init.c

   1 /*******************************************************************************
   2 this code is protected by the GNU affero GPLv3
   3 author:Sylvain BERTRAND <sylvain.bertrand AT gmail dot com>
   4 *******************************************************************************/
   5 /*
   6 we use libraries based on C posix runtime, then we need this to fetch
   7 environment variables from the C posix runtime
   8 */
   9 #include <stdlib.h>
  10
  11 #include <ulinux/compiler_types.h>
  12 #include <ulinux/sysc.h>
  13 #include <ulinux/types.h>
  14 #include <ulinux/error.h>
  15 #include <ulinux/fs.h>
  16 #include <ulinux/signal/signal.h>
  17 #include <ulinux/utils/mem.h>
  18 #include <ulinux/utils/ascii/string/string.h>
  19
  20 #define INIT_C
  21 #include "out.h"
  22 #include "ulinux_namespace.h"
  23 #include "modules.h"
  24 #include "uevents.h"
  25 #include "ramfs.h"
  26 #include "globals.h"
  27 #undef INIT_C
  28
  29 static void sigs_setup(void)
  30 {
  31   ul mask=(~0);
  32   l r;
  33
  34   OUT(PRE "setting up signals...\n");
  35   r=rt_sigprocmask(SIG_BLOCK,&mask,0,sizeof(mask));
  36   if(ISERR(r)){
  37     OUT("ERROR:unable to block all signals (except KILL and STOP)\n");
  38     exit_group(-1);
  39   }
  40   OUT("done\n");
  41 }
  42
  43 static void sysfs_mount(void)
  44 {
  45   OUT(PRE "mounting sysfs...\n");
  46   l r=mount(0,"/sys","sysfs",MS_NOATIME|MS_NODIRATIME,0);
  47   if(ISERR(r)){
  48     OUT("ERROR(%ld):unable to mount sysfs\n",r);
  49     exit_group(-1);
  50   }
  51 }
  52
  53 static void sysfs_umount(void)
  54 {
  55   OUT(PRE "umounting sysfs...\n");
  56   l r=umount("/sys");
  57   if(ISERR(r)){
  58     OUT("ERROR(%ld):unable to umount sysfs\n",r);
  59     exit_group(-1);
  60   }
  61 }
  62
  63 static void proc_mount(void)
  64 {
  65   OUT(PRE "mounting proc...\n");
  66   l r=mount(0,"/proc","proc",MS_NOATIME|MS_NODIRATIME,0);
  67   if(ISERR(r)){
  68     OUT("ERROR(%ld):unable to mount proc\n",r);
  69     exit_group(-1);
  70   }
  71 }
  72
  73 static void proc_umount(void)
  74 {
  75   OUT(PRE "umounting proc...\n");
  76   l r=umount("/proc");
  77   if(ISERR(r)){
  78     OUT("ERROR(%ld):unable to umount proc\n",r);
  79     exit_group(-1);
  80   }
  81 }
  82
  83 static void devtmpfs_mount(void)
  84 {
  85   OUT(PRE "mounting devtmpfs...\n");
  86   l r=mount(0,"/dev","devtmpfs",MS_NOATIME|MS_NODIRATIME,0);
  87   if(ISERR(r)){
  88     OUT("ERROR(%ld):unable to mount devtmpfs\n",r);
  89     exit_group(-1);
  90   }
  91 }
  92
  93 static void devtmpfs_umount(void)
  94 {
  95   OUT(PRE "umounting devtmpfs...\n");
  96   l r=umount("/dev");
  97   if(ISERR(r)){
  98     OUT("ERROR(%ld):unable to umount devtmpfs\n",r);
  99     exit_group(-1);
 100   }
 101 }
 102
 103 static void newroot_mount(void)
 104 {
 105   OUT(PRE "mounting root device %s on /newroot, root file system is %s...\n",
 106                                                     root_dev_path,root_fs_type);
 107   l r=mount(root_dev_path,"/newroot",root_fs_type,MS_NOATIME|MS_NODIRATIME,0);
 108   if(ISERR(r)){
