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, 2010 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   /* GNUC1X   */  { 1,  0,  1,   0,  0,   1,   1,   1 },
  88   /* STDC89   */  { 0,  0,  0,   0,  1,   0,   0,   0 },
  89   /* STDC94   */  { 0,  0,  0,   0,  1,   0,   1,   0 },
  90   /* STDC99   */  { 1,  0,  1,   0,  1,   1,   1,   0 },
  91   /* STDC1X   */  { 1,  0,  1,   0,  1,   1,   1,   0 },
  92   /* GNUCXX   */  { 0,  1,  1,   0,  0,   1,   1,   0 },
  93   /* CXX98    */  { 0,  1,  1,   0,  1,   1,   1,   0 },
  94   /* GNUCXX0X */  { 1,  1,  1,   0,  0,   1,   1,   1 },
  95   /* CXX0X    */  { 1,  1,  1,   0,  1,   1,   1,   1 },
  96   /* ASM      */  { 0,  0,  1,   0,  0,   1,   0,   0 }
  97   /* xid should be 1 for GNUC99, STDC99, GNUCXX, CXX98, GNUCXX0X, and
  98      CXX0X when no longer experimental (when all uses of identifiers
  99      in the compiler have been audited for correct handling of
 100      extended identifiers).  */
 101 };
 102
 103 /* Sets internal flags correctly for a given language.  */
 104 void
 105 cpp_set_lang (cpp_reader *pfile, enum c_lang lang)
 106 {
 107   const struct lang_flags *l = &lang_defaults[(int) lang];
 108
 109   CPP_OPTION (pfile, lang) = lang;
 110
 111   CPP_OPTION (pfile, c99)                        = l->c99;
 112   CPP_OPTION (pfile, cplusplus)                  = l->cplusplus;
 113   CPP_OPTION (pfile, extended_numbers)           = l->extended_numbers;
 114   CPP_OPTION (pfile, extended_identifiers)       = l->extended_identifiers;
 115   CPP_OPTION (pfile, std)                        = l->std;
 116   CPP_OPTION (pfile, trigraphs)                  = l->std;
 117   CPP_OPTION (pfile, cplusplus_comments)         = l->cplusplus_comments;
 118   CPP_OPTION (pfile, digraphs)                   = l->digraphs;
 119   CPP_OPTION (pfile, uliterals)                  = l->uliterals;
 120 }
 121
 122 /* Initialize library global state.  */
 123 static void
 124 init_library (void)
 125 {
 126   static int initialized = 0;
 127
 128   if (! initialized)
 129     {
 130       initialized = 1;
 131
 132       /* Set up the trigraph map.  This doesn't need to do anything if
 133          we were compiled with a compiler that supports C99 designated
 134          initializers.  */
 135       init_trigraph_map ();
 136
 137 #ifdef ENABLE_NLS
 138        (void) bindtextdomain (PACKAGE, LOCALEDIR);
 139 #endif
 140     }
 141 }
 142
 143 /* Initialize a cpp_reader structure.  */
 144 cpp_reader *
 145 cpp_create_reader (enum c_lang lang, hash_table *table,
 146                    struct line_maps *line_table)
 147 {
 148   cpp_reader *pfile;
 149
 150   /* Initialize this instance of the library if it hasn't been already.  */
 151   init_library ();
 152
 153   pfile = XCNEW (cpp_reader);
 154
 155   cpp_set_lang (pfile, lang);
 156   CPP_OPTION (pfile, warn_multichar) = 1;
 157   CPP_OPTION (pfile, discard_comments) = 1;
 158   CPP_OPTION (pfile, discard_comments_in_macro_exp) = 1;
 159   CPP_OPTION (pfile, tabstop) = 8;
 160   CPP_OPTION (pfile, operator_names) = 1;
 161   CPP_OPTION (pfile, warn_trigraphs) = 2;
 162   CPP_OPTION (pfile, warn_endif_labels) = 1;
 163   CPP_OPTION (pfile, cpp_warn_deprecated) = 1;
 164   CPP_OPTION (pfile, cpp_warn_long_long) = 0;
 165   CPP_OPTION (pfile, dollars_in_ident) = 1;
 166   CPP_OPTION (pfile, warn_dollars) = 1;
 167   CPP_OPTION (pfile, warn_variadic_macros) = 1;
 168   CPP_OPTION (pfile, warn_builtin_macro_redefined) = 1;
 169   CPP_OPTION (pfile, warn_normalize) = normalized_C;
 170
 171   /* Default CPP arithmetic to something sensible for the host for the
 172      benefit of dumb users like fix-header.  */
