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
  28 #ifndef DOUBLE_SLASH_IS_DISTINCT_ROOT
  29 # define DOUBLE_SLASH_IS_DISTINCT_ROOT 0
  30 #endif
  31
  32 \f
  33 /* Handling strings.  */
  34
  35 /* Assign STRING to a copy of VALUE if not zero, or to zero.  If
  36    STRING was nonzero, it is freed first.  */
  37 void
  38 assign_string (char **string, const char *value)
  39 {
  40   if (*string)
  41     free (*string);
  42   *string = value ? xstrdup (value) : 0;
  43 }
  44
  45 #if 0
  46 /* This function is currently unused; perhaps it should be removed?  */
  47
  48 /* Allocate a copy of the string quoted as in C, and returns that.  If
  49    the string does not have to be quoted, it returns a null pointer.
  50    The allocated copy should normally be freed with free() after the
  51    caller is done with it.
  52
  53    This is used in one context only: generating the directory file in
  54    incremental dumps.  The quoted string is not intended for human
  55    consumption; it is intended only for unquote_string.  The quoting
  56    is locale-independent, so that users needn't worry about locale
  57    when reading directory files.  This means that we can't use
  58    quotearg, as quotearg is locale-dependent and is meant for human
  59    consumption.  */
  60 static char *
  61 quote_copy_string (const char *string)
  62 {
  63   const char *source = string;
  64   char *destination = 0;
  65   char *buffer = 0;
  66   int copying = 0;
  67
  68   while (*source)
  69     {
  70       int character = *source++;
  71
  72       switch (character)
  73         {
  74         case '\n': case '\\':
  75           if (!copying)
  76             {
  77               size_t length = (source - string) - 1;
  78
  79               copying = 1;
  80               buffer = xmalloc (length + 2 + 2 * strlen (source) + 1);
  81               memcpy (buffer, string, length);
  82               destination = buffer + length;
  83             }
  84           *destination++ = '\\';
  85           *destination++ = character == '\\' ? '\\' : 'n';
  86           break;
  87
  88         default:
  89           if (copying)
  90             *destination++ = character;
  91           break;
  92         }
  93     }
  94   if (copying)
  95     {
  96       *destination = '\0';
  97       return buffer;
  98     }
  99   return 0;
 100 }
 101 #endif
 102
 103 /* Takes a quoted C string (like those produced by quote_copy_string)
 104    and turns it back into the un-quoted original.  This is done in
 105    place.  Returns 0 only if the string was not properly quoted, but
 106    completes the unquoting anyway.
 107
 108    This is used for reading the saved directory file in incremental
 109    dumps.  It is used for decoding old `N' records (demangling names).
 110    But also, it is used for decoding file arguments, would they come
 111    from the shell or a -T file, and for decoding the --exclude
 112    argument.  */
 113 int
 114 unquote_string (char *string)
 115 {
 116   int result = 1;
 117   char *source = string;
 118   char *destination = string;
 119
 120   /* Escape sequences other than \\ and \n are no longer generated by
 121      quote_copy_string, but accept them for backwards compatibility,
 122      and also because unquote_string is used for purposes other than
 123      parsing the output of quote_copy_string.  */
 124
 125   while (*source)
 126     if (*source == '\\')
 127       switch (*++source)
 128         {
 129         case '\\':
 130           *destination++ = '\\';
 131           source++;
 132           break;
 133
 134         case 'a':
 135           *destination++ = '\a';
 136           source++;
 137           break;
 138
 139         case 'b':
 140           *destination++ = '\b';
 141           source++;
 142           break;
 143
 144         case 'f':
 145           *destination++ = '\f';
