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    Contents of /trunk/mkinitrd-magellan/klibc/usr/kinit/initrd.c

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    Revision 1122 - (show annotations) (download)
    Wed Aug 18 21:11:40 2010 UTC (13 years, 8 months ago) by niro
    File MIME type: text/plain
    File size: 4903 byte(s) 
    -updated to klibc-1.5.19
    1 /*
    2 * Handle initrd, thus putting the backwards into backwards compatible
    3 */
    4
    5 #include <stdio.h>
    6 #include <string.h>
    7 #include <unistd.h>
    8 #include <fcntl.h>
    9 #include <errno.h>
    10 #include <sys/stat.h>
    11 #include <sys/mount.h>
    12 #include <sys/ioctl.h>
    13 #include <sys/wait.h>
    14 #include "do_mounts.h"
    15 #include "kinit.h"
    16 #include "xpio.h"
    17
    18 #define BUF_SIZE 65536 /* Should be a power of 2 */
    19
    20 /*
    21 * Copy the initrd to /dev/ram0, copy from the end to the beginning
    22 * to avoid taking 2x the memory.
    23 */
    24 static int rd_copy_uncompressed(int ffd, int dfd)
    25 {
    26 char buffer[BUF_SIZE];
    27 off_t bytes;
    28 struct stat st;
    29
    30 dprintf("kinit: uncompressed initrd\n");
    31
    32 if (ffd < 0 || fstat(ffd, &st) || !S_ISREG(st.st_mode) ||
    33 (bytes = st.st_size) == 0)
    34 return -1;
    35
    36 while (bytes) {
    37 ssize_t blocksize = ((bytes - 1) & (BUF_SIZE - 1)) + 1;
    38 off_t offset = bytes - blocksize;
    39
    40 dprintf("kinit: copying %zd bytes at offset %llu\n",
    41 blocksize, offset);
    42
    43 if (xpread(ffd, buffer, blocksize, offset) != blocksize ||
    44 xpwrite(dfd, buffer, blocksize, offset) != blocksize)
    45 return -1;
    46
    47 ftruncate(ffd, offset); /* Free up memory */
    48 bytes = offset;
    49 }
    50 return 0;
    51 }
    52
    53 static int rd_copy_image(const char *path)
    54 {
    55 int ffd = open(path, O_RDONLY);
    56 int rv = -1;
    57 unsigned char gzip_magic[2];
    58
    59 if (ffd < 0)
    60 goto barf;
    61
    62 if (xpread(ffd, gzip_magic, 2, 0) == 2 &&
    63 gzip_magic[0] == 037 && gzip_magic[1] == 0213) {
    64 FILE *wfd = fopen("/dev/ram0", "w");
    65 if (!wfd)
    66 goto barf;
    67 rv = load_ramdisk_compressed(path, wfd, 0);
    68 fclose(wfd);
    69 } else {
    70 int dfd = open("/dev/ram0", O_WRONLY);
    71 if (dfd < 0)
    72 goto barf;
    73 rv = rd_copy_uncompressed(ffd, dfd);
    74 close(dfd);
    75 }
    76
    77 barf:
    78 if (ffd >= 0)
    79 close(ffd);
    80 return rv;
    81 }
    82
    83 /*
    84 * Run /linuxrc, for emulation of old-style initrd
    85 */
    86 static int run_linuxrc(int argc, char *argv[], dev_t root_dev)
    87 {
    88 int root_fd, old_fd;
    89 pid_t pid;
    90 long realroot = Root_RAM0;
    91 const char *ramdisk_name = "/dev/ram0";
    92 FILE *fp;
    93
    94 dprintf("kinit: mounting initrd\n");
    95 mkdir("/root", 0700);
    96 if (!mount_block(ramdisk_name, "/root", NULL, MS_VERBOSE, NULL))
    97 return -errno;
    98
    99 /* Write the current "real root device" out to procfs */
    100 dprintf("kinit: real_root_dev = %#x\n", root_dev);
    101 fp = fopen("/proc/sys/kernel/real-root-dev", "w");
    102 fprintf(fp, "%u", root_dev);
    103 fclose(fp);
    104
    105 mkdir("/old", 0700);
    106 root_fd = open_cloexec("/", O_RDONLY | O_DIRECTORY, 0);
    107 old_fd = open_cloexec("/old", O_RDONLY | O_DIRECTORY, 0);
    108
    109 if (root_fd < 0 || old_fd < 0)
    110 return -errno;
    111
    112 if (chdir("/root") ||
    113 mount(".", "/", NULL, MS_MOVE, NULL) || chroot("."))