 173   CPP_OPTION (pfile, precision) = CHAR_BIT * sizeof (long);
 174   CPP_OPTION (pfile, char_precision) = CHAR_BIT;
 175   CPP_OPTION (pfile, wchar_precision) = CHAR_BIT * sizeof (int);
 176   CPP_OPTION (pfile, int_precision) = CHAR_BIT * sizeof (int);
 177   CPP_OPTION (pfile, unsigned_char) = 0;
 178   CPP_OPTION (pfile, unsigned_wchar) = 1;
 179   CPP_OPTION (pfile, bytes_big_endian) = 1;  /* does not matter */
 180
 181   /* Default to no charset conversion.  */
 182   CPP_OPTION (pfile, narrow_charset) = _cpp_default_encoding ();
 183   CPP_OPTION (pfile, wide_charset) = 0;
 184
 185   /* Default the input character set to UTF-8.  */
 186   CPP_OPTION (pfile, input_charset) = _cpp_default_encoding ();
 187
 188   /* A fake empty "directory" used as the starting point for files
 189      looked up without a search path.  Name cannot be '/' because we
 190      don't want to prepend anything at all to filenames using it.  All
 191      other entries are correct zero-initialized.  */
 192   pfile->no_search_path.name = (char *) "";
 193
 194   /* Initialize the line map.  */
 195   pfile->line_table = line_table;
 196
 197   /* Initialize lexer state.  */
 198   pfile->state.save_comments = ! CPP_OPTION (pfile, discard_comments);
 199
 200   /* Set up static tokens.  */
 201   pfile->avoid_paste.type = CPP_PADDING;
 202   pfile->avoid_paste.val.source = NULL;
 203   pfile->eof.type = CPP_EOF;
 204   pfile->eof.flags = 0;
 205
 206   /* Create a token buffer for the lexer.  */
 207   _cpp_init_tokenrun (&pfile->base_run, 250);
 208   pfile->cur_run = &pfile->base_run;
 209   pfile->cur_token = pfile->base_run.base;
 210
 211   /* Initialize the base context.  */
 212   pfile->context = &pfile->base_context;
 213   pfile->base_context.macro = 0;
 214   pfile->base_context.prev = pfile->base_context.next = 0;
 215
 216   /* Aligned and unaligned storage.  */
 217   pfile->a_buff = _cpp_get_buff (pfile, 0);
 218   pfile->u_buff = _cpp_get_buff (pfile, 0);
 219
 220   /* Initialize table for push_macro/pop_macro.  */
 221   pfile->pushed_macros = 0;
 222
 223   /* The expression parser stack.  */
 224   _cpp_expand_op_stack (pfile);
 225
 226   /* Initialize the buffer obstack.  */
 227   _obstack_begin (&pfile->buffer_ob, 0, 0,
 228                   (void *(*) (long)) xmalloc,
 229                   (void (*) (void *)) free);
 230
 231   _cpp_init_files (pfile);
 232
 233   _cpp_init_hashtable (pfile, table);
 234
 235   return pfile;
 236 }
 237
 238 /* Set the line_table entry in PFILE.  This is called after reading a
 239    PCH file, as the old line_table will be incorrect.  */
 240 void
 241 cpp_set_line_map (cpp_reader *pfile, struct line_maps *line_table)
 242 {
 243   pfile->line_table = line_table;
 244 }
 245
 246 /* Free resources used by PFILE.  Accessing PFILE after this function
 247    returns leads to undefined behavior.  Returns the error count.  */
 248 void
 249 cpp_destroy (cpp_reader *pfile)
 250 {
 251   cpp_context *context, *contextn;
 252   struct def_pragma_macro *pmacro;
 253   tokenrun *run, *runn;
 254   int i;
 255
 256   free (pfile->op_stack);
 257
 258   while (CPP_BUFFER (pfile) != NULL)
 259     _cpp_pop_buffer (pfile);
 260
 261   if (pfile->out.base)
 262     free (pfile->out.base);
 263
 264   if (pfile->macro_buffer)
 265     {
 266       free (pfile->macro_buffer);
 267       pfile->macro_buffer = NULL;
 268       pfile->macro_buffer_len = 0;
 269     }
 270
 271   if (pfile->deps)
 272     deps_free (pfile->deps);
 273   obstack_free (&pfile->buffer_ob, 0);
 274
 275   _cpp_destroy_hashtable (pfile);
 276   _cpp_cleanup_files (pfile);
