gnu/dist/gettext/gettext-tools/lib/backupfile.c

   1 /* backupfile.c -- make Emacs style backup file names
   2    Copyright (C) 1990-1999, 2000-2003 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; see the file COPYING.
  16    If not, write to the Free Software Foundation,
  17    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
  20    Some algorithms adapted from GNU Emacs. */
  21
  22 #if HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 #include "argmatch.h"
  27 #include "backupfile.h"
  28
  29 #include <stdio.h>
  30 #include <sys/types.h>
  31 #if HAVE_STRING_H
  32 # include <string.h>
  33 #else
  34 # include <strings.h>
  35 #endif
  36
  37 #if HAVE_DIRENT_H
  38 # include <dirent.h>
  39 # define NLENGTH(direct) strlen ((direct)->d_name)
  40 #else
  41 # define dirent direct
  42 # define NLENGTH(direct) ((size_t) (direct)->d_namlen)
  43 # if HAVE_SYS_NDIR_H
  44 #  include <sys/ndir.h>
  45 # endif
  46 # if HAVE_SYS_DIR_H
  47 #  include <sys/dir.h>
  48 # endif
  49 # if HAVE_NDIR_H
  50 #  include <ndir.h>
  51 # endif
  52 #endif
  53
  54 #if CLOSEDIR_VOID
  55 /* Fake a return value. */
  56 # define CLOSEDIR(d) (closedir (d), 0)
  57 #else
  58 # define CLOSEDIR(d) closedir (d)
  59 #endif
  60
  61 #include <stdlib.h>
  62
  63 #include "basename.h"
  64
  65 #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H
  66 # define HAVE_DIR 1
  67 #else
  68 # define HAVE_DIR 0
  69 #endif
  70
  71 #include <limits.h>
  72
  73 /* Upper bound on the string length of an integer converted to string.
  74    302 / 1000 is ceil (log10 (2.0)).  Subtract 1 for the sign bit;
  75    add 1 for integer division truncation; add 1 more for a minus sign.  */
  76 #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2)
  77
  78 /* ISDIGIT differs from isdigit, as follows:
  79    - Its arg may be any int or unsigned int; it need not be an unsigned char.
  80    - It's guaranteed to evaluate its argument exactly once.
  81    - It's typically faster.
  82    Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
  83    only '0' through '9' are digits.  Prefer ISDIGIT to isdigit unless
  84    it's important to use the locale's definition of `digit' even when the
  85    host does not conform to Posix.  */
  86 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
  87
  88 #if D_INO_IN_DIRENT
  89 # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
  90 #else
  91 # define REAL_DIR_ENTRY(dp) 1
  92 #endif
  93
  94 /* The extension added to file names to produce a simple (as opposed
  95    to numbered) backup file name. */
  96 const char *simple_backup_suffix = "~";
  97
  98 #if HAVE_DIR
  99 static int max_backup_version (const char *, const char *);
 100 static int version_number (const char *, const char *, size_t);
 101 #endif
 102
 103 /* Return the name of the new backup file for file FILE,
 104    allocated with malloc.  Return 0 if out of memory.
