizeof(addr_in)) != 0) { 217 | printf("UDP fail to bind port(%d)\n", LOCAL_PORT); 218 | } 219 | 220 | close(tcp_fd); 221 | close(udp_fd); 222 | 223 | printf("TCP and UDP could bind same port seperately\n"); 224 | } 225 | 226 | int main(int argc, const char **argv) 227 | { 228 | struct in_addr addr; 229 | 230 | if (argc < 2) { 231 | printf("Please specify local IP address\n"); 232 | return 1; 233 | } 234 | 235 | memset(&addr, 0, sizeof(addr)); 236 | if (inet_pton(AF_INET, argv[1], &addr) != 1) { 237 | printf("Invalid IP address"); 238 | return 1; 239 | } 240 | 241 | 242 | test_tcp_udp_same_port(&addr); 243 | test_udp_local_addr_same_port(&addr); 244 | test_udp_local_and_any_addr_same_port(&addr); 245 | test_udp_any_and_local_addr_same_port(&addr); 246 | test_udp_any_addr_same_port(); 247 | test_udp_diff_addr_same_port(&addr); 248 | test_udp_any_addr_same_port_diff_ifs(); 249 | 250 | return 0; 251 | } 252 | 253 | 254 | -------------------------------------------------------------------------------- /networks/5.no_listen_tcp_conn/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := no_listen_tcp_conn 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/5.no_listen_tcp_conn/no_listen_tcp_conn.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: no_listen_tcp_conn.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 06/18/2017 10:04:07 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: YOUR NAME (), 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include /* See NOTES */ 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | 27 | #define LOCAL_IP_ADDR (0x7F000001) 28 | #define LOCAL_TCP_PORT (34567) 29 | 30 | int main(void) 31 | { 32 | struct sockaddr_in local, peer; 33 | int ret; 34 | char buf[128]; 35 | int sock = socket(AF_INET, SOCK_STREAM, 0); 36 | 37 | memset(&local, 0, sizeof(local)); 38 | memset(&peer, 0, sizeof(peer)); 39 | 40 | local.sin_family = AF_INET; 41 | local.sin_port = htons(LOCAL_TCP_PORT); 42 | local.sin_addr.s_addr = htonl(LOCAL_IP_ADDR); 43 | 44 | peer = local; 45 | 46 | int flag = 1; 47 | ret = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag)); 48 | if (ret == -1) { 49 | printf("Fail to setsocket SO_REUSEADDR: %s\n", strerror(errno)); 50 | exit(1); 51 | } 52 | 53 | ret = bind(sock, (const struct sockaddr *)&local, sizeof(local)); 54 | ret = connect(sock, (const struct sockaddr *)&peer, sizeof(peer)); 55 | 56 | if (ret) { 57 | printf("Fail to connect myself: %s\n", strerror(errno)); 58 | exit(1); 59 | } 60 | printf("Connect to myself successfully\n"); 61 | 62 | strcpy(buf, "Hello, myself~"); 63 | send(sock, buf, strlen(buf), 0); 64 | 65 | memset(buf, 0, sizeof(buf)); 66 | recv(sock, buf, sizeof(buf), 0); 67 | 68 | printf("Recv the msg: %s\n", buf); 69 | close(sock); 70 | return 0; 71 | } 72 | 73 | -------------------------------------------------------------------------------- /networks/6.tcp_keepalive_reporter/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := tcp_keepalive_reporter 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/6.tcp_keepalive_reporter/tcp_keepalive_report.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: tcp_keepalive_reporter 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 06/18/2017 10:04:07 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: YOUR NAME (), 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include /* See NOTES */ 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | /* According to POSIX.1-2001 */ 27 | #include 28 | /* According to earlier standards */ 29 | #include 30 | #include 31 | #include 32 | #include 33 | #include 34 | #include 35 | 36 | 37 | #define PEER_ADDR (0x7F000001) 38 | #define PEER_PORT (34567) 39 | 40 | //#define USE_SELECT 41 | #define USE_EPOLL 42 | 43 | int main(void) 44 | { 45 | struct sockaddr_in peer; 46 | int ret; 47 | int sock = socket(AF_INET, SOCK_STREAM, 0); 48 | int optval; 49 | int err; 50 | char buf[512]; 51 | socklen_t len = sizeof(err); 52 | 53 | memset(&peer, 0, sizeof(peer)); 54 | 55 | peer.sin_family = AF_INET; 56 | peer.sin_port = htons(PEER_PORT); 57 | peer.sin_addr.s_addr = htonl(PEER_ADDR); 58 | 59 | 60 | ret = connect(sock, (const struct sockaddr *)&peer, sizeof(peer)); 61 | 62 | if (ret) { 63 | printf("Fail to connect myself: %s\n", strerror(errno)); 64 | exit(1); 65 | } 66 | printf("Connect