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 (v == 0 || *v->value == '\0')
 157     return o;
 158
 159   value = (v->recursive ? recursively_expand (v) : v->value);
 160
 161   o = variable_buffer_output (o, value, strlen (value));
 162
 163   if (v->recursive)
 164     free (value);
 165
 166   return o;
 167 }
 168 \f
 169 /* Scan STRING for variable references and expansion-function calls.  Only
 170    LENGTH bytes of STRING are actually scanned.  If LENGTH is -1, scan until
 171    a null byte is found.
 172
 173    Write the results to LINE, which must point into `variable_buffer'.  If
 174    LINE is NULL, start at the beginning of the buffer.
 175    Return a pointer to LINE, or to the beginning of the buffer if LINE is
 176    NULL.  */
 177
 178 char *
 179 variable_expand_string (char *line, char *string, long length)
 180 {
 181   register struct variable *v;
 182   register char *p, *o, *p1;
 183   char save_char = '\0';
 184   unsigned int line_offset;
 185
 186   if (!line)
 187     line = initialize_variable_output();
 188
 189   p = string;
 190   o = line;
 191   line_offset = line - variable_buffer;
 192
 193   if (length >= 0)
 194     {
 195       save_char = string[length];
 196       string[length] = '\0';
 197     }
 198
 199   while (1)
 200     {
 201       /* Copy all following uninteresting chars all at once to the
 202          variable output buffer, and skip them.  Uninteresting chars end
 203          at the next $ or the end of the input.  */
 204
 205       p1 = strchr (p, '$');
 206
 207       o = variable_buffer_output (o, p, p1 != 0 ? p1 - p : strlen (p) + 1);
 208
 209       if (p1 == 0)
 210         break;
 211       p = p1 + 1;
 212
 213       /* Dispatch on the char that follows the $.  */
 214
 215       switch (*p)
 216         {
 217         case '$':
 218           /* $$ seen means output one $ to the variable output buffer.  */
 219           o = variable_buffer_output (o, p, 1);
 220           break;
 221
 222         case '(':
 223         case '{':
 224           /* $(...) or ${...} is the general case of substitution.  */
 225           {
 226             char openparen = *p;
 227             char closeparen = (openparen == '(') ? ')' : '}';
 228             register char *beg = p + 1;
 229             int free_beg = 0;
 230             char *op, *begp;
 231             char *end, *colon;
 232
 233             op = o;
 234             begp = p;
 235             if (handle_function (&op, &begp))
 236               {
 237                 o = op;
 238                 p = begp;
 239                 break;
 240               }
 241
 242             /* Is there a variable reference inside the parens or braces?
 243                If so, expand it before expanding the entire reference.  */
 244
 245             end = strchr (beg, closeparen);
 246             if (end == 0)
 247               /* Unterminated variable reference.  */
 248               fatal (reading_file, _("unterminated variable reference"));
 249             p1 = lindex (beg, end, '$');
 250             if (p1 != 0)
 251               {
 252                 /* BEG now points past the opening paren or brace.
 253                    Count parens or braces until it is matched.  */
 254                 int count = 0;
 255                 for (p = beg; *p != '\0'; ++p)
 256                   {
 257                     if (*p == openparen)
 258                       ++count;
 259                     else if (*p == closeparen && --count < 0)
 260                       break;
 261                   }
 262                 /* If COUNT is >= 0, there were unmatched opening parens
 263                    or braces, so we go to the simple case of a variable name
 264                    such as `$($(a)'.  */
 265                 if (count < 0)
 266                   {
 267                     beg = expand_argument (beg, p); /* Expand the name.  */
 268                     free_beg = 1; /* Remember to free BEG when finished.  */
 269                     end = strchr (beg, '\0');
 270                   }
 271               }
 272             else
 273               /* Advance P to the end of this reference.  After we are
 274                  finished expanding this one, P will be incremented to
 275                  continue the scan.  */
 276               p = end;
 277
 278             /* This is not a reference to a built-in function and
 279                any variable references inside are now expanded.
