libcpp/pch.c

   1 /* Part of CPP library.  (Precompiled header reading/writing.)
   2    Copyright (C) 2000-2021 Free Software Foundation, Inc.
   3
   4 This program is free software; you can redistribute it and/or modify it
   5 under the terms of the GNU General Public License as published by the
   6 Free Software Foundation; either version 3, or (at your option) any
   7 later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program; see the file COPYING3.  If not see
  16 <http://www.gnu.org/licenses/>.  */
  17
  18 #include "config.h"
  19 #include "system.h"
  20 #include "cpplib.h"
  21 #include "internal.h"
  22 #include "hashtab.h"
  23 #include "mkdeps.h"
  24
  25 static int write_macdef (cpp_reader *, cpp_hashnode *, void *);
  26 static int save_idents (cpp_reader *, cpp_hashnode *, void *);
  27 static hashval_t hashmem (const void *, size_t);
  28 static hashval_t cpp_string_hash (const void *);
  29 static int cpp_string_eq (const void *, const void *);
  30 static int count_defs (cpp_reader *, cpp_hashnode *, void *);
  31 static int comp_hashnodes (const void *, const void *);
  32 static int collect_ht_nodes (cpp_reader *, cpp_hashnode *, void *);
  33 static int write_defs (cpp_reader *, cpp_hashnode *, void *);
  34 static int save_macros (cpp_reader *, cpp_hashnode *, void *);
  35 static int _cpp_save_pushed_macros (cpp_reader *, FILE *);
  36 static int _cpp_restore_pushed_macros (cpp_reader *, FILE *);
  37
  38 /* This structure represents a macro definition on disk.  */
  39 struct macrodef_struct
  40 {
  41   unsigned int definition_length;
  42   unsigned short name_length;
  43   unsigned short flags;
  44 };
  45
  46 /* This is how we write out a macro definition.
  47    Suitable for being called by cpp_forall_identifiers.  */
  48
  49 static int
  50 write_macdef (cpp_reader *pfile, cpp_hashnode *hn, void *file_p)
  51 {
  52   FILE *f = (FILE *) file_p;
  53   bool is_void = false;
  54   switch (hn->type)
  55     {
  56     case NT_VOID:
  57       if (! (hn->flags & NODE_POISONED))
  58         return 1;
  59       is_void = true;
  60       goto poisoned;
  61
  62     case NT_BUILTIN_MACRO:
  63       return 1;
  64
  65     case NT_USER_MACRO:
  66       if (hn->value.macro->kind != cmk_assert)
  67         {
  68         poisoned:
  69           struct macrodef_struct s;
  70           const unsigned char *defn;
  71
  72           s.name_length = NODE_LEN (hn);
  73           s.flags = hn->flags & NODE_POISONED;
  74
  75           if (is_void)
  76             {
  77               defn = NODE_NAME (hn);
  78               s.definition_length = s.name_length;
  79             }
  80           else
  81             {
  82               defn = cpp_macro_definition (pfile, hn);
  83               s.definition_length = ustrlen (defn);
  84             }
  85
  86           if (fwrite (&s, sizeof (s), 1, f) != 1
  87               || fwrite (defn, 1, s.definition_length, f) != s.definition_length)
  88             {
  89               cpp_errno (pfile, CPP_DL_ERROR,
  90                          "while writing precompiled header");
  91               return 0;
  92             }
  93         }
  94       return 1;
  95
  96     default:
  97       abort ();
  98     }
  99 }
 100
 101 /* This structure records the names of the defined macros.
