├── .gitignore ├── syscalls ├── proc │ ├── fork.c │ └── getpid.c ├── io │ └── io.c ├── mem │ └── alloc.c └── handler.s ├── iso └── boot │ └── grub │ └── grub.cfg ├── idt ├── idt.s └── idt.c ├── keyboard ├── keyboard.s ├── keyboard.c └── azerty.c ├── boot └── boot.s ├── gdt ├── gdt.s └── gdt.c ├── mem └── paging │ ├── paging.s │ └── paging.c ├── interrupts ├── exceptions │ └── exceptions.c └── irq │ └── irq.c ├── include ├── gdt.h ├── context.h └── tss.h ├── usermode └── ring3.s ├── README.md ├── lib ├── user │ └── sc.s └── kernel │ ├── kmisc.c │ └── kprint.c ├── linker.ld ├── main.c ├── proc ├── process.c └── task.c ├── 8259_PIC └── pic.s ├── Makefile ├── user_programs └── init.c └── COPYING /.gitignore: -------------------------------------------------------------------------------- 1 | *.o 2 | *.elf 3 | *.iso 4 | -------------------------------------------------------------------------------- /syscalls/proc/fork.c: -------------------------------------------------------------------------------- 1 | void fork() 2 | { 3 | 4 | } 5 | -------------------------------------------------------------------------------- /iso/boot/grub/grub.cfg: -------------------------------------------------------------------------------- 1 | menuentry "mel" { 2 | multiboot /boot/mel.elf 3 | } 4 | -------------------------------------------------------------------------------- /syscalls/proc/getpid.c: -------------------------------------------------------------------------------- 1 | extern char current_pid; 2 | 3 | void getpid(char* addr) 4 | { 5 | *addr = current_pid; 6 | } 7 | -------------------------------------------------------------------------------- /idt/idt.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .global load_idt 3 | load_idt: 4 | mov eax, dword ptr [esp+4] 5 | lidt [eax] 6 | ret 7 | -------------------------------------------------------------------------------- /keyboard/keyboard.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .global input 3 | input: 4 | mov edx, dword ptr [(esp+4)] 5 | in al, dx 6 | ret 7 | -------------------------------------------------------------------------------- /boot/boot.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .extern main 3 | .global load_gdt 4 | .global _start 5 | .section .text 6 | .align 4 7 | .long 0x1badb002 8 | .long 0x00000000 9 | .long -0x1badb002 10 | _start: 11 | jmp main 12 | -------------------------------------------------------------------------------- /gdt/gdt.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .global load_gdt 3 | load_gdt: 4 | cli 5 | mov eax, dword ptr [esp+4] 6 | lgdt [eax] 7 | jmp 0x8:longjump 8 | longjump: 9 | mov eax, 0x10 10 | mov ds, eax 11 | mov es, eax 12 | mov fs, eax 13 | mov gs, eax 14 | mov ss, eax 15 | ret 16 | -------------------------------------------------------------------------------- /mem/paging/paging.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .global set_32bit_cr3 3 | .global get_cr3 4 | .global enable_32bit_paging 5 | enable_32bit_paging: 6 | mov eax, cr0 7 | or eax, 0x80000001 8 | mov cr0, eax 9 | ret 10 | set_32bit_cr3: 11 | mov eax, dword ptr [esp+4] 12 | mov cr3, eax 13 | ret 14 | get_cr3: 15 | mov eax, cr3 16 | ret 17 | -------------------------------------------------------------------------------- /interrupts/exceptions/exceptions.c: -------------------------------------------------------------------------------- 1 | void exception_handler(int ex) 2 | { 3 | asm("cli"); 4 | char buf[4]; 5 | itoa(ex, buf); 6 | kprint("An exception has occured.\n",12); 7 | kprint("exception ", 14); 8 | kprint(buf, 14); 9 | kprint("\n", 14); 10 | if (ex == 6) 11 | { 12 | } 13 | while(1); 14 | } 15 | -------------------------------------------------------------------------------- /include/gdt.h: -------------------------------------------------------------------------------- 1 | struct GDT 2 | { 3 | unsigned short limit_0_15; 4 | unsigned short base_0_15; 5 | unsigned char base_16_23; 6 | unsigned char access; 7 | unsigned char granularity; 8 | unsigned char base_24_31; 9 | } __attribute__((packed)); 10 | 11 | struct GDT_PTR 12 | { 13 | unsigned short gdt_size; 14 | struct GDT* gdt_addr; 15 | } __attribute__((packed)); 16 | 17 | 18 | -------------------------------------------------------------------------------- /usermode/ring3.