 277   _cpp_destroy_iconv (pfile);
 278
 279   _cpp_free_buff (pfile->a_buff);
 280   _cpp_free_buff (pfile->u_buff);
 281   _cpp_free_buff (pfile->free_buffs);
 282
 283   for (run = &pfile->base_run; run; run = runn)
 284     {
 285       runn = run->next;
 286       free (run->base);
 287       if (run != &pfile->base_run)
 288         free (run);
 289     }
 290
 291   for (context = pfile->base_context.next; context; context = contextn)
 292     {
 293       contextn = context->next;
 294       free (context);
 295     }
 296
 297   if (pfile->comments.entries)
 298     {
 299       for (i = 0; i < pfile->comments.count; i++)
 300         free (pfile->comments.entries[i].comment);
 301
 302       free (pfile->comments.entries);
 303     }
 304   if (pfile->pushed_macros)
 305     {
 306       do
 307         {
 308           pmacro = pfile->pushed_macros;
 309           pfile->pushed_macros = pmacro->next;
 310           free (pmacro->name);
 311           free (pmacro);
 312         }
 313       while (pfile->pushed_macros);
 314     }
 315
 316   free (pfile);
 317 }
 318
 319 /* This structure defines one built-in identifier.  A node will be
 320    entered in the hash table under the name NAME, with value VALUE.
 321
 322    There are two tables of these.  builtin_array holds all the
 323    "builtin" macros: these are handled by builtin_macro() in
 324    macro.c.  Builtin is somewhat of a misnomer -- the property of
 325    interest is that these macros require special code to compute their
 326    expansions.  The value is a "cpp_builtin_type" enumerator.
 327
 328    operator_array holds the C++ named operators.  These are keywords
 329    which act as aliases for punctuators.  In C++, they cannot be
 330    altered through #define, and #if recognizes them as operators.  In
 331    C, these are not entered into the hash table at all (but see
 332    <iso646.h>).  The value is a token-type enumerator.  */
 333 struct builtin_macro
 334 {
 335   const uchar *const name;
 336   const unsigned short len;
 337   const unsigned short value;
 338   const bool always_warn_if_redefined;
 339 };
 340
 341 #define B(n, t, f)    { DSC(n), t, f }
 342 static const struct builtin_macro builtin_array[] =
 343 {
 344   B("__TIMESTAMP__",     BT_TIMESTAMP,     false),
 345   B("__TIME__",          BT_TIME,          false),
 346   B("__DATE__",          BT_DATE,          false),
 347   B("__FILE__",          BT_FILE,          false),
 348   B("__BASE_FILE__",     BT_BASE_FILE,     false),
 349   B("__LINE__",          BT_SPECLINE,      true),
 350   B("__INCLUDE_LEVEL__", BT_INCLUDE_LEVEL, true),
 351   B("__COUNTER__",       BT_COUNTER,       true),
 352   /* Keep builtins not used for -traditional-cpp at the end, and
 353      update init_builtins() if any more are added.  */
 354   B("_Pragma",           BT_PRAGMA,        true),
 355   B("__STDC__",          BT_STDC,          true),
 356 };
 357 #undef B
 358
 359 struct builtin_operator
 360 {
 361   const uchar *const name;
 362   const unsigned short len;
 363   const unsigned short value;
 364 };
 365
 366 #define B(n, t)    { DSC(n), t }
 367 static const struct builtin_operator operator_array[] =
 368 {
 369   B("and",      CPP_AND_AND),
 370   B("and_eq",   CPP_AND_EQ),
 371   B("bitand",   CPP_AND),
 372   B("bitor",    CPP_OR),
 373   B("compl",    CPP_COMPL),
 374   B("not",      CPP_NOT),
 375   B("not_eq",   CPP_NOT_EQ),
 376   B("or",       CPP_OR_OR),
 377   B("or_eq",    CPP_OR_EQ),
 378   B("xor",      CPP_XOR),
 379   B("xor_eq",   CPP_XOR_EQ)
 380 };
 381 #undef B
 382
 383 /* Mark the C++ named operators in the hash table.  */
 384 static void