 109     OUT("ERROR(%ld):unable to mount root\n",r);
 110     exit_group(-1);
 111   }
 112 }
 113
 114 static void newroot_chdir()
 115 {
 116   OUT(PRE "chdir to /newroot...");
 117   l r=chdir("/newroot");
 118   if(ISERR(r)){
 119     OUT("ERROR(%ld):unable to chdir to /newroot\n",r);
 120     exit_group(-1);
 121   }
 122   OUT("done\n");
 123 }
 124
 125 static void newroot_move(void)
 126 {
 127   OUT(PRE "mount moving . (/newroot) to / ...");
 128   l r=mount(".","/",0,MS_MOVE,0);
 129   if(ISERR(r)){
 130     OUT("ERROR(%ld):unable to mount move . (/newroot) to /\n",r);
 131     exit_group(-1);
 132   }
 133   OUT("done\n");
 134 }
 135
 136 static void newroot_chroot(void)
 137 {
 138   OUT(PRE "chroot to . (/newroot)...");
 139   l r=chroot(".");
 140   if(ISERR(r)){
 141     OUT("ERROR(%ld):unable to chroot to . (/newroot)\n",r);
 142     exit_group(-1);
 143   }
 144   OUT("done\n");
 145 }
 146
 147 /*this parameter *must* be around*/
 148 #define PARAM_NAME "cinitramfs_root_uuid"
 149 static void root_uuid_get(i argc, c **argv)
 150 {
 151   u8 arg;
 152
 153   /*we should use libc getenv to be friendly with the C runtime*/
 154   root_uuid=(u8*)getenv(PARAM_NAME);
 155   if(root_uuid) return;
 156
 157   /*it's not in the environment, then could be in argv, see
 158     Documentation/kernel-parameters.txt*/
 159
 160   if(argc==1) goto fatal_err;
 161
 162   arg=1;
 163   loop{
 164     if(strncmp(argv[arg],PARAM_NAME,sizeof(PARAM_NAME)-1)==0) break;
 165     if(++arg==argc) goto fatal_err;
 166   }
 167   root_uuid=(u8*)argv[arg];
 168   loop if(*root_uuid++==(u8)'=') break;/*lookup for the key/value separator*/
 169   return;
 170
 171 fatal_err:
 172   OUT(PRE "ERROR:unable to find " PARAM_NAME "\n");
 173   exit_group(-1);
 174 }
 175 #undef PARAM_NAME
 176
 177 static void command_line_parse(i argc, c **argv)
 178 {
 179   root_uuid_get(argc, argv);
 180 }
 181
 182 /*
 183 fds 0,1 and 2 are rw /dev/console, see linux/init/main.
 184 Since we use standard C libs, be nice with the C runtime and use main instead of
 185 _start entry point.
 186 */
 187 i main(i argc,c **argv)
 188 {
 189   u8 r0;
 190   l r1;
 191 #ifndef QUIET
 192   static u8 dprintf_buf[DPRINTF_BUF_SZ];
 193   g_dprintf_buf=dprintf_buf;
 194 #endif
 195   sigs_setup();
 196   command_line_parse(argc,argv);
 197   uevents_setup();
 198   sysfs_mount();
 199   proc_mount();
 200   devtmpfs_mount();
 201   modules_setup();
 202   modules_probe_static();
 203   modules_probe_drivers();
 204   r0=uevents_process();
 205   if(r0==ROOT_NOT_FOUND){
 206     OUT(PRE "terminating cinitramfs since no proper root was found\n");
 207     exit_group(-1);
 208   }
 209   /*from here, we located our root*/
 210   uevents_cleanup();
 211   modules_probe_name(root_fs_type);
 212   modules_cleanup();
 213   newroot_mount();
 214   devtmpfs_umount();
 215   proc_umount();
 216   sysfs_umount();
 217   ramfs_cleanup();
 218
 219   newroot_chdir();
 220   newroot_move();
 221   newroot_chroot();
 222
 223   r1=execve("/bin/init");
 224   if(ISERR(r1)){OUT("ERROR(%ld):unable to execve /bin/init\n",r1);}
 225   exit_group(-1);
 226   /*unreachable*/
 227 }