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .global set_usermode 3 | .extern user_test 4 | set_usermode: 5 | mov ax, 0b00100011 6 | mov ds, ax 7 | mov es, ax 8 | mov fs, ax 9 | mov gs, ax 10 | 11 | mov eax, dword ptr [esp+0x8] 12 | add eax, dword ptr [esp+0xc] 13 | push 0b00100011 14 | push eax 15 | pushf 16 | pop ebx 17 | or ebx, 0b1000000000 ##(to enable interrupts in usermode) 18 | push ebx 19 | push 0b00011011 20 | mov ebx, dword ptr [esp+0x14] 21 | push ebx 22 | iret 23 | -------------------------------------------------------------------------------- /syscalls/io/io.c: -------------------------------------------------------------------------------- 1 | void sys_kbd_read(char* buf, int n) 2 | { 3 | unsigned char read; 4 | unsigned char k = 0xff; 5 | int i; 6 | for (i = 0; i < n; i++) 7 | { 8 | if (i != n-1) read = read_keyboard(0); 9 | else read = read_keyboard(1); 10 | k = k2ascii(read, 0); 11 | buf[i] = k; 12 | putchar(k, 13); 13 | } 14 | buf[i] = 0; 15 | asm("leave"); 16 | asm("ret"); 17 | } 18 | 19 | void sys_scr_write(char* buf, int n) 20 | { 21 | int i = 0; 22 | for (i = 0; i < n; i++) putchar(buf[i], 13); 23 | } 24 | -------------------------------------------------------------------------------- /include/context.h: -------------------------------------------------------------------------------- 1 | struct process_context 2 | { 3 | unsigned int eip; 4 | unsigned int eflags; 5 | unsigned int cs; 6 | unsigned int eax; 7 | unsigned int ecx; 8 | unsigned int edx; 9 | unsigned int ebx; 10 | unsigned int esp; 11 | unsigned int ebp; 12 | unsigned int esi; 13 | unsigned int edi; 14 | 15 | unsigned int paddr_data; 16 | unsigned int paddr_code; 17 | unsigned int paddr_stack; 18 | } __attribute__((packed)); 19 | 20 | -------------------------------------------------------------------------------- /syscalls/mem/alloc.c: -------------------------------------------------------------------------------- 1 | unsigned char alloc[0x100*0x400] = {0}; 2 | unsigned int brk_vaddr[0x10] = {0}; 3 | 4 | void brk(int pid, int n) 5 | { 6 | int pages = 0; 7 | for (int i = 0; i < 0x40000; i++) 8 | { 9 | if (pages >= n) break; 10 | if (!(alloc[i])) 11 | { 12 | alloc[i] = (pid << 4) | 1; 13 | pages++; 14 | init_memory(pid, 0xc0+(brk_vaddr[pid]%0x400000), 0x30000000+i*0x1000,1,7); 15 | brk_vaddr[pid] += 0x1000; 16 | } 17 | } 18 | } 19 | 20 | void unbrk(int pid, int n) 21 | { 22 | int pages = 0; 23 | for (int i = 0; i < 0x40000; i++) 24 | { 25 | if (pages >= n) break; 26 | if ((alloc[i] << 4) == pid) 27 | { 28 | alloc[i] = 0; 29 | pages++; 30 | brk_vaddr[pid] -= 0x1000; 31 | } 32 | } 33 | } 34 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # mel 2 | 32-bit hobby kernel. 3 | 4 | ![Screenshot](https://i.imgur.com/fRMQ87i.png) 5 | 6 | It aims to implement the basic features of a kernel: paging, usermode, basic syscalls, scheduling. 7 | 8 | 9 | For the moment there is little interaction that is possible. I will try to implement a shell when the rest is a bit more developed. 10 | 11 | 12 | The memory is subdivided in this way for programs loaded in user mode: 13 | 14 | 15 | |Memory region | Address 16 | |---------------|------------ 17 | |Kernel code | ``0x00100000`` 18 | |Kernel data | ``0x00200000`` 19 | |Kernel stack | ``0x00800000`` 20 | |User data | ``0x10000000`` 21 | |User code | ``0x20000000`` 22 | |User stack | ``0x28000000`` 23 | 24 | -------------------------------------------------------------------------------- /keyboard/keyboard.c: -------------------------------------------------------------------------------- 1 | int ktype = 0; 2 | 3 | unsigned char read_keyboard(int last) 4 | { 5 | unsigned char read; 6 | do 7 | { 8 | read = input(0x64); 9 | } 10 | while (!(read & 1)); 11 | do 12 | { 13 | read = input(0x60); 14 | } while(read&0x80); 15 | return read; 16 | } 17 | 18 | unsigned char read_wait(){ 19 | char read; 20 | while (1) 21 | { 22 | read = input(0x60); 23 | if (read > 0) return read; 24 | } 25 | } 26 | extern char azerty2c(int keycode, int maj); 27 | 28 | char k2ascii(int keycode, int maj) 29 | { 30 | switch(ktype) 31 | { 32 | case 0: return azerty2c(keycode, maj); break; 33 | } 34 | } 35 | -------------------------------------------------------------------------------- /lib/user/sc.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .section .ring3text 3 | .globl kbd_read 4 | .globl scr_write 5 | .globl brk_user 6 | .globl unbrk_user 7 | .globl getpid_user 8 | .globl fork_user 9 | kbd_read: 10 | xor eax, eax 11 | mov ebx, dword ptr [esp+0x4] 12 | mov ecx, dword ptr [esp+0x8] 13 | int 0x30 14 | ret 15 | scr_write: 16 | mov eax, 1 17 | mov ebx, dword ptr [esp+0x4] 18 | mov ecx, dword ptr [esp+0x8] 19 | int 0x30 20 | ret 21 | brk_user: 22 | mov eax, 2 23 | mov ebx, dword ptr [esp+0x4] 24 | int 0x30 25 | ret 26 | unbrk_user: 27 | mov eax, 3 28 | mov ebx, dword ptr [esp+0x4] 29 | int 0x30 30 | ret 31 | getpid_user: 32 | mov eax, 4 33 | mov ebx, dword ptr [esp+0x4] 34 | int 0x30 35 | ret 36 | fork_user: 37 | mov eax, 5 38 | mov ebx, dword ptr [esp] 39 | int 0x30 40 | ret 41 | -------------------------------------------------------------------------------- /interrupts/irq/irq.c: -------------------------------------------------------------------------------- 1 | unsigned char current_key; 2 | void irq_handler(int irq) 3 | { 4 | asm