successfully\n"); 67 | 68 | optval = 1; 69 | ret = setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &optval, sizeof(optval)); 70 | if (ret) { 71 | printf("Fail to set SO_KEEPALIVE\n"); 72 | exit(1); 73 | } 74 | 75 | optval = 5; 76 | ret = setsockopt(sock, IPPROTO_TCP, TCP_KEEPIDLE, &optval, sizeof(optval)); 77 | if (ret) { 78 | printf("Fail to set TCP_KEEPIDLE: %s\n", strerror(errno)); 79 | exit(1); 80 | } 81 | optval = 2; 82 | ret = setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL, &optval, sizeof(optval)); 83 | if (ret) { 84 | printf("Fail to set TCP_KEEPINTVL: %s\n", strerror(errno)); 85 | exit(1); 86 | } 87 | optval = 3; 88 | ret = setsockopt(sock, IPPROTO_TCP, TCP_KEEPCNT, &optval, sizeof(optval)); 89 | if (ret) { 90 | printf("Fail to set TCP_KEEPCNT: %s\n", strerror(errno)); 91 | exit(1); 92 | } 93 | 94 | 95 | #ifdef USE_SELECT 96 | fd_set rfds; 97 | 98 | FD_ZERO(&rfds); 99 | 100 | FD_SET(sock, &rfds); 101 | 102 | ret = select(sock+1, &rfds, NULL, NULL, NULL); 103 | if (ret) { 104 | printf("select returns %d\n", ret); 105 | if (FD_ISSET(sock, &rfds)) { 106 | printf("Receive RD event by select\n"); 107 | } 108 | } 109 | #endif 110 | 111 | #ifdef USE_EPOLL 112 | int ep = epoll_create(1024); 113 | if (ep == -1) { 114 | printf("Fail to epoll_create: %s\n", strerror(errno)); 115 | exit(1); 116 | } 117 | 118 | struct epoll_event evt; 119 | 120 | memset(&evt, 0, sizeof(evt)); 121 | evt.events |= EPOLLIN; 122 | evt.data.fd = sock; 123 | 124 | ret = epoll_ctl(ep, EPOLL_CTL_ADD, sock, &evt); 125 | if (ret) { 126 | printf("Fail to epoll_ctl: %s\n", strerror(errno)); 127 | exit(1); 128 | } 129 | 130 | memset(&evt, 0, sizeof(evt)); 131 | ret = epoll_wait(ep, &evt, 1, -1); 132 | if (ret) { 133 | if (evt.events & EPOLLIN) { 134 | printf("Receive RD event by epoll\n"); 135 | } 136 | } 137 | 138 | close(ep); 139 | #endif 140 | 141 | err = 0; 142 | ret = getsockopt(sock, SOL_SOCKET, SO_ERROR, &err, &len); 143 | if (ret) { 144 | printf("Fail to getsockopt\n"); 145 | exit(1); 146 | } 147 | printf("sock err is %d\n", err); 148 | 149 | ret = read(sock, buf, 512); 150 | printf("Read %d bytes\n", ret); 151 | 152 | close(sock); 153 | return 0; 154 | } 155 | 156 | -------------------------------------------------------------------------------- /networks/7.tcp_send_rst/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := tcp_send_rst 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/7.tcp_send_rst/tcp_send_rst.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: tcp_keepalive_reporter 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 06/18/2017 10:04:07 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: YOUR NAME (), 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include /* See NOTES */ 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | /* According to earlier standards */ 27 | #include 28 | #include 29 | #include 30 | #include 31 | #include 32 | 33 | 34 | #define PEER_ADDR (0x7F000001) 35 | #define PEER_PORT (34567) 36 | 37 | int main(void) 38 | { 39 | struct sockaddr_in local, peer; 40 | struct linger linger; 41 | int ret; 42 | int sock = socket(AF_INET, SOCK_STREAM, 0); 43 | 44 | memset(&peer, 0, sizeof(peer)); 45 | 46 | peer.sin_family = AF_INET; 47 | peer.sin_port = htons(PEER_PORT); 48 | peer.sin_addr.s_addr = htonl(PEER_ADDR); 49 | local = peer; 50 | 51 | int flag = 1; 52 | ret = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag)); 53 | if (ret == -1) { 54 | printf("Fail to setsocket SO_REUSEADDR: %s\n", strerror(errno)); 55 | exit(1); 56 | } 57 | 58 | ret = bind(sock, (const struct sockaddr *)&local, sizeof(local)); 59 | if (ret) { 60 | printf("Fail to bind: %s\n", strerror(errno)); 61 | exit(1); 62 | } 63 | ret = connect(sock, (const struct sockaddr *)&peer, sizeof(peer)); 64 | 65 | if (ret) { 66 | printf("Fail to connect myself: %s\n", strerror(errno)); 67 | exit(1); 68 | } 69 | printf("Connect successfully\n"); 70 | 71 | memset(&linger, 0, sizeof(linger)); 72 | linger.l_onoff = 1; 73 | linger.l_linger = 0; 74 | 75 | ret = setsockopt(sock, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger)); 76 | if (ret) { 77 | printf("Fail to set linger\n"); 78 | exit(1); 79 | } 80 | 81 | close(sock); 82 | 83 | printf("Done\n"); 84 | return 0; 85 | } 86 | 87 | -------------------------------------------------------------------------------- /networks/8.connect_until_fail/accpet_util_fail.