readline/tilde.c

   1 /* tilde.c -- Tilde expansion code (~/foo := $HOME/foo). */
   2
   3 /* Copyright (C) 1988-2009 Free Software Foundation, Inc.
   4
   5    This file is part of the GNU Readline Library (Readline), a library
   6    for reading lines of text with interactive input and history editing.
   7
   8    Readline is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    Readline is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Readline.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #if defined (HAVE_CONFIG_H)
  23 #  include <config.h>
  24 #endif
  25
  26 #if defined (HAVE_UNISTD_H)
  27 #  ifdef _MINIX
  28 #    include <sys/types.h>
  29 #  endif
  30 #  include <unistd.h>
  31 #endif
  32
  33 #if defined (HAVE_STRING_H)
  34 #  include <string.h>
  35 #else /* !HAVE_STRING_H */
  36 #  include <strings.h>
  37 #endif /* !HAVE_STRING_H */
  38
  39 #if defined (HAVE_STDLIB_H)
  40 #  include <stdlib.h>
  41 #else
  42 #  include "ansi_stdlib.h"
  43 #endif /* HAVE_STDLIB_H */
  44
  45 #include <sys/types.h>
  46 #if defined (HAVE_PWD_H)
  47 #include <pwd.h>
  48 #endif
  49
  50 #include "tilde.h"
  51
  52 #if defined (TEST) || defined (STATIC_MALLOC)
  53 static void *xmalloc (), *xrealloc ();
  54 #else
  55 #  include "xmalloc.h"
  56 #endif /* TEST || STATIC_MALLOC */
  57
  58 #if !defined (HAVE_GETPW_DECLS)
  59 #  if defined (HAVE_GETPWUID)
  60 extern struct passwd *getpwuid PARAMS((uid_t));
  61 #  endif
  62 #  if defined (HAVE_GETPWNAM)
  63 extern struct passwd *getpwnam PARAMS((const char *));
  64 #  endif
  65 #endif /* !HAVE_GETPW_DECLS */
  66
  67 #if !defined (savestring)
  68 #define savestring(x) strcpy ((char *)xmalloc (1 + strlen (x)), (x))
  69 #endif /* !savestring */
  70
  71 #if !defined (NULL)
  72 #  if defined (__STDC__)
  73 #    define NULL ((void *) 0)
  74 #  else
  75 #    define NULL 0x0
  76 #  endif /* !__STDC__ */
  77 #endif /* !NULL */
  78
  79 /* If being compiled as part of bash, these will be satisfied from
  80    variables.o.  If being compiled as part of readline, they will
  81    be satisfied from shell.o. */
  82 extern char *sh_get_home_dir PARAMS((void));
  83 extern char *sh_get_env_value PARAMS((const char *));
  84
  85 /* The default value of tilde_additional_prefixes.  This is set to
  86    whitespace preceding a tilde so that simple programs which do not
  87    perform any word separation get desired behaviour. */
  88 static const char *default_prefixes[] =
  89   { " ~", "\t~", (const char *)NULL };
  90
  91 /* The default value of tilde_additional_suffixes.  This is set to
  92    whitespace or newline so that simple programs which do not
  93    perform any word separation get desired behaviour. */
  94 static const char *default_suffixes[] =
  95   { " ", "\n", (const char *)NULL };
  96
  97 /* If non-null, this contains the address of a function that the application
  98    wants called before trying the standard tilde expansions.  The function
  99    is called with the text sans tilde, and returns a malloc()'ed string
 100    which is the expansion, or a NULL pointer if the expansion fails. */
 101 tilde_hook_func_t *tilde_expansion_preexpansion_hook = (tilde_hook_func_t *)NULL;
 102
 103 /* If non-null, this contains the address of a function to call if the
 104    standard meaning for expanding a tilde fails.  The function is called
 105    with the text (sans tilde, as in "foo"), and returns a malloc()'ed string
 106    which is the expansion, or a NULL pointer if there is no expansion. */
 107 tilde_hook_func_t *tilde_expansion_failure_hook = (tilde_hook_func_t *)NULL;
 108
 109 /* When non-null, this is a NULL terminated array of strings which