volatile("push eax"); 5 | asm volatile("mov ax, 0x10"); 6 | asm volatile("mov ds, ax"); 7 | asm volatile("mov es, ax"); 8 | asm volatile("mov fs, ax"); 9 | asm volatile("mov gs, ax"); 10 | asm volatile("pop eax"); 11 | char buf[4]; 12 | itoa(irq, buf); 13 | 14 | if (!irq) 15 | { 16 | context_switch(); 17 | } 18 | 19 | if (irq) 20 | { 21 | // kprint("IRQ ", 14); 22 | // kprint(buf, 14); 23 | // kprint("\n", 14); 24 | } 25 | 26 | if (irq == 1) 27 | { 28 | } 29 | asm volatile("push eax"); 30 | asm volatile("mov ax, 0x23"); 31 | asm volatile("mov ds, ax"); 32 | asm volatile("mov es, ax"); 33 | asm volatile("mov fs, ax"); 34 | asm volatile("mov gs, ax"); 35 | asm volatile("pop eax"); 36 | } 37 | 38 | -------------------------------------------------------------------------------- /linker.ld: -------------------------------------------------------------------------------- 1 | OUTPUT_FORMAT(elf32-i386) 2 | ENTRY(_start) 3 | 4 | SECTIONS 5 | { 6 | . = 0x00100000; 7 | .text BLOCK(4K) : ALIGN(4K) 8 | { 9 | *(.text) 10 | } 11 | . = 0x00200000; 12 | .data BLOCK(4K) : ALIGN(4K) 13 | { 14 | 15 | *(.rodata) 16 | *(.data) 17 | } 18 | .bss BLOCK(4K) (NOLOAD) : ALIGN(4K) 19 | { 20 | page_directories = .; 21 | . += 0x4000; 22 | page_tables = .; 23 | . += 0x1000000; 24 | *(.bss) 25 | } 26 | 27 | /* This is temporary:*/ 28 | . = 0x10000000; 29 | 30 | .ring3data BLOCK(4K) : ALIGN(4K) 31 | { 32 | *(.ring3data) 33 | *(.ring3bss) 34 | } 35 | . = 0x10001000; 36 | .ring3text BLOCK(4K) : ALIGN(4K) 37 | { 38 | *(.ring3text) 39 | } 40 | } 41 | -------------------------------------------------------------------------------- /main.c: -------------------------------------------------------------------------------- 1 | int current_pid = 0; 2 | extern char scheduling; 3 | extern void user_test(void) __attribute__((section(".ring3text"))); 4 | #define DATA 0x40 5 | #define CODE 0x80 6 | #define STACK 0xa0 7 | 8 | #define KERNEL 3 9 | #define USER 7 10 | extern char processes[16]; 11 | void main() 12 | { 13 | free_vram(); 14 | knextpage(); 15 | 16 | kprint("Mel.\n", 10); 17 | kprint("Press any key to continue.\n\n", 13); 18 | 19 | read_keyboard(); 20 | 21 | init_gdt(); 22 | 23 | init_idt(); 24 | init_pic(); 25 | 26 | init_memory(0, 0x00, 0x00000000, 0x10000, KERNEL); 27 | 28 | change_directory(0); 29 | enable_32bit_paging(); 30 | 31 | new_process(0x10000000, 0x10001000, 0x10002000, 1, 1, 1); 32 | 33 | set_usermode(0x20000000, 0x28000000, 0x1000); // run our first usermode program. 34 | 35 | while(1); 36 | } 37 | -------------------------------------------------------------------------------- /syscalls/handler.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | 3 | .globl syscall_handler 4 | 5 | .extern sys_kbd_read 6 | .extern sys_scr_write 7 | .extern brk 8 | .extern unbrk 9 | .extern current_pid 10 | .extern getpid 11 | .extern fork 12 | syscall_handler: 13 | push ebp 14 | pushad 15 | cli 16 | cmp eax, 0 17 | je tr_read 18 | cmp eax, 1 19 | je tr_write 20 | cmp eax, 2 21 | je tr_brk 22 | cmp eax, 3 23 | je tr_unbrk 24 | cmp eax, 4 25 | je tr_getpid 26 | cmp eax, 5 27 | je tr_fork 28 | jmp $ 29 | tr_read: 30 | push ecx 31 | push ebx 32 | call sys_kbd_read 33 | jmp end 34 | tr_write: 35 | push ecx 36 | push ebx 37 | call sys_scr_write 38 | jmp end 39 | tr_brk: 40 | push ebx 41 | push current_pid 42 | call brk 43 | jmp end 44 | tr_unbrk: 45 | push ebx 46 | push current_pid 47 | call unbrk 48 | jmp end 49 | tr_getpid: 50 | push ebx 51 | push current_pid 52 | call getpid 53 | jmp end 54 | tr_fork: 55 | push ebx 56 | push current_pid 57 | call fork 58 | jmp end 59 | end: 60 | add esp, 0x8 61 | popad 62 | pop ebp 63 | sti 64 | iret 65 | -------------------------------------------------------------------------------- /include/tss.h: -------------------------------------------------------------------------------- 1 | struct TSS 2 | { 3 | unsigned short link; 4 | unsigned short res0; 5 | unsigned int esp0; 6 | unsigned short ss0; 7 | unsigned short res1; 8 | unsigned int esp1; 9 | unsigned short ss1; 10 | unsigned short res2; 11 | unsigned int esp2; 12 | unsigned short ss2; 13 | unsigned short res3; 14 | unsigned int cr3; 15 | unsigned int eip; 16 | unsigned int eflags; 17 | unsigned int eax; 18 | unsigned int ecx; 19 | unsigned int edx; 20 | unsigned int ebx; 21 | unsigned int esp; 22 | unsigned int ebp; 23 | unsigned int esi; 24 | unsigned int edi; 25 | unsigned short es; 26 | unsigned short res4; 27 | unsigned short cs; 28 | unsigned short res5; 29 | unsigned short ss; 30 | unsigned short res6; 31 | unsigned short ds; 32 | unsigned short res7; 33 | unsigned short fs; 34 | unsigned short res8; 35 | unsigned short gs; 36 | unsigned short res9; 37 | unsigned short ldtr; 38 | unsigned short res10; 39 | unsigned short res11; 40 | unsigned short iopb; 41 | unsigned int ssp; 