alias.c

   1 /* alias.c -- Not a full alias, but just the kind that we use in the
   2    shell.  Csh style alias is somewhere else (`over there, in a box'). */
   3
   4 /* Copyright (C) 1987-2009 Free Software Foundation, Inc.
   5
   6    This file is part of GNU Bash, the Bourne Again SHell.
   7
   8    Bash 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    Bash 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 Bash.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "config.h"
  23
  24 #if defined (ALIAS)
  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 #include <stdio.h>
  34 #include "chartypes.h"
  35 #include "bashansi.h"
  36 #include "command.h"
  37 #include "general.h"
  38 #include "externs.h"
  39 #include "alias.h"
  40
  41 #if defined (PROGRAMMABLE_COMPLETION)
  42 #  include "pcomplete.h"
  43 #endif
  44
  45 #define ALIAS_HASH_BUCKETS      16      /* must be power of two */
  46
  47 typedef int sh_alias_map_func_t __P((alias_t *));
  48
  49 static void free_alias_data __P((PTR_T));
  50 static alias_t **map_over_aliases __P((sh_alias_map_func_t *));
  51 static void sort_aliases __P((alias_t **));
  52 static int qsort_alias_compare __P((alias_t **, alias_t **));
  53
  54 #if defined (READLINE)
  55 static int skipquotes __P((char *, int));
  56 static int skipws __P((char *, int));
  57 static int rd_token __P((char *, int));
  58 #endif
  59
  60 /* Non-zero means expand all words on the line.  Otherwise, expand
  61    after first expansion if the expansion ends in a space. */
  62 int alias_expand_all = 0;
  63
  64 /* The list of aliases that we have. */
  65 HASH_TABLE *aliases = (HASH_TABLE *)NULL;
  66
  67 void
  68 initialize_aliases ()
  69 {
  70   if (aliases == 0)
  71     aliases = hash_create (ALIAS_HASH_BUCKETS);
  72 }
  73
  74 /* Scan the list of aliases looking for one with NAME.  Return NULL
  75    if the alias doesn't exist, else a pointer to the alias_t. */
  76 alias_t *
  77 find_alias (name)
  78      char *name;
  79 {
  80   BUCKET_CONTENTS *al;
  81
  82   if (aliases == 0)
  83     return ((alias_t *)NULL);
  84
  85   al = hash_search (name, aliases, 0);
  86   return (al ? (alias_t *)al->data : (alias_t *)NULL);
  87 }
  88
  89 /* Return the value of the alias for NAME, or NULL if there is none. */
  90 char *
  91 get_alias_value (name)
  92      char *name;
  93 {
  94   alias_t *alias;
  95
  96   if (aliases == 0)
  97     return ((char *)NULL);
  98
  99   alias = find_alias (name);
 100   return (alias ? alias->value : (char *)NULL);
 101 }
 102
 103 /* Make a new alias from NAME and VALUE.  If NAME can be found,
 104    then replace its value. */
 105 void
 106 add_alias (name, value)
 107      char *name, *value;
 108 {
 109   BUCKET_CONTENTS *elt;
 110   alias_t *temp;
 111   int n;
 112
 113   if (!aliases)
 114     {
 115       initialize_aliases ();
 116       temp = (alias_t *)NULL;
 117     }
 118   else
 119     temp = find_alias (name);
 120
 121   if (temp)
 122     {
 123       free (temp->value);
 124       temp->value = savestring (value);
 125       temp->flags &= ~AL_EXPANDNEXT;
 126       n = value[strlen (value) - 1];
 127       if (n == ' ' || n == '\t')
 128         temp->flags |= AL_EXPANDNEXT;
 129     }
 130   else
 131     {
 132       temp = (alias_t *)xmalloc (sizeof (alias_t));
 133       temp->name = savestring (name);
 134       temp->value = savestring (value);
 135       temp->flags = 0;
 136
 137       n = value[strlen (value) - 1];
 138       if (n == ' ' || n == '\t')
 139         temp->flags |= AL_EXPANDNEXT;
 140
 141       elt = hash_insert (savestring (name), aliases, HASH_NOSRCH);
 142       elt->data = temp;
 143 #if defined (PROGRAMMABLE_COMPLETION)
 144       set_itemlist_dirty (&it_aliases);
 145 #endif
 146     }
 147 }
 148
 149 /* Delete a single alias structure. */
 150 static void
 151 free_alias_data (data)
 152      PTR_T data;
 153 {
 154   register alias_t *a;
 155
 156   a = (alias_t *)data;
 157   free (a->value);
 158   free (a->name);
 159   free (data);
 160 }
 161
 162 /* Remove the alias with name NAME from the alias table.  Returns
