Dogcows Code - chaz/tar/blob - src/system.c

   1 /* System-dependent calls for tar.
   2
   3    Copyright 2003-2008, 2010, 2013-2014 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify it
   6    under the terms of the GNU General Public License as published by the
   7    Free Software Foundation; either version 3, or (at your option) any later
   8    version.
   9
  10    This program is distributed in the hope that it will be useful, but
  11    WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  13    Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License along
  16    with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #include <system.h>
  19
  20 #include "common.h"
  21 #include <priv-set.h>
  22 #include <rmt.h>
  23 #include <signal.h>
  24 #include <wordsplit.h>
  25
  26 static _Noreturn void
  27 xexec (const char *cmd)
  28 {
  29   struct wordsplit ws;
  30
  31   ws.ws_env = (const char **) environ;
  32   if (wordsplit (cmd, &ws, (WRDSF_DEFFLAGS | WRDSF_ENV) & ~WRDSF_NOVAR))
  33     FATAL_ERROR ((0, 0, _("cannot split string '%s': %s"),
  34                   cmd, wordsplit_strerror (&ws)));
  35   execvp (ws.ws_wordv[0], ws.ws_wordv);
  36   exec_fatal (cmd);
  37 }
  38
  39 #if MSDOS
  40
  41 bool
  42 sys_get_archive_stat (void)
  43 {
  44   return 0;
  45 }
  46
  47 bool
  48 sys_file_is_archive (struct tar_stat_info *p)
  49 {
  50   return false;
  51 }
  52
  53 void
  54 sys_save_archive_dev_ino (void)
  55 {
  56 }
  57
  58 void
  59 sys_detect_dev_null_output (void)
  60 {
  61   static char const dev_null[] = "nul";
  62
  63   dev_null_output = (strcmp (archive_name_array[0], dev_null) == 0
  64                      || (! _isrmt (archive)));
  65 }
  66
  67 void
  68 sys_wait_for_child (pid_t child_pid, bool eof)
  69 {
  70 }
  71
  72 void
  73 sys_spawn_shell (void)
  74 {
  75   spawnl (P_WAIT, getenv ("COMSPEC"), "-", 0);
  76 }
  77
  78 /* stat() in djgpp's C library gives a constant number of 42 as the
  79    uid and gid of a file.  So, comparing an FTP'ed archive just after
  80    unpack would fail on MSDOS.  */
  81
  82 bool
  83 sys_compare_uid (struct stat *a, struct stat *b)
  84 {
  85   return true;
  86 }
  87
  88 bool
  89 sys_compare_gid (struct stat *a, struct stat *b)
  90 {
  91   return true;
  92 }
  93
  94 void
  95 sys_compare_links (struct stat *link_data, struct stat *stat_data)
  96 {
  97   return true;
  98 }
  99
 100 int
 101 sys_truncate (int fd)
 102 {
 103   return write (fd, "", 0);
 104 }
 105
 106 size_t
 107 sys_write_archive_buffer (void)
 108 {
 109   return full_write (archive, record_start->buffer, record_size);
 110 }
 111
 112 /* Set ARCHIVE for writing, then compressing an archive.  */
 113 void
 114 sys_child_open_for_compress (void)
 115 {
 116   FATAL_ERROR ((0, 0, _("Cannot use compressed or remote archives")));
 117 }
 118
 119 /* Set ARCHIVE for uncompressing, then reading an archive.  */
 120 void
 121 sys_child_open_for_uncompress (void)
 122 {
 123   FATAL_ERROR ((0, 0, _("Cannot use compressed or remote archives")));
 124 }
 125
 126 #else
 127
 128 extern union block *record_start; /* FIXME */
 129
 130 static struct stat archive_stat; /* stat block for archive file */
 131
 132 bool
 133 sys_get_archive_stat (void)
 134 {
 135   return fstat (archive, &archive_stat) == 0;
 136 }
 137
 138 bool
 139 sys_file_is_archive (struct tar_stat_info *p)
 140 {
 141   return (ar_dev && p->stat.st_dev == ar_dev && p->stat.st_ino == ar_ino);
 142 }
 143
 144 /* Save archive file inode and device numbers */
 145 void
