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

   1 /* Miscellaneous functions, not really specific to GNU tar.
   2
   3    Copyright (C) 1988, 1992, 1994, 1995, 1996, 1997, 1999, 2000, 2001,
   4    2003, 2004, 2005, 2006, 2007, 2009, 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 #include <rmt.h>
  22 #include "common.h"
  23 #include <quotearg.h>
  24 #include <save-cwd.h>
  25 #include <xgetcwd.h>
  26 #include <unlinkdir.h>
  27 #include <utimens.h>
  28
  29 #if HAVE_STROPTS_H
  30 # include <stropts.h>
  31 #endif
  32 #if HAVE_SYS_FILIO_H
  33 # include <sys/filio.h>
  34 #endif
  35
  36 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
  37 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
  38 #endif
  39
  40 \f
  41 /* Handling strings.  */
  42
  43 /* Assign STRING to a copy of VALUE if not zero, or to zero.  If
  44    STRING was nonzero, it is freed first.  */
  45 void
  46 assign_string (char **string, const char *value)
  47 {
  48   if (*string)
  49     free (*string);
  50   *string = value ? xstrdup (value) : 0;
  51 }
  52
  53 /* Allocate a copy of the string quoted as in C, and returns that.  If
  54    the string does not have to be quoted, it returns a null pointer.
  55    The allocated copy should normally be freed with free() after the
  56    caller is done with it.
  57
  58    This is used in one context only: generating the directory file in
  59    incremental dumps.  The quoted string is not intended for human
  60    consumption; it is intended only for unquote_string.  The quoting
  61    is locale-independent, so that users needn't worry about locale
  62    when reading directory files.  This means that we can't use
  63    quotearg, as quotearg is locale-dependent and is meant for human
  64    consumption.  */
  65 char *
  66 quote_copy_string (const char *string)
  67 {
  68   const char *source = string;
  69   char *destination = 0;
  70   char *buffer = 0;
  71   int copying = 0;
  72
  73   while (*source)
  74     {
  75       int character = *source++;
  76
  77       switch (character)
  78         {
  79         case '\n': case '\\':
  80           if (!copying)
  81             {
  82               size_t length = (source - string) - 1;
  83
  84               copying = 1;
  85               buffer = xmalloc (length + 2 + 2 * strlen (source) + 1);
  86               memcpy (buffer, string, length);
  87               destination = buffer + length;
  88             }
  89           *destination++ = '\\';
  90           *destination++ = character == '\\' ? '\\' : 'n';
  91           break;
  92
  93         default:
  94           if (copying)
  95             *destination++ = character;
  96           break;
  97         }
  98     }
  99   if (copying)
 100     {
 101       *destination = '\0';
 102       return buffer;
 103     }
 104   return 0;
 105 }
 106
 107 /* Takes a quoted C string (like those produced by quote_copy_string)
 108    and turns it back into the un-quoted original.  This is done in
 109    place.  Returns 0 only if the string was not properly quoted, but
 110    completes the unquoting anyway.
 111
 112    This is used for reading the saved directory file in incremental
 113    dumps.  It is used for decoding old `N' records (demangling names).
