contrib/texinfo-4/info/tilde.c

   1 /* tilde.c -- tilde expansion code (~/foo := $HOME/foo).
   2    $Id: tilde.c,v 1.3 2004/04/11 17:56:46 karl Exp $
   3
   4    Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1996, 1998, 1999,
   5    2002, 2004 Free Software Foundation, Inc.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20
  21    Written by Brian Fox (bfox@ai.mit.edu). */
  22
  23 /* Include config.h before doing alloca.  */
  24 #include "info.h"
  25 #include "tilde.h"
  26
  27 #if defined (TEST) || defined (STATIC_MALLOC)
  28 static void *xmalloc (), *xrealloc ();
  29 #endif /* TEST || STATIC_MALLOC */
  30
  31 /* The default value of tilde_additional_prefixes.  This is set to
  32    whitespace preceding a tilde so that simple programs which do not
  33    perform any word separation get desired behaviour. */
  34 static char *default_prefixes[] =
  35   { " ~", "\t~", (char *)NULL };
  36
  37 /* The default value of tilde_additional_suffixes.  This is set to
  38    whitespace or newline so that simple programs which do not
  39    perform any word separation get desired behaviour. */
  40 static char *default_suffixes[] =
  41   { " ", "\n", (char *)NULL };
  42
  43 /* If non-null, this contains the address of a function to call if the
  44    standard meaning for expanding a tilde fails.  The function is called
  45    with the text (sans tilde, as in "foo"), and returns a malloc()'ed string
  46    which is the expansion, or a NULL pointer if there is no expansion. */
  47 CFunction *tilde_expansion_failure_hook = (CFunction *)NULL;
  48
  49 /* When non-null, this is a NULL terminated array of strings which
  50    are duplicates for a tilde prefix.  Bash uses this to expand
  51    `=~' and `:~'. */
  52 char **tilde_additional_prefixes = default_prefixes;
  53
  54 /* When non-null, this is a NULL terminated array of strings which match
  55    the end of a username, instead of just "/".  Bash sets this to
  56    `:' and `=~'. */
  57 char **tilde_additional_suffixes = default_suffixes;
  58
  59 /* Find the start of a tilde expansion in STRING, and return the index of
  60    the tilde which starts the expansion.  Place the length of the text
  61    which identified this tilde starter in LEN, excluding the tilde itself. */
  62 static int
  63 tilde_find_prefix (char *string, int *len)
  64 {
  65   register int i, j, string_len;
  66   register char **prefixes = tilde_additional_prefixes;
  67
  68   string_len = strlen (string);
  69   *len = 0;
  70
  71   if (!*string || *string == '~')
  72     return (0);
  73
  74   if (prefixes)
  75     {
  76       for (i = 0; i < string_len; i++)
  77         {
  78           for (j = 0; prefixes[j]; j++)
  79             {
  80               if (strncmp (string + i, prefixes[j], strlen (prefixes[j])) == 0)
  81                 {
  82                   *len = strlen (prefixes[j]) - 1;
  83                   return (i + *len);
  84                 }
  85             }
  86         }
  87     }
  88   return (string_len);
  89 }
  90
  91 /* Find the end of a tilde expansion in STRING, and return the index of
  92    the character which ends the tilde definition.  */
  93 static int
  94 tilde_find_suffix (char *string)
  95 {
  96   register int i, j, string_len;
  97   register char **suffixes = tilde_additional_suffixes;
  98
  99   string_len = strlen (string);
 100
 101   for (i = 0; i < string_len; i++)
 102     {
 103       if (IS_SLASH (string[i]) || !string[i])
 104         break;
 105
 106       for (j = 0; suffixes && suffixes[j]; j++)
 107         {
 108           if (strncmp (string + i, suffixes[j], strlen (suffixes[j])) == 0)
 109             return (i);
 110         }
 111     }
 112   return (i);
 113 }
 114
 115 /* Return a new string which is the result of tilde expanding STRING. */
 116 char *
 117 tilde_expand (char *string)
 118 {
 119   char *result;
 120   int result_size, result_index;
 121
 122   result_size = result_index = 0;
 123   result = (char *)NULL;
 124
 125   /* Scan through STRING expanding tildes as we come to them. */
 126   while (1)
 127     {
 128       register int start, end;
 129       char *tilde_word, *expansion;
 130       int len;
 131
 132       /* Make START point to the tilde which starts the expansion. */
 133       start = tilde_find_prefix (string, &len);
 134
 135       /* Copy the skipped text into the result. */
 136       if ((result_index + start + 1) > result_size)
 137         result = (char *)xrealloc (result, 1 + (result_size += (start + 20)));
 138
 139       strncpy (result + result_index, string, start);
 140       result_index += start;
 141
 142       /* Advance STRING to the starting tilde. */
 143       string += start;
 144
 145       /* Make END be the index of one after the last character of the
 146          username. */
 147       end = tilde_find_suffix (string);
 148
 149       /* If both START and END are zero, we are all done. */
 150       if (!start && !end)
 151         break;
 152
 153       /* Expand the entire tilde word, and copy it into RESULT. */
 154       tilde_word = (char *)xmalloc (1 + end);
 155       strncpy (tilde_word, string, end);
 156       tilde_word[end] = '\0';
 157       string += end;
 158
 159       expansion = tilde_expand_word (tilde_word);
