LXR toybox/toys/posix/cpio.c

   1/* cpio.c - a basic cpio
   2 *
   3 * Written 2013 AD by Isaac Dunham; this code is placed under the
   4 * same license as toybox or as CC0, at your option.
   5 *
   6 * Portions Copyright 2015 by Frontier Silicon Ltd.
   7 *
   8 * http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/cpio.html
   9 * and http://pubs.opengroup.org/onlinepubs/7908799/xcu/cpio.html
  10 *
  11 * Yes, that's SUSv2, the newer standards removed it around the time RPM
  12 * and initramfs started heavily using this archive format.
  13 *
  14 * Modern cpio expanded header to 110 bytes (first field 6 bytes, rest are 8).
  15 * In order: magic ino mode uid gid nlink mtime filesize devmajor devminor
  16 * rdevmajor rdevminor namesize check
  17 * This is the equiavlent of mode -H newc when using GNU CPIO.
  18
  19USE_CPIO(NEWTOY(cpio, "(no-preserve-owner)mduH:p:|i|t|F:v(verbose)o|[!pio][!pot][!pF]", TOYFLAG_BIN))
  20
  21config CPIO
  22  bool "cpio"
  23  default y
  24  help
  25    usage: cpio -{o|t|i|p DEST} [-v] [--verbose] [-F FILE] [--no-preserve-owner]
  26           [ignored: -mdu -H newc]
  27
  28    Copy files into and out of a "newc" format cpio archive.
  29
  30    -F FILE     Use archive FILE instead of stdin/stdout
  31    -p DEST     Copy-pass mode, copy stdin file list to directory DEST
  32    -i  Extract from archive into file system (stdin=archive)
  33    -o  Create archive (stdin=list of files, stdout=archive)
  34    -t  Test files (list only, stdin=archive, stdout=list of files)
  35    -v  Verbose
  36    --no-preserve-owner (don't set ownership during extract)
  37*/
  38
  39#define FOR_cpio
  40#include "toys.h"
  41
  42GLOBALS(
  43  char *F, *p, *H;
  44)
  45
  46// Read strings, tail padded to 4 byte alignment. Argument "align" is amount
  47// by which start of string isn't aligned (usually 0, but header is 110 bytes
  48// which is 2 bytes off because the first field wasn't expanded from 6 to 8).
  49static char *strpad(int fd, unsigned len, unsigned align)
  50{
  51  char *str;
  52
  53  align = (align + len) & 3;
  54  if (align) len += (4-align);
  55  xreadall(fd, str = xmalloc(len+1), len);
  56  str[len]=0; // redundant, in case archive is bad
  57
  58  return str;
  59}
  60
  61//convert hex to uint; mostly to allow using bits of non-terminated strings
  62static unsigned x8u(char *hex)
  63{
  64  unsigned val, inpos = 8, outpos;
  65  char pattern[6];
  66
  67  while (*hex == '0') {
  68    hex++;
  69    if (!--inpos) return 0;
  70  }
  71  // Because scanf gratuitously treats %*X differently than printf does.
  72  sprintf(pattern, "%%%dX%%n", inpos);
  73  sscanf(hex, pattern, &val, &outpos);
  74  if (inpos != outpos) error_exit("bad header");
  75
  76  return val;
  77}
  78
  79void cpio_main(void)
  80{
  81  // Subtle bit: FLAG_o is 1 so we can just use it to select stdin/stdout.
  82  int pipe, afd = FLAG(o);
  83  pid_t pid = 0;
  84
  85  // In passthrough mode, parent stays in original dir and generates archive
  86  // to pipe, child does chdir to new dir and reads archive from stdin (pipe).