 114    But also, it is used for decoding file arguments, would they come
 115    from the shell or a -T file, and for decoding the --exclude
 116    argument.  */
 117 int
 118 unquote_string (char *string)
 119 {
 120   int result = 1;
 121   char *source = string;
 122   char *destination = string;
 123
 124   /* Escape sequences other than \\ and \n are no longer generated by
 125      quote_copy_string, but accept them for backwards compatibility,
 126      and also because unquote_string is used for purposes other than
 127      parsing the output of quote_copy_string.  */
 128
 129   while (*source)
 130     if (*source == '\\')
 131       switch (*++source)
 132         {
 133         case '\\':
 134           *destination++ = '\\';
 135           source++;
 136           break;
 137
 138         case 'a':
 139           *destination++ = '\a';
 140           source++;
 141           break;
 142
 143         case 'b':
 144           *destination++ = '\b';
 145           source++;
 146           break;
 147
 148         case 'f':
 149           *destination++ = '\f';
 150           source++;
 151           break;
 152
 153         case 'n':
 154           *destination++ = '\n';
 155           source++;
 156           break;
 157
 158         case 'r':
 159           *destination++ = '\r';
 160           source++;
 161           break;
 162
 163         case 't':
 164           *destination++ = '\t';
 165           source++;
 166           break;
 167
 168         case 'v':
 169           *destination++ = '\v';
 170           source++;
 171           break;
 172
 173         case '?':
 174           *destination++ = 0177;
 175           source++;
 176           break;
 177
 178         case '0':
 179         case '1':
 180         case '2':
 181         case '3':
 182         case '4':
 183         case '5':
 184         case '6':
 185         case '7':
 186           {
 187             int value = *source++ - '0';
 188
 189             if (*source < '0' || *source > '7')
 190               {
 191                 *destination++ = value;
 192                 break;
 193               }
 194             value = value * 8 + *source++ - '0';
 195             if (*source < '0' || *source > '7')
 196               {
 197                 *destination++ = value;
 198                 break;
 199               }
 200             value = value * 8 + *source++ - '0';
 201             *destination++ = value;
 202             break;
 203           }
 204
 205         default:
 206           result = 0;
 207           *destination++ = '\\';
 208           if (*source)
 209             *destination++ = *source++;
 210           break;
 211         }
 212     else if (source != destination)
 213       *destination++ = *source++;
 214     else
 215       source++, destination++;
 216
 217   if (source != destination)
 218     *destination = '\0';
 219   return result;
 220 }
 221
 222 /* Zap trailing slashes.  */
 223 char *
 224 zap_slashes (char *name)
 225 {
 226   char *q;
 227
 228   if (!name || *name == 0)
 229     return name;
 230   q = name + strlen (name) - 1;
 231   while (q > name && ISSLASH (*q))
 232     *q-- = '\0';
 233   return name;
 234 }
 235
 236 /* Normalize FILE_NAME by removing redundant slashes and "."
 237    components, including redundant trailing slashes.  Leave ".."
 238    alone, as it may be significant in the presence of symlinks and on
 239    platforms where "/.." != "/".  Destructive version: modifies its
 240    argument. */
 241 static void
 242 normalize_filename_x (char *file_name)
 243 {
 244   char *name = file_name + FILE_SYSTEM_PREFIX_LEN (file_name);
 245   char *p;
 246   char const *q;
 247   char c;
 248
 249   /* Don't squeeze leading "//" to "/", on hosts where they're distinct.  */
 250   name += (DOUBLE_SLASH_IS_DISTINCT_ROOT
 251            && ISSLASH (*name) && ISSLASH (name[1]) && ! ISSLASH (name[2]));
 252
 253   /* Omit redundant leading "." components.  */
 254   for (q = p = name; (*p = *q) == '.' && ISSLASH (q[1]); p += !*q)
 255     for (q += 2; ISSLASH (*q); q++)
 256       continue;
 257
 258   /* Copy components from Q to P, omitting redundant slashes and
 259      internal "."  components.  */
 260   while ((*p++ = c = *q++) != '\0')
 261     if (ISSLASH (c))
 262       while (ISSLASH (q[*q == '.']))
 263         q += (*q == '.') + 1;
 264
 265   /* Omit redundant trailing "." component and slash.  */
 266   if (2 < p - name)
 267     {
 268       p -= p[-2] == '.' && ISSLASH (p[-3]);
 269       p -= 2 < p - name && ISSLASH (p[-2]);
 270       p[-1] = '\0';
 271     }
 272 }
 273
 274 /* Normalize NAME by removing redundant slashes and "." components,
 275    including redundant trailing slashes.  Return a normalized
 276    newly-allocated copy.  */
 277
 278 char *
 279 normalize_filename (const char *name)
 280 {
 281   char *copy = NULL;
 282
 283   if (IS_RELATIVE_FILE_NAME (name))
 284     {
 285       /* Set COPY to the absolute file name if possible.