42 | } __attribute__((packed)); 43 | -------------------------------------------------------------------------------- /proc/process.c: -------------------------------------------------------------------------------- 1 | #include 2 | 3 | #define DATA 0x40 4 | #define CODE 0x80 5 | #define STACK 0xa0 6 | extern char processes[16]; 7 | extern struct process_context contexts[16]; 8 | char processes_n = 0; 9 | extern int current_pid; 10 | 11 | int new_process(unsigned int data, unsigned int code, unsigned int stack, 12 | unsigned int sdata, unsigned int scode, unsigned int sstack) 13 | { 14 | if (processes_n == 15) return -1; 15 | processes_n++; 16 | int pid; 17 | for (int i = 0; i < 16; i++) 18 | { 19 | if (!processes[i]) 20 | { 21 | pid = i; 22 | processes[i] = 1; 23 | break; 24 | } 25 | } 26 | init_memory(pid, 0x00, 0x00000000, 0x10000, 3); 27 | 28 | init_memory(pid, DATA, data, sdata, 7); 29 | init_memory(pid, CODE, code, scode, 7); 30 | init_memory(pid, STACK,stack,sstack, 7); 31 | 32 | contexts[pid].cs = 0x1b; 33 | contexts[pid].eflags = 0x200; 34 | 35 | contexts[pid].eip = 0x20000000; 36 | contexts[pid].esp = 0x28000000+sstack*0x1000; 37 | contexts[pid].ebp = 0x28000000+sstack*0x1000; 38 | 39 | } 40 | -------------------------------------------------------------------------------- /8259_PIC/pic.s: -------------------------------------------------------------------------------- 1 | .intel_syntax noprefix 2 | .global init_pic 3 | .global end_interrupt 4 | 5 | .macro .init_master icw4_needed cascade call_addr_interval8 level_triggered 6 | mov al, (\icw4_needed | (\cascade<<1) | (\call_addr_interval8<<2) | (\level_triggered<<3) | (1<<4)) 7 | out 0x20, al 8 | .endm 9 | .macro .init_slave icw4_needed cascade call_addr_interval8 level_triggered 10 | mov al, (\icw4_needed | (\cascade<<1) | (\call_addr_interval8<<2) | (\level_triggered<<3) | (1<<4)) 11 | out 0xA0, al 12 | .endm 13 | 14 | .macro .remap_master_irq int 15 | mov al, \int 16 | out 0x21, al 17 | .endm 18 | .macro .remap_slave_irq int 19 | mov al, \int 20 | out 0xA1, al 21 | .endm 22 | 23 | init_pic: 24 | push ebp 25 | mov ebp, esp 26 | .init_master 0 0 0 0 27 | .init_slave 0 0 0 0 28 | .remap_master_irq 0x20 29 | .remap_slave_irq 0x28 30 | push 15 31 | push offset text 32 | call kprint 33 | leave 34 | ret 35 | 36 | end_interrupt: 37 | push ebp 38 | mov ebp, esp 39 | mov al, 0x20 40 | cmp byte ptr [esp+4], 8 41 | jle ms 42 | out 0xA0, al 43 | ms: 44 | out 0x20, al 45 | leave 46 | ret 47 | 48 | text: 49 | .asciz "Initialized PIC.\n" 50 | -------------------------------------------------------------------------------- /lib/kernel/kmisc.c: -------------------------------------------------------------------------------- 1 | void reverse(char* addr) 2 | { 3 | char tmp; 4 | char* ptr = addr; 5 | char* ptr_end = addr; 6 | while (*ptr_end++); 7 | int len = ptr_end - ptr - 1; 8 | int i; 9 | for (i = 0; i < len/2; i++) 10 | { 11 | tmp = ptr[i]; 12 | ptr[i] = ptr[len-i-1]; 13 | ptr[len-i-1]=tmp; 14 | } 15 | } 16 | 17 | void itoa(int i, char* addr) 18 | { 19 | int j = i; 20 | int m = 10; 21 | int c = 0; 22 | do addr[c++] = "0123456789"[(j%((m*=10)/10)) / (m/100)]; while (i/=10); 23 | addr[c++]=0; 24 | reverse(addr); 25 | } 26 | 27 | void memset(void* addr, int c, int n) { 28 | unsigned char *ptr = (unsigned char*)addr; 29 | while(n--) *ptr++ = c; 30 | } 31 | 32 | void strcpy(char* dest, char* src) 33 | { 34 | while (*dest++ = *src++); 35 | } 36 | 37 | void memcpy(char* dest, char* src, int n) 38 | { 39 | int i; 40 | for (i = 0; i < n; i++) dest[i] = src[i]; 41 | } 42 | 43 | int strcmp(char* s1, char* s2) 44 | { 45 | while (*s1) while (*s1++ != *s2++); 46 | return *s1 - *s2; 47 | } 48 | -------------------------------------------------------------------------------- /mem/paging/paging.c: -------------------------------------------------------------------------------- 1 | extern void set_32bit_cr3(unsigned int cr3_phdr); 2 | extern void enable_32bit_paging(); 3 | 4 | extern unsigned int page_directories[0x10][0x400]; 5 | extern unsigned int page_tables[0x10][0x400][0x400]; 6 | 7 | // 1 block = 4MiB 8 | // 1 page = 4KiB 9 | 10 | void init_memory(int dir, int block, unsigned int paddr, int pages, int perms) 11 | { 12 | int i,j; 13 | int entries = block + pages/0x400; 14 | unsigned int current_paddr; 15 | for (i = block; i < entries; i++) 16 | { 17 | page_directories[dir][i] = (unsigned int)page_tables[dir][i] | perms; 18 | for (j = 0; j < 0x400; j++) 19 | { 20 | current_paddr = paddr + (i - block)*0x400000 + j*0x1000; 21 | page_tables[dir][i][j] = current_paddr | perms; 22 | } 23 | } 24 | for (j = 0; j < pages%0x400; j++) 25 | { 26 | page_directories[dir][i] = (unsigned int)page_tables[dir][i] | perms; 27 | current_paddr = paddr + (i - block)*0x400000 + j*0x1000; 28 | page_tables[dir][i][j] = current_paddr | perms; 29 | } 30 | } 31 | 32 | void change_directory(int dir) 33 | { 34 | set_32bit_cr3(page_directories[dir]); 35 | } 36 | 37 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | RAM=1G 2 | QEMU=qemu-system-i386 -m $(RAM) 3 | KERNEL=-kernel mel.elf 4 | CCFLAGS= -g -c -w -m32 -fno-stack-protector -fno-pie -masm=intel -O0 -I include 5 | LINKER=linker.ld 6 | LDFLAGS= -z noexecstack -m elf_i386 -T $(LINKER) 7 | ASFLAGS= --32 8 | 9 | SRC_BOOT = boot/boot.s 10 | SRC_C = $(shell find -name "*.c") 11 | SRC_S = $(shell find -name "*.s" -not -name "boot.s") 12 | 13 | OBJ_BOOT = bin/boot.elf 14 | OBJ_C = $(SRC_C:%.c=bin/%.elf) 15 | OBJ_S = $(SRC_S:%.s=bin/%_s.elf) 16 | 17 | OBJS = $(OBJ_BOOT) $(OBJ_C) $(OBJ_S) 18 | 19 | mel.elf : dirs $(OBJS) $(LINKER) 20 | @ld $(LDFLAGS) $(OBJS) -o mel.elf 21 | 22 | $(OBJ_BOOT) : $(SRC_BOOT) 23 | @as --32 $(SRC_BOOT) -o $(OBJ_BOOT) 24 | 25 | dirs : 26 | @mkdir -p $(dir $(OBJS)) 27 | 28 | bin/%.elf: %.c 29 | @gcc $(CCFLAGS) $< -o $@ 30 | 31 | bin/%_s.elf : %.s 32 | @as $(ASFLAGS) $< -o $@ 33 | clean: 34 | @rm -rf bin 35 | @rm *.elf 36 | run: 37 | $(QEMU) $(KERNEL) 38 | kvm: 39 | $(QEMU) --enable-kvm $(KERNEL) 40 | debug: 41 | $(QEMU) $(KERNEL) -d in_asm 42 | cpu: 43 | $(QEMU) $(KERNEL) -d cpu 44 | int: 45 | $(QEMU) $(KERNEL) -d int 46 | gdb: 47 | $(QEMU) -s -S $(KERNEL) 48 | mel.iso : mel.elf 49 | cp mel.elf iso/boot/mel.elf 50 | strip iso/boot/mel.elf 51 | grub-mkrescue -o mel.iso iso 52 | rm iso/boot/mel.elf 53 | -------------------------------------------------------------------------------- /proc/task.c: -------------------------------------------------------------------------------- 1 | #include 2 | #define REG(n) *(unsigned int*)(0x007fffbc+n) 3 | char __attribute__((section(".data"))) processes[16]; 4 | extern char processes_n; 5 | extern int current_pid; 6 | 7 | struct process_context __attribute__((section(".data"))) contexts[16]; 8 | 9 | void context_switch() 10 | { 11 | //if (!(processes_n)) return; 12 | contexts[current_pid].eip = REG(0x30); 13 | contexts[current_pid].eflags = REG(0x38); 14 | contexts[current_pid].cs = REG(0x34); 15 | contexts[current_pid].eax = REG(0x1c); 16 | contexts[current_pid].ebx = REG(0x10); 17 | contexts[current_pid].ecx = REG(0x18); 18 | contexts[current_pid].edx = REG(0x14); 19 | contexts[current_pid].edi = REG(0x00); 20 | contexts[current_pid].esi = REG(0x04); 21 | contexts[current_pid].ebp = REG(0x2c); 22 | contexts[current_pid].esp = REG(0x3c); 23 | 24 | do 25 | { 26 | current_pid = (current_pid + 1) % 16; 27 | } while(!(processes[current_pid])); 28 | 29 | change_directory(current_pid); 30 | 31 | REG(0x30) = contexts[current_pid].eip; 32 | REG(0x38) = contexts[current_pid].eflags; 33 | REG(0x34) = contexts[current_pid].cs; 34 | REG(0x1C) = contexts[current_pid].eax; 35 | REG(0x10) = contexts[current_pid].ebx; 36 | REG(0x18) = contexts[current_pid].ecx; 37 | REG(0x14) = contexts[current_pid].edx; 38 | REG(0x00) = contexts[current_pid].edi; 39 | REG(0x04) = contexts[current_pid].esi; 40 | REG(0x2C) = contexts[current_pid].ebp; 41 | REG(0x3C) = contexts[current_pid].esp; 42 | } 43 | -------------------------------------------------------------------------------- /gdt/gdt.c: -------------------------------------------------------------------------------- 1 | #include 2 | #include 3 | #define KERNELSTACK 0x00800000 4 | #define FILL_GDT_ENTRY(n, l015, b015, b1623, ac, gr, b2431) \ 5 | gdt[n].limit_0_15 = l015; \ 6 | gdt[n].base_0_15 = b015; \ 7 | gdt[n].base_16_23 = b1623; \ 8 | gdt[n].access = ac; \ 9 | gdt[n].granularity = gr; \ 10 | gdt[n].base_24_31 = b2431; 11 | 12 | struct GDT gdt[6]; 13 | struct GDT_PTR gdt_ptr; 14 | 15 | extern void load_gdt(struct GDT*); 16 | struct TSS tss; 17 | 18 | void init_gdt() 19 | { 20 | FILL_GDT_ENTRY(0,0,0,0,0,0,0); 21 | 22 | FILL_GDT_ENTRY(1,0xFFFF,0,0,0b10011010,0b11001111,0); //ring0 code 23 | FILL_GDT_ENTRY(2,0xFFFF,0,0,0b10010010,0b11001111,0); //ring0 data 24 | 25 | FILL_GDT_ENTRY(3,0xFFFF,0,0,0b11111010,0b11001111,0); //ring3 code 26 | FILL_GDT_ENTRY(4,0xFFFF,0,0,0b11110010,0b11001111,0); //ring3 data 27 | 28 | memset(&tss, 0, 104); 29 | tss.ss0 = 0x10; 30 | tss.esp0 = KERNELSTACK; 31 | tss.iopb = 104; 32 | 33 | FILL_GDT_ENTRY(5,104,(unsigned int)(&tss)&0xFFFF, ((unsigned int)(&tss)&0x00FF0000)>>16,0xE9,0x00,((unsigned int)(&tss)&0xFF000000)>>24); //tss 34 | 35 | gdt_ptr.gdt_size = sizeof(gdt) - 1; 36 | gdt_ptr.gdt_addr = (struct GDT*)&gdt; 37 | load_gdt((struct GDT*)&gdt_ptr); 38 | kprint("Loaded GDT.\n", 15); 39 | 40 | asm("mov ax, 0x2b"); 41 | asm("ltr ax"); 42 | 43 | kprint("Loaded TSS.