 146           source++;
 147           break;
 148
 149         case 'n':
 150           *destination++ = '\n';
 151           source++;
 152           break;
 153
 154         case 'r':
 155           *destination++ = '\r';
 156           source++;
 157           break;
 158
 159         case 't':
 160           *destination++ = '\t';
 161           source++;
 162           break;
 163
 164         case 'v':
 165           *destination++ = '\v';
 166           source++;
 167           break;
 168
 169         case '?':
 170           *destination++ = 0177;
 171           source++;
 172           break;
 173
 174         case '0':
 175         case '1':
 176         case '2':
 177         case '3':
 178         case '4':
 179         case '5':
 180         case '6':
 181         case '7':
 182           {
 183             int value = *source++ - '0';
 184
 185             if (*source < '0' || *source > '7')
 186               {
 187                 *destination++ = value;
 188                 break;
 189               }
 190             value = value * 8 + *source++ - '0';
 191             if (*source < '0' || *source > '7')
 192               {
 193                 *destination++ = value;
 194                 break;
 195               }
 196             value = value * 8 + *source++ - '0';
 197             *destination++ = value;
 198             break;
 199           }
 200
 201         default:
 202           result = 0;
 203           *destination++ = '\\';
 204           if (*source)
 205             *destination++ = *source++;
 206           break;
 207         }
 208     else if (source != destination)
 209       *destination++ = *source++;
 210     else
 211       source++, destination++;
 212
 213   if (source != destination)
 214     *destination = '\0';
 215   return result;
 216 }
 217
 218 /* Zap trailing slashes.  */
 219 char *
 220 zap_slashes (char *name)
 221 {
 222   char *q;
 223
 224   if (!name || *name == 0)
 225     return name;
 226   q = name + strlen (name) - 1;
 227   while (q > name && ISSLASH (*q))
 228     *q-- = '\0';
 229   return name;
 230 }
 231
 232 /* Normalize FILE_NAME by removing redundant slashes and "."
 233    components, including redundant trailing slashes.  Leave ".."
 234    alone, as it may be significant in the presence of symlinks and on
 235    platforms where "/.." != "/".  Destructive version: modifies its
 236    argument. */
 237 static void
 238 normalize_filename_x (char *file_name)
 239 {
 240   char *name = file_name + FILE_SYSTEM_PREFIX_LEN (file_name);
 241   char *p;
 242   char const *q;
 243   char c;
 244
 245   /* Don't squeeze leading "//" to "/", on hosts where they're distinct.  */
 246   name += (DOUBLE_SLASH_IS_DISTINCT_ROOT
 247            && ISSLASH (*name) && ISSLASH (name[1]) && ! ISSLASH (name[2]));
 248
 249   /* Omit redundant leading "." components.  */
 250   for (q = p = name; (*p = *q) == '.' && ISSLASH (q[1]); p += !*q)
 251     for (q += 2; ISSLASH (*q); q++)
 252       continue;
 253
 254   /* Copy components from Q to P, omitting redundant slashes and
 255      internal "."  components.  */
 256   while ((*p++ = c = *q++) != '\0')
 257     if (ISSLASH (c))
 258       while (ISSLASH (q[*q == '.']))
 259         q += (*q == '.') + 1;
 260
 261   /* Omit redundant trailing "." component and slash.  */
 262   if (2 < p - name)
 263     {
 264       p -= p[-2] == '.' && ISSLASH (p[-3]);
 265       p -= 2 < p - name && ISSLASH (p[-2]);
 266       p[-1] = '\0';
 267     }
 268 }
 269
 270 /* Normalize NAME by removing redundant slashes and "." components,
 271    including redundant trailing slashes.  Return a normalized
 272    newly-allocated copy.  */
 273
 274 char *
 275 normalize_filename (const char *name)
 276 {
 277   char *copy = NULL;
 278
 279   if (IS_RELATIVE_FILE_NAME (name))
 280     {
 281       /* Set COPY to the absolute file name if possible.