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/python 2 | 3 | import sys 4 | import socket 5 | 6 | if __name__ == "__main__": 7 | if len(sys.argv) <= 2: 8 | print "Please specify the address & port" 9 | exit(1) 10 | 11 | addr = sys.argv[1] 12 | port = int(sys.argv[2]) 13 | print "Listen {}:{}".format(addr, port) 14 | 15 | sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 16 | sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) 17 | sock.bind((addr, port)) 18 | sock.listen(1024) 19 | 20 | socks = [] 21 | while True: 22 | try: 23 | new_sock = sock.accept() 24 | socks.append(new_sock) 25 | print "Establish {} connections".format(len(socks)) 26 | except Exception as e: 27 | print "Unexpected error: " + str(e) 28 | break 29 | -------------------------------------------------------------------------------- /networks/8.connect_until_fail/connect_until_fail.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/python 2 | 3 | import sys 4 | import socket 5 | 6 | if __name__ == "__main__": 7 | if len(sys.argv) <= 2: 8 | print "Please specify the address & port" 9 | exit(1) 10 | 11 | addr = sys.argv[1] 12 | port = int(sys.argv[2]) 13 | print "Connect {}:{}".format(addr, port) 14 | 15 | socks = [] 16 | while True: 17 | try: 18 | sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 19 | sock.connect((addr, port)) 20 | print "Connect {} times".format((len(socks))) 21 | socks.append(sock) 22 | except Exception as e: 23 | print "Unexpect error:" + str(e) 24 | break 25 | -------------------------------------------------------------------------------- /networks/9.tcp_unread_shutdown/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -g -shared -fPIC -std=gnu99 9 | LDFLAGS := -lpthread 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := tcp_unread_shutdown 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /networks/9.tcp_unread_shutdown/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | How about the return value of tcp read when receive one TCP RST? 4 | There are two threads. 5 | The server closes the socket after receives the client packet and left the packet in the socket. 6 | So it would trigger one TCP RST to client from server. 7 | 8 | # Conclusion 9 | 10 | The read returns "-1", and errno is set as "ECONNRESET"，"Connection reset by peer". 11 | -------------------------------------------------------------------------------- /networks/9.tcp_unread_shutdown/tcp_unread_shutdown.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: tcp_close_with_data.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 08/31/2016 09:29:46 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: Gao Feng gfree.wind@gmail.com 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | #include 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | #include 28 | #include 29 | #include 30 | #include 31 | #include 32 | 33 | typedef int bool; 34 | 35 | #define true 1 36 | #define false 0 37 | 38 | #define PACKET_CNT 5 39 | 40 | static volatile bool g_server_listen = false; 41 | static volatile bool g_client_send = false; 42 | static volatile bool g_server_close = false; 43 | 44 | static void* client_thread(void *data) 45 | { 46 | int fd = socket(AF_INET, SOCK_STREAM, 0); 47 | int i; 48 | int opt; 49 | 50 | // wait parent listen 51 | while (!g_server_listen) { 52 | sleep(1); 53 | } 54 | 55 | struct sockaddr_in serv_addr; 56 | memset(&serv_addr, 0, sizeof(serv_addr)); 57 | serv_addr.sin_family = AF_INET; 58 | serv_addr.sin_addr.s_addr = 0x010007f; 59 | serv_addr.sin_port = htons(6000); 60 | 61 | connect(fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)); 62 | /* Enable TCP_NODELAY, it could force PUSH */ 63 | opt = 1; 64 | setsockopt(fd, SOL_TCP, TCP_NODELAY, &opt, sizeof(opt)); 65 | 66 | for (i = 0; i < PACKET_CNT; ++i) { 67 | send(fd, "1", 1, 0); 68 | } 69 | g_client_send = true; 70 | 71 | while (!g_server_close) { 72 | sleep(1); 73 | } 74 | 75 | char buf[32]; 76 | int ret = read(fd, buf, sizeof(buf)); 77 | 78 | printf("ret: %d. error: %s(%d)\n", ret, strerror(errno), errno); 79 | 80 | close(fd); 81 | 82 | return NULL; 83 | 84 | } 85 | 86 | int main(void) 87 | { 88 | pthread_t tid; 89 | 90 | signal(SIGPIPE, SIG_IGN); 91 | 92 | pthread_create(&tid, NULL, client_thread, NULL); 