\n", 15); 44 | } 45 | -------------------------------------------------------------------------------- /keyboard/azerty.c: -------------------------------------------------------------------------------- 1 | #define M -0x20*maj 2 | char azerty2c(int keycode, int maj) 3 | { 4 | switch(keycode) 5 | { 6 | case 0x1E : return 'q'M; break; 7 | case 0x30 : return 'b'M; break; 8 | case 0x2E : return 'c'M; break; 9 | case 0x20 : return 'd'M; break; 10 | case 0x12 : return 'e'M; break; 11 | case 0x21 : return 'f'M; break; 12 | case 0x22 : return 'g'M; break; 13 | case 0x23 : return 'h'M; break; 14 | case 0x17 : return 'i'M; break; 15 | case 0x24 : return 'j'M; break; 16 | case 0x25 : return 'k'M; break; 17 | case 0x26 : return 'l'M; break; 18 | case 0x27 : return 'm'M; break; 19 | case 0x31 : return 'n'M; break; 20 | case 0x18 : return 'o'M; break; 21 | case 0x19 : return 'p'M; break; 22 | case 0x10 : return 'a'M; break; 23 | case 0x13 : return 'r'M; break; 24 | case 0x1F : return 's'M; break; 25 | case 0x14 : return 't'M; break; 26 | case 0x16 : return 'u'M; break; 27 | case 0x2F : return 'v'M; break; 28 | case 0x11 : return 'z'M; break; 29 | case 0x2D : return 'x'M; break; 30 | case 0x15 : return 'y'M; break; 31 | case 0x2C : return 'w'M; break; 32 | case 0x39 : return ' '; break; 33 | 34 | case 0x02 : return '1'; break; 35 | case 0x03 : return '2'; break; 36 | case 0x04 : return '3'; break; 37 | case 0x05 : return '4'; break; 38 | case 0x06 : return '5'; break; 39 | case 0x07 : return '6'; break; 40 | case 0x08 : return '7'; break; 41 | case 0x09 : return '8'; break; 42 | case 0x0A : return '9'; break; 43 | case 0x0B : return '0'; break; 44 | case 0x32 : return ','; break; 45 | 46 | case 0x3B : return '['; break; 47 | case 0x44 : return ']'; break; 48 | default : return 0; break; 49 | } 50 | 51 | } 52 | -------------------------------------------------------------------------------- /lib/kernel/kprint.c: -------------------------------------------------------------------------------- 1 | #define SCREEN_LINES 25 2 | #define LINE_SIZE 80 3 | 4 | char *video_ram = (char*)0xB8000; 5 | 6 | int screen_count = SCREEN_LINES; 7 | int line_count = LINE_SIZE; 8 | 9 | void kprint(char *text, char color) 10 | { 11 | while (*text) 12 | { 13 | if (*text != '\n') 14 | { 15 | *video_ram = *text; 16 | } 17 | 18 | video_ram++; 19 | *video_ram = color; 20 | 21 | if (*text != '\n') 22 | { 23 | *video_ram++; 24 | } 25 | else 26 | { 27 | video_ram += line_count*2 +1; 28 | line_count = LINE_SIZE; 29 | screen_count--; 30 | } 31 | 32 | text++; 33 | line_count--; 34 | 35 | if (!screen_count) 36 | { 37 | free_vram(); 38 | video_ram = 0xB8000; 39 | screen_count = SCREEN_LINES; 40 | } 41 | 42 | if (line_count < 0) 43 | { 44 | line_count = LINE_SIZE; 45 | } 46 | } 47 | } 48 | void putchar(char c, char color) 49 | { 50 | char buf[4] = "\0\0\0"; 51 | buf[0] = c; 52 | kprint(buf, color); 53 | } 54 | void kbackline (void) 55 | { 56 | video_ram += line_count*2+1; 57 | line_count = LINE_SIZE; 58 | screen_count--; 59 | } 60 | 61 | void knextpage() 62 | { 63 | int l = 0; 64 | while (l < SCREEN_LINES) 65 | { 66 | kprint("\n", 0); 67 | l++; 68 | } 69 | } 70 | void free_vram() 71 | { 72 | int video_ram_tmp = 0xB8000; 73 | while (video_ram_tmp++ < 0xBFFFF) *(unsigned char*)video_ram_tmp = 0x00; 74 | } 75 | -------------------------------------------------------------------------------- /user_programs/init.c: -------------------------------------------------------------------------------- 1 | // Until I make an ELF loader. 2 | 3 | void user_test(void) __attribute__((section(".ring3text"))); 4 | void user_test(void) __attribute__((naked)); 5 | 6 | void func(void) __attribute__((section(".ring3text"))); 7 | void u_reverse(char* addr) __attribute__((section(".ring3text"))); 8 | void u_itoa(int i, char* addr) __attribute__((section(".ring3text"))); 9 | int u_strcmp(char *str1, char *str2) __attribute__((section(".ring3text"))); 10 | 11 | char strings[0x100] __attribute__((section(".ring3data"))) = "New process, PID \0meli $ \0help\0Nothing yet.\n\0";; 12 | void user_test(void) 13 | { 14 | asm("mov ebp, esp"); 15 | func(); 16 | } 17 | 18 | 19 | void func(void) 20 | { 21 | char buffer[0x10]; 22 | brk_user(3); 23 | char pid; 24 | getpid_user(&pid); 25 | u_itoa((int)pid, &buffer); 26 | scr_write(strings,18); 27 | scr_write(buffer, 1); 28 | scr_write(strings+43, 1); 29 | while(1) 30 | { 31 | scr_write(strings+43, 1); 32 | scr_write(strings+18, 7); 33 | kbd_read(buffer, 4); 34 | if (!u_strcmp(buffer, strings+26)) 35 | { 36 | scr_write("Nothing yet.