  87  if (TT.p) {
  88    if (toys.stacktop) {
  89      // xpopen() doesn't return from child due to vfork(), instead restarts
  90      // with !toys.stacktop
  91      pid = xpopen(0, &pipe, 0);
  92      afd = pipe;
  93    } else {
  94      // child
  95      toys.optflags |= FLAG_i;
  96      xchdir(TT.p);
  97    }
  98  }
  99
 100  if (TT.F) {
 101    int perm = FLAG(o) ? O_CREAT|O_WRONLY|O_TRUNC : O_RDONLY;
 102
 103    afd = xcreate(TT.F, perm, 0644);
 104  }
 105
 106  // read cpio archive
 107
 108  if (FLAG(i) || FLAG(t)) for (;;) {
 109    char *name, *tofree, *data;
 110    unsigned size, mode, uid, gid, timestamp;
 111    int test = FLAG(t), err = 0;
 112
 113    // Read header and name.
 114    if (!(size =readall(afd, toybuf, 110))) break;
 115    if (size != 110 || memcmp(toybuf, "070701", 6)) error_exit("bad header");
 116    tofree = name = strpad(afd, x8u(toybuf+94), 110);
 117    if (!strcmp("TRAILER!!!", name)) {
 118      if (CFG_TOYBOX_FREE) free(tofree);
 119      break;
 120    }
 121
 122    // If you want to extract absolute paths, "cd /" and run cpio.
 123    while (*name == '/') name++;
 124    // TODO: remove .. entries
 125
 126    size = x8u(toybuf+54);
 127    mode = x8u(toybuf+14);
 128    uid = x8u(toybuf+22);
 129    gid = x8u(toybuf+30);
 130    timestamp = x8u(toybuf+46); // unsigned 32 bit, so year 2100 problem
 131
 132    if (FLAG(t) || FLAG(v)) puts(name);
 133
 134    if (!test && strrchr(name, '/') && mkpath(name)) {
 135      perror_msg("mkpath '%s'", name);
 136      test++;
 137    }
 138
 139    // Consume entire record even if it couldn't create file, so we're
 140    // properly aligned with next file.
 141
 142    if (S_ISDIR(mode)) {
 143      if (!test) err = mkdir(name, mode);
 144    } else if (S_ISLNK(mode)) {
 145      data = strpad(afd, size, 0);
 146      if (!test) err = symlink(data, name);
 147      free(data);
 148      // Can't get a filehandle to a symlink, so do special chown
 149      if (!err && !geteuid() && !FLAG(no_preserve_owner))
 150        err = lchown(name, uid, gid);
 151    } else if (S_ISREG(mode)) {
 152      int fd = test ? 0 : open(name, O_CREAT|O_WRONLY|O_TRUNC|O_NOFOLLOW, mode);
 153
 154      // If write fails, we still need to read/discard data to continue with
 155      // archive. Since doing so overwrites errno, report error now
 156      if (fd < 0) {
 157        perror_msg("create %s", name);
 158        test++;
 159      }
 160
 161      data = toybuf;
 162      while (size) {
 163        if (size < sizeof(toybuf)) data = strpad(afd, size, 0);
 164        else xreadall(afd, toybuf, sizeof(toybuf));
 165        if (!test) xwrite(fd, data, data == toybuf ? sizeof(toybuf) : size);
 166        if (data != toybuf) {
 167          free(data);
 168          break;
 169        }
 170        size -= sizeof(toybuf);
 171      }
 172
 173      if (!test) {
 174        // set owner, restore dropped suid bit
 175        if (!geteuid() && !FLAG(no_preserve_owner)) {
 176          err = fchown(fd, uid, gid);
 177          if (!err) err = fchmod(fd, mode);
 178        }
 179        close(fd);
 180      }
 181    } else if (!test)
 182      err = mknod(name, mode, dev_makedev(x8u(toybuf+78), x8u(toybuf+86)));
 183
 184    // Set ownership and timestamp.
 185    if (!test && !err) {
 186      // Creading dir/dev doesn't give us a filehandle, we have to refer to it
 187      // by name to chown/utime, but how do we know it's the same item?
