libcpp/init.c

   1 /* CPP Library.
   2    Copyright (C) 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008,
   4    2009 Free Software Foundation, Inc.
   5    Contributed by Per Bothner, 1994-95.
   6    Based on CCCP program by Paul Rubin, June 1986
   7    Adapted to ANSI C, Richard Stallman, Jan 1987
   8
   9 This program is free software; you can redistribute it and/or modify it
  10 under the terms of the GNU General Public License as published by the
  11 Free Software Foundation; either version 3, or (at your option) any
  12 later version.
  13
  14 This program is distributed in the hope that it will be useful,
  15 but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 GNU General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with this program; see the file COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 #include "config.h"
  24 #include "system.h"
  25 #include "cpplib.h"
  26 #include "internal.h"
  27 #include "mkdeps.h"
  28 #include "localedir.h"
  29
  30 static void init_library (void);
  31 static void mark_named_operators (cpp_reader *, int);
  32 static void read_original_filename (cpp_reader *);
  33 static void read_original_directory (cpp_reader *);
  34 static void post_options (cpp_reader *);
  35
  36 /* If we have designated initializers (GCC >2.7) these tables can be
  37    initialized, constant data.  Otherwise, they have to be filled in at
  38    runtime.  */
  39 #if HAVE_DESIGNATED_INITIALIZERS
  40
  41 #define init_trigraph_map()  /* Nothing.  */
  42 #define TRIGRAPH_MAP \
  43 __extension__ const uchar _cpp_trigraph_map[UCHAR_MAX + 1] = {
  44
  45 #define END };
  46 #define s(p, v) [p] = v,
  47
  48 #else
  49
  50 #define TRIGRAPH_MAP uchar _cpp_trigraph_map[UCHAR_MAX + 1] = { 0 }; \
  51  static void init_trigraph_map (void) { \
  52  unsigned char *x = _cpp_trigraph_map;
  53
  54 #define END }
  55 #define s(p, v) x[p] = v;
  56
  57 #endif
  58
  59 TRIGRAPH_MAP
  60   s('=', '#')   s(')', ']')     s('!', '|')
  61   s('(', '[')   s('\'', '^')    s('>', '}')
  62   s('/', '\\')  s('<', '{')     s('-', '~')
  63 END
  64
  65 #undef s
  66 #undef END
  67 #undef TRIGRAPH_MAP
  68
  69 /* A set of booleans indicating what CPP features each source language
  70    requires.  */
  71 struct lang_flags
  72 {
  73   char c99;
  74   char cplusplus;
  75   char extended_numbers;
  76   char extended_identifiers;
  77   char std;
  78   char cplusplus_comments;
  79   char digraphs;
  80   char uliterals;
  81 };
  82
  83 static const struct lang_flags lang_defaults[] =
  84 { /*              c99 c++ xnum xid std  //   digr ulit */
  85   /* GNUC89   */  { 0,  0,  1,   0,  0,   1,   1,   0 },
  86   /* GNUC99   */  { 1,  0,  1,   0,  0,   1,   1,   1 },
  87   /* STDC89   */  { 0,  0,  0,   0,  1,   0,   0,   0 },
  88   /* STDC94   */  { 0,  0,  0,   0,  1,   0,   1,   0 },
  89   /* STDC99   */  { 1,  0,  1,   0,  1,   1,   1,   0 },
  90   /* GNUCXX   */  { 0,  1,  1,   0,  0,   1,   1,   0 },
  91   /* CXX98    */  { 0,  1,  1,   0,  1,   1,   1,   0 },
  92   /* GNUCXX0X */  { 1,  1,  1,   0,  0,   1,   1,   1 },
  93   /* CXX0X    */  { 1,  1,  1,   0,  1,   1,   1,   1 },
  94   /* ASM      */  { 0,  0,  1,   0,  0,   1,   0,   0 }
  95   /* xid should be 1 for GNUC99, STDC99, GNUCXX, CXX98, GNUCXX0X, and
  96      CXX0X when no longer experimental (when all uses of identifiers
  97      in the compiler have been audited for correct handling of
  98      extended identifiers).  */
  99 };
 100
 101 /* Sets internal flags correctly for a given language.  */
 102 void
 103 cpp_set_lang (cpp_reader *pfile, enum c_lang lang)
 104 {
 105   const struct lang_flags *l = &lang_defaults[(int) lang];