 102    It's also used as a callback structure for size_initial_idents
 103    and save_idents.  */
 104
 105 struct cpp_savedstate
 106 {
 107   /* A hash table of the defined identifiers.  */
 108   htab_t definedhash;
 109   /* The size of the definitions of those identifiers (the size of
 110      'definedstrs').  */
 111   size_t hashsize;
 112   /* Number of definitions */
 113   size_t n_defs;
 114   /* Array of definitions.  In cpp_write_pch_deps it is used for sorting.  */
 115   cpp_hashnode **defs;
 116   /* Space for the next definition.  Definitions are null-terminated
 117      strings.  */
 118   unsigned char *definedstrs;
 119 };
 120
 121 /* Save this identifier into the state: put it in the hash table,
 122    put the definition in 'definedstrs'.  */
 123
 124 static int
 125 save_idents (cpp_reader *pfile ATTRIBUTE_UNUSED, cpp_hashnode *hn, void *ss_p)
 126 {
 127   struct cpp_savedstate *const ss = (struct cpp_savedstate *)ss_p;
 128
 129   if (hn->type != NT_VOID)
 130     {
 131       struct cpp_string news;
 132       void **slot;
 133
 134       news.len = NODE_LEN (hn);
 135       news.text= NODE_NAME (hn);
 136       slot = htab_find_slot (ss->definedhash, &news, INSERT);
 137       if (*slot == NULL)
 138         {
 139           struct cpp_string *sp;
 140           unsigned char *text;
 141
 142           sp = XNEW (struct cpp_string);
 143           *slot = sp;
 144
 145           sp->len = NODE_LEN (hn);
 146           sp->text = text = XNEWVEC (unsigned char, NODE_LEN (hn));
 147           memcpy (text, NODE_NAME (hn), NODE_LEN (hn));
 148         }
 149     }
 150
 151   return 1;
 152 }
 153
 154 /* Hash some memory in a generic way.  */
 155
 156 static hashval_t
 157 hashmem (const void *p_p, size_t sz)
 158 {
 159   const unsigned char *p = (const unsigned char *)p_p;
 160   size_t i;
 161   hashval_t h;
 162
 163   h = 0;
 164   for (i = 0; i < sz; i++)
 165     h = h * 67 - (*p++ - 113);
 166   return h;
 167 }
 168
 169 /* Hash a cpp string for the hashtable machinery.  */
 170
 171 static hashval_t
 172 cpp_string_hash (const void *a_p)
 173 {
 174   const struct cpp_string *a = (const struct cpp_string *) a_p;
 175   return hashmem (a->text, a->len);
 176 }
 177
 178 /* Compare two cpp strings for the hashtable machinery.  */
 179
 180 static int
 181 cpp_string_eq (const void *a_p, const void *b_p)
 182 {
 183   const struct cpp_string *a = (const struct cpp_string *) a_p;
 184   const struct cpp_string *b = (const struct cpp_string *) b_p;
 185   return (a->len == b->len
 186           && memcmp (a->text, b->text, a->len) == 0);
 187 }
 188
 189 /* Free memory associated with cpp_string.  */
 190
 191 static void
 192 cpp_string_free (void *a_p)
 193 {
 194   struct cpp_string *a = (struct cpp_string *) a_p;
 195   free ((void *) a->text);
 196   free (a);
 197 }
 198
 199 /* Save the current definitions of the cpp_reader for dependency
 200    checking purposes.  When writing a precompiled header, this should
 201    be called at the same point in the compilation as cpp_valid_state
 202    would be called when reading the precompiled header back in.  */
 203
 204 int
 205 cpp_save_state (cpp_reader *r, FILE *f)
 206 {
 207   /* Save the list of non-void identifiers for the dependency checking.  */
 208   r->savedstate = XNEW (struct cpp_savedstate);
 209   r->savedstate->definedhash = htab_create (100, cpp_string_hash,
 210                                             cpp_string_eq, cpp_string_free);