 188      // Check that we at least have the right type of entity open, and do
 189      // NOT restore dropped suid bit in this case.
 190      if (!S_ISREG(mode) && !S_ISLNK(mode) && !geteuid()
 191          && !FLAG(no_preserve_owner))
 192      {
 193        int fd = open(name, O_RDONLY|O_NOFOLLOW);
 194        struct stat st;
 195
 196        if (fd != -1 && !fstat(fd, &st) && (st.st_mode&S_IFMT) == (mode&S_IFMT))
 197          err = fchown(fd, uid, gid);
 198        else err = 1;
 199
 200        close(fd);
 201      }
 202
 203      // set timestamp
 204      if (!err) {
 205        struct timespec times[2];
 206
 207        memset(times, 0, sizeof(struct timespec)*2);
 208        times[0].tv_sec = times[1].tv_sec = timestamp;
 209        err = utimensat(AT_FDCWD, name, times, AT_SYMLINK_NOFOLLOW);
 210      }
 211    }
 212
 213    if (err) perror_msg_raw(name);
 214    free(tofree);
 215
 216  // Output cpio archive
 217
 218  } else {
 219    char *name = 0;
 220    size_t size = 0;
 221
 222    for (;;) {
 223      struct stat st;
 224      unsigned nlen, error = 0, zero = 0;
 225      int len, fd = -1;
 226      ssize_t llen;
 227
 228      len = getline(&name, &size, stdin);
 229      if (len<1) break;
 230      if (name[len-1] == '\n') name[--len] = 0;
 231      nlen = len+1;
 232      if (lstat(name, &st) || (S_ISREG(st.st_mode)
 233          && st.st_size && (fd = open(name, O_RDONLY))<0))
 234      {
 235        perror_msg_raw(name);
 236        continue;
 237      }
 238
 239      if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode)) st.st_size = 0;
 240      if (st.st_size >> 32) perror_msg("skipping >2G file '%s'", name);
 241      else {
 242        llen = sprintf(toybuf,
 243          "070701%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X",
 244          (int)st.st_ino, st.st_mode, st.st_uid, st.st_gid, (int)st.st_nlink,
 245          (int)st.st_mtime, (int)st.st_size, dev_major(st.st_dev),
 246          dev_minor(st.st_dev), dev_major(st.st_rdev), dev_minor(st.st_rdev),
 247          nlen, 0);
 248        xwrite(afd, toybuf, llen);
 249        xwrite(afd, name, nlen);
 250
 251        // NUL Pad header up to 4 multiple bytes.
 252        llen = (llen + nlen) & 3;
 253        if (llen) xwrite(afd, &zero, 4-llen);
 254
 255        // Write out body for symlink or regular file
 256        llen = st.st_size;
 257        if (S_ISLNK(st.st_mode)) {
 258          if (readlink(name, toybuf, sizeof(toybuf)-1) == llen)
 259            xwrite(afd, toybuf, llen);
 260          else perror_msg("readlink '%s'", name);
 261        } else while (llen) {
 262          nlen = llen > sizeof(toybuf) ? sizeof(toybuf) : llen;
 263          llen -= nlen;
 264          // If read fails, write anyway (already wrote size in header)
 265          if (nlen != readall(fd, toybuf, nlen))
 266            if (!error++) perror_msg("bad read from file '%s'", name);
 267          xwrite(afd, toybuf, nlen);
 268        }
 269        llen = st.st_size & 3;
 270        if (llen) xwrite(afd, &zero, 4-llen);
 271      }
 272      close(fd);
 273    }
 274    free(name);
 275
 276    memset(toybuf, 0, sizeof(toybuf));
 277    xwrite(afd, toybuf,
 278       sprintf(toybuf, "070701%040X%056X%08XTRAILER!!!", 1, 0x0b, 0)+4);
 279  }
 280  if (TT.F) xclose(afd);
 281
 282  if (TT.p) toys.exitval |= xpclose(pid, pipe);
 283}
 284