 146 sys_save_archive_dev_ino (void)
 147 {
 148   if (!_isrmt (archive) && S_ISREG (archive_stat.st_mode))
 149     {
 150       ar_dev = archive_stat.st_dev;
 151       ar_ino = archive_stat.st_ino;
 152     }
 153   else
 154     ar_dev = 0;
 155 }
 156
 157 /* Detect if outputting to "/dev/null".  */
 158 void
 159 sys_detect_dev_null_output (void)
 160 {
 161   static char const dev_null[] = "/dev/null";
 162   struct stat dev_null_stat;
 163
 164   dev_null_output = (strcmp (archive_name_array[0], dev_null) == 0
 165                      || (! _isrmt (archive)
 166                          && S_ISCHR (archive_stat.st_mode)
 167                          && stat (dev_null, &dev_null_stat) == 0
 168                          && archive_stat.st_dev == dev_null_stat.st_dev
 169                          && archive_stat.st_ino == dev_null_stat.st_ino));
 170 }
 171
 172 void
 173 sys_wait_for_child (pid_t child_pid, bool eof)
 174 {
 175   if (child_pid)
 176     {
 177       int wait_status;
 178
 179       while (waitpid (child_pid, &wait_status, 0) == -1)
 180         if (errno != EINTR)
 181           {
 182             waitpid_error (use_compress_program_option);
 183             break;
 184           }
 185
 186       if (WIFSIGNALED (wait_status))
 187         {
 188           int sig = WTERMSIG (wait_status);
 189           if (!(!eof && sig == SIGPIPE))
 190             FATAL_ERROR ((0, 0, _("Child died with signal %d"), sig));
 191         }
 192       else if (WEXITSTATUS (wait_status) != 0)
 193         FATAL_ERROR ((0, 0, _("Child returned status %d"),
 194                       WEXITSTATUS (wait_status)));
 195     }
 196 }
 197
 198 void
 199 sys_spawn_shell (void)
 200 {
 201   pid_t child;
 202   const char *shell = getenv ("SHELL");
 203   if (! shell)
 204     shell = "/bin/sh";
 205   child = xfork ();
 206   if (child == 0)
 207     {
 208       priv_set_restore_linkdir ();
 209       execlp (shell, "-sh", "-i", NULL);
 210       exec_fatal (shell);
 211     }
 212   else
 213     {
 214       int wait_status;
 215       while (waitpid (child, &wait_status, 0) == -1)
 216         if (errno != EINTR)
 217           {
 218             waitpid_error (shell);
 219             break;
 220           }
 221     }
 222 }
 223
 224 bool
 225 sys_compare_uid (struct stat *a, struct stat *b)
 226 {
 227   return a->st_uid == b->st_uid;
 228 }
 229
 230 bool
 231 sys_compare_gid (struct stat *a, struct stat *b)
 232 {
 233   return a->st_gid == b->st_gid;
 234 }
 235
 236 bool
 237 sys_compare_links (struct stat *link_data, struct stat *stat_data)
 238 {
 239   return stat_data->st_dev == link_data->st_dev
 240          && stat_data->st_ino == link_data->st_ino;
 241 }
 242
 243 int
 244 sys_truncate (int fd)
 245 {
 246   off_t pos = lseek (fd, (off_t) 0, SEEK_CUR);
 247   return pos < 0 ? -1 : ftruncate (fd, pos);
 248 }
 249
 250 /* Return nonzero if NAME is the name of a regular file, or if the file
 251    does not exist (so it would be created as a regular file).  */
 252 static int
 253 is_regular_file (const char *name)
 254 {
 255   struct stat stbuf;
 256
 257   if (stat (name, &stbuf) == 0)
 258     return S_ISREG (stbuf.st_mode);
 259   else
 260     return errno == ENOENT;
 261 }
 262
 263 size_t
 264 sys_write_archive_buffer (void)
 265 {
 266   return rmtwrite (archive, record_start->buffer, record_size);
 267 }
 268
 269 #define PREAD 0                 /* read file descriptor from pipe() */
 270 #define PWRITE 1                /* write file descriptor from pipe() */
 271
 272 /* Duplicate file descriptor FROM into becoming INTO.