 105    FILE must not end with a '/' unless it is the root directory.
 106    Do not call this function if backup_type == none. */
 107
 108 char *
 109 find_backup_file_name (const char *file, enum backup_type backup_type)
 110 {
 111   size_t backup_suffix_size_max;
 112   size_t file_len = strlen (file);
 113   size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4;
 114   char *s;
 115   const char *suffix = simple_backup_suffix;
 116
 117   /* Allow room for simple or `.~N~' backups.  */
 118   backup_suffix_size_max = strlen (simple_backup_suffix) + 1;
 119   if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max)
 120     backup_suffix_size_max = numbered_suffix_size_max;
 121
 122   s = malloc (file_len + backup_suffix_size_max + numbered_suffix_size_max);
 123   if (s)
 124     {
 125       strcpy (s, file);
 126
 127 #if HAVE_DIR
 128       if (backup_type != simple)
 129         {
 130           int highest_backup;
 131           size_t dir_len = basename (s) - s;
 132
 133           strcpy (s + dir_len, ".");
 134           highest_backup = max_backup_version (file + dir_len, s);
 135           if (! (backup_type == numbered_existing && highest_backup == 0))
 136             {
 137               char *numbered_suffix = s + (file_len + backup_suffix_size_max);
 138               sprintf (numbered_suffix, ".~%d~", highest_backup + 1);
 139               suffix = numbered_suffix;
 140             }
 141           strcpy (s, file);
 142         }
 143 #endif /* HAVE_DIR */
 144
 145       addext (s, suffix, '~');
 146     }
 147   return s;
 148 }
 149
 150 #if HAVE_DIR
 151
 152 /* Return the number of the highest-numbered backup file for file
 153    FILE in directory DIR.  If there are no numbered backups
 154    of FILE in DIR, or an error occurs reading DIR, return 0.
 155    */
 156
 157 static int
 158 max_backup_version (const char *file, const char *dir)
 159 {
 160   DIR *dirp;
 161   struct dirent *dp;
 162   int highest_version;
 163   int this_version;
 164   size_t file_name_length;
 165
 166   dirp = opendir (dir);
 167   if (!dirp)
 168     return 0;
 169
 170   highest_version = 0;
 171   file_name_length = strlen (file);
 172
 173   while ((dp = readdir (dirp)) != 0)
 174     {
 175       if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4)
 176         continue;
 177
 178       this_version = version_number (file, dp->d_name, file_name_length);
 179       if (this_version > highest_version)
 180         highest_version = this_version;
 181     }
 182   if (CLOSEDIR (dirp))
 183     return 0;
 184   return highest_version;
 185 }
 186
 187 /* If BACKUP is a numbered backup of BASE, return its version number;
 188    otherwise return 0.  BASE_LENGTH is the length of BASE.
 189    */
 190
 191 static int
 192 version_number (const char *base, const char *backup, size_t base_length)
 193 {
 194   int version;
 195   const char *p;
 196
 197   version = 0;
 198   if (strncmp (base, backup, base_length) == 0
 199       && backup[base_length] == '.'
 200       && backup[base_length + 1] == '~')
 201     {
 202       for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p)
 203         version = version * 10 + *p - '0';
 204       if (p[0] != '~' || p[1])
 205         version = 0;
 206     }
 207   return version;
 208 }
 209 #endif /* HAVE_DIR */
 210
 211 static const char * const backup_args[] =
 212 {
 213   /* In a series of synonyms, present the most meaning full first, so
 214      that argmatch_valid be more readable. */
 215   "none", "off",
 216   "simple", "never",
 217   "existing", "nil",
 218   "numbered", "t",
 219   0
 220 };
 221
 222 static const enum backup_type backup_types[] =
 223 {
 224   none, none,
 225   simple, simple,
 226   numbered_existing, numbered_existing,
 227   numbered, numbered
 228 };
 229
 230 /* Return the type of backup specified by VERSION.
 231    If VERSION is NULL or the empty string, return numbered_existing.
 232    If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
 233    for the specified CONTEXT.  Unambiguous abbreviations are accepted.  */
 234
 235 enum backup_type
 236 get_version (const char *context, const char *version)
 237 {
 238   if (version == 0 || *version == 0)
 239     return numbered_existing;
 240   else
 241     return XARGMATCH (context, version, backup_args, backup_types);
 242 }
 243
 244
 245 /* Return the type of backup specified by VERSION.
 246    If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
 247    If the specified string is invalid or ambiguous, fail with a diagnostic
 248    appropriate for the specified CONTEXT.
 249    Unambiguous abbreviations are accepted.  */
 250
 251 enum backup_type
 252 xget_version (const char *context, const char *version)
 253 {
 254   if (version && *version)
 255     return get_version (context, version);
 256   else
 257     return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));
 258 }