expand.c

   1 /* Variable expansion functions for GNU Make.
   2 Copyright (C) 1988, 89, 91, 92, 93, 95 Free Software Foundation, Inc.
   3 This file is part of GNU Make.
   4
   5 GNU Make is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation; either version 2, or (at your option)
   8 any later version.
   9
  10 GNU Make is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with GNU Make; see the file COPYING.  If not, write to
  17 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18 Boston, MA 02111-1307, USA.  */
  19
  20 #include "make.h"
  21
  22 #include <assert.h>
  23
  24 #include "filedef.h"
  25 #include "job.h"
  26 #include "commands.h"
  27 #include "variable.h"
  28 #include "rule.h"
  29
  30 /* The next two describe the variable output buffer.
  31    This buffer is used to hold the variable-expansion of a line of the
  32    makefile.  It is made bigger with realloc whenever it is too small.
  33    variable_buffer_length is the size currently allocated.
  34    variable_buffer is the address of the buffer.
  35
  36    For efficiency, it's guaranteed that the buffer will always have
  37    VARIABLE_BUFFER_ZONE extra bytes allocated.  This allows you to add a few
  38    extra chars without having to call a function.  Note you should never use
  39    these bytes unless you're _sure_ you have room (you know when the buffer
  40    length was last checked.  */
  41
  42 #define VARIABLE_BUFFER_ZONE    5
  43
  44 static unsigned int variable_buffer_length;
  45 char *variable_buffer;
  46
  47 /* Subroutine of variable_expand and friends:
  48    The text to add is LENGTH chars starting at STRING to the variable_buffer.
  49    The text is added to the buffer at PTR, and the updated pointer into
  50    the buffer is returned as the value.  Thus, the value returned by
  51    each call to variable_buffer_output should be the first argument to
  52    the following call.  */
  53
  54 char *
  55 variable_buffer_output (char *ptr, char *string, unsigned int length)
  56 {
  57   register unsigned int newlen = length + (ptr - variable_buffer);
  58
  59   if ((newlen + VARIABLE_BUFFER_ZONE) > variable_buffer_length)
  60     {
  61       unsigned int offset = ptr - variable_buffer;
  62       variable_buffer_length = (newlen + 100 > 2 * variable_buffer_length
  63                                 ? newlen + 100
  64                                 : 2 * variable_buffer_length);
  65       variable_buffer = (char *) xrealloc (variable_buffer,
  66                                            variable_buffer_length);
  67       ptr = variable_buffer + offset;
  68     }
  69
  70   bcopy (string, ptr, length);
  71   return ptr + length;
  72 }
  73
  74 /* Return a pointer to the beginning of the variable buffer.  */
  75
  76 static char *
  77 initialize_variable_output (void)
  78 {
  79   /* If we don't have a variable output buffer yet, get one.  */
  80
  81   if (variable_buffer == 0)
  82     {
  83       variable_buffer_length = 200;
  84       variable_buffer = (char *) xmalloc (variable_buffer_length);
  85       variable_buffer[0] = '\0';
  86     }
  87
  88   return variable_buffer;
  89 }
  90 \f
  91 /* Recursively expand V.  The returned string is malloc'd.  */
  92
  93 static char *allocated_variable_append PARAMS ((const struct variable *v));
  94
  95 char *
  96 recursively_expand_for_file (struct variable *v, struct file *file)
  97 {
  98   char *value;
  99   struct variable_set_list *save = 0;
 100   int set_reading = 0;
 101
 102   if (v->expanding)
 103     {
 104       if (!v->exp_count)
 105         /* Expanding V causes infinite recursion.  Lose.  */
 106         fatal (reading_file,
 107                _("Recursive variable `%s' references itself (eventually)"),
 108                v->name);
 109       --v->exp_count;
 110     }
 111
 112   if (file)
 113     {
 114       save = current_variable_set_list;
 115       current_variable_set_list = file->variables;
 116     }
 117
 118   /* If we have no other file-reading context, use the variable's context. */
 119   if (!reading_file)
 120     {
 121       set_reading = 1;
 122       reading_file = &v->fileinfo;
 123     }
 124
 125   v->expanding = 1;
 126   if (v->append)
 127     value = allocated_variable_append (v);
 128   else
 129     value = allocated_variable_expand (v->value);
 130   v->expanding = 0;
 131
 132   if (set_reading)
 133     reading_file = 0;
 134   if (file)
 135     current_variable_set_list = save;
 136
 137   return value;
 138 }
 139
 140 /* Expand a simple reference to variable NAME, which is LENGTH chars long.  */
 141
 142 #ifdef __GNUC__
 143 __inline
 144 #endif
 145 static char *
 146 reference_variable (char *o, char *name, unsigned int length)
 147 {
 148   register struct variable *v;
 149   char *value;
 150
 151   v = lookup_variable (name, length);
 152
 153   if (v == 0)
 154     warn_undefined (name, length);
 155
 156   /* If there's no variable by that name or it has no value, stop now.  */
 157   if (v == 0 || (*v->value == '\0' && !v->append))
 158     return o;
 159
 160   value = (v->recursive ? recursively_expand (v) : v->value);
 161
 162   o = variable_buffer_output (o, value, strlen (value));
 163
 164   if (v->recursive)
 165     free (value);
 166
 167   return o;
 168 }
 169 \f
 170 /* Scan STRING for variable references and expansion-function calls.  Only
 171    LENGTH bytes of STRING are actually scanned.  If LENGTH is -1, scan until
 172    a null byte is found.