 273    INTO is closed first and has to be the next available slot.  */
 274 static void
 275 xdup2 (int from, int into)
 276 {
 277   if (from != into)
 278     {
 279       int status = close (into);
 280
 281       if (status != 0 && errno != EBADF)
 282         {
 283           int e = errno;
 284           FATAL_ERROR ((0, e, _("Cannot close")));
 285         }
 286       status = dup (from);
 287       if (status != into)
 288         {
 289           if (status < 0)
 290             {
 291               int e = errno;
 292               FATAL_ERROR ((0, e, _("Cannot dup")));
 293             }
 294           abort ();
 295         }
 296       xclose (from);
 297     }
 298 }
 299
 300 static void wait_for_grandchild (pid_t pid) __attribute__ ((__noreturn__));
 301
 302 /* Propagate any failure of the grandchild back to the parent.  */
 303 static void
 304 wait_for_grandchild (pid_t pid)
 305 {
 306   int wait_status;
 307   int exit_code = 0;
 308
 309   while (waitpid (pid, &wait_status, 0) == -1)
 310     if (errno != EINTR)
 311       {
 312         waitpid_error (use_compress_program_option);
 313         break;
 314       }
 315
 316   if (WIFSIGNALED (wait_status))
 317     raise (WTERMSIG (wait_status));
 318   else if (WEXITSTATUS (wait_status) != 0)
 319     exit_code = WEXITSTATUS (wait_status);
 320
 321   exit (exit_code);
 322 }
 323
 324 /* Set ARCHIVE for writing, then compressing an archive.  */
 325 pid_t
 326 sys_child_open_for_compress (void)
 327 {
 328   int parent_pipe[2];
 329   int child_pipe[2];
 330   pid_t grandchild_pid;
 331   pid_t child_pid;
 332
 333   xpipe (parent_pipe);
 334   child_pid = xfork ();
 335
 336   if (child_pid > 0)
 337     {
 338       /* The parent tar is still here!  Just clean up.  */
 339
 340       archive = parent_pipe[PWRITE];
 341       xclose (parent_pipe[PREAD]);
 342       return child_pid;
 343     }
 344
 345   /* The new born child tar is here!  */
 346
 347   set_program_name (_("tar (child)"));
 348   signal (SIGPIPE, SIG_DFL);
 349
 350   xdup2 (parent_pipe[PREAD], STDIN_FILENO);
 351   xclose (parent_pipe[PWRITE]);
 352
 353   /* Check if we need a grandchild tar.  This happens only if either:
 354      a) the file is to be accessed by rmt: compressor doesn't know how;
 355      b) the file is not a plain file.  */
 356
 357   if (!_remdev (archive_name_array[0])
 358       && is_regular_file (archive_name_array[0]))
 359     {
 360       if (backup_option)
 361         maybe_backup_file (archive_name_array[0], 1);
 362
 363       /* We don't need a grandchild tar.  Open the archive and launch the
 364          compressor.  */
 365       if (strcmp (archive_name_array[0], "-"))
 366         {
 367           archive = creat (archive_name_array[0], MODE_RW);
 368           if (archive < 0)
 369             {
 370               int saved_errno = errno;
 371
 372               if (backup_option)
 373                 undo_last_backup ();
 374               errno = saved_errno;
 375               open_fatal (archive_name_array[0]);
 376             }
 377           xdup2 (archive, STDOUT_FILENO);
 378         }
 379       priv_set_restore_linkdir ();
 380       xexec (use_compress_program_option);
 381     }
 382
 383   /* We do need a grandchild tar.  */
 384
 385   xpipe (child_pipe);
 386   grandchild_pid = xfork ();
 387
 388   if (grandchild_pid == 0)
 389     {
 390       /* The newborn grandchild tar is here!  Launch the compressor.  */
 391
 392       set_program_name (_("tar (grandchild)"));
 393
 394       xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
 395       xclose (child_pipe[PREAD]);
 396       priv_set_restore_linkdir ();
 397       xexec (use_compress_program_option);
 398     }
 399
 400   /* The child tar is still here!  */
 401
 402   /* Prepare for reblocking the data from the compressor into the archive.  */
 403
 404   xdup2 (child_pipe[PREAD], STDIN_FILENO);
 405   xclose (child_pipe[PWRITE]);
 406
 407   if (strcmp (archive_name_array[0], "-") == 0)
 408     archive = STDOUT_FILENO;
 409   else
 410     {
 411       archive = rmtcreat (archive_name_array[0], MODE_RW, rsh_command_option);