 385 mark_named_operators (cpp_reader *pfile, int flags)
 386 {
 387   const struct builtin_operator *b;
 388
 389   for (b = operator_array;
 390        b < (operator_array + ARRAY_SIZE (operator_array));
 391        b++)
 392     {
 393       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 394       hp->flags |= flags;
 395       hp->is_directive = 0;
 396       hp->directive_index = b->value;
 397     }
 398 }
 399
 400 /* Helper function of cpp_type2name. Return the string associated with
 401    named operator TYPE.  */
 402 const char *
 403 cpp_named_operator2name (enum cpp_ttype type)
 404 {
 405   const struct builtin_operator *b;
 406
 407   for (b = operator_array;
 408        b < (operator_array + ARRAY_SIZE (operator_array));
 409        b++)
 410     {
 411       if (type == b->value)
 412         return (const char *) b->name;
 413     }
 414
 415   return NULL;
 416 }
 417
 418 void
 419 cpp_init_special_builtins (cpp_reader *pfile)
 420 {
 421   const struct builtin_macro *b;
 422   size_t n = ARRAY_SIZE (builtin_array);
 423
 424   if (CPP_OPTION (pfile, traditional))
 425     n -= 2;
 426   else if (! CPP_OPTION (pfile, stdc_0_in_system_headers)
 427            || CPP_OPTION (pfile, std))
 428     n--;
 429
 430   for (b = builtin_array; b < builtin_array + n; b++)
 431     {
 432       cpp_hashnode *hp = cpp_lookup (pfile, b->name, b->len);
 433       hp->type = NT_MACRO;
 434       hp->flags |= NODE_BUILTIN;
 435       if (b->always_warn_if_redefined
 436           || CPP_OPTION (pfile, warn_builtin_macro_redefined))
 437         hp->flags |= NODE_WARN;
 438       hp->value.builtin = (enum cpp_builtin_type) b->value;
 439     }
 440 }
 441
 442 /* Read the builtins table above and enter them, and language-specific
 443    macros, into the hash table.  HOSTED is true if this is a hosted
 444    environment.  */
 445 void
 446 cpp_init_builtins (cpp_reader *pfile, int hosted)
 447 {
 448   cpp_init_special_builtins (pfile);
 449
 450   if (!CPP_OPTION (pfile, traditional)
 451       && (! CPP_OPTION (pfile, stdc_0_in_system_headers)
 452           || CPP_OPTION (pfile, std)))
 453     _cpp_define_builtin (pfile, "__STDC__ 1");
 454
 455   if (CPP_OPTION (pfile, cplusplus))
 456     _cpp_define_builtin (pfile, "__cplusplus 1");
 457   else if (CPP_OPTION (pfile, lang) == CLK_ASM)
 458     _cpp_define_builtin (pfile, "__ASSEMBLER__ 1");
 459   else if (CPP_OPTION (pfile, lang) == CLK_STDC94)
 460     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199409L");
 461   else if (CPP_OPTION (pfile, lang) == CLK_STDC1X
 462            || CPP_OPTION (pfile, lang) == CLK_GNUC1X)
 463     _cpp_define_builtin (pfile, "__STDC_VERSION__ 201000L");
 464   else if (CPP_OPTION (pfile, c99))
 465     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199901L");
 466
 467   if (hosted)
 468     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 1");
 469   else
 470     _cpp_define_builtin (pfile, "__STDC_HOSTED__ 0");
 471
 472   if (CPP_OPTION (pfile, objc))
 473     _cpp_define_builtin (pfile, "__OBJC__ 1");
 474 }
 475
 476 /* Sanity-checks are dependent on command-line options, so it is
 477    called as a subroutine of cpp_read_main_file ().  */
 478 #if ENABLE_CHECKING
 479 static void sanity_checks (cpp_reader *);
 480 static void sanity_checks (cpp_reader *pfile)
 481 {
 482   cppchar_t test = 0;
 483   size_t max_precision = 2 * CHAR_BIT * sizeof (cpp_num_part);
 484
 485   /* Sanity checks for assumptions about CPP arithmetic and target
 486      type precisions made by cpplib.  */
 487   test--;
 488   if (test < 1)
 489     cpp_error (pfile, CPP_DL_ICE, "cppchar_t must be an unsigned type");
