src/system.c

   1 /* System-dependent calls for tar.
   2
   3    Copyright (C) 2003, 2004, 2005, 2006, 2007,
   4    2008, 2010 Free Software Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by the
   8    Free Software Foundation; either version 3, or (at your option) any later
   9    version.
  10
  11    This program is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  14    Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License along
  17    with this program; if not, write to the Free Software Foundation, Inc.,
  18    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 #include <system.h>
  21
  22 #include "common.h"
  23 #include <priv-set.h>
  24 #include <rmt.h>
  25 #include <signal.h>
  26
  27 #if MSDOS
  28
  29 bool
  30 sys_get_archive_stat (void)
  31 {
  32   return 0;
  33 }
  34
  35 bool
  36 sys_file_is_archive (struct tar_stat_info *p)
  37 {
  38   return false;
  39 }
  40
  41 void
  42 sys_save_archive_dev_ino (void)
  43 {
  44 }
  45
  46 void
  47 sys_detect_dev_null_output (void)
  48 {
  49   static char const dev_null[] = "nul";
  50
  51   dev_null_output = (strcmp (archive_name_array[0], dev_null) == 0
  52                      || (! _isrmt (archive)));
  53 }
  54
  55 void
  56 sys_wait_for_child (pid_t child_pid, bool eof)
  57 {
  58 }
  59
  60 void
  61 sys_spawn_shell (void)
  62 {
  63   spawnl (P_WAIT, getenv ("COMSPEC"), "-", 0);
  64 }
  65
  66 /* stat() in djgpp's C library gives a constant number of 42 as the
  67    uid and gid of a file.  So, comparing an FTP'ed archive just after
  68    unpack would fail on MSDOS.  */
  69
  70 bool
  71 sys_compare_uid (struct stat *a, struct stat *b)
  72 {
  73   return true;
  74 }
  75
  76 bool
  77 sys_compare_gid (struct stat *a, struct stat *b)
  78 {
  79   return true;
  80 }
  81
  82 void
  83 sys_compare_links (struct stat *link_data, struct stat *stat_data)
  84 {
  85   return true;
  86 }
  87
  88 int
  89 sys_truncate (int fd)
  90 {
  91   return write (fd, "", 0);
  92 }
  93
  94 size_t
  95 sys_write_archive_buffer (void)
  96 {
  97   return full_write (archive, record_start->buffer, record_size);
  98 }
  99
 100 /* Set ARCHIVE for writing, then compressing an archive.  */
 101 void
 102 sys_child_open_for_compress (void)
 103 {
 104   FATAL_ERROR ((0, 0, _("Cannot use compressed or remote archives")));
 105 }
 106
 107 /* Set ARCHIVE for uncompressing, then reading an archive.  */
 108 void
 109 sys_child_open_for_uncompress (void)
 110 {
 111   FATAL_ERROR ((0, 0, _("Cannot use compressed or remote archives")));
 112 }
 113
 114 #else
 115
 116 extern union block *record_start; /* FIXME */
 117
 118 static struct stat archive_stat; /* stat block for archive file */
 119
 120 bool
 121 sys_get_archive_stat (void)
 122 {
 123   return fstat (archive, &archive_stat) == 0;
 124 }
 125
 126 bool
 127 sys_file_is_archive (struct tar_stat_info *p)
 128 {
 129   return (ar_dev && p->stat.st_dev == ar_dev && p->stat.st_ino == ar_ino);
 130 }
 131
 132 /* Save archive file inode and device numbers */
 133 void
 134 sys_save_archive_dev_ino (void)
 135 {
 136   if (!_isrmt (archive) && S_ISREG (archive_stat.st_mode))
 137     {
 138       ar_dev = archive_stat.st_dev;
 139       ar_ino = archive_stat.st_ino;
 140     }
 141   else
 142     ar_dev = 0;
 143 }
 144
