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)(trailer)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    --trailer Add legacy trailer (prevents concatenation)
  38*/
  39
  40#define FOR_cpio
  41#include "toys.h"
  42
  43GLOBALS(
  44  char *F, *p, *H;
  45)
  46
  47// Read strings, tail padded to 4 byte alignment. Argument "align" is amount
  48// by which start of string isn't aligned (usually 0, but header is 110 bytes
  49// which is 2 bytes off because the first field wasn't expanded from 6 to 8).
  50static char *strpad(int fd, unsigned len, unsigned align)
  51{
  52  char *str;
  53
  54  align = (align + len) & 3;
  55  if (align) len += (4-align);
  56  xreadall(fd, str = xmalloc(len+1), len);
  57  str[len]=0; // redundant, in case archive is bad
  58
  59  return str;
  60}
  61
  62//convert hex to uint; mostly to allow using bits of non-terminated strings
  63static unsigned x8u(char *hex)
  64{
  65  unsigned val, inpos = 8, outpos;
  66  char pattern[6];
  67
  68  while (*hex == '0') {
  69    hex++;
  70    if (!--inpos) return 0;
  71  }
  72  // Because scanf gratuitously treats %*X differently than printf does.
  73  sprintf(pattern, "%%%dX%%n", inpos);
  74  sscanf(hex, pattern, &val, &outpos);
  75  if (inpos != outpos) error_exit("bad header");
  76
  77  return val;
  78}
  79
  80void cpio_main(void)
  81{
  82  // Subtle bit: FLAG_o is 1 so we can just use it to select stdin/stdout.
  83  int pipe, afd = toys.optflags & FLAG_o;
  84  pid_t pid = 0;
  85
  86  // In passthrough mode, parent stays in original dir and generates archive
  87  // to pipe, child does chdir to new dir and reads archive from stdin (pipe).
  88  if (TT.p) {
  89    if (toys.stacktop) {
  90      // xpopen() doesn't return from child due to vfork(), instead restarts
  91      // with !toys.stacktop
  92      pid = xpopen(0, &pipe, 0);
  93      afd = pipe;
  94    } else {
  95      // child
  96      toys.optflags |= FLAG_i;
  97      xchdir(TT.p);
  98    }
  99  }
 100
 101  if (TT.F) {
 102    int perm = (toys.optflags & FLAG_o) ? O_CREAT|O_WRONLY|O_TRUNC : O_RDONLY;
 103
 104    afd = xcreate(TT.F, perm, 0644);
 105  }
 106
 107  // read cpio archive
 108
 109  if (toys.optflags & (FLAG_i|FLAG_t)) for (;;) {
 110    char *name, *tofree, *data;
 111    unsigned size, mode, uid, gid, timestamp;
 112    int test = toys.optflags & FLAG_t, err = 0;
 113
 114    // Read header and name.
 115    if (!(size =readall(afd, toybuf, 110))) break;
 116    if (size != 110 || memcmp(toybuf, "070701", 6)) error_exit("bad header");
 117    tofree = name = strpad(afd, x8u(toybuf+94), 110);
 118    if (!strcmp("TRAILER!!!", name)) {
 119      if (CFG_TOYBOX_FREE) free(tofree);
 120      break;
 121    }
 122
 123    // If you want to extract absolute paths, "cd /" and run cpio.
 124    while (*name == '/') name++;
 125    // TODO: remove .. entries
 126
 127    size = x8u(toybuf+54);
 128    mode = x8u(toybuf+14);
 129    uid = x8u(toybuf+22);
 130    gid = x8u(toybuf+30);
 131    timestamp = x8u(toybuf+46); // unsigned 32 bit, so year 2100 problem
 132
 133    if (toys.optflags & (FLAG_t|FLAG_v)) puts(name);
 134
 135    if (!test && strrchr(name, '/') && mkpath(name)) {
 136      perror_msg("mkpath '%s'", name);
 137      test++;
 138    }
 139
 140    // Consume entire record even if it couldn't create file, so we're
 141    // properly aligned with next file.
 142
 143    if (S_ISDIR(mode)) {
 144      if (!test) err = mkdir(name, mode);
 145    } else if (S_ISLNK(mode)) {
 146      data = strpad(afd, size, 0);
 147      if (!test) err = symlink(data, name);
 148      free(data);
 149      // Can't get a filehandle to a symlink, so do special chown
 150      if (!err && !geteuid() && !(toys.optflags & FLAG_no_preserve_owner))
 151        err = lchown(name, uid, gid);
 152    } else if (S_ISREG(mode)) {
 153      int fd = test ? 0 : open(name, O_CREAT|O_WRONLY|O_TRUNC|O_NOFOLLOW, mode);
 154
 155      // If write fails, we still need to read/discard data to continue with
 156      // archive. Since doing so overwrites errno, report error now
 157      if (fd < 0) {
 158        perror_msg("create %s", name);
 159        test++;
 160      }
 161
 162      data = toybuf;
 163      while (size) {
 164        if (size < sizeof(toybuf)) data = strpad(afd, size, 0);
 165        else xreadall(afd, toybuf, sizeof(toybuf));
 166        if (!test) xwrite(fd, data, data == toybuf ? sizeof(toybuf) : size);
 167        if (data != toybuf) {
 168          free(data);
 169          break;
 170        }
 171        size -= sizeof(toybuf);
 172      }
 173
 174      if (!test) {
 175        // set owner, restore dropped suid bit
 176        if (!geteuid() && !(toys.optflags & FLAG_no_preserve_owner)) {
 177          err = fchown(fd, uid, gid);
 178          if (!err) err = fchmod(fd, mode);
 179        }
 180        close(fd);
 181      }
 182    } else if (!test)
 183      err = mknod(name, mode, dev_makedev(x8u(toybuf+78), x8u(toybuf+86)));
 184
 185    // Set ownership and timestamp.