 282
 283          FIXME: There should be no need to get the absolute file name.
 284          getcwd is slow, it might fail, and it does not necessarily
 285          return a canonical name even when it succeeds.  Perhaps we
 286          can use dev+ino pairs instead of names?  */
 287       copy = xgetcwd ();
 288       if (copy)
 289         {
 290           size_t copylen = strlen (copy);
 291           bool need_separator = ! (DOUBLE_SLASH_IS_DISTINCT_ROOT
 292                                    && copylen == 2 && ISSLASH (copy[1]));
 293           copy = xrealloc (copy, copylen + need_separator + strlen (name) + 1);
 294           copy[copylen] = DIRECTORY_SEPARATOR;
 295           strcpy (copy + copylen + need_separator, name);
 296         }
 297       else
 298         WARN ((0, errno, _("Cannot get working directory")));
 299     }
 300
 301   if (! copy)
 302     copy = xstrdup (name);
 303   normalize_filename_x (copy);
 304   return copy;
 305 }
 306
 307 \f
 308 void
 309 replace_prefix (char **pname, const char *samp, size_t slen,
 310                 const char *repl, size_t rlen)
 311 {
 312   char *name = *pname;
 313   size_t nlen = strlen (name);
 314   if (nlen > slen && memcmp (name, samp, slen) == 0 && ISSLASH (name[slen]))
 315     {
 316       if (rlen > slen)
 317         {
 318           name = xrealloc (name, nlen - slen + rlen + 1);
 319           *pname = name;
 320         }
 321       memmove (name + rlen, name + slen, nlen - slen + 1);
 322       memcpy (name, repl, rlen);
 323     }
 324 }
 325
 326 \f
 327 /* Handling numbers.  */
 328
 329 /* Output fraction and trailing digits appropriate for a nanoseconds
 330    count equal to NS, but don't output unnecessary '.' or trailing
 331    zeros.  */
 332
 333 void
 334 code_ns_fraction (int ns, char *p)
 335 {
 336   if (ns == 0)
 337     *p = '\0';
 338   else
 339     {
 340       int i = 9;
 341       *p++ = '.';
 342
 343       while (ns % 10 == 0)
 344         {
 345           ns /= 10;
 346           i--;
 347         }
 348
 349       p[i] = '\0';
 350
 351       for (;;)
 352         {
 353           p[--i] = '0' + ns % 10;
 354           if (i == 0)
 355             break;
 356           ns /= 10;
 357         }
 358     }
 359 }
 360
 361 char const *
 362 code_timespec (struct timespec t, char sbuf[TIMESPEC_STRSIZE_BOUND])
 363 {
 364   time_t s = t.tv_sec;
 365   int ns = t.tv_nsec;
 366   char *np;
 367   bool negative = s < 0;
 368
 369   /* ignore invalid values of ns */
 370   if (BILLION <= ns || ns < 0)
 371     ns = 0;
 372
 373   if (negative && ns != 0)
 374     {
 375       s++;
 376       ns = BILLION - ns;
 377     }
 378
 379   np = umaxtostr (negative ? - (uintmax_t) s : (uintmax_t) s, sbuf + 1);
 380   if (negative)
 381     *--np = '-';
 382   code_ns_fraction (ns, sbuf + UINTMAX_STRSIZE_BOUND);
 383   return np;
 384 }
 385 \f
 386 /* File handling.  */
 387
 388 /* Saved names in case backup needs to be undone.  */
 389 static char *before_backup_name;
 390 static char *after_backup_name;
 391
 392 /* Return 1 if FILE_NAME is obviously "." or "/".  */
 393 static bool
 394 must_be_dot_or_slash (char const *file_name)
 395 {
 396   file_name += FILE_SYSTEM_PREFIX_LEN (file_name);
 397
 398   if (ISSLASH (file_name[0]))
 399     {
 400       for (;;)
 401         if (ISSLASH (file_name[1]))
 402           file_name++;
 403         else if (file_name[1] == '.'
 404                  && ISSLASH (file_name[2 + (file_name[2] == '.')]))
 405           file_name += 2 + (file_name[2] == '.');
 406         else
 407           return ! file_name[1];
 408     }
 409   else
 410     {
 411       while (file_name[0] == '.' && ISSLASH (file_name[1]))
 412         {
 413           file_name += 2;
 414           while (ISSLASH (*file_name))
 415             file_name++;
 416         }
 417
 418       return ! file_name[0] || (file_name[0] == '.' && ! file_name[1]);
 419     }
 420 }
 421
 422 /* Some implementations of rmdir let you remove '.' or '/'.
 423    Report an error with errno set to zero for obvious cases of this;
 424    otherwise call rmdir.  */
 425 static int
 426 safer_rmdir (const char *file_name)
 427 {
 428   if (must_be_dot_or_slash (file_name))
 429     {
 430       errno = 0;
 431       return -1;
 432     }
 433
 434   return rmdir (file_name);
 435 }
 436
 437 /* Remove FILE_NAME, returning 1 on success.  If FILE_NAME is a directory,
 438    then if OPTION is RECURSIVE_REMOVE_OPTION is set remove FILE_NAME
 439    recursively; otherwise, remove it only if it is empty.  If FILE_NAME is
 440    a directory that cannot be removed (e.g., because it is nonempty)
 441    and if OPTION is WANT_DIRECTORY_REMOVE_OPTION, then return -1.
