src/ln.c

   1 /* `ln' program to create links between files.
   2    Copyright (C) 1986, 1989, 1990, 1991 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; if not, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17 \f
  18 /* Written by Mike Parker and David MacKenzie. */
  19
  20 #ifdef _AIX
  21  #pragma alloca
  22 #endif
  23
  24 #ifdef HAVE_CONFIG_H
  25 #if defined (CONFIG_BROKETS)
  26 /* We use <config.h> instead of "config.h" so that a compilation
  27    using -I. -I$srcdir will use ./config.h rather than $srcdir/config.h
  28    (which it would do because it found this file in $srcdir).  */
  29 #include <config.h>
  30 #else
  31 #include "config.h"
  32 #endif
  33 #endif
  34
  35 #include <stdio.h>
  36 #include <sys/types.h>
  37 #include <getopt.h>
  38 #include "system.h"
  39 #include "backupfile.h"
  40 #include "version.h"
  41
  42 int link ();                    /* Some systems don't declare this anywhere. */
  43
  44 #ifdef S_ISLNK
  45 int symlink ();
  46 #endif
  47
  48 /* Construct a string NEW_DEST by concatenating DEST, a slash, and
  49    basename(SOURCE) in alloca'd memory.  Don't modify DEST or SOURCE.  */
  50
  51 #define PATH_BASENAME_CONCAT(new_dest, dest, source)                    \
  52     do                                                                  \
  53       {                                                                 \
  54         char *source_base;                                              \
  55         char *tmp_source;                                               \
  56                                                                         \
  57         tmp_source = (char *) alloca (strlen ((source)) + 1);           \
  58         strcpy (tmp_source, (source));                                  \
  59         strip_trailing_slashes (tmp_source);                            \
  60         source_base = basename (tmp_source);                            \
  61                                                                         \
  62         (new_dest) = (char *) alloca (strlen ((dest)) + 1               \
  63                                       + strlen (source_base) + 1);      \
  64         stpcpy (stpcpy (stpcpy ((new_dest), (dest)), "/"), source_base);\
  65       }                                                                 \
  66     while (0)
  67
  68 char *basename ();
  69 enum backup_type get_version ();
  70 int isdir ();
  71 int yesno ();
  72 void error ();
  73 void strip_trailing_slashes ();
  74 char *stpcpy ();
  75
  76 static void usage ();
  77 static int do_link ();
  78
  79 /* The name by which the program was run, for error messages.  */
  80 char *program_name;
  81
  82 /* A pointer to the function used to make links.  This will point to either
  83    `link' or `symlink'. */
  84 static int (*linkfunc) ();
  85
  86 /* If nonzero, make symbolic links; otherwise, make hard links.  */
  87 static int symbolic_link;
  88
  89 /* If nonzero, ask the user before removing existing files.  */
  90 static int interactive;
  91
  92 /* If nonzero, remove existing files unconditionally.  */
  93 static int remove_existing_files;
  94
  95 /* If nonzero, list each file as it is moved. */
  96 static int verbose;
  97
  98 /* If nonzero, allow the superuser to make hard links to directories. */
  99 static int hard_dir_link;
 100
 101 /* If non-zero, display usage information and exit.  */
 102 static int show_help;
 103
 104 /* If non-zero, print the version on standard output and exit.  */
 105 static int show_version;
 106
 107 static struct option const long_options[] =
 108 {
 109   {"backup", no_argument, NULL, 'b'},
 110   {"directory", no_argument, &hard_dir_link, 1},
 111   {"force", no_argument, NULL, 'f'},
 112   {"interactive", no_argument, NULL, 'i'},
 113   {"suffix", required_argument, NULL, 'S'},
 114   {"symbolic", no_argument, &symbolic_link, 1},
 115   {"verbose", no_argument, &verbose, 1},
 116   {"version-control", required_argument, NULL, 'V'},
 117   {"help", no_argument, &show_help, 1},
 118   {"version", no_argument, &show_version, 1},
 119   {NULL, 0, NULL, 0}
 120 };
 121
 122 void
 123 main (argc, argv)
 124      int argc;
 125      char **argv;
 126 {
 127   int c;
 128   int errors;
 129   int make_backups = 0;
 130   char *version;
 131
 132   version = getenv ("SIMPLE_BACKUP_SUFFIX");
 133   if (version)
 134     simple_backup_suffix = version;
 135   version = getenv ("VERSION_CONTROL");
 136   program_name = argv[0];
 137   linkfunc = link;
 138   symbolic_link = remove_existing_files = interactive = verbose
 139     = hard_dir_link = 0;
 140   errors = 0;
 141
 142   while ((c = getopt_long (argc, argv, "bdfisvFS:V:", long_options, (int *) 0))
 143          != EOF)
 144     {
 145       switch (c)
 146         {
 147         case 0:                 /* Long-named option. */
 148           break;
 149         case 'b':
 150           make_backups = 1;
 151           break;
 152         case 'd':
 153         case 'F':
 154           hard_dir_link = 1;
 155           break;
 156         case 'f':
 157           remove_existing_files = 1;
 158           interactive = 0;
 159           break;
 160         case 'i':
 161           remove_existing_files = 0;
 162           interactive = 1;
 163           break;
 164         case 's':
 165 #ifdef S_ISLNK
 166           symbolic_link = 1;
 167 #else
 168           error (1, 0, "symbolic links are not supported on this system");
 169 #endif
 170           break;
 171         case 'v':
 172           verbose = 1;
 173           break;
 174         case 'S':