 286
 287          FIXME: There should be no need to get the absolute file name.
 288          getcwd is slow, it might fail, and it does not necessarily
 289          return a canonical name even when it succeeds.  Perhaps we
 290          can use dev+ino pairs instead of names?  */
 291       copy = xgetcwd ();
 292       if (copy)
 293         {
 294           size_t copylen = strlen (copy);
 295           bool need_separator = ! (DOUBLE_SLASH_IS_DISTINCT_ROOT
 296                                    && copylen == 2 && ISSLASH (copy[1]));
 297           copy = xrealloc (copy, copylen + need_separator + strlen (name) + 1);
 298           copy[copylen] = DIRECTORY_SEPARATOR;
 299           strcpy (copy + copylen + need_separator, name);
 300         }
 301       else
 302         WARN ((0, errno, _("Cannot get working directory")));
 303     }
 304
 305   if (! copy)
 306     copy = xstrdup (name);
 307   normalize_filename_x (copy);
 308   return copy;
 309 }
 310
 311 \f
 312 void
 313 replace_prefix (char **pname, const char *samp, size_t slen,
 314                 const char *repl, size_t rlen)
 315 {
 316   char *name = *pname;
 317   size_t nlen = strlen (name);
 318   if (nlen > slen && memcmp (name, samp, slen) == 0 && ISSLASH (name[slen]))
 319     {
 320       if (rlen > slen)
 321         {
 322           name = xrealloc (name, nlen - slen + rlen + 1);
 323           *pname = name;
 324         }
 325       memmove (name + rlen, name + slen, nlen - slen + 1);
 326       memcpy (name, repl, rlen);
 327     }
 328 }
 329
 330 \f
 331 /* Handling numbers.  */
 332
 333 /* Output fraction and trailing digits appropriate for a nanoseconds
 334    count equal to NS, but don't output unnecessary '.' or trailing
 335    zeros.  */
 336
 337 void
 338 code_ns_fraction (int ns, char *p)
 339 {
 340   if (ns == 0)
 341     *p = '\0';
 342   else
 343     {
 344       int i = 9;
 345       *p++ = '.';
 346
 347       while (ns % 10 == 0)
 348         {
 349           ns /= 10;
 350           i--;
 351         }
 352
 353       p[i] = '\0';
 354
 355       for (;;)
 356         {
 357           p[--i] = '0' + ns % 10;
 358           if (i == 0)
 359             break;
 360           ns /= 10;
 361         }
 362     }
 363 }
 364
 365 char const *
 366 code_timespec (struct timespec t, char sbuf[TIMESPEC_STRSIZE_BOUND])
 367 {
 368   time_t s = t.tv_sec;
 369   int ns = t.tv_nsec;
 370   char *np;
 371   bool negative = s < 0;
 372
 373   /* ignore invalid values of ns */
 374   if (BILLION <= ns || ns < 0)
 375     ns = 0;
 376
 377   if (negative && ns != 0)
 378     {
 379       s++;
 380       ns = BILLION - ns;
 381     }
 382
 383   np = umaxtostr (negative ? - (uintmax_t) s : (uintmax_t) s, sbuf + 1);
 384   if (negative)
 385     *--np = '-';
 386   code_ns_fraction (ns, sbuf + UINTMAX_STRSIZE_BOUND);
 387   return np;
 388 }
 389 \f
 390 /* File handling.  */
 391
 392 /* Saved names in case backup needs to be undone.  */
 393 static char *before_backup_name;
 394 static char *after_backup_name;
 395
 396 /* Return 1 if FILE_NAME is obviously "." or "/".  */
 397 static bool
 398 must_be_dot_or_slash (char const *file_name)
 399 {
 400   file_name += FILE_SYSTEM_PREFIX_LEN (file_name);
 401
 402   if (ISSLASH (file_name[0]))
 403     {
 404       for (;;)
 405         if (ISSLASH (file_name[1]))
 406           file_name++;
 407         else if (file_name[1] == '.'
 408                  && ISSLASH (file_name[2 + (file_name[2] == '.')]))
 409           file_name += 2 + (file_name[2] == '.');
 410         else
 411           return ! file_name[1];
 412     }
 413   else
 414     {
 415       while (file_name[0] == '.' && ISSLASH (file_name[1]))
 416         {
 417           file_name += 2;
 418           while (ISSLASH (*file_name))
 419             file_name++;
 420         }
 421
 422       return ! file_name[0] || (file_name[0] == '.' && ! file_name[1]);
 423     }
 424 }
 425
 426 /* Some implementations of rmdir let you remove '.' or '/'.