 145 /* Detect if outputting to "/dev/null".  */
 146 void
 147 sys_detect_dev_null_output (void)
 148 {
 149   static char const dev_null[] = "/dev/null";
 150   struct stat dev_null_stat;
 151
 152   dev_null_output = (strcmp (archive_name_array[0], dev_null) == 0
 153                      || (! _isrmt (archive)
 154                          && S_ISCHR (archive_stat.st_mode)
 155                          && stat (dev_null, &dev_null_stat) == 0
 156                          && archive_stat.st_dev == dev_null_stat.st_dev
 157                          && archive_stat.st_ino == dev_null_stat.st_ino));
 158 }
 159
 160 void
 161 sys_wait_for_child (pid_t child_pid, bool eof)
 162 {
 163   if (child_pid)
 164     {
 165       int wait_status;
 166
 167       while (waitpid (child_pid, &wait_status, 0) == -1)
 168         if (errno != EINTR)
 169           {
 170             waitpid_error (use_compress_program_option);
 171             break;
 172           }
 173
 174       if (WIFSIGNALED (wait_status))
 175         {
 176           int sig = WTERMSIG (wait_status);
 177           if (!(!eof && sig == SIGPIPE))
 178             FATAL_ERROR ((0, 0, _("Child died with signal %d"), sig));
 179         }
 180       else if (WEXITSTATUS (wait_status) != 0)
 181         FATAL_ERROR ((0, 0, _("Child returned status %d"),
 182                       WEXITSTATUS (wait_status)));
 183     }
 184 }
 185
 186 void
 187 sys_spawn_shell (void)
 188 {
 189   pid_t child;
 190   const char *shell = getenv ("SHELL");
 191   if (! shell)
 192     shell = "/bin/sh";
 193   child = xfork ();
 194   if (child == 0)
 195     {
 196       priv_set_restore_linkdir ();
 197       execlp (shell, "-sh", "-i", (char *) 0);
 198       exec_fatal (shell);
 199     }
 200   else
 201     {
 202       int wait_status;
 203       while (waitpid (child, &wait_status, 0) == -1)
 204         if (errno != EINTR)
 205           {
 206             waitpid_error (shell);
 207             break;
 208           }
 209     }
 210 }
 211
 212 bool
 213 sys_compare_uid (struct stat *a, struct stat *b)
 214 {
 215   return a->st_uid == b->st_uid;
 216 }
 217
 218 bool
 219 sys_compare_gid (struct stat *a, struct stat *b)
 220 {
 221   return a->st_gid == b->st_gid;
 222 }
 223
 224 bool
 225 sys_compare_links (struct stat *link_data, struct stat *stat_data)
 226 {
 227   return stat_data->st_dev == link_data->st_dev
 228          && stat_data->st_ino == link_data->st_ino;
 229 }
 230
 231 int
 232 sys_truncate (int fd)
 233 {
 234   off_t pos = lseek (fd, (off_t) 0, SEEK_CUR);
 235   return pos < 0 ? -1 : ftruncate (fd, pos);
 236 }
 237
 238 /* Return nonzero if NAME is the name of a regular file, or if the file
 239    does not exist (so it would be created as a regular file).  */
 240 static int
 241 is_regular_file (const char *name)
 242 {
 243   struct stat stbuf;
 244
 245   if (stat (name, &stbuf) == 0)
 246     return S_ISREG (stbuf.st_mode);
 247   else
 248     return errno == ENOENT;
 249 }
 250
 251 size_t
 252 sys_write_archive_buffer (void)
 253 {
 254   return rmtwrite (archive, record_start->buffer, record_size);
 255 }
 256
 257 #define PREAD 0                 /* read file descriptor from pipe() */
 258 #define PWRITE 1                /* write file descriptor from pipe() */
 259
 260 /* Duplicate file descriptor FROM into becoming INTO.