 175           simple_backup_suffix = optarg;
 176           break;
 177         case 'V':
 178           version = optarg;
 179           break;
 180         default:
 181           usage ();
 182           break;
 183         }
 184     }
 185
 186   if (show_version)
 187     {
 188       printf ("%s\n", version_string);
 189       exit (0);
 190     }
 191
 192   if (show_help)
 193     usage ();
 194
 195   if (optind == argc)
 196     usage ();
 197
 198   if (make_backups)
 199     backup_type = get_version (version);
 200
 201 #ifdef S_ISLNK
 202   if (symbolic_link)
 203     linkfunc = symlink;
 204 #endif
 205
 206   if (optind == argc - 1)
 207     errors = do_link (argv[optind], ".");
 208   else if (optind == argc - 2)
 209     {
 210       struct stat source_stats;
 211       char *source;
 212       char *dest;
 213       char *new_dest;
 214
 215       source = argv[optind];
 216       dest = argv[optind + 1];
 217
 218       /* When the destination is specified with a trailing slash and the
 219          source exists but is not a directory, convert the user's command
 220          `ln source dest/' to `ln source dest/basename(source)'.  */
 221
 222       if (dest[strlen (dest) - 1] == '/'
 223           && lstat (source, &source_stats) == 0
 224           && !S_ISDIR (source_stats.st_mode))
 225         {
 226           PATH_BASENAME_CONCAT (new_dest, dest, source);
 227         }
 228       else
 229         {
 230           new_dest = dest;
 231         }
 232
 233       errors = do_link (source, new_dest);
 234     }
 235   else
 236     {
 237       char *to;
 238
 239       to = argv[argc - 1];
 240       if (!isdir (to))
 241         error (1, 0, "when making multiple links, last argument must be a directory");
 242       for (; optind < argc - 1; ++optind)
 243         errors += do_link (argv[optind], to);
 244     }
 245
 246   exit (errors != 0);
 247 }
 248
 249 /* Make a link DEST to existing file SOURCE.
 250    If DEST is a directory, put the link to SOURCE in that directory.
 251    Return 1 if there is an error, otherwise 0.  */
 252
 253 static int
 254 do_link (source, dest)
 255      char *source;
 256      char *dest;
 257 {
 258   struct stat dest_stats;
 259   char *dest_backup = NULL;
 260
 261   /* isdir uses stat instead of lstat.
 262      On SVR4, link does not follow symlinks, so this check disallows
 263      making hard links to symlinks that point to directories.  Big deal.
 264      On other systems, link follows symlinks, so this check is right.  */
 265   if (!symbolic_link && !hard_dir_link && isdir (source))
 266     {
 267       error (0, 0, "%s: hard link not allowed for directory", source);
 268       return 1;
 269     }
 270   if (isdir (dest))
 271     {
 272       /* Target is a directory; build the full filename. */
 273       char *new_dest;
 274       PATH_BASENAME_CONCAT (new_dest, dest, source);
 275       dest = new_dest;
 276     }
 277
 278   if (lstat (dest, &dest_stats) == 0)
 279     {
 280       if (S_ISDIR (dest_stats.st_mode))
 281         {
 282           error (0, 0, "%s: cannot overwrite directory", dest);
 283           return 1;
 284         }
 285       if (interactive)
 286         {
 287           fprintf (stderr, "%s: replace `%s'? ", program_name, dest);
 288           if (!yesno ())
 289             return 0;
 290         }
 291       else if (!remove_existing_files)
 292         {
 293           error (0, 0, "%s: File exists", dest);
 294           return 1;
 295         }
 296
 297       if (backup_type != none)
 298         {
 299           char *tmp_backup = find_backup_file_name (dest);
 300           if (tmp_backup == NULL)
 301             error (1, 0, "virtual memory exhausted");
 302           dest_backup = (char *) alloca (strlen (tmp_backup) + 1);
 303           strcpy (dest_backup, tmp_backup);
 304           free (tmp_backup);
 305           if (rename (dest, dest_backup))
 306             {
 307               if (errno != ENOENT)
 308                 {
 309                   error (0, errno, "cannot backup `%s'", dest);
 310                   return 1;
 311                 }
 312               else
 313                 dest_backup = NULL;
 314             }
 315         }
 316       else if (unlink (dest) && errno != ENOENT)
 317         {
 318           error (0, errno, "cannot remove old link to `%s'", dest);
 319           return 1;
 320         }
 321     }
 322   else if (errno != ENOENT)
 323     {
 324       error (0, errno, "%s", dest);
 325       return 1;
 326     }
 327
 328   if (verbose)
 329     printf ("%s -> %s\n", source, dest);
 330
 331   if ((*linkfunc) (source, dest) == 0)
 332     {
 333       return 0;
 334     }
 335
 336   error (0, errno, "cannot %slink `%s' to `%s'",
 337 #ifdef S_ISLNK
 338              linkfunc == symlink ? "symbolic " : "",
 339 #else
 340              "",
 341 #endif
 342              source, dest);
 343
 344   if (dest_backup)
 345     {
 346       if (rename (dest_backup, dest))
 347         error (0, errno, "cannot un-backup `%s'", dest);
 348     }
 349   return 1;
 350 }
 351
 352 static void
 353 usage ()
 354 {
 355   fprintf (stderr, "\
 356 Usage: %s [options] source [dest]\n\
 357        %s [options] source... directory\n\
 358 Options:\n\
 359        [-bdfisvF] [-S backup-suffix] [-V {numbered,existing,simple}]\n\
 360        [--version-control={numbered,existing,simple}] [--backup] [--directory]\n\
 361        [--force] [--interactive] [--symbolic] [--verbose]\n\
 362        [--suffix=backup-suffix] [--help] [--version]\n",
 363            program_name, program_name);
 364   exit (1);
 365 }