├── .gitignore
├── Creating Containerd.pdf
├── LICENSE
├── Makefile
├── cloexec.c
└── parent.c


/.gitignore:
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1 | exec-fifo
2 | cloexec
3 | parent
4 | 


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/Creating Containerd.pdf:
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https://raw.githubusercontent.com/crosbymichael/dockercon-2016/912e3f1884ecfa39901001551a3ce415bba9539c/Creating Containerd.pdf


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/LICENSE:
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 1 | Copyright (c) 2016 Michael Crosby. crosbymichael@gmail.com
 2 | 
 3 | Permission is hereby granted, free of charge, to any person
 4 | obtaining a copy of this software and associated documentation 
 5 | files (the "Software"), to deal in the Software without 
 6 | restriction, including without limitation the rights to use, copy, 
 7 | modify, merge, publish, distribute, sublicense, and/or sell copies 
 8 | of the Software, and to permit persons to whom the Software is 
 9 | furnished to do so, subject to the following conditions:
10 | 
11 | The above copyright notice and this permission notice shall be 
12 | included in all copies or substantial portions of the Software.
13 | 
14 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
15 | EXPRESS OR IMPLIED,
16 | INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
18 | IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 
19 | HOLDERS BE LIABLE FOR ANY CLAIM, 
20 | DAMAGES OR OTHER LIABILITY, 
21 | WHETHER IN AN ACTION OF CONTRACT, 
22 | TORT OR OTHERWISE, 
23 | ARISING FROM, OUT OF OR IN CONNECTION WITH 
24 | THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 | 


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/Makefile:
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 1 | 
 2 | all:
 3 | 	gcc -o cloexec cloexec.c
 4 | 	gcc -o parent parent.c
 5 | 
 6 | clean:
 7 | 	rm -f cloexec
 8 | 	rm -f parent
 9 | 	rm -f exit-fifo
10 | 


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/cloexec.c:
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 1 | #include <stdio.h>
 2 | #include <stdlib.h>
 3 | #include <errno.h>
 4 | #include <sys/types.h>
 5 | #include <sys/stat.h>
 6 | #include <fcntl.h>
 7 | #include <unistd.h>
 8 | #include <string.h>
 9 | 
10 | int main()
11 | {
12 | 	if (mkfifo("exit-fifo", 0666) != 0) {
13 | 		printf("%s\n", strerror(errno));
14 | 		exit(EXIT_FAILURE);
15 | 	}
16 | 	int fd = open("exit-fifo", O_WRONLY | O_CLOEXEC, 0);
17 | 	if (fd < 0) {
18 | 		printf("%s\n", strerror(errno));
19 | 		exit(EXIT_FAILURE);
20 | 	}
21 | 	pause();
22 | }
23 | 


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/parent.c:
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 1 | #include <stdlib.h>
 2 | #include <stdio.h>
 3 | #include <errno.h>
 4 | #include <sys/types.h>
 5 | #include <sys/wait.h>
 6 | #include <unistd.h>
 7 | #include <string.h>
 8 | #include <sys/prctl.h>
 9 | 
10 | int main(int argc, char **argv)
11 | {
12 | 	if (argc > 1 && strcmp(argv[1], "--subreaper") == 0) {
13 | 		prctl(PR_SET_CHILD_SUBREAPER, 1);
14 | 	}
15 | 	printf("main() parent %d\n", getpid());
16 | 
17 | 	pid_t pid = fork();
18 | 	if (pid == 0) {
19 | 		pid_t child = fork();
20 | 		if (child == 0) {
21 | 			printf("child process %d with parent %d\n", getpid(),
22 | 			       getppid());
23 | 			sleep(3);
24 | 			printf("child process %d with new parent %d\n",
25 | 			       getpid(), getppid());
26 | 			sleep(2);
27 | 			exit(EXIT_SUCCESS);
28 | 		}
29 | 		sleep(2);
30 | 		printf("parent %d exiting\n", getpid());
31 | 		exit(EXIT_SUCCESS);
32 | 	}
33 | 
34 | 	int status;
35 | 	waitpid(pid, &status, 0);
36 | 	sleep(1);
37 | 
38 | 	printf("trying to wait on child\n");
39 | 	if (waitpid(-1, &status, 0) < 1) {
40 | 		printf("%s\n", strerror(errno));
41 | 		exit(EXIT_FAILURE);
42 | 	}
43 | 	printf("success waiting on the child of my child\n");
44 | }
45 | 


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