 163    the number of aliases left in the table, or -1 if the alias didn't
 164    exist. */
 165 int
 166 remove_alias (name)
 167      char *name;
 168 {
 169   BUCKET_CONTENTS *elt;
 170
 171   if (aliases == 0)
 172     return (-1);
 173
 174   elt = hash_remove (name, aliases, 0);
 175   if (elt)
 176     {
 177       free_alias_data (elt->data);
 178       free (elt->key);          /* alias name */
 179       free (elt);               /* XXX */
 180 #if defined (PROGRAMMABLE_COMPLETION)
 181       set_itemlist_dirty (&it_aliases);
 182 #endif
 183       return (aliases->nentries);
 184     }
 185   return (-1);
 186 }
 187
 188 /* Delete all aliases. */
 189 void
 190 delete_all_aliases ()
 191 {
 192   if (aliases == 0)
 193     return;
 194
 195   hash_flush (aliases, free_alias_data);
 196   hash_dispose (aliases);
 197   aliases = (HASH_TABLE *)NULL;
 198 #if defined (PROGRAMMABLE_COMPLETION)
 199   set_itemlist_dirty (&it_aliases);
 200 #endif
 201 }
 202
 203 /* Return an array of aliases that satisfy the conditions tested by FUNCTION.
 204    If FUNCTION is NULL, return all aliases. */
 205 static alias_t **
 206 map_over_aliases (function)
 207      sh_alias_map_func_t *function;
 208 {
 209   register int i;
 210   register BUCKET_CONTENTS *tlist;
 211   alias_t *alias, **list;
 212   int list_index;
 213
 214   i = HASH_ENTRIES (aliases);
 215   if (i == 0)
 216     return ((alias_t **)NULL);
 217
 218   list = (alias_t **)xmalloc ((i + 1) * sizeof (alias_t *));
 219   for (i = list_index = 0; i < aliases->nbuckets; i++)
 220     {
 221       for (tlist = hash_items (i, aliases); tlist; tlist = tlist->next)
 222         {
 223           alias = (alias_t *)tlist->data;
 224
 225           if (!function || (*function) (alias))
 226             {
 227               list[list_index++] = alias;
 228               list[list_index] = (alias_t *)NULL;
 229             }
 230         }
 231     }
 232   return (list);
 233 }
 234
 235 static void
 236 sort_aliases (array)
 237      alias_t **array;
 238 {
 239   qsort (array, strvec_len ((char **)array), sizeof (alias_t *), (QSFUNC *)qsort_alias_compare);
 240 }
 241
 242 static int
 243 qsort_alias_compare (as1, as2)
 244      alias_t **as1, **as2;
 245 {
 246   int result;
 247
 248   if ((result = (*as1)->name[0] - (*as2)->name[0]) == 0)
 249     result = strcmp ((*as1)->name, (*as2)->name);
 250
 251   return (result);
 252 }
 253
 254 /* Return a sorted list of all defined aliases */
 255 alias_t **
 256 all_aliases ()
 257 {
 258   alias_t **list;
 259
 260   if (aliases == 0 || HASH_ENTRIES (aliases) == 0)
 261     return ((alias_t **)NULL);
 262
 263   list = map_over_aliases ((sh_alias_map_func_t *)NULL);
 264   if (list)
 265     sort_aliases (list);
 266   return (list);
 267 }
 268
 269 char *
 270 alias_expand_word (s)
 271      char *s;
 272 {
 273   alias_t *r;
 274
 275   r = find_alias (s);
 276   return (r ? savestring (r->value) : (char *)NULL);
 277 }
 278
 279 /* Readline support functions -- expand all aliases in a line. */
 280
 281 #if defined (READLINE)
 282
 283 /* Return non-zero if CHARACTER is a member of the class of characters
 284    that are self-delimiting in the shell (this really means that these
 285    characters delimit tokens). */
 286 #define self_delimiting(character) (member ((character), " \t\n\r;|&()"))
 287
 288 /* Return non-zero if CHARACTER is a member of the class of characters
 289    that delimit commands in the shell. */
 290 #define command_separator(character) (member ((character), "\r\n;|&("))
 291
 292 /* If this is 1, we are checking the next token read for alias expansion
 293    because it is the first word in a command. */
 294 static int command_word;
 295
 296 /* This is for skipping quoted strings in alias expansions. */
 297 #define quote_char(c)  (((c) == '\'') || ((c) == '"'))
 298
 299 /* Consume a quoted string from STRING, starting at string[START] (so
 300    string[START] is the opening quote character), and return the index
 301    of the closing quote character matching the opening quote character.