93 | 94 | int listen_fd = socket(AF_INET, SOCK_STREAM, 0); 95 | if (listen_fd == -1) { 96 | printf("socket failed\n"); 97 | goto err1; 98 | } 99 | 100 | int opt = 1; 101 | setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); 102 | 103 | struct sockaddr_in serv_addr; 104 | 105 | memset(&serv_addr, 0, sizeof(serv_addr)); 106 | serv_addr.sin_family = AF_INET; 107 | serv_addr.sin_addr.s_addr = htonl(INADDR_ANY); 108 | serv_addr.sin_port = htons(6000); 109 | 110 | if (bind(listen_fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr))) { 111 | printf("bind failed\n"); 112 | goto err2; 113 | } 114 | 115 | if (listen(listen_fd, 5)) { 116 | printf("listen failed\n"); 117 | goto err2; 118 | } 119 | g_server_listen = true; 120 | 121 | int client = accept(listen_fd, NULL, 0); 122 | if (client == -1) { 123 | printf("accept failed\n"); 124 | goto err2; 125 | } 126 | 127 | if (!g_client_send) { 128 | sleep(1); 129 | } 130 | 131 | shutdown(client, SHUT_RDWR); 132 | close(client); 133 | printf("server: close fd\n"); 134 | g_server_close = true; 135 | 136 | err2: 137 | close(listen_fd); 138 | err1: 139 | pthread_join(tid, NULL); 140 | 141 | return 0; 142 | } 143 | -------------------------------------------------------------------------------- /networks/README.md: -------------------------------------------------------------------------------- 1 | # 1.tcp_close_with_data 2 | 3 | ## 问题 4 | 5 | 当没有读取完所有的TCP数据，就关闭套接字，是否会有问题？ 6 | 这种情况与读完数据再关闭是否一致? 7 | 8 | ## Question 9 | 10 | Is it ok that close the TCP socket before read all bytes? 11 | Is it same as that close fd after read all bytes? 12 | 13 | ## Answer 14 | No! 15 | 16 | # 2.tcp_push_packet 17 | 18 | ## 问题 19 | 20 | 如何让TCP协议栈不对数据做优化，一次send调用就对应一个数据包。 21 | 22 | 23 | # 3.tcp_read_hit_rst 24 | 25 | ## 问题 26 | 27 | 28 | 当tcp套接字read调用，遇到对端发送RST报文时，返回值是什么？ 29 | 30 | ## Answer 31 | 32 | read返回-1，errno是ECONNRESET，即Connection reset by peer 33 | 34 | 35 | # 4.reuse_addr_option 36 | 37 | 38 | ## 问题 39 | 40 | 41 | 什么时候需要使用SO_REUSEADDR? 42 | 43 | 44 | ## Answer 45 | 46 | 47 | 当proto, addr, 和port三个元素都相同时，需要使用SO_REUSEADDR。 48 | 49 | 其中INADDR_ANY表示任意地址，其与所有地址视为相同。 50 | 51 | 52 | # 5.no_listen_tcp_conn 53 | 54 | ## 问题 55 | 没有listen调用，是否可以建立tcp连接 56 | 57 | 58 | # 6.tcp_keepalive_reporter 59 | 当TCP的KeepAlive机制判定连接超时，应用层如何得到通知。 60 | 61 | 62 | 63 | # 7.tcp_send_rst 64 | 应用层如何强制TCP发送RST中断连接。 65 | 66 | 67 | # 8.connect_until_fail 68 | 尝试一直连接，直到失败 69 | 70 | # 9.tcp_unread_shutdown 71 | 关闭未读数据的tcp端口 72 | 73 | # 10.udp_listen_unexpected_port 74 | 没有bind的udp socket，“监听”了非期望端口。 75 | -------------------------------------------------------------------------------- /process/1.child_inherit_flock/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -Werror -shared -fPIC 9 | LDFLAGS := 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := child_inherit_flock 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /process/1.child_inherit_flock/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | This prarent process flocks one file, then forks one child process. Then the parent exits directly, while the child sleeps 30 seconds. 4 | At that time, run this process again. You would find the second instance blocks until the child of first instance exits. 5 | 6 | # Conclusion 7 | 8 | The flock is shared between the parent and child process. Although the flock would be release automatically when process exits, it must be done until both of parent and child exit. 9 | -------------------------------------------------------------------------------- /process/1.child_inherit_flock/child_inherit_flock.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: child_inherit_flock.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 08/26/2016 10:01:43 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: YOUR NAME (), 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | 28 | int main(void) 29 | { 30 | int fd = open("./test_flock.txt", O_RDWR|O_CREAT, 0644); 31 | if (fd == -1) { 32 | printf("Fail to open file\n"); 33 | exit(1); 34 | } 35 | 36 | int ret = flock(fd, LOCK_EX); 37 | if (ret == -1) { 38 | printf("Fail to flock\n"); 39 | exit(1); 40 | } 41 | printf("Parent get the flock at the first time\n"); 42 | 43 | pid_t child = fork(); 44 | if (child == -1) { 45 | printf("Fail to fork\n"); 46 | exit(1); 47 | } else if (child == 0) { 