 160       free (tilde_word);
 161
 162       len = strlen (expansion);
 163       if ((result_index + len + 1) > result_size)
 164         result = (char *)xrealloc (result, 1 + (result_size += (len + 20)));
 165
 166       strcpy (result + result_index, expansion);
 167       result_index += len;
 168       free (expansion);
 169     }
 170
 171   result[result_index] = '\0';
 172
 173   return (result);
 174 }
 175
 176 /* Do the work of tilde expansion on FILENAME.  FILENAME starts with a
 177    tilde.  If there is no expansion, call tilde_expansion_failure_hook. */
 178 char *
 179 tilde_expand_word (char *filename)
 180 {
 181   char *dirname = filename ? xstrdup (filename) : NULL;
 182
 183   if (dirname && *dirname == '~')
 184     {
 185       char *temp_name;
 186       if (!dirname[1] || IS_SLASH (dirname[1]))
 187         {
 188           /* Prepend $HOME to the rest of the string. */
 189           char *temp_home = getenv ("HOME");
 190
 191           /* If there is no HOME variable, look up the directory in
 192              the password database. */
 193           if (!temp_home)
 194             {
 195               struct passwd *entry;
 196
 197               entry = (struct passwd *) getpwuid (getuid ());
 198               if (entry)
 199                 temp_home = entry->pw_dir;
 200             }
 201
 202           temp_name = xmalloc (1 + strlen (&dirname[1])
 203                                + (temp_home ? strlen (temp_home) : 0));
 204           if (temp_home)
 205             strcpy (temp_name, temp_home);
 206           else
 207             temp_name[0] = 0;
 208           strcat (temp_name, &dirname[1]);
 209           free (dirname);
 210           dirname = xstrdup (temp_name);
 211           free (temp_name);
 212         }
 213       else
 214         {
 215           struct passwd *user_entry;
 216           char *username = xmalloc (257);
 217           int i, c;
 218
 219           for (i = 1; (c = dirname[i]); i++)
 220             {
 221               if (IS_SLASH (c))
 222                 break;
 223               else
 224                 username[i - 1] = c;
 225             }
 226           username[i - 1] = 0;
 227
 228           if (!(user_entry = (struct passwd *) getpwnam (username)))
 229             {
 230               /* If the calling program has a special syntax for
 231                  expanding tildes, and we couldn't find a standard
 232                  expansion, then let them try. */
 233               if (tilde_expansion_failure_hook)
 234                 {
 235                   char *expansion = (*tilde_expansion_failure_hook) (username);
 236
 237                   if (expansion)
 238                     {
 239                       temp_name = xmalloc (1 + strlen (expansion)
 240                                            + strlen (&dirname[i]));
 241                       strcpy (temp_name, expansion);
 242                       strcat (temp_name, &dirname[i]);
 243                       free (expansion);
 244                       goto return_name;
 245                     }
 246                 }
 247               /* We shouldn't report errors. */
 248             }
 249           else
 250             {
 251               temp_name = xmalloc (1 + strlen (user_entry->pw_dir)
 252                                    + strlen (&dirname[i]));
 253               strcpy (temp_name, user_entry->pw_dir);
 254               strcat (temp_name, &dirname[i]);
 255
 256             return_name:
 257               free (dirname);
 258               dirname = xstrdup (temp_name);
 259               free (temp_name);
 260             }
 261
 262           endpwent ();
 263           free (username);
 264         }
 265     }
 266   return dirname;
 267 }
 268
 269 \f
 270 #if defined (TEST)
 271 #undef NULL
 272 #include <stdio.h>
 273
 274 main (argc, argv)
 275      int argc;
 276      char **argv;
 277 {
 278   char *result, line[512];
 279   int done = 0;
 280
 281   while (!done)
 282     {
 283       printf ("~expand: ");
 284       fflush (stdout);
 285
 286       if (!gets (line))
 287         strcpy (line, "done");
 288
 289       if ((strcmp (line, "done") == 0) ||
 290           (strcmp (line, "quit") == 0) ||
 291           (strcmp (line, "exit") == 0))
 292         {
 293           done = 1;
 294           break;
 295         }
 296
 297       result = tilde_expand (line);
 298       printf ("  --> %s\n", result);
 299       free (result);
 300     }
 301   xexit (0);
 302 }
 303
 304 static void memory_error_and_abort ();
 305
 306 static void *
 307 xmalloc (bytes)
 308      int bytes;
 309 {
 310   void *temp = (void *)malloc (bytes);
 311
 312   if (!temp)
 313     memory_error_and_abort ();
 314   return (temp);
 315 }
 316
 317 static void *
 318 xrealloc (pointer, bytes)
 319      void *pointer;
 320      int bytes;
 321 {
 322   void *temp;
 323
 324   if (!pointer)
 325     temp = (char *)malloc (bytes);
 326   else
 327     temp = (char *)realloc (pointer, bytes);
 328
 329   if (!temp)
 330     memory_error_and_abort ();
 331
 332   return (temp);
 333 }
 334
 335 static void
 336 memory_error_and_abort ()
 337 {
 338   fprintf (stderr, _("readline: Out of virtual memory!\n"));
 339   abort ();
 340 }
 341 #endif /* TEST */
 342