 261    INTO is closed first and has to be the next available slot.  */
 262 static void
 263 xdup2 (int from, int into)
 264 {
 265   if (from != into)
 266     {
 267       int status = close (into);
 268
 269       if (status != 0 && errno != EBADF)
 270         {
 271           int e = errno;
 272           FATAL_ERROR ((0, e, _("Cannot close")));
 273         }
 274       status = dup (from);
 275       if (status != into)
 276         {
 277           if (status < 0)
 278             {
 279               int e = errno;
 280               FATAL_ERROR ((0, e, _("Cannot dup")));
 281             }
 282           abort ();
 283         }
 284       xclose (from);
 285     }
 286 }
 287
 288 static void wait_for_grandchild (pid_t pid) __attribute__ ((__noreturn__));
 289
 290 /* Propagate any failure of the grandchild back to the parent.  */
 291 static void
 292 wait_for_grandchild (pid_t pid)
 293 {
 294   int wait_status;
 295   int exit_code = 0;
 296
 297   while (waitpid (pid, &wait_status, 0) == -1)
 298     if (errno != EINTR)
 299       {
 300         waitpid_error (use_compress_program_option);
 301         break;
 302       }
 303
 304   if (WIFSIGNALED (wait_status))
 305     raise (WTERMSIG (wait_status));
 306   else if (WEXITSTATUS (wait_status) != 0)
 307     exit_code = WEXITSTATUS (wait_status);
 308
 309   exit (exit_code);
 310 }
 311
 312 /* Set ARCHIVE for writing, then compressing an archive.  */
 313 pid_t
 314 sys_child_open_for_compress (void)
 315 {
 316   int parent_pipe[2];
 317   int child_pipe[2];
 318   pid_t grandchild_pid;
 319   pid_t child_pid;
 320
 321   xpipe (parent_pipe);
 322   child_pid = xfork ();
 323
 324   if (child_pid > 0)
 325     {
 326       /* The parent tar is still here!  Just clean up.  */
 327
 328       archive = parent_pipe[PWRITE];
 329       xclose (parent_pipe[PREAD]);
 330       return child_pid;
 331     }
 332
 333   /* The new born child tar is here!  */
 334
 335   set_program_name (_("tar (child)"));
 336   signal (SIGPIPE, SIG_DFL);
 337
 338   xdup2 (parent_pipe[PREAD], STDIN_FILENO);
 339   xclose (parent_pipe[PWRITE]);
 340
 341   /* Check if we need a grandchild tar.  This happens only if either:
 342      a) the file is to be accessed by rmt: compressor doesn't know how;
 343      b) the file is not a plain file.  */
 344
 345   if (!_remdev (archive_name_array[0])
 346       && is_regular_file (archive_name_array[0]))
 347     {
 348       if (backup_option)
 349         maybe_backup_file (archive_name_array[0], 1);
 350
 351       /* We don't need a grandchild tar.  Open the archive and launch the
 352          compressor.  */
 353       if (strcmp (archive_name_array[0], "-"))
 354         {
 355           archive = creat (archive_name_array[0], MODE_RW);
 356           if (archive < 0)
 357             {
 358               int saved_errno = errno;
 359
 360               if (backup_option)
 361                 undo_last_backup ();
 362               errno = saved_errno;
 363               open_fatal (archive_name_array[0]);
 364             }
 365           xdup2 (archive, STDOUT_FILENO);
 366         }
 367       priv_set_restore_linkdir ();
 368       execlp (use_compress_program_option, use_compress_program_option, NULL);
 369       exec_fatal (use_compress_program_option);
 370     }
 371
 372   /* We do need a grandchild tar.  */
 373
 374   xpipe (child_pipe);
 375   grandchild_pid = xfork ();
 376
 377   if (grandchild_pid == 0)
 378     {
 379       /* The newborn grandchild tar is here!  Launch the compressor.  */
 380
 381       set_program_name (_("tar (grandchild)"));
 382
 383       xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
 384       xclose (child_pipe[PREAD]);
 385       priv_set_restore_linkdir ();
 386       execlp (use_compress_program_option, use_compress_program_option,
 387               (char *) 0);
 388       exec_fatal (use_compress_program_option);
 389     }
 390
 391   /* The child tar is still here!  */
 392
