lib/backup-find.c

   1 /* backupfile.c -- make Emacs style backup file names
   2
   3    Copyright 2017-2018 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 #include "backup-internal.h"
  21
  22 #include "argmatch.h"
  23 #include "xalloc.h"
  24
  25 #include <stdlib.h>
  26
  27 /* Return the name of a backup file for the existing file FILE,
  28    allocated with malloc.  Report an error and exit if out of memory.
  29    Do not call this function if backup_type == no_backups.  */
  30
  31 char *
  32 find_backup_file_name (char const *file, enum backup_type backup_type)
  33 {
  34   char *result = backupfile_internal (file, backup_type, false);
  35   if (!result)
  36     xalloc_die ();
  37   return result;
  38 }
  39
  40 static char const *const backup_args[] =
  41 {
  42   /* In a series of synonyms, present the most meaningful first, so
  43      that argmatch_valid be more readable. */
  44   "none", "off",
  45   "simple", "never",
  46   "existing", "nil",
  47   "numbered", "t",
  48   NULL
  49 };
  50
  51 static const enum backup_type backup_types[] =
  52 {
  53   no_backups, no_backups,
  54   simple_backups, simple_backups,
  55   numbered_existing_backups, numbered_existing_backups,
  56   numbered_backups, numbered_backups
  57 };
  58
  59 /* Ensure that these two vectors have the same number of elements,
  60    not counting the final NULL in the first one.  */
  61 ARGMATCH_VERIFY (backup_args, backup_types);
  62
  63 /* Return the type of backup specified by VERSION.
  64    If VERSION is NULL or the empty string, return numbered_existing_backups.
  65    If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
  66    for the specified CONTEXT.  Unambiguous abbreviations are accepted.  */
  67
  68 enum backup_type
  69 get_version (char const *context, char const *version)
  70 {
  71   if (version == 0 || *version == 0)
  72     return numbered_existing_backups;
  73   else
  74     return XARGMATCH (context, version, backup_args, backup_types);
  75 }
  76
  77
  78 /* Return the type of backup specified by VERSION.
  79    If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
  80    If the specified string is invalid or ambiguous, fail with a diagnostic
  81    appropriate for the specified CONTEXT.
  82    Unambiguous abbreviations are accepted.  */
  83
  84 enum backup_type
  85 xget_version (char const *context, char const *version)
  86 {
  87   if (version && *version)
  88     return get_version (context, version);
  89   else
  90     return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));
  91 }