 211   cpp_forall_identifiers (r, save_idents, r->savedstate);
 212
 213   /* Write out the list of defined identifiers.  */
 214   cpp_forall_identifiers (r, write_macdef, f);
 215
 216   return 0;
 217 }
 218
 219 /* Calculate the 'hashsize' field of the saved state.  */
 220
 221 static int
 222 count_defs (cpp_reader *pfile ATTRIBUTE_UNUSED, cpp_hashnode *hn, void *ss_p)
 223 {
 224   struct cpp_savedstate *const ss = (struct cpp_savedstate *)ss_p;
 225
 226   switch (hn->type)
 227     {
 228     case NT_BUILTIN_MACRO:
 229       return 1;
 230
 231     case NT_USER_MACRO:
 232       if (hn->value.macro->kind == cmk_assert)
 233         return 1;
 234
 235       /* fall through.  */
 236
 237     case NT_VOID:
 238       {
 239         struct cpp_string news;
 240         void **slot;
 241
 242         news.len = NODE_LEN (hn);
 243         news.text = NODE_NAME (hn);
 244         slot = (void **) htab_find (ss->definedhash, &news);
 245         if (slot == NULL)
 246           {
 247             ss->hashsize += NODE_LEN (hn) + 1;
 248             ss->n_defs += 1;
 249           }
 250       }
 251       return 1;
 252
 253     default:
 254       abort ();
 255     }
 256 }
 257
 258 /* Collect the identifiers into the state's string table.  */
 259 static int
 260 write_defs (cpp_reader *pfile ATTRIBUTE_UNUSED, cpp_hashnode *hn, void *ss_p)
 261 {
 262   struct cpp_savedstate *const ss = (struct cpp_savedstate *)ss_p;
 263
 264   switch (hn->type)
 265     {
 266     case NT_BUILTIN_MACRO:
 267       return 1;
 268
 269     case NT_USER_MACRO:
 270       if (hn->value.macro->kind == cmk_assert)
 271         return 1;
 272
 273       /* fall through.  */
 274
 275     case NT_VOID:
 276       {
 277         struct cpp_string news;
 278         void **slot;
 279
 280         news.len = NODE_LEN (hn);
 281         news.text = NODE_NAME (hn);
 282         slot = (void **) htab_find (ss->definedhash, &news);
 283         if (slot == NULL)
 284           {
 285             ss->defs[ss->n_defs] = hn;
 286             ss->n_defs += 1;
 287           }
 288       }
 289       return 1;
 290
 291     default:
 292       abort ();
 293     }
 294 }
 295
 296 /* Comparison function for qsort.  The arguments point to pointers of
 297    type ht_hashnode *.  */
 298 static int
 299 comp_hashnodes (const void *px, const void *py)
 300 {
 301   cpp_hashnode *x = *(cpp_hashnode **) px;
 302   cpp_hashnode *y = *(cpp_hashnode **) py;
 303   return ustrcmp (NODE_NAME (x), NODE_NAME (y));
 304 }
 305
 306 /* Write out the remainder of the dependency information.  This should be
 307    called after the PCH is ready to be saved.  */
 308
 309 int
 310 cpp_write_pch_deps (cpp_reader *r, FILE *f)
 311 {
 312   struct macrodef_struct z;
 313   struct cpp_savedstate *const ss = r->savedstate;
 314   unsigned char *definedstrs;
 315   size_t i;
 316
 317   /* Collect the list of identifiers which have been seen and
 318      weren't defined to anything previously.  */
 319   ss->hashsize = 0;
 320   ss->n_defs = 0;
 321   cpp_forall_identifiers (r, count_defs, ss);
 322
 323   ss->defs = XNEWVEC (cpp_hashnode *, ss->n_defs);
 324   ss->n_defs = 0;
 325   cpp_forall_identifiers (r, write_defs, ss);
 326
 327   /* Sort the list, copy it into a buffer, and write it out.  */
 328   qsort (ss->defs, ss->n_defs, sizeof (cpp_hashnode *), &comp_hashnodes);
 329   definedstrs = ss->definedstrs = XNEWVEC (unsigned char, ss->hashsize);
 330   for (i = 0; i < ss->n_defs; ++i)