 393   /* Prepare for reblocking the data from the compressor into the archive.  */
 394
 395   xdup2 (child_pipe[PREAD], STDIN_FILENO);
 396   xclose (child_pipe[PWRITE]);
 397
 398   if (strcmp (archive_name_array[0], "-") == 0)
 399     archive = STDOUT_FILENO;
 400   else
 401     {
 402       archive = rmtcreat (archive_name_array[0], MODE_RW, rsh_command_option);
 403       if (archive < 0)
 404         open_fatal (archive_name_array[0]);
 405     }
 406
 407   /* Let's read out of the stdin pipe and write an archive.  */
 408
 409   while (1)
 410     {
 411       size_t status = 0;
 412       char *cursor;
 413       size_t length;
 414
 415       /* Assemble a record.  */
 416
 417       for (length = 0, cursor = record_start->buffer;
 418            length < record_size;
 419            length += status, cursor += status)
 420         {
 421           size_t size = record_size - length;
 422
 423           status = safe_read (STDIN_FILENO, cursor, size);
 424           if (status == SAFE_READ_ERROR)
 425             read_fatal (use_compress_program_option);
 426           if (status == 0)
 427             break;
 428         }
 429
 430       /* Copy the record.  */
 431
 432       if (status == 0)
 433         {
 434           /* We hit the end of the file.  Write last record at
 435              full length, as the only role of the grandchild is
 436              doing proper reblocking.  */
 437
 438           if (length > 0)
 439             {
 440               memset (record_start->buffer + length, 0, record_size - length);
 441               status = sys_write_archive_buffer ();
 442               if (status != record_size)
 443                 archive_write_error (status);
 444             }
 445
 446           /* There is nothing else to read, break out.  */
 447           break;
 448         }
 449
 450       status = sys_write_archive_buffer ();
 451       if (status != record_size)
 452         archive_write_error (status);
 453     }
 454
 455   wait_for_grandchild (grandchild_pid);
 456 }
 457
 458 static void
 459 run_decompress_program (void)
 460 {
 461   int i;
 462   const char *p, *prog = NULL;
 463
 464   for (p = first_decompress_program (&i); p; p = next_decompress_program (&i))
 465     {
 466       if (prog)
 467         {
 468           WARNOPT (WARN_DECOMPRESS_PROGRAM,
 469                    (0, errno, _("cannot run %s"), prog));
 470           WARNOPT (WARN_DECOMPRESS_PROGRAM,
 471                    (0, 0, _("trying %s"), p));
 472         }
 473       prog = p;
 474       execlp (p, p, "-d", NULL);
 475     }
 476   if (!prog)
 477     FATAL_ERROR ((0, 0, _("unable to run decompression program")));
 478   exec_fatal (prog);
 479 }
 480
 481 /* Set ARCHIVE for uncompressing, then reading an archive.  */
 482 pid_t
 483 sys_child_open_for_uncompress (void)
 484 {
 485   int parent_pipe[2];
 486   int child_pipe[2];
 487   pid_t grandchild_pid;
 488   pid_t child_pid;
 489
 490   xpipe (parent_pipe);
 491   child_pid = xfork ();
 492
 493   if (child_pid > 0)
 494     {
 495       /* The parent tar is still here!  Just clean up.  */
 496
 497       archive = parent_pipe[PREAD];
 498       xclose (parent_pipe[PWRITE]);
 499       return child_pid;
 500     }
 501
 502   /* The newborn child tar is here!  */
 503
 504   set_program_name (_("tar (child)"));
 505   signal (SIGPIPE, SIG_DFL);
 506
 507   xdup2 (parent_pipe[PWRITE], STDOUT_FILENO);
 508   xclose (parent_pipe[PREAD]);
 509
 510   /* Check if we need a grandchild tar.  This happens only if either:
 511      a) we're reading stdin: to force unblocking;
 512      b) the file is to be accessed by rmt: compressor doesn't know how;
 513      c) the file is not a plain file.  */
 514
 515   if (strcmp (archive_name_array[0], "-") != 0
 516       && !_remdev (archive_name_array[0])
 517       && is_regular_file (archive_name_array[0]))
 518     {
 519       /* We don't need a grandchild tar.  Open the archive and lauch the
 520          uncompressor.  */
 521