 106
 107   CPP_OPTION (pfile, lang) = lang;
 108
 109   CPP_OPTION (pfile, c99)                        = l->c99;
 110   CPP_OPTION (pfile, cplusplus)                  = l->cplusplus;
 111   CPP_OPTION (pfile, extended_numbers)           = l->extended_numbers;
 112   CPP_OPTION (pfile, extended_identifiers)       = l->extended_identifiers;
 113   CPP_OPTION (pfile, std)                        = l->std;
 114   CPP_OPTION (pfile, trigraphs)                  = l->std;
 115   CPP_OPTION (pfile, cplusplus_comments)         = l->cplusplus_comments;
 116   CPP_OPTION (pfile, digraphs)                   = l->digraphs;
 117   CPP_OPTION (pfile, uliterals)                  = l->uliterals;
 118 }
 119
 120 /* Initialize library global state.  */
 121 static void
 122 init_library (void)
 123 {
 124   static int initialized = 0;
 125
 126   if (! initialized)
 127     {
 128       initialized = 1;
 129
 130       /* Set up the trigraph map.  This doesn't need to do anything if
 131          we were compiled with a compiler that supports C99 designated
 132          initializers.  */
 133       init_trigraph_map ();
 134
 135 #ifdef ENABLE_NLS
 136        (void) bindtextdomain (PACKAGE, LOCALEDIR);
 137 #endif
 138     }
 139 }
 140
 141 /* Initialize a cpp_reader structure.  */
 142 cpp_reader *
 143 cpp_create_reader (enum c_lang lang, hash_table *table,
 144                    struct line_maps *line_table)
 145 {
 146   cpp_reader *pfile;
 147
 148   /* Initialize this instance of the library if it hasn't been already.  */
 149   init_library ();
 150
 151   pfile = XCNEW (cpp_reader);
 152
 153   cpp_set_lang (pfile, lang);
 154   CPP_OPTION (pfile, warn_multichar) = 1;
 155   CPP_OPTION (pfile, discard_comments) = 1;
 156   CPP_OPTION (pfile, discard_comments_in_macro_exp) = 1;
 157   CPP_OPTION (pfile, show_column) = 1;
 158   CPP_OPTION (pfile, tabstop) = 8;
 159   CPP_OPTION (pfile, operator_names) = 1;
 160   CPP_OPTION (pfile, warn_trigraphs) = 2;
 161   CPP_OPTION (pfile, warn_endif_labels) = 1;
 162   CPP_OPTION (pfile, warn_deprecated) = 1;
 163   CPP_OPTION (pfile, warn_long_long) = 0;
 164   CPP_OPTION (pfile, dollars_in_ident) = 1;
 165   CPP_OPTION (pfile, warn_dollars) = 1;
 166   CPP_OPTION (pfile, warn_variadic_macros) = 1;
 167   CPP_OPTION (pfile, warn_builtin_macro_redefined) = 1;
 168   CPP_OPTION (pfile, warn_normalize) = normalized_C;
 169
 170   /* Default CPP arithmetic to something sensible for the host for the
 171      benefit of dumb users like fix-header.  */
 172   CPP_OPTION (pfile, precision) = CHAR_BIT * sizeof (long);
 173   CPP_OPTION (pfile, char_precision) = CHAR_BIT;
 174   CPP_OPTION (pfile, wchar_precision) = CHAR_BIT * sizeof (int);
 175   CPP_OPTION (pfile, int_precision) = CHAR_BIT * sizeof (int);
 176   CPP_OPTION (pfile, unsigned_char) = 0;
 177   CPP_OPTION (pfile, unsigned_wchar) = 1;
 178   CPP_OPTION (pfile, bytes_big_endian) = 1;  /* does not matter */
 179
 180   /* Default to no charset conversion.  */
 181   CPP_OPTION (pfile, narrow_charset) = _cpp_default_encoding ();
 182   CPP_OPTION (pfile, wide_charset) = 0;
 183
 184   /* Default the input character set to UTF-8.  */
 185   CPP_OPTION (pfile, input_charset) = _cpp_default_encoding ();
 186
 187   /* A fake empty "directory" used as the starting point for files
 188      looked up without a search path.  Name cannot be '/' because we
 189      don't want to prepend anything at all to filenames using it.  All
 190      other entries are correct zero-initialized.  */
 191   pfile->no_search_path.name = (char *) "";
 192
 193   /* Initialize the line map.  */
 194   pfile->line_table = line_table;
 195
 196   /* Initialize lexer state.  */