 186    if (!test && !err) {
 187      // Creading dir/dev doesn't give us a filehandle, we have to refer to it
 188      // by name to chown/utime, but how do we know it's the same item?
 189      // Check that we at least have the right type of entity open, and do
 190      // NOT restore dropped suid bit in this case.
 191      if (!S_ISREG(mode) && !S_ISLNK(mode) && !geteuid()
 192          && !(toys.optflags & FLAG_no_preserve_owner))
 193      {
 194        int fd = open(name, O_RDONLY|O_NOFOLLOW);
 195        struct stat st;
 196
 197        if (fd != -1 && !fstat(fd, &st) && (st.st_mode&S_IFMT) == (mode&S_IFMT))
 198          err = fchown(fd, uid, gid);
 199        else err = 1;
 200
 201        close(fd);
 202      }
 203
 204      // set timestamp
 205      if (!err) {
 206        struct timespec times[2];
 207
 208        memset(times, 0, sizeof(struct timespec)*2);
 209        times[0].tv_sec = times[1].tv_sec = timestamp;
 210        err = utimensat(AT_FDCWD, name, times, AT_SYMLINK_NOFOLLOW);
 211      }
 212    }
 213
 214    if (err) perror_msg_raw(name);
 215    free(tofree);
 216
 217  // Output cpio archive
 218
 219  } else {
 220    char *name = 0;
 221    size_t size = 0;
 222
 223    for (;;) {
 224      struct stat st;
 225      unsigned nlen, error = 0, zero = 0;
 226      int len, fd = -1;
 227      ssize_t llen;
 228
 229      len = getline(&name, &size, stdin);
 230      if (len<1) break;
 231      if (name[len-1] == '\n') name[--len] = 0;
 232      nlen = len+1;
 233      if (lstat(name, &st) || (S_ISREG(st.st_mode)
 234          && st.st_size && (fd = open(name, O_RDONLY))<0))
 235      {
 236        perror_msg_raw(name);
 237        continue;
 238      }
 239
 240      if (!S_ISREG(st.st_mode) && !S_ISLNK(st.st_mode)) st.st_size = 0;
 241      if (st.st_size >> 32) perror_msg("skipping >2G file '%s'", name);
 242      else {
 243        llen = sprintf(toybuf,
 244          "070701%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X%08X",
 245          (int)st.st_ino, st.st_mode, st.st_uid, st.st_gid, (int)st.st_nlink,
 246          (int)st.st_mtime, (int)st.st_size, dev_major(st.st_dev),
 247          dev_minor(st.st_dev), dev_major(st.st_rdev), dev_minor(st.st_rdev),
 248          nlen, 0);
 249        xwrite(afd, toybuf, llen);
 250        xwrite(afd, name, nlen);
 251
 252        // NUL Pad header up to 4 multiple bytes.
 253        llen = (llen + nlen) & 3;
 254        if (llen) xwrite(afd, &zero, 4-llen);
 255
 256        // Write out body for symlink or regular file
 257        llen = st.st_size;
 258        if (S_ISLNK(st.st_mode)) {
 259          if (readlink(name, toybuf, sizeof(toybuf)-1) == llen)
 260            xwrite(afd, toybuf, llen);
 261          else perror_msg("readlink '%s'", name);
 262        } else while (llen) {
 263          nlen = llen > sizeof(toybuf) ? sizeof(toybuf) : llen;
 264          llen -= nlen;
 265          // If read fails, write anyway (already wrote size in header)
 266          if (nlen != readall(fd, toybuf, nlen))
 267            if (!error++) perror_msg("bad read from file '%s'", name);
 268          xwrite(afd, toybuf, nlen);
 269        }
 270        llen = st.st_size & 3;
 271        if (llen) xwrite(afd, &zero, 4-llen);
 272      }
 273      close(fd);
 274    }
 275    free(name);
 276
 277    if (FLAG_trailer) {
 278      memset(toybuf, 0, sizeof(toybuf));
 279      xwrite(afd, toybuf,
 280        sprintf(toybuf, "070701%040X%056X%08XTRAILER!!!", 1, 0x0b, 0)+4);
 281    }
 282  }
 283  if (TT.F) xclose(afd);
 284
 285  if (TT.p) toys.exitval |= xpclose(pid, pipe);
 286}
 287