 490
 491   if (CPP_OPTION (pfile, precision) > max_precision)
 492     cpp_error (pfile, CPP_DL_ICE,
 493                "preprocessor arithmetic has maximum precision of %lu bits;"
 494                " target requires %lu bits",
 495                (unsigned long) max_precision,
 496                (unsigned long) CPP_OPTION (pfile, precision));
 497
 498   if (CPP_OPTION (pfile, precision) < CPP_OPTION (pfile, int_precision))
 499     cpp_error (pfile, CPP_DL_ICE,
 500                "CPP arithmetic must be at least as precise as a target int");
 501
 502   if (CPP_OPTION (pfile, char_precision) < 8)
 503     cpp_error (pfile, CPP_DL_ICE, "target char is less than 8 bits wide");
 504
 505   if (CPP_OPTION (pfile, wchar_precision) < CPP_OPTION (pfile, char_precision))
 506     cpp_error (pfile, CPP_DL_ICE,
 507                "target wchar_t is narrower than target char");
 508
 509   if (CPP_OPTION (pfile, int_precision) < CPP_OPTION (pfile, char_precision))
 510     cpp_error (pfile, CPP_DL_ICE,
 511                "target int is narrower than target char");
 512
 513   /* This is assumed in eval_token() and could be fixed if necessary.  */
 514   if (sizeof (cppchar_t) > sizeof (cpp_num_part))
 515     cpp_error (pfile, CPP_DL_ICE,
 516                "CPP half-integer narrower than CPP character");
 517
 518   if (CPP_OPTION (pfile, wchar_precision) > BITS_PER_CPPCHAR_T)
 519     cpp_error (pfile, CPP_DL_ICE,
 520                "CPP on this host cannot handle wide character constants over"
 521                " %lu bits, but the target requires %lu bits",
 522                (unsigned long) BITS_PER_CPPCHAR_T,
 523                (unsigned long) CPP_OPTION (pfile, wchar_precision));
 524 }
 525 #else
 526 # define sanity_checks(PFILE)
 527 #endif
 528
 529 /* This is called after options have been parsed, and partially
 530    processed.  */
 531 void
 532 cpp_post_options (cpp_reader *pfile)
 533 {
 534   int flags;
 535
 536   sanity_checks (pfile);
 537
 538   post_options (pfile);
 539
 540   /* Mark named operators before handling command line macros.  */
 541   flags = 0;
 542   if (CPP_OPTION (pfile, cplusplus) && CPP_OPTION (pfile, operator_names))
 543     flags |= NODE_OPERATOR;
 544   if (CPP_OPTION (pfile, warn_cxx_operator_names))
 545     flags |= NODE_DIAGNOSTIC | NODE_WARN_OPERATOR;
 546   if (flags != 0)
 547     mark_named_operators (pfile, flags);
 548 }
 549
 550 /* Setup for processing input from the file named FNAME, or stdin if
 551    it is the empty string.  Return the original filename
 552    on success (e.g. foo.i->foo.c), or NULL on failure.  */
 553 const char *
 554 cpp_read_main_file (cpp_reader *pfile, const char *fname)
 555 {
 556   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE)
 557     {
 558       if (!pfile->deps)
 559         pfile->deps = deps_init ();
 560
 561       /* Set the default target (if there is none already).  */
 562       deps_add_default_target (pfile->deps, fname);
 563     }
 564
 565   pfile->main_file
 566     = _cpp_find_file (pfile, fname, &pfile->no_search_path, false, 0);
 567   if (_cpp_find_failed (pfile->main_file))
 568     return NULL;
 569
 570   _cpp_stack_file (pfile, pfile->main_file, false);
 571
 572   /* For foo.i, read the original filename foo.c now, for the benefit
 573      of the front ends.  */
 574   if (CPP_OPTION (pfile, preprocessed))
 575     {
 576       read_original_filename (pfile);
 577       fname = pfile->line_table->maps[pfile->line_table->used-1].to_file;
 578     }
 579   return fname;
 580 }
 581
 582 /* For preprocessed files, if the first tokens are of the form # NUM.
