src/realpath.c

   1 /* realpath - print the resolved path
   2    Copyright (C) 2011-2013 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 3 of the License, or
   7    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Pádraig Brady.  */
  18
  19 #include <config.h>
  20 #include <getopt.h>
  21 #include <stdio.h>
  22 #include <sys/types.h>
  23
  24 #include "system.h"
  25 #include "canonicalize.h"
  26 #include "error.h"
  27 #include "quote.h"
  28 #include "relpath.h"
  29
  30 /* The official name of this program (e.g., no 'g' prefix).  */
  31 #define PROGRAM_NAME "realpath"
  32
  33 #define AUTHORS proper_name_utf8 ("Padraig Brady", "P\303\241draig Brady")
  34
  35 enum
  36 {
  37   RELATIVE_TO_OPTION = CHAR_MAX + 1,
  38   RELATIVE_BASE_OPTION
  39 };
  40
  41 static bool verbose = true;
  42 static bool logical;
  43 static bool use_nuls;
  44 static const char *can_relative_to;
  45 static const char *can_relative_base;
  46
  47 static struct option const longopts[] =
  48 {
  49   {"canonicalize-existing", no_argument, NULL, 'e'},
  50   {"canonicalize-missing", no_argument, NULL, 'm'},
  51   {"relative-to", required_argument, NULL, RELATIVE_TO_OPTION},
  52   {"relative-base", required_argument, NULL, RELATIVE_BASE_OPTION},
  53   {"quiet", no_argument, NULL, 'q'},
  54   {"strip", no_argument, NULL, 's' /* FIXME: deprecate in 2013 or so */},
  55   {"no-symlinks", no_argument, NULL, 's'},
  56   {"zero", no_argument, NULL, 'z'},
  57   {"logical", no_argument, NULL, 'L'},
  58   {"physical", no_argument, NULL, 'P'},
  59   {GETOPT_HELP_OPTION_DECL},
  60   {GETOPT_VERSION_OPTION_DECL},
  61   {NULL, 0, NULL, 0}
  62 };
  63
  64 void
  65 usage (int status)
  66 {
  67   if (status != EXIT_SUCCESS)
  68     emit_try_help ();
  69   else
  70     {
  71       printf (_("Usage: %s [OPTION]... FILE...\n"), program_name);
  72       fputs (_("\
  73 Print the resolved absolute file name;\n\
  74 all but the last component must exist\n\
  75 \n\
  76 "), stdout);
  77       fputs (_("\
  78   -e, --canonicalize-existing  all components of the path must exist\n\
  79   -m, --canonicalize-missing   no components of the path need exist\n\
  80   -L, --logical                resolve '..' components before symlinks\n\
  81   -P, --physical               resolve symlinks as encountered (default)\n\
  82   -q, --quiet                  suppress most error messages\n\
  83       --relative-to=FILE       print the resolved path relative to FILE\n\
  84       --relative-base=FILE     print absolute paths unless paths below FILE\n\
  85   -s, --strip, --no-symlinks   don't expand symlinks\n\
  86   -z, --zero                   separate output with NUL rather than newline\n\
  87 \n\
  88 "), stdout);
  89       fputs (HELP_OPTION_DESCRIPTION, stdout);
  90       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  91       emit_ancillary_info ();
  92     }
  93   exit (status);
  94 }
  95
  96 /* A wrapper around canonicalize_filename_mode(),
  97    to call it twice when in LOGICAL mode.  */
  98 static char *
  99 realpath_canon (const char *fname, int can_mode)
 100 {
 101   char *can_fname = canonicalize_filename_mode (fname, can_mode);
 102   if (logical && can_fname)  /* canonicalize again to resolve symlinks.  */
 103     {
 104       can_mode &= ~CAN_NOLINKS;
 105       char *can_fname2 = canonicalize_filename_mode (can_fname, can_mode);
 106       free (can_fname);
 107       return can_fname2;
 108     }
 109   return can_fname;
 110 }
 111
 112 /* Test whether canonical prefix is parent or match of path.  */
 113 static bool _GL_ATTRIBUTE_PURE
 114 path_prefix (const char *prefix, const char *path)
 115 {
 116   /* We already know prefix[0] and path[0] are '/'.  */
 117   prefix++;
 118   path++;
 119
 120   /* '/' is the prefix of everything except '//' (since we know '//'
 121      is only present after canonicalization if it is distinct).  */
 122   if (!*prefix)
 123     return *path != '/';
 124
 125   /* Likewise, '//' is a prefix of any double-slash path.  */
 126   if (*prefix == '/' && !prefix[1])
 127     return *path == '/';
 128
 129   /* Any other prefix has a non-slash portion.  */
 130   while (*prefix && *path)
 131     {
 132       if (*prefix != *path)
 133         break;