 197   pfile->state.save_comments = ! CPP_OPTION (pfile, discard_comments);
 198
 199   /* Set up static tokens.  */
 200   pfile->avoid_paste.type = CPP_PADDING;
 201   pfile->avoid_paste.val.source = NULL;
 202   pfile->eof.type = CPP_EOF;
 203   pfile->eof.flags = 0;
 204
 205   /* Create a token buffer for the lexer.  */
 206   _cpp_init_tokenrun (&pfile->base_run, 250);
 207   pfile->cur_run = &pfile->base_run;
 208   pfile->cur_token = pfile->base_run.base;
 209
 210   /* Initialize the base context.  */
 211   pfile->context = &pfile->base_context;
 212   pfile->base_context.macro = 0;
 213   pfile->base_context.prev = pfile->base_context.next = 0;
 214
 215   /* Aligned and unaligned storage.  */
 216   pfile->a_buff = _cpp_get_buff (pfile, 0);
 217   pfile->u_buff = _cpp_get_buff (pfile, 0);
 218
 219   /* Initialize table for push_macro/pop_macro.  */
 220   pfile->pushed_macros = 0;
 221
 222   /* The expression parser stack.  */
 223   _cpp_expand_op_stack (pfile);
 224
 225   /* Initialize the buffer obstack.  */
 226   _obstack_begin (&pfile->buffer_ob, 0, 0,
 227                   (void *(*) (long)) xmalloc,
 228                   (void (*) (void *)) free);
 229
 230   _cpp_init_files (pfile);
 231
 232   _cpp_init_hashtable (pfile, table);
 233
 234   return pfile;
 235 }
 236
 237 /* Set the line_table entry in PFILE.  This is called after reading a
 238    PCH file, as the old line_table will be incorrect.  */
 239 void
 240 cpp_set_line_map (cpp_reader *pfile, struct line_maps *line_table)
 241 {
 242   pfile->line_table = line_table;
 243 }
 244
 245 /* Free resources used by PFILE.  Accessing PFILE after this function
 246    returns leads to undefined behavior.  Returns the error count.  */
 247 void
 248 cpp_destroy (cpp_reader *pfile)
 249 {
 250   cpp_context *context, *contextn;
 251   struct def_pragma_macro *pmacro;
 252   tokenrun *run, *runn;
 253   int i;
 254
 255   free (pfile->op_stack);
 256
 257   while (CPP_BUFFER (pfile) != NULL)
 258     _cpp_pop_buffer (pfile);
 259
 260   if (pfile->out.base)
 261     free (pfile->out.base);
 262
 263   if (pfile->macro_buffer)
 264     {
 265       free (pfile->macro_buffer);
 266       pfile->macro_buffer = NULL;
 267       pfile->macro_buffer_len = 0;
 268     }
 269
 270   if (pfile->deps)
 271     deps_free (pfile->deps);
 272   obstack_free (&pfile->buffer_ob, 0);
 273
 274   _cpp_destroy_hashtable (pfile);
 275   _cpp_cleanup_files (pfile);
 276   _cpp_destroy_iconv (pfile);
 277
 278   _cpp_free_buff (pfile->a_buff);
 279   _cpp_free_buff (pfile->u_buff);
 280   _cpp_free_buff (pfile->free_buffs);
 281
 282   for (run = &pfile->base_run; run; run = runn)
 283     {
 284       runn = run->next;
 285       free (run->base);
 286       if (run != &pfile->base_run)
 287         free (run);
 288     }
 289
 290   for (context = pfile->base_context.next; context; context = contextn)
 291     {
 292       contextn = context->next;
 293       free (context);
 294     }
 295
 296   if (pfile->comments.entries)
 297     {
 298       for (i = 0; i < pfile->comments.count; i++)
 299         free (pfile->comments.entries[i].comment);
 300
 301       free (pfile->comments.entries);
 302     }
 303   if (pfile->pushed_macros)
 304     {
 305       do
 306         {
 307           pmacro = pfile->pushed_macros;
 308           pfile->pushed_macros = pmacro->next;
 309           free (pmacro->name);
 310           free (pmacro);
 311         }
 312       while (pfile->pushed_macros);
 313     }
 314
 315   free (pfile);
 316 }
 317
 318 /* This structure defines one built-in identifier.  A node will be
 319    entered in the hash table under the name NAME, with value VALUE.