\n", 14); 37 | } 38 | } 39 | asm("jmp $"); 40 | } 41 | 42 | void u_reverse(char* addr) 43 | { 44 | char tmp; 45 | char* ptr = addr; 46 | char* ptr_end = addr; 47 | while (*ptr_end++); 48 | int len = ptr_end - ptr - 1; 49 | int i; 50 | for (i = 0; i < len/2; i++) 51 | { 52 | tmp = ptr[i]; 53 | ptr[i] = ptr[len-i-1]; 54 | ptr[len-i-1]=tmp; 55 | } 56 | } 57 | 58 | void u_itoa(int i, char* addr) 59 | { 60 | int j = i; 61 | int m = 10; 62 | int c = 0; 63 | volatile char num[] = "0123456789"; 64 | do addr[c++] = num[(j%((m*=10)/10)) / (m/100)]; while (i/=10); 65 | addr[c++]=0; 66 | u_reverse(addr); 67 | } 68 | 69 | 70 | 71 | int u_strcmp(char *str1, char *str2) 72 | { 73 | while (*str1++) 74 | { 75 | if (*str1 != *str2++) return 1; 76 | } 77 | return 0; 78 | } 79 | 80 | -------------------------------------------------------------------------------- /idt/idt.c: -------------------------------------------------------------------------------- 1 | extern void end_interrupt(int n); 2 | #define FILL_IDT_ENTRY(n, base, ss1, type1) \ 3 | idt[n].base_0_15 = base & 0xffff; \ 4 | idt[n].ss = ss1; \ 5 | idt[n].z = 0; \ 6 | idt[n].type = type1; \ 7 | idt[n].base_16_31 = (base >> 16) & 0xffff; 8 | 9 | #define HANDLE(n) \ 10 | asm volatile("cli"); \ 11 | asm volatile("push ebp"); \ 12 | asm volatile ("pushad"); \ 13 | irq_handler(n); \ 14 | end_interrupt(n); \ 15 | asm volatile("popad"); \ 16 | asm volatile("add esp, 0xc"); \ 17 | asm volatile("pop ebp"); \ 18 | asm volatile("sti"); \ 19 | asm volatile("iret"); 20 | struct IDT 21 | { 22 | unsigned short base_0_15; 23 | unsigned short ss; 24 | unsigned char z; 25 | unsigned char type; 26 | unsigned short base_16_31; 27 | } __attribute__((packed)); 28 | 29 | 30 | struct IDT_PTR 31 | { 32 | unsigned short idt_size; // limit size of all IDT segments 33 | struct IDT* idt_addr; // base address of the first IDT segment 34 | } __attribute__((packed)); 35 | 36 | void irq0() {HANDLE(0);} 37 | void irq1() {HANDLE(1);} 38 | void irq2() {HANDLE(2);} 39 | void irq3() {HANDLE(3);} 40 | void irq4() {HANDLE(4);} 41 | void irq5() {HANDLE(5);} 42 | void irq6() {HANDLE(6);} 43 | void irq7() {HANDLE(7);} 44 | void irq8() {HANDLE(8);} 45 | void irq9() {HANDLE(9);} 46 | void irq10() {HANDLE(10);} 47 | void irq11() {HANDLE(11);} 48 | void irq12() {HANDLE(12);} 49 | void irq13() {HANDLE(13);} 50 | void irq14() {HANDLE(14);} 51 | void irq15() {HANDLE(15);} 52 | 53 | void ex0() {exception_handler(0); } 54 | void ex1() {exception_handler(1); } 55 | void ex2() {exception_handler(2); } 56 | void ex3() {exception_handler(3); } 57 | void ex4() {exception_handler(4); } 58 | void ex5() {exception_handler(5); } 59 | void ex6() {exception_handler(6); } 60 | void ex7() {exception_handler(7); } 61 | void ex8() {exception_handler(8); } 62 | void ex9() {exception_handler(9); } 63 | void ex10() {exception_handler(10); } 64 | void ex11() {exception_handler(11); } 65 | void ex12() {exception_handler(12); } 66 | void ex13() {exception_handler(13); } 67 | void ex14() {exception_handler(14); } 68 | void ex15() {exception_handler(15); } 69 | void ex16() {exception_handler(16); } 70 | void ex17() {exception_handler(17); } 71 | void ex18() {exception_handler(18); } 72 | void ex19() {exception_handler(19); } 73 | void ex20() {exception_handler(20); } 74 | void ex21() {exception_handler(21); } 75 | void ex22() {exception_handler(22); } 76 | void ex23() {exception_handler(23); } 77 | void ex24() {exception_handler(24); } 78 | void ex25() {exception_handler(25); } 79 | void ex26() {exception_handler(26); } 80 | void ex27() {exception_handler(27); } 81 | void ex28() {exception_handler(28); } 82 | void ex29() {exception_handler(29); } 83 | void ex30() {exception_handler(30); } 84 | void ex31() {exception_handler(31); } 85 | 86 | extern void syscall_handler(); 87 | 88 | struct IDT idt[256]; 89 | struct IDT_PTR idt_ptr; 90 | void init_idt() 91 | { 92 | FILL_IDT_ENTRY(0x00, (unsigned int)&ex0, 0x8, 0x8F); 93 | FILL_IDT_ENTRY(0x01, (unsigned int)&ex1, 0x8, 0x8F); 94 | FILL_IDT_ENTRY(0x02, (unsigned int)&ex2, 0x8, 0x8F); 95 | FILL_IDT_ENTRY(0x03, (unsigned int)&ex3, 0x8, 0x8F); 96 | FILL_IDT_ENTRY(0x04, (unsigned int)&ex4, 0x8, 0x8F); 97 | FILL_IDT_ENTRY(0x05, (unsigned int)&ex5, 0x8, 0x8F); 98 | FILL_IDT_ENTRY(0x06, (unsigned int)&ex6, 0x8, 0x8F); 99 | FILL_IDT_ENTRY(0x07, (unsigned int)&ex7, 0x8, 0x8F); 100 | FILL_IDT_ENTRY(0x08, (unsigned int)&ex8, 0x8, 0x8F); 101 | FILL_IDT_ENTRY(0x09, (unsigned int)&ex9, 0x8, 0x8F); 102 | FILL_IDT_ENTRY(0x0A, (unsigned int)&ex10, 0x8, 0x8F); 103 | FILL_IDT_ENTRY(0x0B, (unsigned int)&ex11, 0x8, 0x8F); 104 | FILL_IDT_ENTRY(0x0C, (unsigned int)&ex12, 0x8, 0x8F); 105 | FILL_IDT_ENTRY(0x0D, (unsigned int)&ex13, 0x8, 0x8F); 106 | FILL_IDT_ENTRY(0x0E, (unsigned int)&ex14, 0x8, 0x8F); 107 | FILL_IDT_ENTRY(0x0F, (unsigned int)&ex15, 0x8, 0x8F); 108 | FILL_IDT_ENTRY(0x10, (unsigned int)&ex16, 0x8, 0x8F); 109 | FILL_IDT_ENTRY(0x11, (unsigned int)&ex17, 0x8, 0x8F); 110 | FILL_IDT_ENTRY(0x12, (unsigned int)&ex18, 0x8, 0x8F); 111 | FILL_IDT_ENTRY(0x13, (unsigned int)&ex19, 0x8, 0x8F); 112 | FILL_IDT_ENTRY(0x14, (unsigned int)&ex20, 0x8, 0x8F); 113 | FILL_IDT_ENTRY(0x15, (unsigned int)&ex21, 0x8, 0x8F); 114 | FILL_IDT_ENTRY(0x16, (unsigned int)&ex22, 0x8, 0x8F); 115 | FILL_IDT_ENTRY(0x17, (unsigned int)&ex23, 