 134       prefix++;
 135       path++;
 136     }
 137   return (!*prefix && (*path == '/' || !*path));
 138 }
 139
 140 static bool
 141 isdir (const char *path)
 142 {
 143   struct stat sb;
 144   if (stat (path, &sb) != 0)
 145     error (EXIT_FAILURE, errno, _("cannot stat %s"), quote (path));
 146   return S_ISDIR (sb.st_mode);
 147 }
 148
 149 static bool
 150 process_path (const char *fname, int can_mode)
 151 {
 152   char *can_fname = realpath_canon (fname, can_mode);
 153   if (!can_fname)
 154     {
 155       if (verbose)
 156         error (0, errno, "%s", quote (fname));
 157       return false;
 158     }
 159
 160   if (!can_relative_to
 161       || (can_relative_base && !path_prefix (can_relative_base, can_fname))
 162       || (can_relative_to && !relpath (can_fname, can_relative_to, NULL, 0)))
 163     fputs (can_fname, stdout);
 164
 165   putchar (use_nuls ? '\0' : '\n');
 166
 167   free (can_fname);
 168
 169   return true;
 170 }
 171
 172 int
 173 main (int argc, char **argv)
 174 {
 175   bool ok = true;
 176   int can_mode = CAN_ALL_BUT_LAST;
 177   const char *relative_to = NULL;
 178   const char *relative_base = NULL;
 179
 180   initialize_main (&argc, &argv);
 181   set_program_name (argv[0]);
 182   setlocale (LC_ALL, "");
 183   bindtextdomain (PACKAGE, LOCALEDIR);
 184   textdomain (PACKAGE);
 185
 186   atexit (close_stdout);
 187
 188   while (1)
 189     {
 190       int c = getopt_long (argc, argv, "eLmPqsz", longopts, NULL);
 191       if (c == -1)
 192         break;
 193       switch (c)
 194         {
 195         case 'e':
 196           can_mode &= ~CAN_MODE_MASK;
 197           can_mode |= CAN_EXISTING;
 198           break;
 199         case 'm':
 200           can_mode &= ~CAN_MODE_MASK;
 201           can_mode |= CAN_MISSING;
 202           break;
 203         case 'L':
 204           can_mode |= CAN_NOLINKS;
 205           logical = true;
 206           break;
 207         case 's':
 208           can_mode |= CAN_NOLINKS;
 209           logical = false;
 210           break;
 211         case 'P':
 212           can_mode &= ~CAN_NOLINKS;
 213           logical = false;
 214           break;
 215         case 'q':
 216           verbose = false;
 217           break;
 218         case 'z':
 219           use_nuls = true;
 220           break;
 221         case RELATIVE_TO_OPTION:
 222           relative_to = optarg;
 223           break;
 224         case RELATIVE_BASE_OPTION:
 225           relative_base = optarg;
 226           break;
 227         case_GETOPT_HELP_CHAR;
 228         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 229         default:
 230           usage (EXIT_FAILURE);
 231         }
 232     }
 233
 234   if (optind >= argc)
 235     {
 236       error (0, 0, _("missing operand"));
 237       usage (EXIT_FAILURE);
 238     }
 239
 240   if (relative_base && !relative_to)
 241     relative_to = relative_base;
 242
 243   bool need_dir = (can_mode & CAN_MODE_MASK) == CAN_EXISTING;
 244   if (relative_to)
 245     {
 246       can_relative_to = realpath_canon (relative_to, can_mode);
 247       if (!can_relative_to)
 248         error (EXIT_FAILURE, errno, "%s", quote (relative_to));
 249       if (need_dir && !isdir (can_relative_to))
 250         error (EXIT_FAILURE, ENOTDIR, "%s", quote (relative_to));
 251     }
 252   if (relative_base == relative_to)
 253     can_relative_base = can_relative_to;
 254   else if (relative_base)
 255     {
 256       char *base = realpath_canon (relative_base, can_mode);
 257       if (!base)
 258         error (EXIT_FAILURE, errno, "%s", quote (relative_base));
 259       if (need_dir && !isdir (base))
 260         error (EXIT_FAILURE, ENOTDIR, "%s", quote (relative_base));
 261       /* --relative-to is a no-op if it does not have --relative-base
 262            as a prefix */
 263       if (path_prefix (base, can_relative_to))
 264         can_relative_base = base;
 265       else
 266         {
 267           free (base);
 268           can_relative_base = can_relative_to;
 269           can_relative_to = NULL;
 270         }
 271     }
 272
 273   for (; optind < argc; ++optind)
 274     ok &= process_path (argv[optind], can_mode);
 275
 276   exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
 277 }