 412       if (archive < 0)
 413         open_fatal (archive_name_array[0]);
 414     }
 415
 416   /* Let's read out of the stdin pipe and write an archive.  */
 417
 418   while (1)
 419     {
 420       size_t status = 0;
 421       char *cursor;
 422       size_t length;
 423
 424       /* Assemble a record.  */
 425
 426       for (length = 0, cursor = record_start->buffer;
 427            length < record_size;
 428            length += status, cursor += status)
 429         {
 430           size_t size = record_size - length;
 431
 432           status = safe_read (STDIN_FILENO, cursor, size);
 433           if (status == SAFE_READ_ERROR)
 434             read_fatal (use_compress_program_option);
 435           if (status == 0)
 436             break;
 437         }
 438
 439       /* Copy the record.  */
 440
 441       if (status == 0)
 442         {
 443           /* We hit the end of the file.  Write last record at
 444              full length, as the only role of the grandchild is
 445              doing proper reblocking.  */
 446
 447           if (length > 0)
 448             {
 449               memset (record_start->buffer + length, 0, record_size - length);
 450               status = sys_write_archive_buffer ();
 451               if (status != record_size)
 452                 archive_write_error (status);
 453             }
 454
 455           /* There is nothing else to read, break out.  */
 456           break;
 457         }
 458
 459       status = sys_write_archive_buffer ();
 460       if (status != record_size)
 461         archive_write_error (status);
 462     }
 463
 464   wait_for_grandchild (grandchild_pid);
 465 }
 466
 467 static void
 468 run_decompress_program (void)
 469 {
 470   int i;
 471   const char *p, *prog = NULL;
 472   struct wordsplit ws;
 473   int wsflags = (WRDSF_DEFFLAGS | WRDSF_ENV | WRDSF_DOOFFS) & ~WRDSF_NOVAR;
 474
 475   ws.ws_env = (const char **) environ;
 476   ws.ws_offs = 1;
 477
 478   for (p = first_decompress_program (&i); p; p = next_decompress_program (&i))
 479     {
 480       if (prog)
 481         {
 482           WARNOPT (WARN_DECOMPRESS_PROGRAM,
 483                    (0, errno, _("cannot run %s"), prog));
 484           WARNOPT (WARN_DECOMPRESS_PROGRAM,
 485                    (0, 0, _("trying %s"), p));
 486         }
 487       if (wordsplit (p, &ws, wsflags))
 488         FATAL_ERROR ((0, 0, _("cannot split string '%s': %s"),
 489                       p, wordsplit_strerror (&ws)));
 490       wsflags |= WRDSF_REUSE;
 491       memmove(ws.ws_wordv, ws.ws_wordv + ws.ws_offs,
 492               sizeof(ws.ws_wordv[0])*ws.ws_wordc);
 493       ws.ws_wordv[ws.ws_wordc] = (char *) "-d";
 494       prog = p;
 495       execvp (ws.ws_wordv[0], ws.ws_wordv);
 496       ws.ws_wordv[ws.ws_wordc] = NULL;
 497     }
 498   if (!prog)
 499     FATAL_ERROR ((0, 0, _("unable to run decompression program")));
 500   exec_fatal (prog);
 501 }
 502
 503 /* Set ARCHIVE for uncompressing, then reading an archive.  */
 504 pid_t
 505 sys_child_open_for_uncompress (void)
 506 {
 507   int parent_pipe[2];
 508   int child_pipe[2];
 509   pid_t grandchild_pid;
 510   pid_t child_pid;
 511
 512   xpipe (parent_pipe);
 513   child_pid = xfork ();
 514
 515   if (child_pid > 0)
 516     {
 517       /* The parent tar is still here!  Just clean up.  */
 518
 519       archive = parent_pipe[PREAD];
 520       xclose (parent_pipe[PWRITE]);
 521       return child_pid;
 522     }
 523
 524   /* The newborn child tar is here!  */
 525
 526   set_program_name (_("tar (child)"));
 527   signal (SIGPIPE, SIG_DFL);
 528
 529   xdup2 (parent_pipe[PWRITE], STDOUT_FILENO);
 530   xclose (parent_pipe[PREAD]);
 531
 532   /* Check if we need a grandchild tar.  This happens only if either:
 533      a) we're reading stdin: to force unblocking;
 534      b) the file is to be accessed by rmt: compressor doesn't know how;
 535      c) the file is not a plain file.  */
 536
 537   if (strcmp (archive_name_array[0], "-") != 0
 538       && !_remdev (archive_name_array[0])
 539       && is_regular_file (archive_name_array[0]))