 427    Report an error with errno set to zero for obvious cases of this;
 428    otherwise call rmdir.  */
 429 static int
 430 safer_rmdir (const char *file_name)
 431 {
 432   if (must_be_dot_or_slash (file_name))
 433     {
 434       errno = 0;
 435       return -1;
 436     }
 437
 438   return rmdir (file_name);
 439 }
 440
 441 /* Remove FILE_NAME, returning 1 on success.  If FILE_NAME is a directory,
 442    then if OPTION is RECURSIVE_REMOVE_OPTION is set remove FILE_NAME
 443    recursively; otherwise, remove it only if it is empty.  If FILE_NAME is
 444    a directory that cannot be removed (e.g., because it is nonempty)
 445    and if OPTION is WANT_DIRECTORY_REMOVE_OPTION, then return -1.
 446    Return 0 on error, with errno set; if FILE_NAME is obviously the working
 447    directory return zero with errno set to zero.  */
 448 int
 449 remove_any_file (const char *file_name, enum remove_option option)
 450 {
 451   /* Try unlink first if we cannot unlink directories, as this saves
 452      us a system call in the common case where we're removing a
 453      non-directory.  */
 454   bool try_unlink_first = cannot_unlink_dir ();
 455
 456   if (try_unlink_first)
 457     {
 458       if (unlink (file_name) == 0)
 459         return 1;
 460
 461       /* POSIX 1003.1-2001 requires EPERM when attempting to unlink a
 462          directory without appropriate privileges, but many Linux
 463          kernels return the more-sensible EISDIR.  */
 464       if (errno != EPERM && errno != EISDIR)
 465         return 0;
 466     }
 467
 468   if (safer_rmdir (file_name) == 0)
 469     return 1;
 470
 471   switch (errno)
 472     {
 473     case ENOTDIR:
 474       return !try_unlink_first && unlink (file_name) == 0;
 475
 476     case 0:
 477     case EEXIST:
 478 #if defined ENOTEMPTY && ENOTEMPTY != EEXIST
 479     case ENOTEMPTY:
 480 #endif
 481       switch (option)
 482         {
 483         case ORDINARY_REMOVE_OPTION:
 484           break;
 485
 486         case WANT_DIRECTORY_REMOVE_OPTION:
 487           return -1;
 488
 489         case RECURSIVE_REMOVE_OPTION:
 490           {
 491             char *directory = savedir (file_name);
 492             char const *entry;
 493             size_t entrylen;
 494
 495             if (! directory)
 496               return 0;
 497
 498             for (entry = directory;
 499                  (entrylen = strlen (entry)) != 0;
 500                  entry += entrylen + 1)
 501               {
 502                 char *file_name_buffer = new_name (file_name, entry);
 503                 int r = remove_any_file (file_name_buffer,
 504                                          RECURSIVE_REMOVE_OPTION);
 505                 int e = errno;
 506                 free (file_name_buffer);
 507
 508                 if (! r)
 509                   {
 510                     free (directory);
 511                     errno = e;
 512                     return 0;
 513                   }
 514               }
 515
 516             free (directory);
 517             return safer_rmdir (file_name) == 0;
 518           }
 519         }
 520       break;
 521     }
 522
 523   return 0;
 524 }
 525
 526 /* Check if FILE_NAME already exists and make a backup of it right now.