 331     {
 332       size_t len = NODE_LEN (ss->defs[i]);
 333       memcpy (definedstrs, NODE_NAME (ss->defs[i]), len + 1);
 334       definedstrs += len + 1;
 335     }
 336
 337   memset (&z, 0, sizeof (z));
 338   z.definition_length = ss->hashsize;
 339   if (fwrite (&z, sizeof (z), 1, f) != 1
 340       || fwrite (ss->definedstrs, ss->hashsize, 1, f) != 1)
 341     {
 342       cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
 343       return -1;
 344     }
 345   free (ss->definedstrs);
 346   free (ss->defs);
 347   htab_delete (ss->definedhash);
 348
 349   /* Free the saved state.  */
 350   free (ss);
 351   r->savedstate = NULL;
 352
 353   /* Save the next value of __COUNTER__. */
 354   if (fwrite (&r->counter, sizeof (r->counter), 1, f) != 1)
 355     {
 356       cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
 357       return -1;
 358     }
 359
 360   return 0;
 361 }
 362
 363 /* Write out the definitions of the preprocessor, in a form suitable for
 364    cpp_read_state.  */
 365
 366 int
 367 cpp_write_pch_state (cpp_reader *r, FILE *f)
 368 {
 369   if (!r->deps)
 370     r->deps = deps_init ();
 371
 372   if (deps_save (r->deps, f) != 0)
 373     {
 374       cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
 375       return -1;
 376     }
 377
 378   if (! _cpp_save_file_entries (r, f))
 379     {
 380       cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
 381       return -1;
 382     }
 383
 384   /* Save the next __COUNTER__ value.  When we include a precompiled header,
 385      we need to start at the offset we would have if the header had been
 386      included normally. */
 387   if (fwrite (&r->counter, sizeof (r->counter), 1, f) != 1)
 388     {
 389       cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
 390       return -1;
 391     }
 392
 393   /* Write saved macros.  */
 394   if (! _cpp_save_pushed_macros (r, f))
 395     {
 396       cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
 397       return -1;
 398     }
 399
 400   return 0;
 401 }
 402
 403 static int
 404 _cpp_restore_pushed_macros (cpp_reader *r, FILE *f)
 405 {
 406   size_t count_saved = 0;
 407   size_t i;
 408   struct def_pragma_macro *p;
 409   size_t nlen;
 410   uchar *defn;
 411   size_t defnlen;
 412
 413   if (fread (&count_saved, sizeof (count_saved), 1, f) != 1)
 414     return 0;
 415   if (! count_saved)
 416     return 1;
 417   for (i = 0; i < count_saved; i++)
 418     {
 419       if (fread (&nlen, sizeof (nlen), 1, f) != 1)
 420         return 0;
 421       p = XNEW (struct def_pragma_macro);
 422       memset (p, 0, sizeof (struct def_pragma_macro));
 423       p->name = XNEWVAR (char, nlen + 1);
 424       p->name[nlen] = 0;
 425       if (fread (p->name, nlen, 1, f) != 1)
 426         return 0;
 427       if (fread (&defnlen, sizeof (defnlen), 1, f) != 1)
 428         return 0;
 429       if (defnlen == 0)
 430         p->is_undef = 1;
 431       else
 432         {
 433           defn = XNEWVEC (uchar, defnlen + 1);
 434           defn[defnlen] = 0;
 435
 436           if (fread (defn, defnlen, 1, f) != 1)
 437             return 0;
 438
 439           p->definition = defn;
 440           if (fread (&(p->line), sizeof (location_t), 1, f) != 1)
 441             return 0;
 442           defnlen = 0;
 443           if (fread (&defnlen, sizeof (defnlen), 1, f) != 1)
 444             return 0;
 445           p->syshdr = ((defnlen & 1) != 0 ? 1 : 0);