 173
 174    Write the results to LINE, which must point into `variable_buffer'.  If
 175    LINE is NULL, start at the beginning of the buffer.
 176    Return a pointer to LINE, or to the beginning of the buffer if LINE is
 177    NULL.  */
 178
 179 char *
 180 variable_expand_string (char *line, char *string, long length)
 181 {
 182   register struct variable *v;
 183   register char *p, *o, *p1;
 184   char save_char = '\0';
 185   unsigned int line_offset;
 186
 187   if (!line)
 188     line = initialize_variable_output();
 189
 190   p = string;
 191   o = line;
 192   line_offset = line - variable_buffer;
 193
 194   if (length >= 0)
 195     {
 196       save_char = string[length];
 197       string[length] = '\0';
 198     }
 199
 200   while (1)
 201     {
 202       /* Copy all following uninteresting chars all at once to the
 203          variable output buffer, and skip them.  Uninteresting chars end
 204          at the next $ or the end of the input.  */
 205
 206       p1 = strchr (p, '$');
 207
 208       o = variable_buffer_output (o, p, p1 != 0 ? p1 - p : strlen (p) + 1);
 209
 210       if (p1 == 0)
 211         break;
 212       p = p1 + 1;
 213
 214       /* Dispatch on the char that follows the $.  */
 215
 216       switch (*p)
 217         {
 218         case '$':
 219           /* $$ seen means output one $ to the variable output buffer.  */
 220           o = variable_buffer_output (o, p, 1);
 221           break;
 222
 223         case '(':
 224         case '{':
 225           /* $(...) or ${...} is the general case of substitution.  */
 226           {
 227             char openparen = *p;
 228             char closeparen = (openparen == '(') ? ')' : '}';
 229             register char *beg = p + 1;
 230             int free_beg = 0;
 231             char *op, *begp;
 232             char *end, *colon;
 233
 234             op = o;
 235             begp = p;
 236             if (handle_function (&op, &begp))
 237               {
 238                 o = op;
 239                 p = begp;
 240                 break;
 241               }
 242
 243             /* Is there a variable reference inside the parens or braces?
 244                If so, expand it before expanding the entire reference.  */
 245
 246             end = strchr (beg, closeparen);
 247             if (end == 0)
 248               /* Unterminated variable reference.  */
 249               fatal (reading_file, _("unterminated variable reference"));
 250             p1 = lindex (beg, end, '$');
 251             if (p1 != 0)
 252               {
 253                 /* BEG now points past the opening paren or brace.
 254                    Count parens or braces until it is matched.  */
 255                 int count = 0;
 256                 for (p = beg; *p != '\0'; ++p)
 257                   {
 258                     if (*p == openparen)
 259                       ++count;
 260                     else if (*p == closeparen && --count < 0)
 261                       break;
 262                   }
 263                 /* If COUNT is >= 0, there were unmatched opening parens
 264                    or braces, so we go to the simple case of a variable name
 265                    such as `$($(a)'.  */
 266                 if (count < 0)
 267                   {
 268                     beg = expand_argument (beg, p); /* Expand the name.  */
 269                     free_beg = 1; /* Remember to free BEG when finished.  */
 270                     end = strchr (beg, '\0');
 271                   }
 272               }
 273             else
 274               /* Advance P to the end of this reference.  After we are
 275                  finished expanding this one, P will be incremented to
 276                  continue the scan.  */
 277               p = end;
 278
 279             /* This is not a reference to a built-in function and
 280                any variable references inside are now expanded.