 110    are duplicates for a tilde prefix.  Bash uses this to expand
 111    `=~' and `:~'. */
 112 char **tilde_additional_prefixes = (char **)default_prefixes;
 113
 114 /* When non-null, this is a NULL terminated array of strings which match
 115    the end of a username, instead of just "/".  Bash sets this to
 116    `:' and `=~'. */
 117 char **tilde_additional_suffixes = (char **)default_suffixes;
 118
 119 static int tilde_find_prefix PARAMS((const char *, int *));
 120 static int tilde_find_suffix PARAMS((const char *));
 121 static char *isolate_tilde_prefix PARAMS((const char *, int *));
 122 static char *glue_prefix_and_suffix PARAMS((char *, const char *, int));
 123
 124 /* Find the start of a tilde expansion in STRING, and return the index of
 125    the tilde which starts the expansion.  Place the length of the text
 126    which identified this tilde starter in LEN, excluding the tilde itself. */
 127 static int
 128 tilde_find_prefix (string, len)
 129      const char *string;
 130      int *len;
 131 {
 132   register int i, j, string_len;
 133   register char **prefixes;
 134
 135   prefixes = tilde_additional_prefixes;
 136
 137   string_len = strlen (string);
 138   *len = 0;
 139
 140   if (*string == '\0' || *string == '~')
 141     return (0);
 142
 143   if (prefixes)
 144     {
 145       for (i = 0; i < string_len; i++)
 146         {
 147           for (j = 0; prefixes[j]; j++)
 148             {
 149               if (strncmp (string + i, prefixes[j], strlen (prefixes[j])) == 0)
 150                 {
 151                   *len = strlen (prefixes[j]) - 1;
 152                   return (i + *len);
 153                 }
 154             }
 155         }
 156     }
 157   return (string_len);
 158 }
 159
 160 /* Find the end of a tilde expansion in STRING, and return the index of
 161    the character which ends the tilde definition.  */
 162 static int
 163 tilde_find_suffix (string)
 164      const char *string;
 165 {
 166   register int i, j, string_len;
 167   register char **suffixes;
 168
 169   suffixes = tilde_additional_suffixes;
 170   string_len = strlen (string);
 171
 172   for (i = 0; i < string_len; i++)
 173     {
 174 #if defined (__MSDOS__)
 175       if (string[i] == '/' || string[i] == '\\' /* || !string[i] */)
 176 #else
 177       if (string[i] == '/' /* || !string[i] */)
 178 #endif
 179         break;
 180
 181       for (j = 0; suffixes && suffixes[j]; j++)
 182         {
 183           if (strncmp (string + i, suffixes[j], strlen (suffixes[j])) == 0)
 184             return (i);
 185         }
 186     }
 187   return (i);
 188 }
 189
 190 /* Return a new string which is the result of tilde expanding STRING. */
 191 char *
 192 tilde_expand (string)
 193      const char *string;
 194 {
 195   char *result;
 196   int result_size, result_index;
 197
 198   result_index = result_size = 0;
 199   if (result = strchr (string, '~'))
 200     result = (char *)xmalloc (result_size = (strlen (string) + 16));
 201   else
 202     result = (char *)xmalloc (result_size = (strlen (string) + 1));
 203
 204   /* Scan through STRING expanding tildes as we come to them. */
 205   while (1)
 206     {
 207       register int start, end;
 208       char *tilde_word, *expansion;
 209       int len;
 210
 211       /* Make START point to the tilde which starts the expansion. */
 212       start = tilde_find_prefix (string, &len);
 213
 214       /* Copy the skipped text into the result. */
 215       if ((result_index + start + 1) > result_size)
 216         result = (char *)xrealloc (result, 1 + (result_size += (start + 20)));
 217
 218       strncpy (result + result_index, string, start);