 446           p->used =  ((defnlen & 2) != 0 ? 1 : 0);
 447         }
 448
 449       p->next = r->pushed_macros;
 450       r->pushed_macros = p;
 451     }
 452   return 1;
 453 }
 454
 455 static int
 456 _cpp_save_pushed_macros (cpp_reader *r, FILE *f)
 457 {
 458   size_t count_saved = 0;
 459   size_t i;
 460   struct def_pragma_macro *p,**pp;
 461   size_t defnlen;
 462
 463   /* Get count. */
 464   p = r->pushed_macros;
 465   while (p != NULL)
 466     {
 467       count_saved++;
 468       p = p->next;
 469     }
 470   if (fwrite (&count_saved, sizeof (count_saved), 1, f) != 1)
 471     return 0;
 472   if (!count_saved)
 473     return 1;
 474
 475   pp = (struct def_pragma_macro **) alloca (sizeof (struct def_pragma_macro *)
 476                                             * count_saved);
 477   /* Store them in reverse order.  */
 478   p = r->pushed_macros;
 479   i = count_saved;
 480   while (p != NULL)
 481     {
 482       --i;
 483       pp[i] = p;
 484       p = p->next;
 485     }
 486   for (i = 0; i < count_saved; i++)
 487     {
 488       defnlen = strlen (pp[i]->name);
 489       if (fwrite (&defnlen, sizeof (size_t), 1, f) != 1
 490           || fwrite (pp[i]->name, defnlen, 1, f) != 1)
 491         return 0;
 492       if (pp[i]->is_undef)
 493         {
 494           defnlen = 0;
 495           if (fwrite (&defnlen, sizeof (size_t), 1, f) != 1)
 496             return 0;
 497         }
 498       else
 499         {
 500           defnlen = ustrlen (pp[i]->definition);
 501           if (fwrite (&defnlen, sizeof (size_t), 1, f) != 1
 502               || fwrite (pp[i]->definition, defnlen, 1, f) != 1)
 503             return 0;
 504           if (fwrite (&(pp[i]->line), sizeof (location_t), 1, f) != 1)
 505             return 0;
 506           defnlen = 0;
 507           defnlen |= (pp[i]->syshdr != 0 ? 1 : 0);
 508           defnlen |= (pp[i]->used != 0 ? 2 : 0);
 509           if (fwrite (&defnlen, sizeof (defnlen), 1, f) != 1)
 510             return 0;
 511         }
 512     }
 513   return 1;
 514 }
 515
 516
 517 /* Data structure to transform hash table nodes into a sorted list */
 518
 519 struct ht_node_list
 520 {
 521   /* Array of nodes */
 522   cpp_hashnode **defs;
 523   /* Number of nodes in the array */
 524   size_t n_defs;
 525   /* Size of the allocated array */
 526   size_t asize;
 527 };
 528
 529 /* Callback for collecting identifiers from hash table */
 530
 531 static int
 532 collect_ht_nodes (cpp_reader *pfile ATTRIBUTE_UNUSED, cpp_hashnode *hn,
 533                   void *nl_p)
 534 {
 535   struct ht_node_list *const nl = (struct ht_node_list *)nl_p;
 536
 537   if (hn->type != NT_VOID || hn->flags & NODE_POISONED)
 538     {
 539       if (nl->n_defs == nl->asize)
 540         {
 541           nl->asize *= 2;
 542           nl->defs = XRESIZEVEC (cpp_hashnode *, nl->defs, nl->asize);
 543         }
 544
 545       nl->defs[nl->n_defs] = hn;
 546       ++nl->n_defs;
 547     }
 548   return 1;
 549 }
 550
 551
 552 /* Return nonzero if FD is a precompiled header which is consistent
 553    with the preprocessor's current definitions.  It will be consistent
 554    when:
 555
 556    - anything that was defined just before the PCH was generated
 557      is defined the same way now; and
 558    - anything that was not defined then, but is defined now, was not
 559      used by the PCH.
 560
 561    NAME is used to print warnings if `warn_invalid_pch' is set in the
 562    reader's flags.