 540     {
 541       /* We don't need a grandchild tar.  Open the archive and lauch the
 542          uncompressor.  */
 543
 544       archive = open (archive_name_array[0], O_RDONLY | O_BINARY, MODE_RW);
 545       if (archive < 0)
 546         open_fatal (archive_name_array[0]);
 547       xdup2 (archive, STDIN_FILENO);
 548       priv_set_restore_linkdir ();
 549       run_decompress_program ();
 550     }
 551
 552   /* We do need a grandchild tar.  */
 553
 554   xpipe (child_pipe);
 555   grandchild_pid = xfork ();
 556
 557   if (grandchild_pid == 0)
 558     {
 559       /* The newborn grandchild tar is here!  Launch the uncompressor.  */
 560
 561       set_program_name (_("tar (grandchild)"));
 562
 563       xdup2 (child_pipe[PREAD], STDIN_FILENO);
 564       xclose (child_pipe[PWRITE]);
 565       priv_set_restore_linkdir ();
 566       run_decompress_program ();
 567     }
 568
 569   /* The child tar is still here!  */
 570
 571   /* Prepare for unblocking the data from the archive into the
 572      uncompressor.  */
 573
 574   xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
 575   xclose (child_pipe[PREAD]);
 576
 577   if (strcmp (archive_name_array[0], "-") == 0)
 578     archive = STDIN_FILENO;
 579   else
 580     archive = rmtopen (archive_name_array[0], O_RDONLY | O_BINARY,
 581                        MODE_RW, rsh_command_option);
 582   if (archive < 0)
 583     open_fatal (archive_name_array[0]);
 584
 585   /* Let's read the archive and pipe it into stdout.  */
 586
 587   while (1)
 588     {
 589       char *cursor;
 590       size_t maximum;
 591       size_t count;
 592       size_t status;
 593
 594       clear_read_error_count ();
 595
 596     error_loop:
 597       status = rmtread (archive, record_start->buffer, record_size);
 598       if (status == SAFE_READ_ERROR)
 599         {
 600           archive_read_error ();
 601           goto error_loop;
 602         }
 603       if (status == 0)
 604         break;
 605       cursor = record_start->buffer;
 606       maximum = status;
 607       while (maximum)
 608         {
 609           count = maximum < BLOCKSIZE ? maximum : BLOCKSIZE;
 610           if (full_write (STDOUT_FILENO, cursor, count) != count)
 611             write_error (use_compress_program_option);
 612           cursor += count;
 613           maximum -= count;
 614         }
 615     }
 616
 617   xclose (STDOUT_FILENO);
 618
 619   wait_for_grandchild (grandchild_pid);
 620 }
 621
 622 \f
 623
 624 static void
 625 dec_to_env (char const *envar, uintmax_t num)
 626 {
 627   char buf[UINTMAX_STRSIZE_BOUND];
 628   char *numstr;
 629
 630   numstr = STRINGIFY_BIGINT (num, buf);
 631   if (setenv (envar, numstr, 1) != 0)
 632     xalloc_die ();
 633 }
 634
 635 static void
 636 time_to_env (char const *envar, struct timespec t)
 637 {
 638   char buf[TIMESPEC_STRSIZE_BOUND];
 639   if (setenv (envar, code_timespec (t, buf), 1) != 0)
 640     xalloc_die ();
 641 }
 642
 643 static void
 644 oct_to_env (char const *envar, unsigned long num)
 645 {
 646   char buf[1+1+(sizeof(unsigned long)*CHAR_BIT+2)/3];
 647
 648   snprintf (buf, sizeof buf, "0%lo", num);
 649   if (setenv (envar, buf, 1) != 0)
 650     xalloc_die ();
 651 }
 652
 653 static void
 654 str_to_env (char const *envar, char const *str)
 655 {
 656   if (str)
 657     {
 658       if (setenv (envar, str, 1) != 0)
 659         xalloc_die ();
 660     }
 661   else
 662     unsetenv (envar);
 663 }
 664
 665 static void
 666 chr_to_env (char const *envar, char c)
 667 {
 668   char buf[2];
 669   buf[0] = c;
 670   buf[1] = 0;
 671   if (setenv (envar, buf, 1) != 0)
 672     xalloc_die ();
 673 }
 674
 675 static void
 676 stat_to_env (char *name, char type, struct tar_stat_info *st)
 677 {
 678   str_to_env ("TAR_VERSION", PACKAGE_VERSION);
 679   str_to_env ("TAR_ARCHIVE", *archive_name_cursor);
 680   dec_to_env ("TAR_VOLUME", archive_name_cursor - archive_name_array + 1);
 681   dec_to_env ("TAR_BLOCKING_FACTOR", blocking_factor);
 682   str_to_env ("TAR_FORMAT",
 683               archive_format_string (current_format == DEFAULT_FORMAT ?