48 | printf("Child sleeps now\n"); 49 | sleep(30); 50 | printf("Child wakes up and exits\n"); 51 | exit(1); 52 | } 53 | 54 | printf("Parent exit\n"); 55 | 56 | return 0; 57 | } 58 | 59 | -------------------------------------------------------------------------------- /process/2.child_share_flock/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -Werror -shared -fPIC 9 | LDFLAGS := 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := child_inherit_flock 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /process/2.child_share_flock/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | The prarent process holds one flock, then forks one child process. Now the flock is shared between with child and parent. Then child sleeps 30 seconds, and parent releases the lock, then tries to get the lock again. 4 | 5 | 6 | # Conclusion 7 | 8 | The parent could get the flock immediately although child does not exit. Because the flock is shared between child and parent, actually there is one instance of flock between child and parent. So when the parent releases the flock, the child does not own the flock yet. So parent could get the lock again immediately. 9 | 10 | 11 | -------------------------------------------------------------------------------- /process/2.child_share_flock/child_share_flock.c: -------------------------------------------------------------------------------- 1 | /* 2 | * ===================================================================================== 3 | * 4 | * Filename: child_inherit_flock.c 5 | * 6 | * Description: 7 | * 8 | * Version: 1.0 9 | * Created: 08/26/2016 10:01:43 PM 10 | * Revision: none 11 | * Compiler: gcc 12 | * 13 | * Author: YOUR NAME (), 14 | * Company: 15 | * 16 | * ===================================================================================== 17 | */ 18 | #include 19 | #include 20 | 21 | #include 22 | #include 23 | #include 24 | #include 25 | #include 26 | #include 27 | 28 | int main(void) 29 | { 30 | int fd = open("./test_flock.txt", O_RDWR|O_CREAT, 0644); 31 | if (fd == -1) { 32 | printf("Fail to open file\n"); 33 | exit(1); 34 | } 35 | 36 | int ret = flock(fd, LOCK_EX); 37 | if (ret == -1) { 38 | printf("Fail to flock\n"); 39 | exit(1); 40 | } 41 | printf("Parent get the flock at the first time\n"); 42 | 43 | pid_t child = fork(); 44 | if (child == -1) { 45 | printf("Fail to fork\n"); 46 | exit(1); 47 | } else if (child == 0) { 48 | printf("Child sleeps now\n"); 49 | sleep(30); 50 | printf("Child wakes up and exits\n"); 51 | exit(1); 52 | } 53 | 54 | flock(fd, LOCK_UN); 55 | printf("Parent release the lock\n"); 56 | printf("Parent tries to get flock again\n"); 57 | flock(fd, LOCK_EX); 58 | printf("Parent gets the lock at the second time\n"); 59 | 60 | waitpid(child, NULL, 0); 61 | 62 | printf("Parent exit\n"); 63 | 64 | return 0; 65 | } 66 | 67 | -------------------------------------------------------------------------------- /process/3.fork_and_print/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -Werror -shared -fPIC 9 | LDFLAGS := 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := fork_and_print 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /process/3.fork_and_print/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | The parent printfs string "Hello,", then forks one child, then printf "I'm parent\n". 4 | And the child printf "I'm child\n". 5 | 6 | How about the output? 7 | 8 | # Answer 9 | 10 | Hello, I'm parent 11 | Hello, I'm child 12 | or 13 | Hello, I'm child 14 | Hello, I'm parent 15 | 16 | # Conclusion 17 | Because the printf uses the line buffer by default, so the "Hello," is not printed acutally 18 | when parent forks child. Then the line buffer is inherited by child. 19 | 20 | So the child also could print "Hello, " likes its parent. 21 | 22 | 23 | 24 | 25 | -------------------------------------------------------------------------------- /process/3.fork_and_print/fork_and_print.