 522       archive = open (archive_name_array[0], O_RDONLY | O_BINARY, MODE_RW);
 523       if (archive < 0)
 524         open_fatal (archive_name_array[0]);
 525       xdup2 (archive, STDIN_FILENO);
 526       priv_set_restore_linkdir ();
 527       run_decompress_program ();
 528     }
 529
 530   /* We do need a grandchild tar.  */
 531
 532   xpipe (child_pipe);
 533   grandchild_pid = xfork ();
 534
 535   if (grandchild_pid == 0)
 536     {
 537       /* The newborn grandchild tar is here!  Launch the uncompressor.  */
 538
 539       set_program_name (_("tar (grandchild)"));
 540
 541       xdup2 (child_pipe[PREAD], STDIN_FILENO);
 542       xclose (child_pipe[PWRITE]);
 543       priv_set_restore_linkdir ();
 544       run_decompress_program ();
 545     }
 546
 547   /* The child tar is still here!  */
 548
 549   /* Prepare for unblocking the data from the archive into the
 550      uncompressor.  */
 551
 552   xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
 553   xclose (child_pipe[PREAD]);
 554
 555   if (strcmp (archive_name_array[0], "-") == 0)
 556     archive = STDIN_FILENO;
 557   else
 558     archive = rmtopen (archive_name_array[0], O_RDONLY | O_BINARY,
 559                        MODE_RW, rsh_command_option);
 560   if (archive < 0)
 561     open_fatal (archive_name_array[0]);
 562
 563   /* Let's read the archive and pipe it into stdout.  */
 564
 565   while (1)
 566     {
 567       char *cursor;
 568       size_t maximum;
 569       size_t count;
 570       size_t status;
 571
 572       clear_read_error_count ();
 573
 574     error_loop:
 575       status = rmtread (archive, record_start->buffer, record_size);
 576       if (status == SAFE_READ_ERROR)
 577         {
 578           archive_read_error ();
 579           goto error_loop;
 580         }
 581       if (status == 0)
 582         break;
 583       cursor = record_start->buffer;
 584       maximum = status;
 585       while (maximum)
 586         {
 587           count = maximum < BLOCKSIZE ? maximum : BLOCKSIZE;
 588           if (full_write (STDOUT_FILENO, cursor, count) != count)
 589             write_error (use_compress_program_option);
 590           cursor += count;
 591           maximum -= count;
 592         }
 593     }
 594
 595   xclose (STDOUT_FILENO);
 596
 597   wait_for_grandchild (grandchild_pid);
 598 }
 599
 600 \f
 601
 602 static void
 603 dec_to_env (char const *envar, uintmax_t num)
 604 {
 605   char buf[UINTMAX_STRSIZE_BOUND];
 606   char *numstr;
 607
 608   numstr = STRINGIFY_BIGINT (num, buf);
 609   if (setenv (envar, numstr, 1) != 0)
 610     xalloc_die ();
 611 }
 612
 613 static void
 614 time_to_env (char const *envar, struct timespec t)
 615 {
 616   char buf[TIMESPEC_STRSIZE_BOUND];
 617   if (setenv (envar, code_timespec (t, buf), 1) != 0)
 618     xalloc_die ();
 619 }
 620
 621 static void
 622 oct_to_env (char const *envar, unsigned long num)
 623 {
 624   char buf[1+1+(sizeof(unsigned long)*CHAR_BIT+2)/3];
 625
 626   snprintf (buf, sizeof buf, "0%lo", num);
 627   if (setenv (envar, buf, 1) != 0)
 628     xalloc_die ();
 629 }
 630
 631 static void
 632 str_to_env (char const *envar, char const *str)
 633 {
 634   if (str)
 635     {
 636       if (setenv (envar, str, 1) != 0)
 637         xalloc_die ();
 638     }
 639   else
 640     unsetenv (envar);
 641 }
 642
 643 static void
 644 chr_to_env (char const *envar, char c)
 645 {
 646   char buf[2];
 647   buf[0] = c;
 648   buf[1] = 0;
 649   if (setenv (envar, buf, 1) != 0)
 650     xalloc_die ();
 651 }
 652
 653 static void
 654 stat_to_env (char *name, char type, struct tar_stat_info *st)
 655 {
 656   str_to_env ("TAR_VERSION", PACKAGE_VERSION);
 657   str_to_env ("TAR_ARCHIVE", *archive_name_cursor);
 658   dec_to_env ("TAR_VOLUME", archive_name_cursor - archive_name_array + 1);
 659   dec_to_env ("TAR_BLOCKING_FACTOR", blocking_factor);
 660   str_to_env ("TAR_FORMAT",
 661               archive_format_string (current_format == DEFAULT_FORMAT ?