0x8, 0x8F); 116 | FILL_IDT_ENTRY(0x18, (unsigned int)&ex24, 0x8, 0x8F); 117 | FILL_IDT_ENTRY(0x19, (unsigned int)&ex25, 0x8, 0x8F); 118 | FILL_IDT_ENTRY(0x1A, (unsigned int)&ex26, 0x8, 0x8F); 119 | FILL_IDT_ENTRY(0x1B, (unsigned int)&ex27, 0x8, 0x8F); 120 | FILL_IDT_ENTRY(0x1C, (unsigned int)&ex28, 0x8, 0x8F); 121 | FILL_IDT_ENTRY(0x1D, (unsigned int)&ex29, 0x8, 0x8F); 122 | FILL_IDT_ENTRY(0x1E, (unsigned int)&ex30, 0x8, 0x8F); 123 | FILL_IDT_ENTRY(0x1F, (unsigned int)&ex31, 0x8, 0x8F); 124 | 125 | FILL_IDT_ENTRY(0x20, (unsigned int)&irq0, 0x8, 0x8E); 126 | FILL_IDT_ENTRY(0x21, (unsigned int)&irq1, 0x8, 0x8E); 127 | FILL_IDT_ENTRY(0x22, (unsigned int)&irq2, 0x8, 0x8E); 128 | FILL_IDT_ENTRY(0x23, (unsigned int)&irq3, 0x8, 0x8E); 129 | FILL_IDT_ENTRY(0x24, (unsigned int)&irq4, 0x8, 0x8E); 130 | FILL_IDT_ENTRY(0x25, (unsigned int)&irq5, 0x8, 0x8E); 131 | FILL_IDT_ENTRY(0x26, (unsigned int)&irq6, 0x8, 0x8E); 132 | FILL_IDT_ENTRY(0x27, (unsigned int)&irq7, 0x8, 0x8E); 133 | FILL_IDT_ENTRY(0x28, (unsigned int)&irq8, 0x8, 0x8E); 134 | FILL_IDT_ENTRY(0x29, (unsigned int)&irq9, 0x8, 0x8E); 135 | FILL_IDT_ENTRY(0x2A, (unsigned int)&irq10, 0x8, 0x8E); 136 | FILL_IDT_ENTRY(0x2B, (unsigned int)&irq11, 0x8, 0x8E); 137 | FILL_IDT_ENTRY(0x2C, (unsigned int)&irq12, 0x8, 0x8E); 138 | FILL_IDT_ENTRY(0x2D, (unsigned int)&irq13, 0x8, 0x8E); 139 | FILL_IDT_ENTRY(0x2E, (unsigned int)&irq14, 0x8, 0x8E); 140 | FILL_IDT_ENTRY(0x2F, (unsigned int)&irq15, 0x8, 0x8E); 141 | 142 | FILL_IDT_ENTRY(0x30, (unsigned int)&syscall_handler, 0x8, 0xEE); 143 | 144 | idt_ptr.idt_size = sizeof(idt) - 1; 145 | idt_ptr.idt_addr = (struct IDT*)&idt; 146 | load_idt((struct IDT*)&idt_ptr); 147 | kprint("Loaded IDT.\n", 15); 148 | 149 | } 150 | -------------------------------------------------------------------------------- /COPYING: -------------------------------------------------------------------------------- 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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You may not convey a covered 525 | work if you are a party to an arrangement with a third party that is 526 | in the business of distributing software, under which you make payment 527 | to the third party based on the extent of your activity of conveying 528 | the work, and under which the third party grants, to any of the 529 | parties who would receive the covered work from you, a discriminatory 530 | patent license (a) in connection with copies of the covered work 531 | conveyed by you (or copies made from those copies), or (b) primarily 532 | for and in connection with specific products or compilations that 533 | contain the covered work, unless you entered into that arrangement, 534 | or that patent license was granted, prior to 28 March 2007. 535 | 536 | Nothing in this License shall be construed as excluding or limiting 537 | any implied license or other defenses to infringement that may 538 | otherwise be available to you under applicable patent law. 539 | 540 | 12. No Surrender of Others' Freedom. 541 | 542 | If conditions are imposed on you (whether by court order, agreement or 543 | otherwise) that contradict the conditions of this License, they do not 544 | excuse you from the conditions of this License. If you cannot convey a 545 | covered work so as to satisfy simultaneously your obligations under this 546 | License and any other pertinent obligations, then as a consequence you may 547 | not convey it at all. For example, if you agree to terms that obligate you 548 | to collect a royalty for further conveying from those to whom you convey 549 | the Program, the only way you could satisfy both those terms and this 550 | License would be to refrain entirely from conveying the Program. 551 | 552 | 13. Use with the GNU Affero General Public License. 553 | 554 | Notwithstanding any other provision of this License, you have 555 | permission to link or combine any covered work with a work licensed 556 | under version 3 of the GNU Affero General Public License into a single 557 | combined work, and to convey the resulting work. The terms of this 558 | License will continue to apply to the part which is the covered work, 559 | but the special requirements of the GNU Affero General Public License, 560 | section 13, concerning interaction through a network will apply to the 561 | combination as such. 562 | 563 | 14. Revised Versions of this License. 564 | 565 | The Free Software Foundation may publish revised and/or new versions of 566 | the GNU General Public License from time to time. 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 | 635 | Copyright (C) 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 | Copyright (C) 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 | --------------------------------------------------------------------------------