 684                                      archive_format : current_format));
 685   chr_to_env ("TAR_FILETYPE", type);
 686   oct_to_env ("TAR_MODE", st->stat.st_mode);
 687   str_to_env ("TAR_FILENAME", name);
 688   str_to_env ("TAR_REALNAME", st->file_name);
 689   str_to_env ("TAR_UNAME", st->uname);
 690   str_to_env ("TAR_GNAME", st->gname);
 691   time_to_env ("TAR_ATIME", st->atime);
 692   time_to_env ("TAR_MTIME", st->mtime);
 693   time_to_env ("TAR_CTIME", st->ctime);
 694   dec_to_env ("TAR_SIZE", st->stat.st_size);
 695   dec_to_env ("TAR_UID", st->stat.st_uid);
 696   dec_to_env ("TAR_GID", st->stat.st_gid);
 697
 698   switch (type)
 699     {
 700     case 'b':
 701     case 'c':
 702       dec_to_env ("TAR_MINOR", minor (st->stat.st_rdev));
 703       dec_to_env ("TAR_MAJOR", major (st->stat.st_rdev));
 704       unsetenv ("TAR_LINKNAME");
 705       break;
 706
 707     case 'l':
 708     case 'h':
 709       unsetenv ("TAR_MINOR");
 710       unsetenv ("TAR_MAJOR");
 711       str_to_env ("TAR_LINKNAME", st->link_name);
 712       break;
 713
 714     default:
 715       unsetenv ("TAR_MINOR");
 716       unsetenv ("TAR_MAJOR");
 717       unsetenv ("TAR_LINKNAME");
 718       break;
 719     }
 720 }
 721
 722 static pid_t global_pid;
 723 static void (*pipe_handler) (int sig);
 724
 725 int
 726 sys_exec_command (char *file_name, int typechar, struct tar_stat_info *st)
 727 {
 728   int p[2];
 729
 730   xpipe (p);
 731   pipe_handler = signal (SIGPIPE, SIG_IGN);
 732   global_pid = xfork ();
 733
 734   if (global_pid != 0)
 735     {
 736       xclose (p[PREAD]);
 737       return p[PWRITE];
 738     }
 739
 740   /* Child */
 741   xdup2 (p[PREAD], STDIN_FILENO);
 742   xclose (p[PWRITE]);
 743
 744   stat_to_env (file_name, typechar, st);
 745
 746   priv_set_restore_linkdir ();
 747   xexec (to_command_option);
 748 }
 749
 750 void
 751 sys_wait_command (void)
 752 {
 753   int status;
 754
 755   if (global_pid < 0)
 756     return;
 757
 758   signal (SIGPIPE, pipe_handler);
 759   while (waitpid (global_pid, &status, 0) == -1)
 760     if (errno != EINTR)
 761       {
 762         global_pid = -1;
 763         waitpid_error (to_command_option);
 764         return;
 765       }
 766
 767   if (WIFEXITED (status))
 768     {
 769       if (!ignore_command_error_option && WEXITSTATUS (status))
 770         ERROR ((0, 0, _("%lu: Child returned status %d"),
 771                 (unsigned long) global_pid, WEXITSTATUS (status)));
 772     }
 773   else if (WIFSIGNALED (status))
 774     {
 775       WARN ((0, 0, _("%lu: Child terminated on signal %d"),
 776              (unsigned long) global_pid, WTERMSIG (status)));
 777     }
 778   else
 779     ERROR ((0, 0, _("%lu: Child terminated on unknown reason"),
 780             (unsigned long) global_pid));
 781
 782   global_pid = -1;
 783 }
 784
 785 int
 786 sys_exec_info_script (const char **archive_name, int volume_number)
 787 {
 788   pid_t pid;
 789   char uintbuf[UINTMAX_STRSIZE_BOUND];
 790   int p[2];
 791   static void (*saved_handler) (int sig);
 792
 793   xpipe (p);