 320
 321    There are two tables of these.  builtin_array holds all the
 322    "builtin" macros: these are handled by builtin_macro() in
 323    macro.c.  Builtin is somewhat of a misnomer -- the property of
 324    interest is that these macros require special code to compute their
 325    expansions.  The value is a "builtin_type" enumerator.
 326
 327    operator_array holds the C++ named operators.  These are keywords
 328    which act as aliases for punctuators.  In C++, they cannot be
 329    altered through #define, and #if recognizes them as operators.  In
 330    C, these are not entered into the hash table at all (but see
 331    <iso646.h>).  The value is a token-type enumerator.  */
 332 struct builtin_macro
 333 {
 334   const uchar *const name;
 335   const unsigned short len;
 336   const unsigned short value;
 337   const bool always_warn_if_redefined;
 338 };
 339
 340 #define B(n, t, f)    { DSC(n), t, f }
 341 static const struct builtin_macro builtin_array[] =
 342 {
 343   B("__TIMESTAMP__",     BT_TIMESTAMP,     false),
 344   B("__TIME__",          BT_TIME,          false),
 345   B("__DATE__",          BT_DATE,          false),
 346   B("__FILE__",          BT_FILE,          false),
 347   B("__BASE_FILE__",     BT_BASE_FILE,     false),
 348   B("__LINE__",          BT_SPECLINE,      true),
 349   B("__INCLUDE_LEVEL__", BT_INCLUDE_LEVEL, true),
 350   B("__COUNTER__",       BT_COUNTER,       true),
 351   /* Keep builtins not used for -traditional-cpp at the end, and
 352      update init_builtins() if any more are added.  */
 353   B("_Pragma",           BT_PRAGMA,        true),
 354   B("__STDC__",          BT_STDC,          true),
 355 };
 356 #undef B
 357
 358 struct builtin_operator
 359 {
 360   const uchar *const name;
 361   const unsigned short len;
 362   const unsigned short value;
 363 };
 364
 365 #define B(n, t)    { DSC(n), t }
 366 static const struct builtin_operator operator_array[] =
 367 {
 368   B("and",      CPP_AND_AND),
 369   B("and_eq",   CPP_AND_EQ),
 370   B("bitand",   CPP_AND),
 371   B("bitor",    CPP_OR),
 372   B("compl",    CPP_COMPL),
 373   B("not",      CPP_NOT),
 374   B("not_eq",   CPP_NOT_EQ),
 375   B("or",       CPP_OR_OR),
 376   B("or_eq",    CPP_OR_EQ),
 377   B("xor",      CPP_XOR),
 378   B("xor_eq",   CPP_XOR_EQ)
 379 };
 380 #undef B
 381
 382 /* Mark the C++ named operators in the hash table.  */
 383 static void
 384 mark_named_operators (cpp_reader *pfile, int flags)
 385 {
 386   const struct builtin_operator *b;
 387
 388   for (b = operator_array;
 389        b < (operator_array + ARRAY_SIZE (operator_array));
 390        b++)
 391     {
 392       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 393       hp->flags |= flags;
 394       hp->is_directive = 0;
 395       hp->directive_index = b->value;
 396     }
 397 }
 398
 399 /* Helper function of cpp_type2name. Return the string associated with
 400    named operator TYPE.  */
 401 const char *
 402 cpp_named_operator2name (enum cpp_ttype type)
 403 {
 404   const struct builtin_operator *b;
 405
 406   for (b = operator_array;
 407        b < (operator_array + ARRAY_SIZE (operator_array));
 408        b++)
 409     {
 410       if (type == b->value)
 411         return (const char *) b->name;
 412     }
 413
 414   return NULL;
 415 }
 416
 417 void
 418 cpp_init_special_builtins (cpp_reader *pfile)
 419 {
 420   const struct builtin_macro *b;
 421   size_t n = ARRAY_SIZE (builtin_array);
 422
 423   if (CPP_OPTION (pfile, traditional))
 424     n -= 2;
 425   else if (! CPP_OPTION (pfile, stdc_0_in_system_headers)
 426            || CPP_OPTION (pfile, std))