 281                Is the resultant text a substitution reference?  */
 282
 283             colon = lindex (beg, end, ':');
 284             if (colon)
 285               {
 286                 /* This looks like a substitution reference: $(FOO:A=B).  */
 287                 char *subst_beg, *subst_end, *replace_beg, *replace_end;
 288
 289                 subst_beg = colon + 1;
 290                 subst_end = lindex (subst_beg, end, '=');
 291                 if (subst_end == 0)
 292                   /* There is no = in sight.  Punt on the substitution
 293                      reference and treat this as a variable name containing
 294                      a colon, in the code below.  */
 295                   colon = 0;
 296                 else
 297                   {
 298                     replace_beg = subst_end + 1;
 299                     replace_end = end;
 300
 301                     /* Extract the variable name before the colon
 302                        and look up that variable.  */
 303                     v = lookup_variable (beg, colon - beg);
 304                     if (v == 0)
 305                       warn_undefined (beg, colon - beg);
 306
 307                     /* If the variable is not empty, perform the
 308                        substitution.  */
 309                     if (v != 0 && *v->value != '\0')
 310                       {
 311                         char *pattern, *replace, *ppercent, *rpercent;
 312                         char *value = (v->recursive
 313                                        ? recursively_expand (v)
 314                                        : v->value);
 315
 316                         /* Copy the pattern and the replacement.  Add in an
 317                            extra % at the beginning to use in case there
 318                            isn't one in the pattern.  */
 319                         pattern = (char *) alloca (subst_end - subst_beg + 2);
 320                         *(pattern++) = '%';
 321                         bcopy (subst_beg, pattern, subst_end - subst_beg);
 322                         pattern[subst_end - subst_beg] = '\0';
 323
 324                         replace = (char *) alloca (replace_end
 325                                                    - replace_beg + 2);
 326                         *(replace++) = '%';
 327                         bcopy (replace_beg, replace,
 328                                replace_end - replace_beg);
 329                         replace[replace_end - replace_beg] = '\0';
 330
 331                         /* Look for %.  Set the percent pointers properly
 332                            based on whether we find one or not.  */
 333                         ppercent = find_percent (pattern);
 334                         if (ppercent)
 335                           {
 336                             ++ppercent;
 337                             rpercent = 0;
 338                           }
 339                         else
 340                           {
 341                             ppercent = pattern;
 342                             rpercent = replace;
 343                             --pattern;
 344                             --replace;
 345                           }
 346
 347                         o = patsubst_expand (o, value, pattern, replace,
 348                                              ppercent, rpercent);
 349
 350                         if (v->recursive)
 351                           free (value);
 352                       }
 353                   }
 354               }
 355
 356             if (colon == 0)
 357               /* This is an ordinary variable reference.
 358                  Look up the value of the variable.  */
 359                 o = reference_variable (o, beg, end - beg);
 360
 361           if (free_beg)
 362             free (beg);
 363           }
 364           break;
 365
 366         case '\0':
 367           break;
 368
 369         default:
 370           if (isblank ((unsigned char)p[-1]))
 371             break;
 372
 373           /* A $ followed by a random char is a variable reference:
 374              $a is equivalent to $(a).  */
 375           {
 376             /* We could do the expanding here, but this way
 377                avoids code repetition at a small performance cost.  */
 378             char name[5];
 379             name[0] = '$';
 380             name[1] = '(';
 381             name[2] = *p;
 382             name[3] = ')';
 383             name[4] = '\0';
 384             p1 = allocated_variable_expand (name);
 385             o = variable_buffer_output (o, p1, strlen (p1));
 386             free (p1);
 387           }
 388
 389           break;
 390         }
 391
 392       if (*p == '\0')
 393         break;
 394       else
 395         ++p;
 396     }
 397
 398   if (save_char)
 399     string[length] = save_char;
 400
 401   (void)variable_buffer_output (o, "", 1);
 402   return (variable_buffer + line_offset);
 403 }
 404 \f
 405 /* Scan LINE for variable references and expansion-function calls.
 406    Build in `variable_buffer' the result of expanding the references and calls.
 407    Return the address of the resulting string, which is null-terminated
 408    and is valid only until the next time this function is called.  */
 409
 410 char *
 411 variable_expand (char *line)
 412 {
 413   return variable_expand_string(NULL, line, (long)-1);
 414 }
 415 \f
 416 /* Expand an argument for an expansion function.
 417    The text starting at STR and ending at END is variable-expanded
 418    into a null-terminated string that is returned as the value.