 662                                      archive_format : current_format));
 663   chr_to_env ("TAR_FILETYPE", type);
 664   oct_to_env ("TAR_MODE", st->stat.st_mode);
 665   str_to_env ("TAR_FILENAME", name);
 666   str_to_env ("TAR_REALNAME", st->file_name);
 667   str_to_env ("TAR_UNAME", st->uname);
 668   str_to_env ("TAR_GNAME", st->gname);
 669   time_to_env ("TAR_ATIME", st->atime);
 670   time_to_env ("TAR_MTIME", st->mtime);
 671   time_to_env ("TAR_CTIME", st->ctime);
 672   dec_to_env ("TAR_SIZE", st->stat.st_size);
 673   dec_to_env ("TAR_UID", st->stat.st_uid);
 674   dec_to_env ("TAR_GID", st->stat.st_gid);
 675
 676   switch (type)
 677     {
 678     case 'b':
 679     case 'c':
 680       dec_to_env ("TAR_MINOR", minor (st->stat.st_rdev));
 681       dec_to_env ("TAR_MAJOR", major (st->stat.st_rdev));
 682       unsetenv ("TAR_LINKNAME");
 683       break;
 684
 685     case 'l':
 686     case 'h':
 687       unsetenv ("TAR_MINOR");
 688       unsetenv ("TAR_MAJOR");
 689       str_to_env ("TAR_LINKNAME", st->link_name);
 690       break;
 691
 692     default:
 693       unsetenv ("TAR_MINOR");
 694       unsetenv ("TAR_MAJOR");
 695       unsetenv ("TAR_LINKNAME");
 696       break;
 697     }
 698 }
 699
 700 static pid_t global_pid;
 701 static RETSIGTYPE (*pipe_handler) (int sig);
 702
 703 int
 704 sys_exec_command (char *file_name, int typechar, struct tar_stat_info *st)
 705 {
 706   int p[2];
 707   char *argv[4];
 708
 709   xpipe (p);
 710   pipe_handler = signal (SIGPIPE, SIG_IGN);
 711   global_pid = xfork ();
 712
 713   if (global_pid != 0)
 714     {
 715       xclose (p[PREAD]);
 716       return p[PWRITE];
 717     }
 718
 719   /* Child */
 720   xdup2 (p[PREAD], STDIN_FILENO);
 721   xclose (p[PWRITE]);
 722
 723   stat_to_env (file_name, typechar, st);
 724
 725   argv[0] = "/bin/sh";
 726   argv[1] = "-c";
 727   argv[2] = to_command_option;
 728   argv[3] = NULL;
 729
 730   priv_set_restore_linkdir ();
 731   execv ("/bin/sh", argv);
 732
 733   exec_fatal (file_name);
 734 }
 735
 736 void
 737 sys_wait_command (void)
 738 {
 739   int status;
 740
 741   if (global_pid < 0)
 742     return;
 743
 744   signal (SIGPIPE, pipe_handler);
 745   while (waitpid (global_pid, &status, 0) == -1)
 746     if (errno != EINTR)
 747       {
 748         global_pid = -1;
 749         waitpid_error (to_command_option);
 750         return;
 751       }
 752
 753   if (WIFEXITED (status))
 754     {
 755       if (!ignore_command_error_option && WEXITSTATUS (status))
 756         ERROR ((0, 0, _("%lu: Child returned status %d"),
 757                 (unsigned long) global_pid, WEXITSTATUS (status)));
 758     }
 759   else if (WIFSIGNALED (status))
 760     {
 761       WARN ((0, 0, _("%lu: Child terminated on signal %d"),
 762              (unsigned long) global_pid, WTERMSIG (status)));
 763     }
 764   else
 765     ERROR ((0, 0, _("%lu: Child terminated on unknown reason"),
 766             (unsigned long) global_pid));
 767
 768   global_pid = -1;
 769 }
 770
 771 int
 772 sys_exec_info_script (const char **archive_name, int volume_number)
 773 {
 774   pid_t pid;
 775   char *argv[4];
 776   char uintbuf[UINTMAX_STRSIZE_BOUND];
 777   int p[2];
 778   static RETSIGTYPE (*saved_handler) (int sig);
 779
 780   xpipe (p);
 781   saved_handler = signal (SIGPIPE, SIG_IGN);
 782
 783   pid = xfork ();