 427     n--;
 428
 429   for (b = builtin_array; b < builtin_array + n; b++)
 430     {
 431       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 432       hp->type = NT_MACRO;
 433       hp->flags |= NODE_BUILTIN;
 434       if (b->always_warn_if_redefined
 435           || CPP_OPTION (pfile, warn_builtin_macro_redefined))
 436         hp->flags |= NODE_WARN;
 437       hp->value.builtin = (enum cpp_builtin_type) b->value;
 438     }
 439 }
 440
 441 /* Read the builtins table above and enter them, and language-specific
 442    macros, into the hash table.  HOSTED is true if this is a hosted
 443    environment.  */
 444 void
 445 cpp_init_builtins (cpp_reader *pfile, int hosted)
 446 {
 447   cpp_init_special_builtins (pfile);
 448
 449   if (!CPP_OPTION (pfile, traditional)
 450       && (! CPP_OPTION (pfile, stdc_0_in_system_headers)
 451           || CPP_OPTION (pfile, std)))
 452     _cpp_define_builtin (pfile, "__STDC__ 1");
 453
 454   if (CPP_OPTION (pfile, cplusplus))
 455     _cpp_define_builtin (pfile, "__cplusplus 1");
 456   else if (CPP_OPTION (pfile, lang) == CLK_ASM)
 457     _cpp_define_builtin (pfile, "__ASSEMBLER__ 1");
 458   else if (CPP_OPTION (pfile, lang) == CLK_STDC94)
 459     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199409L");
 460   else if (CPP_OPTION (pfile, c99))
 461     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199901L");
 462
 463   if (hosted)
 464     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 1");
 465   else
 466     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 0");
 467
 468   if (CPP_OPTION (pfile, objc))
 469     _cpp_define_builtin (pfile, "__OBJC__ 1");
 470 }
 471
 472 /* Sanity-checks are dependent on command-line options, so it is
 473    called as a subroutine of cpp_read_main_file ().  */
 474 #if ENABLE_CHECKING
 475 static void sanity_checks (cpp_reader *);
 476 static void sanity_checks (cpp_reader *pfile)
 477 {
 478   cppchar_t test = 0;
 479   size_t max_precision = 2 * CHAR_BIT * sizeof (cpp_num_part);
 480
 481   /* Sanity checks for assumptions about CPP arithmetic and target
 482      type precisions made by cpplib.  */
 483   test--;
 484   if (test < 1)
 485     cpp_error (pfile, CPP_DL_ICE, "cppchar_t must be an unsigned type");
 486
 487   if (CPP_OPTION (pfile, precision) > max_precision)
 488     cpp_error (pfile, CPP_DL_ICE,
 489                "preprocessor arithmetic has maximum precision of %lu bits;"
 490                " target requires %lu bits",
 491                (unsigned long) max_precision,
 492                (unsigned long) CPP_OPTION (pfile, precision));
 493
 494   if (CPP_OPTION (pfile, precision) < CPP_OPTION (pfile, int_precision))
 495     cpp_error (pfile, CPP_DL_ICE,
 496                "CPP arithmetic must be at least as precise as a target int");
 497
 498   if (CPP_OPTION (pfile, char_precision) < 8)
 499     cpp_error (pfile, CPP_DL_ICE, "target char is less than 8 bits wide");
 500
 501   if (CPP_OPTION (pfile, wchar_precision) < CPP_OPTION (pfile, char_precision))
 502     cpp_error (pfile, CPP_DL_ICE,
 503                "target wchar_t is narrower than target char");
 504
 505   if (CPP_OPTION (pfile, int_precision) < CPP_OPTION (pfile, char_precision))
 506     cpp_error (pfile, CPP_DL_ICE,
 507                "target int is narrower than target char");
 508
 509   /* This is assumed in eval_token() and could be fixed if necessary.  */
 510   if (sizeof (cppchar_t) > sizeof (cpp_num_part))
 511     cpp_error (pfile, CPP_DL_ICE,
 512                "CPP half-integer narrower than CPP character");
 513
 514   if (CPP_OPTION (pfile, wchar_precision) > BITS_PER_CPPCHAR_T)