 442    Return 0 on error, with errno set; if FILE_NAME is obviously the working
 443    directory return zero with errno set to zero.  */
 444 int
 445 remove_any_file (const char *file_name, enum remove_option option)
 446 {
 447   /* Try unlink first if we cannot unlink directories, as this saves
 448      us a system call in the common case where we're removing a
 449      non-directory.  */
 450   bool try_unlink_first = cannot_unlink_dir ();
 451
 452   if (try_unlink_first)
 453     {
 454       if (unlink (file_name) == 0)
 455         return 1;
 456
 457       /* POSIX 1003.1-2001 requires EPERM when attempting to unlink a
 458          directory without appropriate privileges, but many Linux
 459          kernels return the more-sensible EISDIR.  */
 460       if (errno != EPERM && errno != EISDIR)
 461         return 0;
 462     }
 463
 464   if (safer_rmdir (file_name) == 0)
 465     return 1;
 466
 467   switch (errno)
 468     {
 469     case ENOTDIR:
 470       return !try_unlink_first && unlink (file_name) == 0;
 471
 472     case 0:
 473     case EEXIST:
 474 #if defined ENOTEMPTY && ENOTEMPTY != EEXIST
 475     case ENOTEMPTY:
 476 #endif
 477       switch (option)
 478         {
 479         case ORDINARY_REMOVE_OPTION:
 480           break;
 481
 482         case WANT_DIRECTORY_REMOVE_OPTION:
 483           return -1;
 484
 485         case RECURSIVE_REMOVE_OPTION:
 486           {
 487             char *directory = savedir (file_name);
 488             char const *entry;
 489             size_t entrylen;
 490
 491             if (! directory)
 492               return 0;
 493
 494             for (entry = directory;
 495                  (entrylen = strlen (entry)) != 0;
 496                  entry += entrylen + 1)
 497               {
 498                 char *file_name_buffer = new_name (file_name, entry);
 499                 int r = remove_any_file (file_name_buffer,
 500                                          RECURSIVE_REMOVE_OPTION);
 501                 int e = errno;
 502                 free (file_name_buffer);
 503
 504                 if (! r)
 505                   {
 506                     free (directory);
 507                     errno = e;
 508                     return 0;
 509                   }
 510               }
 511
 512             free (directory);
 513             return safer_rmdir (file_name) == 0;
 514           }
 515         }
 516       break;
 517     }
 518
 519   return 0;
 520 }
 521
 522 /* Check if FILE_NAME already exists and make a backup of it right now.
 523    Return success (nonzero) only if the backup is either unneeded, or
 524    successful.  For now, directories are considered to never need
 525    backup.  If THIS_IS_THE_ARCHIVE is nonzero, this is the archive and
 526    so, we do not have to backup block or character devices, nor remote
 527    entities.  */
 528 bool
 529 maybe_backup_file (const char *file_name, bool this_is_the_archive)
 530 {
 531   struct stat file_stat;
 532
 533   assign_string (&before_backup_name, file_name);
 534
 535   /* A run situation may exist between Emacs or other GNU programs trying to
 536      make a backup for the same file simultaneously.  If theoretically
 537      possible, real problems are unlikely.  Doing any better would require a
 538      convention, GNU-wide, for all programs doing backups.  */
 539
 540   assign_string (&after_backup_name, 0);
 541
 542   /* Check if we really need to backup the file.  */
 543
 544   if (this_is_the_archive && _remdev (file_name))
 545     return true;
 546
 547   if (stat (file_name, &file_stat))
 548     {
 549       if (errno == ENOENT)
 550         return true;
 551
 552       stat_error (file_name);
 553       return false;
 554     }
 555
 556   if (S_ISDIR (file_stat.st_mode))
 557     return true;
 558
 559   if (this_is_the_archive
 560       && (S_ISBLK (file_stat.st_mode) || S_ISCHR (file_stat.st_mode)))
 561     return true;
 562
 563   after_backup_name = find_backup_file_name (file_name, backup_type);
 564   if (! after_backup_name)
 565     xalloc_die ();
 566
 567   if (rename (before_backup_name, after_backup_name) == 0)
 568     {
 569       if (verbose_option)
 570         fprintf (stdlis, _("Renaming %s to %s\n"),
 571                  quote_n (0, before_backup_name),
 572                  quote_n (1, after_backup_name));
 573       return true;
 574     }
 575   else
 576     {
 577       /* The backup operation failed.  */
 578       int e = errno;
 579       ERROR ((0, e, _("%s: Cannot rename to %s"),
 580               quotearg_colon (before_backup_name),
 581               quote_n (1, after_backup_name)));
 582       assign_string (&after_backup_name, 0);
 583       return false;
 584     }
 585 }
 586
 587 /* Try to restore the recently backed up file to its original name.