 784
 785   if (pid != 0)
 786     {
 787       /* Master */
 788
 789       int rc;
 790       int status;
 791       char *buf = NULL;
 792       size_t size = 0;
 793       FILE *fp;
 794
 795       xclose (p[PWRITE]);
 796       fp = fdopen (p[PREAD], "r");
 797       rc = getline (&buf, &size, fp);
 798       fclose (fp);
 799
 800       if (rc > 0 && buf[rc-1] == '\n')
 801         buf[--rc] = 0;
 802
 803       while (waitpid (pid, &status, 0) == -1)
 804         if (errno != EINTR)
 805           {
 806             signal (SIGPIPE, saved_handler);
 807             waitpid_error (info_script_option);
 808             return -1;
 809           }
 810
 811       signal (SIGPIPE, saved_handler);
 812
 813       if (WIFEXITED (status))
 814         {
 815           if (WEXITSTATUS (status) == 0 && rc > 0)
 816             *archive_name = buf;
 817           else
 818             free (buf);
 819           return WEXITSTATUS (status);
 820         }
 821
 822       free (buf);
 823       return -1;
 824     }
 825
 826   /* Child */
 827   setenv ("TAR_VERSION", PACKAGE_VERSION, 1);
 828   setenv ("TAR_ARCHIVE", *archive_name, 1);
 829   setenv ("TAR_VOLUME", STRINGIFY_BIGINT (volume_number, uintbuf), 1);
 830   setenv ("TAR_BLOCKING_FACTOR",
 831           STRINGIFY_BIGINT (blocking_factor, uintbuf), 1);
 832   setenv ("TAR_SUBCOMMAND", subcommand_string (subcommand_option), 1);
 833   setenv ("TAR_FORMAT",
 834           archive_format_string (current_format == DEFAULT_FORMAT ?
 835                                  archive_format : current_format), 1);
 836   setenv ("TAR_FD", STRINGIFY_BIGINT (p[PWRITE], uintbuf), 1);
 837
 838   xclose (p[PREAD]);
 839
 840   argv[0] = "/bin/sh";
 841   argv[1] = "-c";
 842   argv[2] = (char *) info_script_option;
 843   argv[3] = NULL;
 844
 845   priv_set_restore_linkdir ();
 846   execv (argv[0], argv);
 847
 848   exec_fatal (info_script_option);
 849 }
 850
 851 void
 852 sys_exec_checkpoint_script (const char *script_name,
 853                             const char *archive_name,
 854                             int checkpoint_number)
 855 {
 856   pid_t pid;
 857   char *argv[4];
 858   char uintbuf[UINTMAX_STRSIZE_BOUND];
 859
 860   pid = xfork ();
 861
 862   if (pid != 0)
 863     {
 864       /* Master */
 865
 866       int status;
 867
 868       while (waitpid (pid, &status, 0) == -1)
 869         if (errno != EINTR)
 870           {
 871             waitpid_error (script_name);
 872             break;
 873           }
 874
 875       return;
 876     }
 877
 878   /* Child */
 879   setenv ("TAR_VERSION", PACKAGE_VERSION, 1);
 880   setenv ("TAR_ARCHIVE", archive_name, 1);
 881   setenv ("TAR_CHECKPOINT", STRINGIFY_BIGINT (checkpoint_number, uintbuf), 1);
 882   setenv ("TAR_BLOCKING_FACTOR",
 883           STRINGIFY_BIGINT (blocking_factor, uintbuf), 1);
 884   setenv ("TAR_SUBCOMMAND", subcommand_string (subcommand_option), 1);
 885   setenv ("TAR_FORMAT",
 886           archive_format_string (current_format == DEFAULT_FORMAT ?
 887                                  archive_format : current_format), 1);
 888   argv[0] = "/bin/sh";
 889   argv[1] = "-c";
 890   argv[2] = (char *) script_name;
 891   argv[3] = NULL;
 892
 893   priv_set_restore_linkdir ();
 894   execv (argv[0], argv);
 895
 896   exec_fatal (script_name);
 897 }
 898
 899 #endif /* not MSDOS */