    114 return -errno;
    115
    116 pid = vfork();
    117 if (pid == 0) {
    118 setsid();
    119 /* Looks like linuxrc doesn't get the init environment
    120 or parameters. Weird, but so is the whole linuxrc bit. */
    121 execl("/linuxrc", "linuxrc", NULL);
    122 _exit(255);
    123 } else if (pid > 0) {
    124 dprintf("kinit: Waiting for linuxrc to complete...\n");
    125 while (waitpid(pid, NULL, 0) != pid) ;
    126 dprintf("kinit: linuxrc done\n");
    127 } else {
    128 return -errno;
    129 }
    130
    131 if (fchdir(old_fd) ||
    132 mount("/", ".", NULL, MS_MOVE, NULL) ||
    133 fchdir(root_fd) || chroot("."))
    134 return -errno;
    135
    136 close(root_fd);
    137 close(old_fd);
    138
    139 getintfile("/proc/sys/kernel/real-root-dev", &realroot);
    140
    141 /* If realroot is Root_RAM0, then the initrd did any necessary work */
    142 if (realroot == Root_RAM0) {
    143 if (mount("/old", "/root", NULL, MS_MOVE, NULL))
    144 return -errno;
    145 } else {
    146 mount_root(argc, argv, (dev_t) realroot, NULL);
    147
    148 /* If /root/initrd exists, move the initrd there, otherwise discard */
    149 if (!mount("/old", "/root/initrd", NULL, MS_MOVE, NULL)) {
    150 /* We're good */
    151 } else {
    152 int olddev = open(ramdisk_name, O_RDWR);
    153 umount2("/old", MNT_DETACH);
    154 if (olddev < 0 ||
    155 ioctl(olddev, BLKFLSBUF, (long)0) ||
    156 close(olddev)) {
    157 fprintf(stderr,
    158 "%s: Cannot flush initrd contents\n",
    159 progname);
    160 }
    161 }
    162 }
    163
    164 rmdir("/old");
    165 return 0;
    166 }
    167
    168 int initrd_load(int argc, char *argv[], dev_t root_dev)
    169 {
    170 if (access("/initrd.image", R_OK))
    171 return 0; /* No initrd */
    172
    173 dprintf("kinit: initrd found\n");
    174
    175 create_dev("/dev/ram0", Root_RAM0);
    176
    177 if (rd_copy_image("/initrd.image") || unlink("/initrd.image")) {
    178 fprintf(stderr, "%s: initrd installation failed (too big?)\n",
    179 progname);
    180 return 0; /* Failed to copy initrd */
    181 }
    182
    183 dprintf("kinit: initrd copied\n");
    184
    185 if (root_dev == Root_MULTI) {
    186 dprintf("kinit: skipping linuxrc: incompatible with multiple roots\n");
    187 /* Mounting initrd as ordinary root */
    188 return 0;
    189 }
    190
    191 if (root_dev != Root_RAM0) {
    192 int err;
    193 dprintf("kinit: running linuxrc\n");
    194 err = run_linuxrc(argc, argv, root_dev);
    195 if (err)
    196 fprintf(stderr, "%s: running linuxrc: %s\n", progname,
    197 strerror(-err));
    198 return 1; /* initrd is root, or run_linuxrc took care of it */
    199 } else {
    200 dprintf("kinit: permament (or pivoting) initrd, not running linuxrc\n");
    201 return 0; /* Mounting initrd as ordinary root */
    202 }
    203 }