 527    Return success (nonzero) only if the backup is either unneeded, or
 528    successful.  For now, directories are considered to never need
 529    backup.  If THIS_IS_THE_ARCHIVE is nonzero, this is the archive and
 530    so, we do not have to backup block or character devices, nor remote
 531    entities.  */
 532 bool
 533 maybe_backup_file (const char *file_name, bool this_is_the_archive)
 534 {
 535   struct stat file_stat;
 536
 537   assign_string (&before_backup_name, file_name);
 538
 539   /* A run situation may exist between Emacs or other GNU programs trying to
 540      make a backup for the same file simultaneously.  If theoretically
 541      possible, real problems are unlikely.  Doing any better would require a
 542      convention, GNU-wide, for all programs doing backups.  */
 543
 544   assign_string (&after_backup_name, 0);
 545
 546   /* Check if we really need to backup the file.  */
 547
 548   if (this_is_the_archive && _remdev (file_name))
 549     return true;
 550
 551   if (stat (file_name, &file_stat))
 552     {
 553       if (errno == ENOENT)
 554         return true;
 555
 556       stat_error (file_name);
 557       return false;
 558     }
 559
 560   if (S_ISDIR (file_stat.st_mode))
 561     return true;
 562
 563   if (this_is_the_archive
 564       && (S_ISBLK (file_stat.st_mode) || S_ISCHR (file_stat.st_mode)))
 565     return true;
 566
 567   after_backup_name = find_backup_file_name (file_name, backup_type);
 568   if (! after_backup_name)
 569     xalloc_die ();
 570
 571   if (rename (before_backup_name, after_backup_name) == 0)
 572     {
 573       if (verbose_option)
 574         fprintf (stdlis, _("Renaming %s to %s\n"),
 575                  quote_n (0, before_backup_name),
 576                  quote_n (1, after_backup_name));
 577       return true;
 578     }
 579   else
 580     {
 581       /* The backup operation failed.  */
 582       int e = errno;
 583       ERROR ((0, e, _("%s: Cannot rename to %s"),
 584               quotearg_colon (before_backup_name),
 585               quote_n (1, after_backup_name)));
 586       assign_string (&after_backup_name, 0);
 587       return false;
 588     }
 589 }
 590
 591 /* Try to restore the recently backed up file to its original name.
 592    This is usually only needed after a failed extraction.  */
 593 void
 594 undo_last_backup (void)
 595 {
 596   if (after_backup_name)
 597     {
 598       if (rename (after_backup_name, before_backup_name) != 0)
 599         {
 600           int e = errno;
 601           ERROR ((0, e, _("%s: Cannot rename to %s"),
 602                   quotearg_colon (after_backup_name),
 603                   quote_n (1, before_backup_name)));
 604         }
 605       if (verbose_option)
 606         fprintf (stdlis, _("Renaming %s back to %s\n"),
 607                  quote_n (0, after_backup_name),
 608                  quote_n (1, before_backup_name));
 609       assign_string (&after_backup_name, 0);
 610     }
 611 }
 612
 613 /* Depending on DEREF, apply either stat or lstat to (NAME, BUF).  */
 614 int
 615 deref_stat (bool deref, char const *name, struct stat *buf)
 616 {
 617   return deref ? stat (name, buf) : lstat (name, buf);
 618 }
 619
 620 /* Set FD's (i.e., FILE's) access time to TIMESPEC[0].  If that's not
 621    possible to do by itself, set its access and data modification
 622    times to TIMESPEC[0] and TIMESPEC[1], respectively.  */
 623 int
 624 set_file_atime (int fd, char const *file, struct timespec const timespec[2])
 625 {
 626 #ifdef _FIOSATIME
 627   if (0 <= fd)
 628     {
 629       struct timeval timeval;
 630       timeval.tv_sec = timespec[0].tv_sec;
 631       timeval.tv_usec = timespec[0].tv_nsec / 1000;
 632       if (ioctl (fd, _FIOSATIME, &timeval) == 0)
 633         return 0;
 634     }
 635 #endif
 636
 637   return gl_futimens (fd, file, timespec);
 638 }
 639
 640 /* A description of a working directory.  */
 641 struct wd
 642 {
 643   char const *name;
 644   int saved;
 645   struct saved_cwd saved_cwd;
 646 };
 647
 648 /* A vector of chdir targets.  wd[0] is the initial working directory.  */
 649 static struct wd *wd;
 650
 651 /* The number of working directories in the vector.  */
 652 static size_t wd_count;
 653
 654 /* The allocated size of the vector.  */
 655 static size_t wd_alloc;
 656
 657 int
 658 chdir_count ()
 659 {
 660   if (wd_count == 0)
 661     return wd_count;
 662   return wd_count - 1;
 663 }
 664
 665 /* DIR is the operand of a -C option; add it to vector of chdir targets,
 666    and return the index of its location.  */
 667 int
 668 chdir_arg (char const *dir)
 669 {
 670   if (wd_count == wd_alloc)
 671     {
 672       if (wd_alloc == 0)
 673         {
 674           wd_alloc = 2;
 675           wd = xmalloc (sizeof *wd * wd_alloc);
 676         }
 677       else
 678         wd = x2nrealloc (wd, &wd_alloc, sizeof *wd);
 679
 680       if (! wd_count)
 681         {
 682           wd[wd_count].name = ".";
 683           wd[wd_count].saved = 0;
 684           wd_count++;
 685         }
 686     }
 687
 688   /* Optimize the common special case of the working directory,
 689      or the working directory as a prefix.  */
 690   if (dir[0])
 691     {
 692       while (dir[0] == '.' && ISSLASH (dir[1]))
 693         for (dir += 2;  ISSLASH (*dir);  dir++)
 694           continue;
 695       if (! dir[dir[0] == '.'])