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | 4 | 5 | #include 6 | #include 7 | 8 | int main(void) 9 | { 10 | pid_t child; 11 | 12 | printf("Hello, "); 13 | 14 | child = fork(); 15 | if (child == -1) { 16 | printf("fork failed\n"); 17 | exit(1); 18 | } else if (child == 0) { 19 | // Child 20 | printf("I'm child\n"); 21 | exit(0); 22 | } 23 | 24 | // Parent 25 | printf("I'm parent\n"); 26 | 27 | waitpid(child, NULL, 0); 28 | 29 | return 0; 30 | } 31 | -------------------------------------------------------------------------------- /process/4.fork_with_fd/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -Werror -shared -fPIC 9 | LDFLAGS := 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := fork_with_fd 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /process/4.fork_with_fd/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | The parent process opens one file "./test1.txt", and forks one child. 4 | Both of parent and child opens another file "./test2.txt" after fork. 5 | Then the parent writes "I'm parent\n" into these two files, while child does 6 | the same thing too. 7 | 8 | How about the content of these two files? 9 | 10 | # Answer 11 | 12 | ./test1.txt: 13 | 14 | 15 | I'm parent 16 | 17 | I'm child 18 | 19 | ./test2.txt 20 | 21 | I'm child 22 | 23 | Notic: The content may be different in your environment. 24 | The schedule policy of fork is decided by /proc/sys/kernel/sched_child_runs_first. 25 | 26 | Anyway, the parent and child overlap the content of "./test2.txt", 27 | but "./test1.txt" not. 28 | 29 | # Conclusion 30 | The fd of parent and child shares one same fd and owns same kernel struct which 31 | maintains the file offset. So the content of "./test1.txt" does not overlap. 32 | 33 | The fd which is created after fork owns its file strcture in kernel, so the file 34 | offset is not shared between parent and child. 35 | 36 | 37 | -------------------------------------------------------------------------------- /process/4.fork_with_fd/fork_with_fd.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include 5 | #include 6 | #include 7 | #include 8 | 9 | 10 | int main(void) 11 | { 12 | int fd1 = open("./test1.txt", O_WRONLY|O_CREAT, 0644); 13 | if (fd1 == -1) { 14 | printf("Fail to open ./test1.txt\n"); 15 | exit(1); 16 | } 17 | 18 | pid_t child = fork(); 19 | if (child == -1) { 20 | printf("Fail to fork\n"); 21 | exit(1); 22 | } else if (child == 0) { 23 | // Child 24 | int fd2 = open("./test2.txt", O_WRONLY|O_CREAT, 0644); 25 | if (fd2 == -1) { 26 | printf("Child fails to open ./test2.txt\n"); 27 | exit(1); 28 | } 29 | 30 | write(fd1, "I'm child\n", sizeof("I'm child\n")); 31 | write(fd2, "I'm child\n", sizeof("I'm child\n")); 32 | 33 | close(fd1); 34 | close(fd2); 35 | 36 | exit(0); 37 | } 38 | 39 | // Parent 40 | int fd2 = open("./test2.txt", O_WRONLY|O_CREAT, 0644); 41 | if (fd2 == -1) { 42 | printf("Parent fails to open ./test2.txt\n"); 43 | waitpid(child, NULL, 0); 44 | exit(1); 45 | } 46 | 47 | write(fd1, "I'm parent\n", sizeof("I'm parent\n")); 48 | write(fd2, "I'm parent\n", sizeof("I'm parent\n")); 49 | 50 | close(fd1); 51 | close(fd2); 52 | 53 | 54 | waitpid(child, NULL, 0); 55 | 56 | return 0; 57 | } 58 | -------------------------------------------------------------------------------- /process/README.md: -------------------------------------------------------------------------------- 1 | # 1.child_inherit_flock 2 | 3 | ## 问题 4 | 5 | 当进程退出时，flock可以被自动释放。那么当父进程持有flock并且fork了一个子进程，然后退出。这个flock锁是否还会在父进程推出时释放吗？ 6 | 7 | ## Question 8 | The flock could be released automatically when process exits. How about it when parent holds one flock and forks one child then exit? Is the flock released after parent exits? 9 | 10 | ## Answer 11 | No! 12 | 13 | # 2.child_share_flock 14 | 15 | ## 问题 16 | 17 | 既然flock是由父进程和子进程共享，那么父进程持有flock锁并fork一个子进程，这时flock是共享的。那么这时在子进程未退出的情况下，父进程 18 | 释放了锁，然后再次尝试获取这个flock，会怎么样呢？父进程会因为子进程持有锁而阻塞吗？ 19 | 20 | ## Question 21 | 22 | The flock is shared between parent and child process. The parent process holds one flock and forks one child process. Now the flock is shared. How about the parent releases the lock and tries to lock it while child is alive ? Is it blocked because child still holds the lock? 23 | 24 | ## Answer 25 | 26 | No ! 27 | 28 | 29 | # 3.fork_and_print 30 | 31 | ## 问题 32 | 33 | 一个有关print和fork有趣的问题 34 | 35 | ## Question 36 | 37 | One interesting problem about printf and fork. 38 | 39 | ## Answer 40 | 41 | Please check out the codes in 3.fork_and_print :)) 42 | 43 | 44 | # 4.fork_with_fd 45 | 46 | ## 问题 47 | 当父子进程同时往一个文件里写数据是什么样的情况呢？ 48 | 情况1:子进程的fd是fork继承下来的； 49 | 情况2:父子进程的fd是fork以后分别打开的; 50 | 这两种情况写入的结果一样的吗？ 