 280                Is the resultant text a substitution reference?  */
 281
 282             colon = lindex (beg, end, ':');
 283             if (colon)
 284               {
 285                 /* This looks like a substitution reference: $(FOO:A=B).  */
 286                 char *subst_beg, *subst_end, *replace_beg, *replace_end;
 287
 288                 subst_beg = colon + 1;
 289                 subst_end = lindex (subst_beg, end, '=');
 290                 if (subst_end == 0)
 291                   /* There is no = in sight.  Punt on the substitution
 292                      reference and treat this as a variable name containing
 293                      a colon, in the code below.  */
 294                   colon = 0;
 295                 else
 296                   {
 297                     replace_beg = subst_end + 1;
 298                     replace_end = end;
 299
 300                     /* Extract the variable name before the colon
 301                        and look up that variable.  */
 302                     v = lookup_variable (beg, colon - beg);
 303                     if (v == 0)
 304                       warn_undefined (beg, colon - beg);
 305
 306                     if (v != 0 && *v->value != '\0')
 307                       {
 308                         char *value = (v->recursive ? recursively_expand (v)
 309                                        : v->value);
 310                         char *pattern, *percent;
 311                         if (free_beg)
 312                           {
 313                             *subst_end = '\0';
 314                             pattern = subst_beg;
 315                           }
 316                         else
 317                           {
 318                             pattern = (char *) alloca (subst_end - subst_beg
 319                                                        + 1);
 320                             bcopy (subst_beg, pattern, subst_end - subst_beg);
 321                             pattern[subst_end - subst_beg] = '\0';
 322                           }
 323                         percent = find_percent (pattern);
 324                         if (percent != 0)
 325                           {
 326                             char *replace;
 327                             if (free_beg)
 328                               {
 329                                 *replace_end = '\0';
 330                                 replace = replace_beg;
 331                               }
 332                             else
 333                               {
 334                                 replace = (char *) alloca (replace_end
 335                                                            - replace_beg
 336                                                            + 1);
 337                                 bcopy (replace_beg, replace,
 338                                        replace_end - replace_beg);
 339                                 replace[replace_end - replace_beg] = '\0';
 340                               }
 341
 342                             o = patsubst_expand (o, value, pattern, replace,
 343                                                  percent, (char *) 0);
 344                           }
 345                         else
 346                           o = subst_expand (o, value,
 347                                             pattern, replace_beg,
 348                                             strlen (pattern),
 349                                             end - replace_beg,
 350                                             0, 1);
 351                         if (v->recursive)
 352                           free (value);
 353                       }
 354                   }
 355               }
 356
 357             if (colon == 0)
 358               /* This is an ordinary variable reference.
 359                  Look up the value of the variable.  */
 360                 o = reference_variable (o, beg, end - beg);
 361
 362           if (free_beg)
 363             free (beg);
 364           }
 365           break;
 366
 367         case '\0':
 368           break;
 369
 370         default:
 371           if (isblank ((unsigned char)p[-1]))
 372             break;
 373
 374           /* A $ followed by a random char is a variable reference:
 375              $a is equivalent to $(a).  */
 376           {
 377             /* We could do the expanding here, but this way
 378                avoids code repetition at a small performance cost.  */
 379             char name[5];
 380             name[0] = '$';
 381             name[1] = '(';
 382             name[2] = *p;
 383             name[3] = ')';
 384             name[4] = '\0';
 385             p1 = allocated_variable_expand (name);
 386             o = variable_buffer_output (o, p1, strlen (p1));
 387             free (p1);
 388           }
 389
 390           break;
 391         }
 392
 393       if (*p == '\0')
 394         break;
 395       else
 396         ++p;
 397     }
 398
 399   if (save_char)
 400     string[length] = save_char;
 401
 402   (void)variable_buffer_output (o, "", 1);
 403   return (variable_buffer + line_offset);
 404 }
 405 \f
 406 /* Scan LINE for variable references and expansion-function calls.
 407    Build in `variable_buffer' the result of expanding the references and calls.
 408    Return the address of the resulting string, which is null-terminated
 409    and is valid only until the next time this function is called.  */
 410
 411 char *
 412 variable_expand (char *line)
 413 {
 414   return variable_expand_string(NULL, line, (long)-1);
 415 }
 416 \f
 417 /* Expand an argument for an expansion function.
 418    The text starting at STR and ending at END is variable-expanded
 419    into a null-terminated string that is returned as the value.