 588    This is usually only needed after a failed extraction.  */
 589 void
 590 undo_last_backup (void)
 591 {
 592   if (after_backup_name)
 593     {
 594       if (rename (after_backup_name, before_backup_name) != 0)
 595         {
 596           int e = errno;
 597           ERROR ((0, e, _("%s: Cannot rename to %s"),
 598                   quotearg_colon (after_backup_name),
 599                   quote_n (1, before_backup_name)));
 600         }
 601       if (verbose_option)
 602         fprintf (stdlis, _("Renaming %s back to %s\n"),
 603                  quote_n (0, after_backup_name),
 604                  quote_n (1, before_backup_name));
 605       assign_string (&after_backup_name, 0);
 606     }
 607 }
 608
 609 /* Depending on DEREF, apply either stat or lstat to (NAME, BUF).  */
 610 int
 611 deref_stat (bool deref, char const *name, struct stat *buf)
 612 {
 613   return deref ? stat (name, buf) : lstat (name, buf);
 614 }
 615
 616 /* Use futimens if possible, utimensat otherwise.  */
 617 int
 618 fd_utimensat (int fd, int parentfd, char const *file,
 619               struct timespec const ts[2], int atflag)
 620 {
 621   if (0 <= fd)
 622     {
 623       int result = futimens (fd, ts);
 624       if (! (result < 0 && errno == ENOSYS))
 625         return result;
 626     }
 627
 628   return utimensat (parentfd, file, ts, atflag);
 629 }
 630
 631 /* Set FD's (i.e., FILE's) access time to ATIME.
 632    ATFLAG controls symbolic-link following, in the style of openat.  */
 633 int
 634 set_file_atime (int fd, char const *file, struct timespec atime, int atflag)
 635 {
 636   struct timespec ts[2];
 637   ts[0] = atime;
 638   ts[1].tv_nsec = UTIME_OMIT;
 639   return fd_utimensat (fd, AT_FDCWD, file, ts, atflag);
 640 }
 641
 642 /* A description of a working directory.  */
 643 struct wd
 644 {
 645   /* The directory's name.  */
 646   char const *name;
 647
 648   /* A negative value if no attempt has been made to save the
 649      directory, 0 if it was saved successfully, and a positive errno
 650      value if it was not saved successfully.  */
 651   int err;
 652
 653   /* The saved version of the directory, if ERR == 0.  */
 654   struct saved_cwd saved_cwd;
 655 };
 656
 657 /* A vector of chdir targets.  wd[0] is the initial working directory.  */
 658 static struct wd *wd;
 659
 660 /* The number of working directories in the vector.  */
 661 static size_t wd_count;
 662
 663 /* The allocated size of the vector.  */
 664 static size_t wd_alloc;
 665
 666 int
 667 chdir_count ()
 668 {
 669   if (wd_count == 0)
 670     return wd_count;
 671   return wd_count - 1;
 672 }
 673
 674 /* DIR is the operand of a -C option; add it to vector of chdir targets,
 675    and return the index of its location.  */
 676 int
 677 chdir_arg (char const *dir)
 678 {
 679   if (wd_count == wd_alloc)
 680     {
 681       if (wd_alloc == 0)
 682         {
 683           wd_alloc = 2;
 684           wd = xmalloc (sizeof *wd * wd_alloc);
 685         }
 686       else
 687         wd = x2nrealloc (wd, &wd_alloc, sizeof *wd);
 688
 689       if (! wd_count)
 690         {
 691           wd[wd_count].name = ".";
 692           wd[wd_count].err = -1;
 693           wd_count++;
 694         }
 695     }
 696
 697   /* Optimize the common special case of the working directory,
 698      or the working directory as a prefix.  */
 699   if (dir[0])
 700     {
 701       while (dir[0] == '.' && ISSLASH (dir[1]))
 702         for (dir += 2;  ISSLASH (*dir);  dir++)
 703           continue;
 704       if (! dir[dir[0] == '.'])