 419    This is done without clobbering `variable_buffer' or the current
 420    variable-expansion that is in progress.  */
 421
 422 char *
 423 expand_argument (const char *str, const char *end)
 424 {
 425   char *tmp;
 426
 427   if (str == end)
 428     return xstrdup("");
 429
 430   if (!end || *end == '\0')
 431     return allocated_variable_expand ((char *)str);
 432
 433   tmp = (char *) alloca (end - str + 1);
 434   bcopy (str, tmp, end - str);
 435   tmp[end - str] = '\0';
 436
 437   return allocated_variable_expand (tmp);
 438 }
 439 \f
 440 /* Expand LINE for FILE.  Error messages refer to the file and line where
 441    FILE's commands were found.  Expansion uses FILE's variable set list.  */
 442
 443 static char *
 444 variable_expand_for_file (char *line, struct file *file)
 445 {
 446   char *result;
 447   struct variable_set_list *save;
 448
 449   if (file == 0)
 450     return variable_expand (line);
 451
 452   save = current_variable_set_list;
 453   current_variable_set_list = file->variables;
 454   if (file->cmds && file->cmds->fileinfo.filenm)
 455     reading_file = &file->cmds->fileinfo;
 456   else
 457     reading_file = 0;
 458   result = variable_expand (line);
 459   current_variable_set_list = save;
 460   reading_file = 0;
 461
 462   return result;
 463 }
 464 \f
 465 /* Like allocated_variable_expand, but for += target-specific variables.
 466    First recursively construct the variable value from its appended parts in
 467    any upper variable sets.  Then expand the resulting value.  */
 468
 469 static char *
 470 variable_append (const char *name, unsigned int length,
 471                  const struct variable_set_list *set)
 472 {
 473   const struct variable *v;
 474   char *buf = 0;
 475
 476   /* If there's nothing left to check, return the empty buffer.  */
 477   if (!set)
 478     return initialize_variable_output ();
 479
 480   /* Try to find the variable in this variable set.  */
 481   v = lookup_variable_in_set (name, length, set->set);
 482
 483   /* If there isn't one, look to see if there's one in a set above us.  */
 484   if (!v)
 485     return variable_append (name, length, set->next);
 486
 487   /* If this variable type is append, first get any upper values.
 488      If not, initialize the buffer.  */
 489   if (v->append)
 490     buf = variable_append (name, length, set->next);
 491   else
 492     buf = initialize_variable_output ();
 493
 494   /* Append this value to the buffer, and return it.
 495      If we already have a value, first add a space.  */
 496   if (buf > variable_buffer)
 497     buf = variable_buffer_output (buf, " ", 1);
 498
 499   return variable_buffer_output (buf, v->value, strlen (v->value));
 500 }
 501
 502
 503 static char *
 504 allocated_variable_append (const struct variable *v)
 505 {
 506   char *val, *retval;
 507
 508   /* Construct the appended variable value.  */
 509
 510   char *obuf = variable_buffer;
 511   unsigned int olen = variable_buffer_length;
 512
 513   variable_buffer = 0;
 514
 515   val = variable_append (v->name, strlen (v->name), current_variable_set_list);
 516   variable_buffer_output (val, "", 1);
 517   val = variable_buffer;
 518
 519   variable_buffer = obuf;
 520   variable_buffer_length = olen;
 521
 522   /* Now expand it and return that.  */
 523
 524   retval = allocated_variable_expand (val);
 525
 526   free (val);
 527   return retval;
 528 }
 529
 530 /* Like variable_expand_for_file, but the returned string is malloc'd.
 531    This function is called a lot.  It wants to be efficient.  */
 532
 533 char *
 534 allocated_variable_expand_for_file (char *line, struct file *file)
 535 {
 536   char *value;
 537
 538   char *obuf = variable_buffer;
 539   unsigned int olen = variable_buffer_length;
 540
 541   variable_buffer = 0;
 542
 543   value = variable_expand_for_file (line, file);
 544
 545 #if 0
 546   /* Waste a little memory and save time.  */
 547   value = xrealloc (value, strlen (value))
 548 #endif
 549
 550   variable_buffer = obuf;
 551   variable_buffer_length = olen;
 552
 553   return value;
 554 }
 555
 556 /* Install a new variable_buffer context, returning the current one for
 557    safe-keeping.  */
 558
 559 void
 560 install_variable_buffer (char **bufp, unsigned int *lenp)
 561 {
 562   *bufp = variable_buffer;
 563   *lenp = variable_buffer_length;
 564
 565   variable_buffer = 0;
 566   initialize_variable_output ();
 567 }
 568
 569 /* Restore a previously-saved variable_buffer setting (free the current one).
 570  */
 571
 572 void
 573 restore_variable_buffer (char *buf, unsigned int len)
 574 {
 575   free (variable_buffer);
 576
 577   variable_buffer = buf;
 578   variable_buffer_length = len;
 579 }