 219       result_index += start;
 220
 221       /* Advance STRING to the starting tilde. */
 222       string += start;
 223
 224       /* Make END be the index of one after the last character of the
 225          username. */
 226       end = tilde_find_suffix (string);
 227
 228       /* If both START and END are zero, we are all done. */
 229       if (!start && !end)
 230         break;
 231
 232       /* Expand the entire tilde word, and copy it into RESULT. */
 233       tilde_word = (char *)xmalloc (1 + end);
 234       strncpy (tilde_word, string, end);
 235       tilde_word[end] = '\0';
 236       string += end;
 237
 238       expansion = tilde_expand_word (tilde_word);
 239       xfree (tilde_word);
 240
 241       len = strlen (expansion);
 242 #ifdef __CYGWIN__
 243       /* Fix for Cygwin to prevent ~user/xxx from expanding to //xxx when
 244          $HOME for `user' is /.  On cygwin, // denotes a network drive. */
 245       if (len > 1 || *expansion != '/' || *string != '/')
 246 #endif
 247         {
 248           if ((result_index + len + 1) > result_size)
 249             result = (char *)xrealloc (result, 1 + (result_size += (len + 20)));
 250
 251           strcpy (result + result_index, expansion);
 252           result_index += len;
 253         }
 254       xfree (expansion);
 255     }
 256
 257   result[result_index] = '\0';
 258
 259   return (result);
 260 }
 261
 262 /* Take FNAME and return the tilde prefix we want expanded.  If LENP is
 263    non-null, the index of the end of the prefix into FNAME is returned in
 264    the location it points to. */
 265 static char *
 266 isolate_tilde_prefix (fname, lenp)
 267      const char *fname;
 268      int *lenp;
 269 {
 270   char *ret;
 271   int i;
 272
 273   ret = (char *)xmalloc (strlen (fname));
 274 #if defined (__MSDOS__)
 275   for (i = 1; fname[i] && fname[i] != '/' && fname[i] != '\\'; i++)
 276 #else
 277   for (i = 1; fname[i] && fname[i] != '/'; i++)
 278 #endif
 279     ret[i - 1] = fname[i];
 280   ret[i - 1] = '\0';
 281   if (lenp)
 282     *lenp = i;
 283   return ret;
 284 }
 285
 286 #if 0
 287 /* Public function to scan a string (FNAME) beginning with a tilde and find
 288    the portion of the string that should be passed to the tilde expansion
 289    function.  Right now, it just calls tilde_find_suffix and allocates new
 290    memory, but it can be expanded to do different things later. */
 291 char *
 292 tilde_find_word (fname, flags, lenp)
 293      const char *fname;
 294      int flags, *lenp;
 295 {
 296   int x;
 297   char *r;
 298
 299   x = tilde_find_suffix (fname);
 300   if (x == 0)
 301     {
 302       r = savestring (fname);
 303       if (lenp)
 304         *lenp = 0;
 305     }
 306   else
 307     {
 308       r = (char *)xmalloc (1 + x);
 309       strncpy (r, fname, x);
 310       r[x] = '\0';
 311       if (lenp)
 312         *lenp = x;
 313     }
 314
 315   return r;
 316 }
 317 #endif
 318
 319 /* Return a string that is PREFIX concatenated with SUFFIX starting at
 320    SUFFIND. */
 321 static char *
 322 glue_prefix_and_suffix (prefix, suffix, suffind)
 323      char *prefix;
 324      const char *suffix;
 325      int suffind;
 326 {
 327   char *ret;
 328   int plen, slen;
 329
 330   plen = (prefix && *prefix) ? strlen (prefix) : 0;
 331   slen = strlen (suffix + suffind);
 332   ret = (char *)xmalloc (plen + slen + 1);
 333   if (plen)
 334     strcpy (ret, prefix);
 335   strcpy (ret + plen, suffix + suffind);
 336   return ret;
 337 }
 338
 339 /* Do the work of tilde expansion on FILENAME.  FILENAME starts with a
 340    tilde.  If there is no expansion, call tilde_expansion_failure_hook.
