preinit.c (1886B)
1 #ifdef PREINIT_USE_LIBC 2 #include <string.h> 3 #include <unistd.h> 4 #include <fcntl.h> 5 #include <sys/mount.h> 6 #include <sys/wait.h> 7 #include <string.h> 8 #else 9 #include <nolibc.h> 10 #endif 11 #include <asm/setup.h> 12 13 #define ERR(x) write(2, x, strlen(x)) 14 #define AVER(c) do { if(c < 0) ERR("failed: " #c); } while(0) 15 16 static int begins_with(char * str, char * prefix) 17 { 18 while(*prefix) { 19 if(*str == '\0') return 0; 20 if(*str != *prefix) return 0; 21 str++; 22 prefix++; 23 } 24 return 1; 25 } 26 27 static void fork_exec(char * command, char *args[]) 28 { 29 int fork_pid = fork(); 30 AVER(fork_pid); 31 if(fork_pid > 0) 32 wait(NULL); 33 else 34 AVER(execve(command, args, NULL)); 35 } 36 37 char banner[] = "Running pre-init...\n"; 38 char buf[COMMAND_LINE_SIZE]; 39 40 int main(int argc, char *argv[], char *envp[]) 41 { 42 #ifndef PREINIT_USE_LIBC 43 asm("la $gp, _gp\nsw $gp,16($sp)"); 44 #endif 45 char *rootdevice = 0; 46 char *p = buf; 47 write(1, banner, strlen(banner)); 48 49 mount("none", "/proc", "proc", 0, NULL); 50 51 int cmdline = open("/proc/cmdline", O_RDONLY, 0); 52 53 if(cmdline>=0) { 54 int len = read(cmdline, buf, sizeof buf - 1); 55 buf[len]='\0'; 56 write(1, "cmdline ", 8); 57 write(1, buf, len); 58 }; 59 60 while(*p) { 61 if(begins_with(p, "root=")) { 62 rootdevice = p + 5; 63 while(*p && (*p != ' ')) p++; 64 *p= '\0'; 65 } 66 while(*p && (*p != ' ')) p++; 67 p++; 68 } 69 70 if(rootdevice) { 71 write(1, "rootdevice ", 11); 72 write(1, rootdevice, strlen(rootdevice)); 73 write(1, "\n", 1); 74 75 AVER(mount(rootdevice, "/target/persist", "jffs2", 0, NULL)); 76 AVER(mount("/target/persist/nix", "/target/nix", 77 "bind", MS_BIND, NULL)); 78 79 char *exec_args[] = { "activate", "/target", NULL }; 80 fork_exec("/target/persist/activate", exec_args); 81 AVER(chdir("/target")); 82 83 AVER(mount("/target", "/", "bind", MS_BIND | MS_REC, NULL)); 84 AVER(chroot(".")); 85 argv[0] = "init"; 86 argv[1] = NULL; 87 88 AVER(execve("/persist/init", argv, envp)); 89 } 90 }