 563 */
 564
 565 int
 566 cpp_valid_state (cpp_reader *r, const char *name, int fd)
 567 {
 568   struct macrodef_struct m;
 569   size_t namebufsz = 256;
 570   unsigned char *namebuf = XNEWVEC (unsigned char, namebufsz);
 571   unsigned char *undeftab = NULL;
 572   struct ht_node_list nl = { 0, 0, 0 };
 573   unsigned char *first, *last;
 574   unsigned int i;
 575   unsigned int counter;
 576
 577   /* Read in the list of identifiers that must be defined
 578      Check that they are defined in the same way.  */
 579   for (;;)
 580     {
 581       cpp_hashnode *h;
 582       const unsigned char *newdefn;
 583
 584       if (read (fd, &m, sizeof (m)) != sizeof (m))
 585         goto error;
 586
 587       if (m.name_length == 0)
 588         break;
 589
 590       /* If this file is already preprocessed, there won't be any
 591          macros defined, and that's OK.  */
 592       if (CPP_OPTION (r, preprocessed))
 593         {
 594           if (lseek (fd, m.definition_length, SEEK_CUR) == -1)
 595             goto error;
 596           continue;
 597         }
 598
 599       if (m.definition_length > namebufsz)
 600         {
 601           free (namebuf);
 602           namebufsz = m.definition_length + 256;
 603           namebuf = XNEWVEC (unsigned char, namebufsz);
 604         }
 605
 606       if ((size_t)read (fd, namebuf, m.definition_length)
 607           != m.definition_length)
 608         goto error;
 609
 610       h = cpp_lookup (r, namebuf, m.name_length);
 611       if (m.flags & NODE_POISONED
 612           || h->flags & NODE_POISONED)
 613         {
 614           if (CPP_OPTION (r, warn_invalid_pch))
 615             cpp_warning_syshdr (r, CPP_W_INVALID_PCH,
 616                                 "%s: not used because `%.*s' is poisoned",
 617                                 name, m.name_length, namebuf);
 618           goto fail;
 619         }
 620
 621       if (h->type == NT_VOID)
 622         {
 623           /* It's ok if __GCC_HAVE_DWARF2_CFI_ASM becomes undefined,
 624              as in, when the PCH file is created with -g and we're
 625              attempting to use it without -g.  Restoring the PCH file
 626              is supposed to bring in this definition *and* enable the
 627              generation of call frame information, so that precompiled
 628              definitions that take this macro into account, to decide
 629              what asm to emit, won't issue .cfi directives when the
 630              compiler doesn't.  */
 631           if (!(h->flags & NODE_USED)
 632               && m.name_length == sizeof ("__GCC_HAVE_DWARF2_CFI_ASM") - 1
 633               && !memcmp (namebuf, "__GCC_HAVE_DWARF2_CFI_ASM", m.name_length))
 634             continue;
 635
 636           if (CPP_OPTION (r, warn_invalid_pch))
 637             cpp_warning_syshdr (r, CPP_W_INVALID_PCH,
 638                                 "%s: not used because `%.*s' not defined",
 639                                 name, m.name_length, namebuf);
 640           goto fail;
 641         }
 642
 643       newdefn = cpp_macro_definition (r, h);
 644
 645       if (m.definition_length != ustrlen (newdefn)
 646           || memcmp (namebuf, newdefn, m.definition_length) != 0)
 647         {
 648           if (CPP_OPTION (r, warn_invalid_pch))
 649             cpp_warning_syshdr (r, CPP_W_INVALID_PCH,
 650                "%s: not used because `%.*s' defined as `%s' not `%.*s'",
 651                        name, m.name_length, namebuf, newdefn + m.name_length,
 652                        m.definition_length - m.name_length,
 653                        namebuf +  m.name_length);
 654           goto fail;
 655         }
 656     }
 657   free (namebuf);
 658   namebuf = NULL;
 659
 660   /* Read in the list of identifiers that must not be defined.