 705         return wd_count - 1;
 706     }
 707
 708   wd[wd_count].name = dir;
 709   wd[wd_count].err = -1;
 710   return wd_count++;
 711 }
 712
 713 /* Index of current directory.  */
 714 int chdir_current;
 715
 716 /* Change to directory I.  If I is 0, change to the initial working
 717    directory; otherwise, I must be a value returned by chdir_arg.  */
 718 void
 719 chdir_do (int i)
 720 {
 721   if (chdir_current != i)
 722     {
 723       struct wd *prev = &wd[chdir_current];
 724       struct wd *curr = &wd[i];
 725
 726       if (prev->err < 0)
 727         {
 728           prev->err = 0;
 729           if (save_cwd (&prev->saved_cwd) != 0)
 730             prev->err = errno;
 731           else if (0 <= prev->saved_cwd.desc)
 732             {
 733               /* Make sure we still have at least one descriptor available.  */
 734               int fd1 = prev->saved_cwd.desc;
 735               int fd2 = dup (fd1);
 736               if (0 <= fd2)
 737                 close (fd2);
 738               else if (errno == EMFILE)
 739                 {
 740                   /* Force restore_cwd to use chdir_long.  */
 741                   close (fd1);
 742                   prev->saved_cwd.desc = -1;
 743                   prev->saved_cwd.name = xgetcwd ();
 744                   if (! prev->saved_cwd.name)
 745                     prev->err = errno;
 746                 }
 747               else
 748                 prev->err = errno;
 749             }
 750         }
 751
 752       if (0 <= curr->err)
 753         {
 754           int err = curr->err;
 755           if (err == 0 && restore_cwd (&curr->saved_cwd) != 0)
 756             err = errno;
 757           if (err)
 758             FATAL_ERROR ((0, err, _("Cannot restore working directory")));
 759         }
 760       else
 761         {
 762           if (i && ! ISSLASH (curr->name[0]))
 763             chdir_do (i - 1);
 764           if (chdir (curr->name) != 0)
 765             chdir_fatal (curr->name);
 766         }
 767
 768       chdir_current = i;
 769     }
 770 }
 771 \f
 772 void
 773 close_diag (char const *name)
 774 {
 775   if (ignore_failed_read_option)
 776     close_warn (name);
 777   else
 778     close_error (name);
 779 }
 780
 781 void
 782 open_diag (char const *name)
 783 {
 784   if (ignore_failed_read_option)
 785     open_warn (name);
 786   else
 787     open_error (name);
 788 }
 789
 790 void
 791 read_diag_details (char const *name, off_t offset, size_t size)
 792 {
 793   if (ignore_failed_read_option)
 794     read_warn_details (name, offset, size);
 795   else
 796     read_error_details (name, offset, size);
 797 }
 798
 799 void
 800 readlink_diag (char const *name)
 801 {
 802   if (ignore_failed_read_option)
 803     readlink_warn (name);
 804   else
 805     readlink_error (name);
 806 }
 807
 808 void
 809 savedir_diag (char const *name)
 810 {
 811   if (ignore_failed_read_option)
 812     savedir_warn (name);
 813   else
 814     savedir_error (name);
 815 }
 816
 817 void
 818 seek_diag_details (char const *name, off_t offset)
 819 {
 820   if (ignore_failed_read_option)
 821     seek_warn_details (name, offset);
 822   else
 823     seek_error_details (name, offset);
 824 }
 825
 826 void
 827 stat_diag (char const *name)
 828 {
 829   if (ignore_failed_read_option)
 830     stat_warn (name);
 831   else
 832     stat_error (name);
 833 }
 834
 835 void