 420    This is done without clobbering `variable_buffer' or the current
 421    variable-expansion that is in progress.  */
 422
 423 char *
 424 expand_argument (const char *str, const char *end)
 425 {
 426   char *tmp;
 427
 428   if (str == end)
 429     return xstrdup("");
 430
 431   if (!end || *end == '\0')
 432     return allocated_variable_expand ((char *)str);
 433
 434   tmp = (char *) alloca (end - str + 1);
 435   bcopy (str, tmp, end - str);
 436   tmp[end - str] = '\0';
 437
 438   return allocated_variable_expand (tmp);
 439 }
 440 \f
 441 /* Expand LINE for FILE.  Error messages refer to the file and line where
 442    FILE's commands were found.  Expansion uses FILE's variable set list.  */
 443
 444 static char *
 445 variable_expand_for_file (char *line, struct file *file)
 446 {
 447   char *result;
 448   struct variable_set_list *save;
 449
 450   if (file == 0)
 451     return variable_expand (line);
 452
 453   save = current_variable_set_list;
 454   current_variable_set_list = file->variables;
 455   if (file->cmds && file->cmds->fileinfo.filenm)
 456     reading_file = &file->cmds->fileinfo;
 457   else
 458     reading_file = 0;
 459   result = variable_expand (line);
 460   current_variable_set_list = save;
 461   reading_file = 0;
 462
 463   return result;
 464 }
 465 \f
 466 /* Like allocated_variable_expand, but for += target-specific variables.
 467    First recursively construct the variable value from its appended parts in
 468    any upper variable sets.  Then expand the resulting value.  */
 469
 470 static char *
 471 variable_append (const char *name, unsigned int length,
 472                  const struct variable_set_list *set)
 473 {
 474   const struct variable *v;
 475   char *buf = 0;
 476
 477   /* If there's nothing left to check, return the empty buffer.  */
 478   if (!set)
 479     return initialize_variable_output ();
 480
 481   /* Try to find the variable in this variable set.  */
 482   v = lookup_variable_in_set (name, length, set->set);
 483
 484   /* If there isn't one, look to see if there's one in a set above us.  */
 485   if (!v)
 486     return variable_append (name, length, set->next);
 487
 488   /* If this variable type is append, first get any upper values.
 489      If not, initialize the buffer.  */
 490   if (v->append)
 491     buf = variable_append (name, length, set->next);
 492   else
 493     buf = initialize_variable_output ();
 494
 495   /* Append this value to the buffer, and return it.
 496      If we already have a value, first add a space.  */
 497   if (buf > variable_buffer)
 498     buf = variable_buffer_output (buf, " ", 1);
 499
 500   return variable_buffer_output (buf, v->value, strlen (v->value));
 501 }
 502
 503
 504 static char *
 505 allocated_variable_append (const struct variable *v)
 506 {
 507   char *val, *retval;
 508
 509   /* Construct the appended variable value.  */
 510
 511   char *obuf = variable_buffer;
 512   unsigned int olen = variable_buffer_length;
 513
 514   variable_buffer = 0;
 515
 516   val = variable_append (v->name, strlen (v->name), current_variable_set_list);
 517   variable_buffer_output (val, "", 1);
 518   val = variable_buffer;
 519
 520   variable_buffer = obuf;
 521   variable_buffer_length = olen;
 522
 523   /* Now expand it and return that.  */
 524
 525   retval = allocated_variable_expand (val);
 526
 527   free (val);
 528   return retval;
 529 }
 530
 531 /* Like variable_expand_for_file, but the returned string is malloc'd.
 532    This function is called a lot.  It wants to be efficient.  */
 533
 534 char *
 535 allocated_variable_expand_for_file (char *line, struct file *file)
 536 {
 537   char *value;
 538
 539   char *obuf = variable_buffer;
 540   unsigned int olen = variable_buffer_length;
 541
 542   variable_buffer = 0;
 543
 544   value = variable_expand_for_file (line, file);
 545
 546 #if 0
 547   /* Waste a little memory and save time.  */
 548   value = xrealloc (value, strlen (value))
 549 #endif
 550
 551   variable_buffer = obuf;
 552   variable_buffer_length = olen;
 553
 554   return value;
 555 }
 556
 557 /* Install a new variable_buffer context, returning the current one for
 558    safe-keeping.  */
 559
 560 void
 561 install_variable_buffer (char **bufp, unsigned int *lenp)
 562 {
 563   *bufp = variable_buffer;
 564   *lenp = variable_buffer_length;
 565
 566   variable_buffer = 0;
 567   initialize_variable_output ();
 568 }
 569
 570 /* Restore a previously-saved variable_buffer setting (free the current one).
 571  */
 572
 573 void
 574 restore_variable_buffer (char *buf, unsigned int len)
 575 {
 576   free (variable_buffer);
 577
 578   variable_buffer = buf;
 579   variable_buffer_length = len;
 580 }