 661      Check that they really aren't.  */
 662   undeftab = XNEWVEC (unsigned char, m.definition_length);
 663   if ((size_t) read (fd, undeftab, m.definition_length) != m.definition_length)
 664     goto error;
 665
 666   /* Collect identifiers from the current hash table.  */
 667   nl.n_defs = 0;
 668   nl.asize = 10;
 669   nl.defs = XNEWVEC (cpp_hashnode *, nl.asize);
 670   cpp_forall_identifiers (r, &collect_ht_nodes, &nl);
 671   qsort (nl.defs, nl.n_defs, sizeof (cpp_hashnode *), &comp_hashnodes);
 672
 673   /* Loop through nl.defs and undeftab, both of which are sorted lists.
 674      There should be no matches.  */
 675   first = undeftab;
 676   last = undeftab + m.definition_length;
 677   i = 0;
 678
 679   while (first < last && i < nl.n_defs)
 680     {
 681       int cmp = ustrcmp (first, NODE_NAME (nl.defs[i]));
 682
 683       if (cmp < 0)
 684         first += ustrlen (first) + 1;
 685       else if (cmp > 0)
 686         ++i;
 687       else
 688         {
 689           if (CPP_OPTION (r, warn_invalid_pch))
 690             cpp_warning_syshdr (r, CPP_W_INVALID_PCH,
 691                                 "%s: not used because `%s' is defined",
 692                                 name, first);
 693           goto fail;
 694         }
 695     }
 696
 697   free(nl.defs);
 698   nl.defs = NULL;
 699   free (undeftab);
 700   undeftab = NULL;
 701
 702   /* Read in the next value of __COUNTER__.
 703      Check that (a) __COUNTER__ was not used in the pch or (b) __COUNTER__
 704      has not been used in this translation unit. */
 705   if (read (fd, &counter, sizeof (counter)) != sizeof (counter))
 706     goto error;
 707   if (counter && r->counter)
 708     {
 709       if (CPP_OPTION (r, warn_invalid_pch))
 710         cpp_warning_syshdr (r, CPP_W_INVALID_PCH,
 711                             "%s: not used because `__COUNTER__' is invalid",
 712                             name);
 713       goto fail;
 714     }
 715
 716   /* We win!  */
 717   return 0;
 718
 719  error:
 720   cpp_errno (r, CPP_DL_ERROR, "while reading precompiled header");
 721
 722  fail:
 723   free (namebuf);
 724   free (undeftab);
 725   free (nl.defs);
 726   return 1;
 727 }
 728
 729 /* Save all the existing macros.  */
 730
 731 struct save_macro_data
 732 {
 733   uchar **defns;
 734   size_t count;
 735   size_t array_size;
 736   char **saved_pragmas;
 737 };
 738
 739 /* Save the definition of a single macro, so that it will persist
 740    across a PCH restore.  Because macro data is in GCed memory, which
 741    will be blown away by PCH, it must be temporarily copied to
 742    malloced memory.  (The macros will refer to identifier nodes which
 743    are also GCed and so on, so the copying is done by turning them
 744    into self-contained strings.)  The assumption is that most macro
 745    definitions will come from the PCH file, not from the compilation
 746    before the PCH file is loaded, so it doesn't matter that this is
 747    a little expensive.