 515     cpp_error (pfile, CPP_DL_ICE,
 516                "CPP on this host cannot handle wide character constants over"
 517                " %lu bits, but the target requires %lu bits",
 518                (unsigned long) BITS_PER_CPPCHAR_T,
 519                (unsigned long) CPP_OPTION (pfile, wchar_precision));
 520 }
 521 #else
 522 # define sanity_checks(PFILE)
 523 #endif
 524
 525 /* This is called after options have been parsed, and partially
 526    processed.  */
 527 void
 528 cpp_post_options (cpp_reader *pfile)
 529 {
 530   int flags;
 531
 532   sanity_checks (pfile);
 533
 534   post_options (pfile);
 535
 536   /* Mark named operators before handling command line macros.  */
 537   flags = 0;
 538   if (CPP_OPTION (pfile, cplusplus) && CPP_OPTION (pfile, operator_names))
 539     flags |= NODE_OPERATOR;
 540   if (CPP_OPTION (pfile, warn_cxx_operator_names))
 541     flags |= NODE_DIAGNOSTIC | NODE_WARN_OPERATOR;
 542   if (flags != 0)
 543     mark_named_operators (pfile, flags);
 544 }
 545
 546 /* Setup for processing input from the file named FNAME, or stdin if
 547    it is the empty string.  Return the original filename
 548    on success (e.g. foo.i->foo.c), or NULL on failure.  */
 549 const char *
 550 cpp_read_main_file (cpp_reader *pfile, const char *fname)
 551 {
 552   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE)
 553     {
 554       if (!pfile->deps)
 555         pfile->deps = deps_init ();
 556
 557       /* Set the default target (if there is none already).  */
 558       deps_add_default_target (pfile->deps, fname);
 559     }
 560
 561   pfile->main_file
 562     = _cpp_find_file (pfile, fname, &pfile->no_search_path, false, 0);
 563   if (_cpp_find_failed (pfile->main_file))
 564     return NULL;
 565
 566   _cpp_stack_file (pfile, pfile->main_file, false);
 567
 568   /* For foo.i, read the original filename foo.c now, for the benefit
 569      of the front ends.  */
 570   if (CPP_OPTION (pfile, preprocessed))
 571     {
 572       read_original_filename (pfile);
 573       fname = pfile->line_table->maps[pfile->line_table->used-1].to_file;
 574     }
 575   return fname;
 576 }
 577
 578 /* For preprocessed files, if the first tokens are of the form # NUM.
 579    handle the directive so we know the original file name.  This will
 580    generate file_change callbacks, which the front ends must handle
 581    appropriately given their state of initialization.  */
 582 static void
 583 read_original_filename (cpp_reader *pfile)
 584 {
 585   const cpp_token *token, *token1;
 586
 587   /* Lex ahead; if the first tokens are of the form # NUM, then
 588      process the directive, otherwise back up.  */
 589   token = _cpp_lex_direct (pfile);
 590   if (token->type == CPP_HASH)
 591     {
 592       pfile->state.in_directive = 1;
 593       token1 = _cpp_lex_direct (pfile);
 594       _cpp_backup_tokens (pfile, 1);
 595       pfile->state.in_directive = 0;
 596
 597       /* If it's a #line directive, handle it.  */
 598       if (token1->type == CPP_NUMBER)
 599         {
 600           _cpp_handle_directive (pfile, token->flags & PREV_WHITE);
 601           read_original_directory (pfile);
 602           return;
 603         }
 604     }
 605
 606   /* Backup as if nothing happened.  */
 607   _cpp_backup_tokens (pfile, 1);
 608 }
 609
 610 /* For preprocessed files, if the tokens following the first filename
 611    line is of the form # <line> "/path/name//", handle the
 612    directive so we know the original current directory.  */
 613 static void
 614 read_original_directory (cpp_reader *pfile)
 615 {