 302    This handles single matching pairs of unquoted quotes; it could afford
 303    to be a little smarter... This skips words between balanced pairs of
 304    quotes, words where the first character is quoted with a `\', and other
 305    backslash-escaped characters. */
 306
 307 static int
 308 skipquotes (string, start)
 309      char *string;
 310      int start;
 311 {
 312   register int i;
 313   int delimiter = string[start];
 314
 315   /* i starts at START + 1 because string[START] is the opening quote
 316      character. */
 317   for (i = start + 1 ; string[i] ; i++)
 318     {
 319       if (string[i] == '\\')
 320         {
 321           i++;          /* skip backslash-quoted quote characters, too */
 322           if (string[i] == 0)
 323             break;
 324           continue;
 325         }
 326
 327       if (string[i] == delimiter)
 328         return i;
 329     }
 330   return (i);
 331 }
 332
 333 /* Skip the white space and any quoted characters in STRING, starting at
 334    START.  Return the new index into STRING, after zero or more characters
 335    have been skipped. */
 336 static int
 337 skipws (string, start)
 338      char *string;
 339      int start;
 340 {
 341   register int i;
 342   int pass_next, backslash_quoted_word;
 343   unsigned char peekc;
 344
 345   /* skip quoted strings, in ' or ", and words in which a character is quoted
 346      with a `\'. */
 347   i = backslash_quoted_word = pass_next = 0;
 348
 349   /* Skip leading whitespace (or separator characters), and quoted words.
 350      But save it in the output.  */
 351
 352   for (i = start; string[i]; i++)
 353     {
 354       if (pass_next)
 355         {
 356           pass_next = 0;
 357           continue;
 358         }
 359
 360       if (whitespace (string[i]))
 361         {
 362           backslash_quoted_word = 0; /* we are no longer in a backslash-quoted word */
 363           continue;
 364         }
 365
 366       if (string[i] == '\\')
 367         {
 368           peekc = string[i+1];
 369           if (peekc == 0)
 370             break;
 371           if (ISLETTER (peekc))
 372             backslash_quoted_word++;    /* this is a backslash-quoted word */
 373           else
 374             pass_next++;
 375           continue;
 376         }
 377
 378       /* This only handles single pairs of non-escaped quotes.  This
 379          overloads backslash_quoted_word to also mean that a word like
 380          ""f is being scanned, so that the quotes will inhibit any expansion
 381          of the word. */
 382       if (quote_char(string[i]))
 383         {
 384           i = skipquotes (string, i);
 385           /* This could be a line that contains a single quote character,
 386              in which case skipquotes () terminates with string[i] == '\0'
 387              (the end of the string).  Check for that here. */
 388           if (string[i] == '\0')
 389             break;
 390
 391           peekc = string[i + 1];
 392           if (ISLETTER (peekc))
 393             backslash_quoted_word++;
 394           continue;
 395         }
 396
 397       /* If we're in the middle of some kind of quoted word, let it
 398          pass through. */
 399       if (backslash_quoted_word)
 400         continue;
 401
 402       /* If this character is a shell command separator, then set a hint for
 403          alias_expand that the next token is the first word in a command. */
 404
 405       if (command_separator (string[i]))
 406         {
 407           command_word++;
 408           continue;
 409         }
 410       break;
 411     }
 412   return (i);
 413 }
 414
 415 /* Characters that may appear in a token.  Basically, anything except white
 416    space and a token separator. */
 417 #define token_char(c)   (!((whitespace (string[i]) || self_delimiting (string[i]))))
 418
 419 /* Read from START in STRING until the next separator character, and return
 420    the index of that separator.  Skip backslash-quoted characters.  Call
 421    skipquotes () for quoted strings in the middle or at the end of tokens,
 422    so all characters show up (e.g. foo'' and foo""bar) */
 423 static int
 424 rd_token (string, start)
 425      char *string;
 426      int start;
 427 {
 428   register int i;
 429
 430   /* From here to next separator character is a token. */
 431   for (i = start; string[i] && token_char (string[i]); i++)
 432     {
 433       if (string[i] == '\\')
 434         {
 435           i++;  /* skip backslash-escaped character */
 436           if (string[i] == 0)
 437             break;
 438           continue;
 439         }
 440
 441       /* If this character is a quote character, we want to call skipquotes
 442          to get the whole quoted portion as part of this word.  That word
 443          will not generally match an alias, even if te unquoted word would