51 | 52 | ## Question 53 | How about the content when both of parent and child process write the same file? 54 | case1: The child's fd is inherited from parent; 55 | case2: The fd of parent and child is opened after fork; 56 | How about these two cases? Is it same? 57 | 58 | ## Answer 59 | 60 | No. It's totally different!!! 61 | 62 | 63 | 64 | 65 | 66 | -------------------------------------------------------------------------------- /signal/1.waitpid_sigchld_ignore/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -Werror -shared -fPIC 9 | LDFLAGS := 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := waitpid_sigchld_ignore 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /signal/1.waitpid_sigchld_ignore/README.md: -------------------------------------------------------------------------------- 1 | # 描述 2 | 3 | 这个程序将SIGCHLD设置为SIG_IGN，然后fork两个子进程。第一个子进程会sleep 30秒， 4 | 而第二个子进程会直接退出。 5 | 6 | 父进程先waitpid第二个进程，然后再waitpid第一个。 7 | 8 | # Description 9 | 10 | This program sets SIGCHLD as SIG_IGN, and forks two child processes. The first 11 | child sleeps 30 seconds, and second child exits directly. 12 | 13 | The parent process waits the second child firstly, then waits the first. 14 | 15 | # 结论 16 | 17 | 当SIGCHLD被置为SIG_IGN时，waitpid仍然会立刻返回，而不是等待所有子进程终止 18 | 才退出。 19 | 这与"man 2 waitpid"的描述不符。 20 | 21 | # Conclustion 22 | When the SIGCHILD is ignored, the waitpid still return immediately without 23 | waiting all child processes terminate. 24 | 25 | It is oppsite the description of "man 2 waitpid". 26 | 27 | # 原因 28 | 29 | 当使用waitpid等待子进程2时，这里指定了pid。但是由于SIGCHLD是被设置为忽略的， 30 | 所以子进程2退出后，其状态不会保存。 31 | 因此waitpid会因为得不到指定进程的状态而返回错误，No child process，并立刻返回。 32 | 33 | # Reason 34 | 35 | Because when waitpid for child2, we specify the pid. But the SICHLD is ignored, 36 | the exit status of child2 is not saved. 37 | So the waitpid fail to get the child2's status and returns error, and show the reason "No child processes", then 38 | return immediately 39 | 40 | 41 | 42 | 43 | -------------------------------------------------------------------------------- /signal/1.waitpid_sigchld_ignore/waitpid_sigchld_ignore.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include 5 | #include 6 | #include 7 | #include 8 | #include 9 | 10 | int main(void) 11 | { 12 | pid_t child1, child2; 13 | 14 | printf("Parent is running\n"); 15 | 16 | signal(SIGCHLD, SIG_IGN); 17 | 18 | 19 | child1 = fork(); 20 | if (child1 == -1) { 21 | printf("Fail to fork child1\n"); 22 | exit(1); 23 | } else if (child1 == 0) { 24 | printf("Child1 enter sleep\n"); 25 | sleep(30); 26 | printf("Child1 wakes up and exit\n"); 27 | exit(0); 28 | } 29 | 30 | printf("Fork child1 successfully\n"); 31 | child2 = fork(); 32 | if (child2 == -1) { 33 | printf("Fail to fork child2\n"); 34 | waitpid(child1, NULL, 0); 35 | exit(1); 36 | } else if (child2 == 0) { 37 | printf("Child2 exit now\n"); 38 | exit(0); 39 | } 40 | 41 | printf("Fork child2 successfully, and wait child2\n"); 42 | sleep(3); 43 | pid_t ret = waitpid(child2, NULL, 0); 44 | if (ret == -1) { 45 | printf("waitpid child2 return -1, errno(%d): %s\n", 46 | errno, strerror(errno)); 47 | } 48 | printf("Wait child1 now\n"); 49 | waitpid(child1, NULL, 0); 50 | 51 | printf("Parent exit\n"); 52 | 53 | return 0; 54 | } 55 | -------------------------------------------------------------------------------- /signal/2.waitanypid_sigchld_ignore/Makefile: -------------------------------------------------------------------------------- 1 | # 2 | # Author Feng Gao 3 | # 4 | # 5 | 6 | .PHONY: all clean depend 7 | 8 | CFLAGS := -Wall -Werror -shared -fPIC 9 | LDFLAGS := 10 | CC := gcc 11 | 12 | SRCS := $(wildcard *.c) 13 | DEPS := $(patsubst %.c,%.d,$(SRCS)) 14 | OBJS := $(patsubst %.c,%.o,$(SRCS)) 15 | 16 | 17 | TARGET := waitanypid_sigchld_ignore 18 | 19 | all: $(TARGET) 20 | 21 | $(TARGET): $(OBJS) $(DEPS) 22 | $(CC) $(OBJS) -o $(TARGET) $(LDFLAGS) 23 | 24 | %.d:%.c 25 | $(CC) -M $(CFLAGS) $< > $@ 26 | 27 | %.o:%.c 28 | $(CC) -c $(CFLAGS) $< -o $@ 29 | 30 | explain: 31 | @echo "The information represents in the program:" 32 | @echo "Final executable name: $(PRGM)" 33 | @echo "Source files: $(SRCS)" 34 | @echo "Object files: $(OBJS)" 35 | 36 | depend:$(DEPS) 37 | @echo "Dependencies are now up-to-date" 38 | 39 | clean: 40 | rm -f $(TARGET) $(OBJS) $(DEPS) 41 | 42 | -include $(DEPS) 43 | -------------------------------------------------------------------------------- /signal/2.waitanypid_sigchld_ignore/README.md: -------------------------------------------------------------------------------- 1 | # Description 2 | 3 | This program sets SIGCHLD as SIG_IGN, and forks two child processes. The first 4 | child sleeps 30 seconds, and second child exits directly. 