 616   const cpp_token *hash, *token;
 617
 618   /* Lex ahead; if the first tokens are of the form # NUM, then
 619      process the directive, otherwise back up.  */
 620   hash = _cpp_lex_direct (pfile);
 621   if (hash->type != CPP_HASH)
 622     {
 623       _cpp_backup_tokens (pfile, 1);
 624       return;
 625     }
 626
 627   token = _cpp_lex_direct (pfile);
 628
 629   if (token->type != CPP_NUMBER)
 630     {
 631       _cpp_backup_tokens (pfile, 2);
 632       return;
 633     }
 634
 635   token = _cpp_lex_direct (pfile);
 636
 637   if (token->type != CPP_STRING
 638       || ! (token->val.str.len >= 5
 639             && token->val.str.text[token->val.str.len-2] == '/'
 640             && token->val.str.text[token->val.str.len-3] == '/'))
 641     {
 642       _cpp_backup_tokens (pfile, 3);
 643       return;
 644     }
 645
 646   if (pfile->cb.dir_change)
 647     {
 648       char *debugdir = (char *) alloca (token->val.str.len - 3);
 649
 650       memcpy (debugdir, (const char *) token->val.str.text + 1,
 651               token->val.str.len - 4);
 652       debugdir[token->val.str.len - 4] = '\0';
 653
 654       pfile->cb.dir_change (pfile, debugdir);
 655     }
 656 }
 657
 658 /* This is called at the end of preprocessing.  It pops the last
 659    buffer and writes dependency output.
 660
 661    Maybe it should also reset state, such that you could call
 662    cpp_start_read with a new filename to restart processing.  */
 663 void
 664 cpp_finish (cpp_reader *pfile, FILE *deps_stream)
 665 {
 666   /* Warn about unused macros before popping the final buffer.  */
 667   if (CPP_OPTION (pfile, warn_unused_macros))
 668     cpp_forall_identifiers (pfile, _cpp_warn_if_unused_macro, NULL);
 669
 670   /* lex.c leaves the final buffer on the stack.  This it so that
 671      it returns an unending stream of CPP_EOFs to the client.  If we
 672      popped the buffer, we'd dereference a NULL buffer pointer and
 673      segfault.  It's nice to allow the client to do worry-free excess
 674      cpp_get_token calls.  */
 675   while (pfile->buffer)
 676     _cpp_pop_buffer (pfile);
 677
 678   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE
 679       && deps_stream)
 680     {
 681       deps_write (pfile->deps, deps_stream, 72);
 682
 683       if (CPP_OPTION (pfile, deps.phony_targets))
 684         deps_phony_targets (pfile->deps, deps_stream);
 685     }
 686
 687   /* Report on headers that could use multiple include guards.  */
 688   if (CPP_OPTION (pfile, print_include_names))
 689     _cpp_report_missing_guards (pfile);
 690 }
 691
 692 static void
 693 post_options (cpp_reader *pfile)
 694 {
 695   /* -Wtraditional is not useful in C++ mode.  */
 696   if (CPP_OPTION (pfile, cplusplus))
 697     CPP_OPTION (pfile, warn_traditional) = 0;
 698
 699   /* Permanently disable macro expansion if we are rescanning
 700      preprocessed text.  Read preprocesed source in ISO mode.  */
 701   if (CPP_OPTION (pfile, preprocessed))
 702     {
 703       if (!CPP_OPTION (pfile, directives_only))
 704         pfile->state.prevent_expansion = 1;
 705       CPP_OPTION (pfile, traditional) = 0;
 706     }
 707
 708   if (CPP_OPTION (pfile, warn_trigraphs) == 2)
 709     CPP_OPTION (pfile, warn_trigraphs) = !CPP_OPTION (pfile, trigraphs);
 710
 711   if (CPP_OPTION (pfile, traditional))
 712     {
 713       CPP_OPTION (pfile, cplusplus_comments) = 0;
 714
 715       /* Traditional CPP does not accurately track column information.  */
 716       CPP_OPTION (pfile, show_column) = 0;
 717       CPP_OPTION (pfile, trigraphs) = 0;
 718       CPP_OPTION (pfile, warn_trigraphs) = 0;
 719     }
 720 }