 444          have.  The presence of the quotes in the token serves then to
 445          inhibit expansion. */
 446       if (quote_char (string[i]))
 447         {
 448           i = skipquotes (string, i);
 449           /* This could be a line that contains a single quote character,
 450              in which case skipquotes () terminates with string[i] == '\0'
 451              (the end of the string).  Check for that here. */
 452           if (string[i] == '\0')
 453             break;
 454
 455           /* Now string[i] is the matching quote character, and the
 456              quoted portion of the token has been scanned. */
 457           continue;
 458         }
 459     }
 460   return (i);
 461 }
 462
 463 /* Return a new line, with any aliases substituted. */
 464 char *
 465 alias_expand (string)
 466      char *string;
 467 {
 468   register int i, j, start;
 469   char *line, *token;
 470   int line_len, tl, real_start, expand_next, expand_this_token;
 471   alias_t *alias;
 472
 473   line_len = strlen (string) + 1;
 474   line = (char *)xmalloc (line_len);
 475   token = (char *)xmalloc (line_len);
 476
 477   line[0] = i = 0;
 478   expand_next = 0;
 479   command_word = 1; /* initialized to expand the first word on the line */
 480
 481   /* Each time through the loop we find the next word in line.  If it
 482      has an alias, substitute the alias value.  If the value ends in ` ',
 483      then try again with the next word.  Else, if there is no value, or if
 484      the value does not end in space, we are done. */
 485
 486   for (;;)
 487     {
 488
 489       token[0] = 0;
 490       start = i;
 491
 492       /* Skip white space and quoted characters */
 493       i = skipws (string, start);
 494
 495       if (start == i && string[i] == '\0')
 496         {
 497           free (token);
 498           return (line);
 499         }
 500
 501       /* copy the just-skipped characters into the output string,
 502          expanding it if there is not enough room. */
 503       j = strlen (line);
 504       tl = i - start;   /* number of characters just skipped */
 505       RESIZE_MALLOCED_BUFFER (line, j, (tl + 1), line_len, (tl + 50));
 506       strncpy (line + j, string + start, tl);
 507       line[j + tl] = '\0';
 508
 509       real_start = i;
 510
 511       command_word = command_word || (command_separator (string[i]));
 512       expand_this_token = (command_word || expand_next);
 513       expand_next = 0;
 514
 515       /* Read the next token, and copy it into TOKEN. */
 516       start = i;
 517       i = rd_token (string, start);
 518
 519       tl = i - start;   /* token length */
 520
 521       /* If tl == 0, but we're not at the end of the string, then we have a
 522          single-character token, probably a delimiter */
 523       if (tl == 0 && string[i] != '\0')
 524         {
 525           tl = 1;
 526           i++;          /* move past it */
 527         }
 528
 529       strncpy (token, string + start, tl);
 530       token [tl] = '\0';
 531
 532       /* If there is a backslash-escaped character quoted in TOKEN,
 533          then we don't do alias expansion.  This should check for all
 534          other quoting characters, too. */
 535       if (mbschr (token, '\\'))
 536         expand_this_token = 0;
 537
 538       /* If we should be expanding here, if we are expanding all words, or if
 539          we are in a location in the string where an expansion is supposed to
 540          take place, see if this word has a substitution.  If it does, then do
 541          the expansion.  Note that we defer the alias value lookup until we
 542          are sure we are expanding this token. */
 543
 544       if ((token[0]) &&
 545           (expand_this_token || alias_expand_all) &&
 546           (alias = find_alias (token)))
 547         {
 548           char *v;
 549           int vlen, llen;
 550
 551           v = alias->value;
 552           vlen = strlen (v);
 553           llen = strlen (line);
 554
 555           /* +3 because we possibly add one more character below. */
 556           RESIZE_MALLOCED_BUFFER (line, llen, (vlen + 3), line_len, (vlen + 50));
 557
 558           strcpy (line + llen, v);
 559
 560           if ((expand_this_token && vlen && whitespace (v[vlen - 1])) ||
 561               alias_expand_all)
 562             expand_next = 1;
 563         }
 564       else
 565         {
 566           int llen, tlen;
 567
 568           llen = strlen (line);
 569           tlen = i - real_start; /* tlen == strlen(token) */
 570
 571           RESIZE_MALLOCED_BUFFER (line, llen, (tlen + 1), line_len, (llen + tlen + 50));
 572
 573           strncpy (line + llen, string + real_start, tlen);
 574           line[llen + tlen] = '\0';
 575         }
 576       command_word = 0;
 577     }
 578 }
 579 #endif /* READLINE */
 580 #endif /* ALIAS */