 836 file_removed_diag (const char *name, bool top_level,
 837                    void (*diagfn) (char const *name))
 838 {
 839   if (!top_level && errno == ENOENT)
 840     {
 841       WARNOPT (WARN_FILE_REMOVED,
 842                (0, 0, _("%s: File removed before we read it"),
 843                 quotearg_colon (name)));
 844       set_exit_status (TAREXIT_DIFFERS);
 845     }
 846   else
 847     diagfn (name);
 848 }
 849
 850 void
 851 dir_removed_diag (const char *name, bool top_level,
 852                    void (*diagfn) (char const *name))
 853 {
 854   if (!top_level && errno == ENOENT)
 855     {
 856       WARNOPT (WARN_FILE_REMOVED,
 857                (0, 0, _("%s: Directory removed before we read it"),
 858                 quotearg_colon (name)));
 859       set_exit_status (TAREXIT_DIFFERS);
 860     }
 861   else
 862     diagfn (name);
 863 }
 864
 865 void
 866 write_fatal_details (char const *name, ssize_t status, size_t size)
 867 {
 868   write_error_details (name, status, size);
 869   fatal_exit ();
 870 }
 871
 872 /* Fork, aborting if unsuccessful.  */
 873 pid_t
 874 xfork (void)
 875 {
 876   pid_t p = fork ();
 877   if (p == (pid_t) -1)
 878     call_arg_fatal ("fork", _("child process"));
 879   return p;
 880 }
 881
 882 /* Create a pipe, aborting if unsuccessful.  */
 883 void
 884 xpipe (int fd[2])
 885 {
 886   if (pipe (fd) < 0)
 887     call_arg_fatal ("pipe", _("interprocess channel"));
 888 }
 889
 890 /* Return PTR, aligned upward to the next multiple of ALIGNMENT.
 891    ALIGNMENT must be nonzero.  The caller must arrange for ((char *)
 892    PTR) through ((char *) PTR + ALIGNMENT - 1) to be addressable
 893    locations.  */
 894
 895 static inline void *
 896 ptr_align (void *ptr, size_t alignment)
 897 {
 898   char *p0 = ptr;
 899   char *p1 = p0 + alignment - 1;
 900   return p1 - (size_t) p1 % alignment;
 901 }
 902
 903 /* Return the address of a page-aligned buffer of at least SIZE bytes.
 904    The caller should free *PTR when done with the buffer.  */
 905
 906 void *
 907 page_aligned_alloc (void **ptr, size_t size)
 908 {
 909   size_t alignment = getpagesize ();
 910   size_t size1 = size + alignment;
 911   if (size1 < size)
 912     xalloc_die ();
 913   *ptr = xmalloc (size1);
 914   return ptr_align (*ptr, alignment);
 915 }
 916
 917 \f
 918
 919 struct namebuf
 920 {
 921   char *buffer;         /* directory, `/', and directory member */
 922   size_t buffer_size;   /* allocated size of name_buffer */
 923   size_t dir_length;    /* length of directory part in buffer */
 924 };
 925
 926 namebuf_t
 927 namebuf_create (const char *dir)
 928 {
 929   namebuf_t buf = xmalloc (sizeof (*buf));
 930   buf->buffer_size = strlen (dir) + 2;
 931   buf->buffer = xmalloc (buf->buffer_size);
 932   strcpy (buf->buffer, dir);
 933   buf->dir_length = strlen (buf->buffer);
 934   if (!ISSLASH (buf->buffer[buf->dir_length - 1]))
 935     buf->buffer[buf->dir_length++] = DIRECTORY_SEPARATOR;
 936   return buf;
 937 }
 938
 939 void
 940 namebuf_free (namebuf_t buf)
 941 {
 942   free (buf->buffer);
 943   free (buf);
 944 }
 945
 946 char *
 947 namebuf_name (namebuf_t buf, const char *name)
 948 {
 949   size_t len = strlen (name);
 950   while (buf->dir_length + len + 1 >= buf->buffer_size)
 951     buf->buffer = x2realloc (buf->buffer, &buf->buffer_size);
 952   strcpy (buf->buffer + buf->dir_length, name);
 953   return buf->buffer;
 954 }