5 | 6 | The parent process waits the second child firstly, then waits the first. 7 | 8 | # Conclustion 9 | When the SIGCHLD is set as SIG_IGN, parent invokes waitpid to wait any child process. 10 | The waitpid would block until all childs exit. 11 | 12 | It conforms to the description of "man 2 waitpid". 13 | 14 | # Reason 15 | 16 | Why the result is different with example1? 17 | Because this waitpid is not specified the pid, so it would not return error when 18 | one child process exits. Only when all child processes exit, the waitpid find there 19 | is no child, and return error. 20 | 21 | 22 | 23 | -------------------------------------------------------------------------------- /signal/2.waitanypid_sigchld_ignore/waitanypid_sigchld_ignore.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #include 4 | #include 5 | #include 6 | #include 7 | #include 8 | #include 9 | 10 | int main(void) 11 | { 12 | pid_t child1, child2; 13 | 14 | printf("Parent is running\n"); 15 | 16 | signal(SIGCHLD, SIG_IGN); 17 | 18 | 19 | child1 = fork(); 20 | if (child1 == -1) { 21 | printf("Fail to fork child1\n"); 22 | exit(1); 23 | } else if (child1 == 0) { 24 | printf("Child1 enter sleep\n"); 25 | sleep(30); 26 | printf("Child1 wakes up and exit\n"); 27 | exit(0); 28 | } 29 | 30 | printf("Fork child1 successfully\n"); 31 | child2 = fork(); 32 | if (child2 == -1) { 33 | printf("Fail to fork child2\n"); 34 | waitpid(child1, NULL, 0); 35 | exit(1); 36 | } else if (child2 == 0) { 37 | printf("Child2 exit now\n"); 38 | exit(0); 39 | } 40 | 41 | printf("Fork child2 successfully, and wait any child\n"); 42 | pid_t ret = waitpid(-1, NULL, 0); 43 | if (ret == -1) { 44 | printf("waitpid return -1, errno(%d): %s\n", errno, strerror(errno)); 45 | } 46 | 47 | printf("Parent exit\n"); 48 | 49 | return 0; 50 | } 51 | -------------------------------------------------------------------------------- /signal/README.md: -------------------------------------------------------------------------------- 1 | #1. waitpid_sigchld_ignore: 2 | 3 | ## 问题 4 | 5 | 当SIGCHLD被设置为SIG_IGN时，对waitpid有什么影响呢？ 6 | 根据"man 2 waitpid"的描述，是否会真的阻塞呢？ 7 | 8 | ## Question 9 | 10 | 11 | When SIGCHLD is ignored, how about waitpid? 12 | 13 | The following is from "man 2 waitpid" 14 | /******************************************************************************************************/ 15 | 16 | 17 | POSIX.1-2001 specifies that if the disposition of SIGCHLD is set to SIG_IGN or the SA_NOCLDWAIT flag 18 | is set for SIGCHLD (see sigaction(2)), then children that terminate do not become zombies and a call 19 | to wait() or waitpid() will block until all children have terminated, and then fail with errno set to 20 | ECHILD. (The original POSIX standard left the behavior of setting SIGCHLD to SIG_IGN unspecified. 21 | Note that even though the default disposition of SIGCHLD is "ignore", explicitly setting the disposi‐ 22 | tion to SIG_IGN results in different treatment of zombie process children.) 23 | 24 | Linux 2.6 conforms to the POSIX requirements. However, Linux 2.4 (and earlier) does not: if a wait() 25 | or waitpid() call is made while SIGCHLD is being ignored, the call behaves just as though SIGCHLD were 26 | not being ignored, that is, the call blocks until the next child terminates and then returns the 27 | process ID and status of that child. 28 | 29 | 30 | /******************************************************************************************************/ 31 | 32 | Is it really blocked? 33 | 34 | ## Answer 35 | No! 36 | 37 | # 2.waitanypid_sigchld_ignore 38 | 39 | ## 问题 40 | 41 | 当使用waitpid等待任意pid时，而不是指定pid，又会怎么样呢？ 42 | 与问题1会有什么不同吗？是否也会阻塞呢？ 43 | 44 | ## Qeustion 45 | 46 | How about wait any pid instead of wait specific pid in case2? Is it different ? Is it block too? 47 | 48 | ## Answer 49 | Yes! This waitpid blocks until all childs exits. 50 | 51 | 52 | --------------------------------------------------------------------------------