 748
 749    It would reduce the cost even further if macros defined in the PCH
 750    file were not saved in this way, but this is not done (yet), except
 751    for builtins, and for #assert by default.  */
 752
 753 static int
 754 save_macros (cpp_reader *r, cpp_hashnode *h, void *data_p)
 755 {
 756   struct save_macro_data *data = (struct save_macro_data *)data_p;
 757
 758   if (cpp_user_macro_p (h))
 759     {
 760       if (data->count == data->array_size)
 761         {
 762           data->array_size *= 2;
 763           data->defns = XRESIZEVEC (uchar *, data->defns, (data->array_size));
 764         }
 765
 766       const uchar * defn = cpp_macro_definition (r, h);
 767       size_t defnlen = ustrlen (defn);
 768
 769       data->defns[data->count] = (uchar *) xmemdup (defn, defnlen, defnlen + 2);
 770       data->defns[data->count][defnlen] = '\n';
 771       data->count++;
 772     }
 773
 774   return 1;
 775 }
 776
 777 /* Prepare to restore the state, by saving the currently-defined
 778    macros in 'data'.  */
 779
 780 void
 781 cpp_prepare_state (cpp_reader *r, struct save_macro_data **data)
 782 {
 783   struct save_macro_data *d = XNEW (struct save_macro_data);
 784
 785   d->array_size = 512;
 786   d->defns = XNEWVEC (uchar *, d->array_size);
 787   d->count = 0;
 788   cpp_forall_identifiers (r, save_macros, d);
 789   d->saved_pragmas = _cpp_save_pragma_names (r);
 790   *data = d;
 791 }
 792
 793 /* Given a precompiled header that was previously determined to be valid,
 794    apply all its definitions (and undefinitions) to the current state.
 795    DEPNAME is passed to deps_restore.  */
 796
 797 int
 798 cpp_read_state (cpp_reader *r, const char *name, FILE *f,
 799                 struct save_macro_data *data)
 800 {
 801   size_t i;
 802   struct lexer_state old_state;
 803   unsigned int counter;
 804
 805   /* Restore spec_nodes, which will be full of references to the old
 806      hashtable entries and so will now be invalid.  */
 807   {
 808     struct spec_nodes *s = &r->spec_nodes;
 809     s->n_defined        = cpp_lookup (r, DSC("defined"));
 810     s->n_true           = cpp_lookup (r, DSC("true"));
 811     s->n_false          = cpp_lookup (r, DSC("false"));
 812     s->n__VA_ARGS__     = cpp_lookup (r, DSC("__VA_ARGS__"));
 813     s->n__VA_OPT__      = cpp_lookup (r, DSC("__VA_OPT__"));
 814   }
 815
 816   old_state = r->state;
 817   r->state.in_directive = 1;
 818   r->state.prevent_expansion = 1;
 819   r->state.angled_headers = 0;
 820
 821   /* Run through the carefully-saved macros, insert them.  */
 822   for (i = 0; i < data->count; i++)
 823     {
 824       cpp_hashnode *h;
 825       size_t namelen;
 826       uchar *defn;
 827
 828       namelen = ustrcspn (data->defns[i], "( \n");
 829       h = cpp_lookup (r, data->defns[i], namelen);
 830       defn = data->defns[i] + namelen;
 831
 832       /* The PCH file is valid, so we know that if there is a definition
 833          from the PCH file it must be the same as the one we had
 834          originally, and so do not need to restore it.  */
 835       if (h->type == NT_VOID)
 836         {
 837           if (cpp_push_buffer (r, defn, ustrchr (defn, '\n') - defn, true)
 838               != NULL)
 839             {
 840               _cpp_clean_line (r);
 841               if (!_cpp_create_definition (r, h))
 842                 abort ();
 843               _cpp_pop_buffer (r);
 844             }
 845           else
 846             abort ();
 847         }
 848
 849       free (data->defns[i]);
 850     }
 851   r->state = old_state;
 852
 853   _cpp_restore_pragma_names (r, data->saved_pragmas);
 854
 855   free (data);
 856
 857   if (deps_restore (r->deps, f, CPP_OPTION (r, restore_pch_deps) ? name : NULL)
 858       != 0)
 859     goto error;
 860
 861   if (! _cpp_read_file_entries (r, f))
 862     goto error;
 863
 864   if (fread (&counter, sizeof (counter), 1, f) != 1)
 865     goto error;
 866
 867   if (!r->counter)
 868     r->counter = counter;
 869
 870   /* Read pushed macros. */
 871   if (! _cpp_restore_pushed_macros (r, f))
 872     goto error;
 873   return 0;
 874
 875  error:
 876   cpp_errno (r, CPP_DL_ERROR, "while reading precompiled header");
 877   return -1;
 878 }