 341    This always returns a newly-allocated string, never static storage. */
 342 char *
 343 tilde_expand_word (filename)
 344      const char *filename;
 345 {
 346   char *dirname, *expansion, *username;
 347   int user_len;
 348   struct passwd *user_entry;
 349
 350   if (filename == 0)
 351     return ((char *)NULL);
 352
 353   if (*filename != '~')
 354     return (savestring (filename));
 355
 356   /* A leading `~/' or a bare `~' is *always* translated to the value of
 357      $HOME or the home directory of the current user, regardless of any
 358      preexpansion hook. */
 359   if (filename[1] == '\0' || filename[1] == '/')
 360     {
 361       /* Prefix $HOME to the rest of the string. */
 362       expansion = sh_get_env_value ("HOME");
 363
 364       /* If there is no HOME variable, look up the directory in
 365          the password database. */
 366       if (expansion == 0)
 367         expansion = sh_get_home_dir ();
 368
 369       return (glue_prefix_and_suffix (expansion, filename, 1));
 370     }
 371
 372   username = isolate_tilde_prefix (filename, &user_len);
 373
 374   if (tilde_expansion_preexpansion_hook)
 375     {
 376       expansion = (*tilde_expansion_preexpansion_hook) (username);
 377       if (expansion)
 378         {
 379           dirname = glue_prefix_and_suffix (expansion, filename, user_len);
 380           xfree (username);
 381           xfree (expansion);
 382           return (dirname);
 383         }
 384     }
 385
 386   /* No preexpansion hook, or the preexpansion hook failed.  Look in the
 387      password database. */
 388   dirname = (char *)NULL;
 389 #if defined (HAVE_GETPWNAM)
 390   user_entry = getpwnam (username);
 391 #else
 392   user_entry = 0;
 393 #endif
 394   if (user_entry == 0)
 395     {
 396       /* If the calling program has a special syntax for expanding tildes,
 397          and we couldn't find a standard expansion, then let them try. */
 398       if (tilde_expansion_failure_hook)
 399         {
 400           expansion = (*tilde_expansion_failure_hook) (username);
 401           if (expansion)
 402             {
 403               dirname = glue_prefix_and_suffix (expansion, filename, user_len);
 404               xfree (expansion);
 405             }
 406         }
 407       /* If we don't have a failure hook, or if the failure hook did not
 408          expand the tilde, return a copy of what we were passed. */
 409       if (dirname == 0)
 410         dirname = savestring (filename);
 411     }
 412 #if defined (HAVE_GETPWENT)
 413   else
 414     dirname = glue_prefix_and_suffix (user_entry->pw_dir, filename, user_len);
 415 #endif
 416
 417   xfree (username);
 418 #if defined (HAVE_GETPWENT)
 419   endpwent ();
 420 #endif
 421   return (dirname);
 422 }
 423
 424 \f
 425 #if defined (TEST)
 426 #undef NULL
 427 #include <stdio.h>
 428
 429 main (argc, argv)
 430      int argc;
 431      char **argv;
 432 {
 433   char *result, line[512];
 434   int done = 0;
 435
 436   while (!done)
 437     {
 438       printf ("~expand: ");
 439       fflush (stdout);
 440
 441       if (!gets (line))
 442         strcpy (line, "done");
 443
 444       if ((strcmp (line, "done") == 0) ||
 445           (strcmp (line, "quit") == 0) ||
 446           (strcmp (line, "exit") == 0))
 447         {
 448           done = 1;
 449           break;
 450         }
 451
 452       result = tilde_expand (line);
 453       printf ("  --> %s\n", result);
 454       free (result);
 455     }
 456   exit (0);
 457 }
 458
 459 static void memory_error_and_abort ();
 460
 461 static void *
 462 xmalloc (bytes)
 463      size_t bytes;
 464 {
 465   void *temp = (char *)malloc (bytes);
 466
 467   if (!temp)
 468     memory_error_and_abort ();
 469   return (temp);
 470 }
 471
 472 static void *
 473 xrealloc (pointer, bytes)
 474      void *pointer;
 475      int bytes;
 476 {
 477   void *temp;
 478
 479   if (!pointer)
 480     temp = malloc (bytes);
 481   else
 482     temp = realloc (pointer, bytes);
 483
 484   if (!temp)
 485     memory_error_and_abort ();
 486
 487   return (temp);
 488 }
 489
 490 static void
 491 memory_error_and_abort ()
 492 {
 493   fprintf (stderr, "readline: out of virtual memory\n");
 494   abort ();
 495 }
 496
 497 /*
 498  * Local variables:
 499  * compile-command: "gcc -g -DTEST -o tilde tilde.c"
 500  * end:
 501  */
 502 #endif /* TEST */