 794   saved_handler = signal (SIGPIPE, SIG_IGN);
 795
 796   pid = xfork ();
 797
 798   if (pid != 0)
 799     {
 800       /* Master */
 801
 802       int rc;
 803       int status;
 804       char *buf = NULL;
 805       size_t size = 0;
 806       FILE *fp;
 807
 808       xclose (p[PWRITE]);
 809       fp = fdopen (p[PREAD], "r");
 810       rc = getline (&buf, &size, fp);
 811       fclose (fp);
 812
 813       if (rc > 0 && buf[rc-1] == '\n')
 814         buf[--rc] = 0;
 815
 816       while (waitpid (pid, &status, 0) == -1)
 817         if (errno != EINTR)
 818           {
 819             signal (SIGPIPE, saved_handler);
 820             waitpid_error (info_script_option);
 821             return -1;
 822           }
 823
 824       signal (SIGPIPE, saved_handler);
 825
 826       if (WIFEXITED (status))
 827         {
 828           if (WEXITSTATUS (status) == 0 && rc > 0)
 829             *archive_name = buf;
 830           else
 831             free (buf);
 832           return WEXITSTATUS (status);
 833         }
 834
 835       free (buf);
 836       return -1;
 837     }
 838
 839   /* Child */
 840   setenv ("TAR_VERSION", PACKAGE_VERSION, 1);
 841   setenv ("TAR_ARCHIVE", *archive_name, 1);
 842   setenv ("TAR_VOLUME", STRINGIFY_BIGINT (volume_number, uintbuf), 1);
 843   setenv ("TAR_BLOCKING_FACTOR",
 844           STRINGIFY_BIGINT (blocking_factor, uintbuf), 1);
 845   setenv ("TAR_SUBCOMMAND", subcommand_string (subcommand_option), 1);
 846   setenv ("TAR_FORMAT",
 847           archive_format_string (current_format == DEFAULT_FORMAT ?
 848                                  archive_format : current_format), 1);
 849   setenv ("TAR_FD", STRINGIFY_BIGINT (p[PWRITE], uintbuf), 1);
 850
 851   xclose (p[PREAD]);
 852
 853   priv_set_restore_linkdir ();
 854   xexec (info_script_option);
 855 }
 856
 857 void
 858 sys_exec_checkpoint_script (const char *script_name,
 859                             const char *archive_name,
 860                             int checkpoint_number)
 861 {
 862   pid_t pid;
 863   char uintbuf[UINTMAX_STRSIZE_BOUND];
 864
 865   pid = xfork ();
 866
 867   if (pid != 0)
 868     {
 869       /* Master */
 870
 871       int status;
 872
 873       while (waitpid (pid, &status, 0) == -1)
 874         if (errno != EINTR)
 875           {
 876             waitpid_error (script_name);
 877             break;
 878           }
 879
 880       return;
 881     }
 882
 883   /* Child */
 884   setenv ("TAR_VERSION", PACKAGE_VERSION, 1);
 885   setenv ("TAR_ARCHIVE", archive_name, 1);
 886   setenv ("TAR_CHECKPOINT", STRINGIFY_BIGINT (checkpoint_number, uintbuf), 1);
 887   setenv ("TAR_BLOCKING_FACTOR",
 888           STRINGIFY_BIGINT (blocking_factor, uintbuf), 1);
 889   setenv ("TAR_SUBCOMMAND", subcommand_string (subcommand_option), 1);
 890   setenv ("TAR_FORMAT",
 891           archive_format_string (current_format == DEFAULT_FORMAT ?
 892                                  archive_format : current_format), 1);
 893   priv_set_restore_linkdir ();
 894   xexec (script_name);
 895 }
 896
 897 #endif /* not MSDOS */