 696         return wd_count - 1;
 697     }
 698
 699   wd[wd_count].name = dir;
 700   wd[wd_count].saved = 0;
 701   return wd_count++;
 702 }
 703
 704 /* Change to directory I.  If I is 0, change to the initial working
 705    directory; otherwise, I must be a value returned by chdir_arg.  */
 706 void
 707 chdir_do (int i)
 708 {
 709   static int previous;
 710
 711   if (previous != i)
 712     {
 713       struct wd *prev = &wd[previous];
 714       struct wd *curr = &wd[i];
 715
 716       if (! prev->saved)
 717         {
 718           int err = 0;
 719           prev->saved = 1;
 720           if (save_cwd (&prev->saved_cwd) != 0)
 721             err = errno;
 722           else if (0 <= prev->saved_cwd.desc)
 723             {
 724               /* Make sure we still have at least one descriptor available.  */
 725               int fd1 = prev->saved_cwd.desc;
 726               int fd2 = dup (fd1);
 727               if (0 <= fd2)
 728                 close (fd2);
 729               else if (errno == EMFILE)
 730                 {
 731                   /* Force restore_cwd to use chdir_long.  */
 732                   close (fd1);
 733                   prev->saved_cwd.desc = -1;
 734                   prev->saved_cwd.name = xgetcwd ();
 735                   if (! prev->saved_cwd.name)
 736                     err = errno;
 737                 }
 738               else
 739                 err = errno;
 740             }
 741
 742           if (err)
 743             FATAL_ERROR ((0, err, _("Cannot save working directory")));
 744         }
 745
 746       if (curr->saved)
 747         {
 748           if (restore_cwd (&curr->saved_cwd))
 749             FATAL_ERROR ((0, 0, _("Cannot change working directory")));
 750         }
 751       else
 752         {
 753           if (i && ! ISSLASH (curr->name[0]))
 754             chdir_do (i - 1);
 755           if (chdir (curr->name) != 0)
 756             chdir_fatal (curr->name);
 757         }
 758
 759       previous = i;
 760     }
 761 }
 762 \f
 763 void
 764 close_diag (char const *name)
 765 {
 766   if (ignore_failed_read_option)
 767     close_warn (name);
 768   else
 769     close_error (name);
 770 }
 771
 772 void
 773 open_diag (char const *name)
 774 {
 775   if (ignore_failed_read_option)
 776     open_warn (name);
 777   else
 778     open_error (name);
 779 }
 780
 781 void
 782 read_diag_details (char const *name, off_t offset, size_t size)
 783 {
 784   if (ignore_failed_read_option)
 785     read_warn_details (name, offset, size);
 786   else
 787     read_error_details (name, offset, size);
 788 }
 789
 790 void
 791 readlink_diag (char const *name)
 792 {
 793   if (ignore_failed_read_option)
 794     readlink_warn (name);
 795   else
 796     readlink_error (name);
 797 }
 798
 799 void
 800 savedir_diag (char const *name)
 801 {
 802   if (ignore_failed_read_option)
 803     savedir_warn (name);
 804   else
 805     savedir_error (name);
 806 }
 807
 808 void
 809 seek_diag_details (char const *name, off_t offset)
 810 {
 811   if (ignore_failed_read_option)
 812     seek_warn_details (name, offset);
 813   else
 814     seek_error_details (name, offset);
 815 }
 816
 817 void
 818 stat_diag (char const *name)
 819 {
 820   if (ignore_failed_read_option)
 821     stat_warn (name);
 822   else
 823     stat_error (name);
 824 }
 825
 826 void
 827 file_removed_diag (const char *name, bool top_level,
 828                    void (*diagfn) (char const *name))
 829 {
 830   if (!top_level && errno == ENOENT)
 831     {
 832       WARNOPT (WARN_FILE_REMOVED,
 833                (0, 0, _("%s: File removed before we read it"),
 834                 quotearg_colon (name)));
 835       set_exit_status (TAREXIT_DIFFERS);
 836     }
 837   else
 838     diagfn (name);
 839 }
 840
 841 void
 842 dir_removed_diag (const char *name, bool top_level,
 843                    void (*diagfn) (char const *name))
 844 {
 845   if (!top_level && errno == ENOENT)
 846     {
 847       WARNOPT (WARN_FILE_REMOVED,
 848                (0, 0, _("%s: Directory removed before we read it"),
 849                 quotearg_colon (name)));
 850       set_exit_status (TAREXIT_DIFFERS);
 851     }
 852   else
 853     diagfn (name);
 854 }
 855
 856 void
 857 write_fatal_details (char const *name, ssize_t status, size_t size)
 858 {
 859   write_error_details (name, status, size);
 860   fatal_exit ();
 861 }
 862
 863 /* Fork, aborting if unsuccessful.  */
 864 pid_t
 865 xfork (void)
 866 {
 867   pid_t p = fork ();
 868   if (p == (pid_t) -1)
 869     call_arg_fatal ("fork", _("child process"));
 870   return p;
 871 }
 872
 873 /* Create a pipe, aborting if unsuccessful.  */
 874 void
 875 xpipe (int fd[2])
 876 {
 877   if (pipe (fd) < 0)
 878     call_arg_fatal ("pipe", _("interprocess channel"));
 879 }
 880
 881 /* Return PTR, aligned upward to the next multiple of ALIGNMENT.
 882    ALIGNMENT must be nonzero.  The caller must arrange for ((char *)
 883    PTR) through ((char *) PTR + ALIGNMENT - 1) to be addressable
 884    locations.  */
 885
 886 static inline void *
 887 ptr_align (void *ptr, size_t alignment)
 888 {
 889   char *p0 = ptr;
 890   char *p1 = p0 + alignment - 1;
 891   return p1 - (size_t) p1 % alignment;
 892 }
 893
 894 /* Return the address of a page-aligned buffer of at least SIZE bytes.
 895    The caller should free *PTR when done with the buffer.  */
 896
 897 void *
 898 page_aligned_alloc (void **ptr, size_t size)
 899 {
 900   size_t alignment = getpagesize ();
 901   size_t size1 = size + alignment;
 902   if (size1 < size)
 903     xalloc_die ();
 904   *ptr = xmalloc (size1);
 905   return ptr_align (*ptr, alignment);
 906 }
 907
 908 \f
 909
 910 struct namebuf
 911 {
 912   char *buffer;         /* directory, `/', and directory member */
 913   size_t buffer_size;   /* allocated size of name_buffer */
 914   size_t dir_length;    /* length of directory part in buffer */
 915 };
 916
 917 namebuf_t
 918 namebuf_create (const char *dir)
 919 {
 920   namebuf_t buf = xmalloc (sizeof (*buf));
 921   buf->buffer_size = strlen (dir) + 2;
 922   buf->buffer = xmalloc (buf->buffer_size);
 923   strcpy (buf->buffer, dir);
 924   buf->dir_length = strlen (buf->buffer);
 925   if (!ISSLASH (buf->buffer[buf->dir_length - 1]))
 926     buf->buffer[buf->dir_length++] = DIRECTORY_SEPARATOR;
 927   return buf;
 928 }
 929
 930 void
 931 namebuf_free (namebuf_t buf)
 932 {
 933   free (buf->buffer);
 934   free (buf);
 935 }
 936
 937 char *
 938 namebuf_name (namebuf_t buf, const char *name)
 939 {
 940   size_t len = strlen (name);
 941   while (buf->dir_length + len + 1 >= buf->buffer_size)
 942     buf->buffer = x2realloc (buf->buffer, &buf->buffer_size);
 943   strcpy (buf->buffer + buf->dir_length, name);
 944   return buf->buffer;
 945 }