 583    handle the directive so we know the original file name.  This will
 584    generate file_change callbacks, which the front ends must handle
 585    appropriately given their state of initialization.  */
 586 static void
 587 read_original_filename (cpp_reader *pfile)
 588 {
 589   const cpp_token *token, *token1;
 590
 591   /* Lex ahead; if the first tokens are of the form # NUM, then
 592      process the directive, otherwise back up.  */
 593   token = _cpp_lex_direct (pfile);
 594   if (token->type == CPP_HASH)
 595     {
 596       pfile->state.in_directive = 1;
 597       token1 = _cpp_lex_direct (pfile);
 598       _cpp_backup_tokens (pfile, 1);
 599       pfile->state.in_directive = 0;
 600
 601       /* If it's a #line directive, handle it.  */
 602       if (token1->type == CPP_NUMBER
 603           && _cpp_handle_directive (pfile, token->flags & PREV_WHITE))
 604         {
 605           read_original_directory (pfile);
 606           return;
 607         }
 608     }
 609
 610   /* Backup as if nothing happened.  */
 611   _cpp_backup_tokens (pfile, 1);
 612 }
 613
 614 /* For preprocessed files, if the tokens following the first filename
 615    line is of the form # <line> "/path/name//", handle the
 616    directive so we know the original current directory.  */
 617 static void
 618 read_original_directory (cpp_reader *pfile)
 619 {
 620   const cpp_token *hash, *token;
 621
 622   /* Lex ahead; if the first tokens are of the form # NUM, then
 623      process the directive, otherwise back up.  */
 624   hash = _cpp_lex_direct (pfile);
 625   if (hash->type != CPP_HASH)
 626     {
 627       _cpp_backup_tokens (pfile, 1);
 628       return;
 629     }
 630
 631   token = _cpp_lex_direct (pfile);
 632
 633   if (token->type != CPP_NUMBER)
 634     {
 635       _cpp_backup_tokens (pfile, 2);
 636       return;
 637     }
 638
 639   token = _cpp_lex_direct (pfile);
 640
 641   if (token->type != CPP_STRING
 642       || ! (token->val.str.len >= 5
 643             && token->val.str.text[token->val.str.len-2] == '/'
 644             && token->val.str.text[token->val.str.len-3] == '/'))
 645     {
 646       _cpp_backup_tokens (pfile, 3);
 647       return;
 648     }
 649
 650   if (pfile->cb.dir_change)
 651     {
 652       char *debugdir = (char *) alloca (token->val.str.len - 3);
 653
 654       memcpy (debugdir, (const char *) token->val.str.text + 1,
 655               token->val.str.len - 4);
 656       debugdir[token->val.str.len - 4] = '\0';
 657
 658       pfile->cb.dir_change (pfile, debugdir);
 659     }
 660 }
 661
 662 /* This is called at the end of preprocessing.  It pops the last
 663    buffer and writes dependency output.
 664
 665    Maybe it should also reset state, such that you could call
 666    cpp_start_read with a new filename to restart processing.  */
 667 void
 668 cpp_finish (cpp_reader *pfile, FILE *deps_stream)
 669 {
 670   /* Warn about unused macros before popping the final buffer.  */
 671   if (CPP_OPTION (pfile, warn_unused_macros))
 672     cpp_forall_identifiers (pfile, _cpp_warn_if_unused_macro, NULL);
 673
 674   /* lex.c leaves the final buffer on the stack.  This it so that
 675      it returns an unending stream of CPP_EOFs to the client.  If we
 676      popped the buffer, we'd dereference a NULL buffer pointer and
 677      segfault.  It's nice to allow the client to do worry-free excess
 678      cpp_get_token calls.  */
 679   while (pfile->buffer)
 680     _cpp_pop_buffer (pfile);
 681
 682   if (CPP_OPTION (pfile, deps.style) != DEPS_NONE
 683       && deps_stream)
 684     {
 685       deps_write (pfile->deps, deps_stream, 72);
 686
 687       if (CPP_OPTION (pfile, deps.phony_targets))
 688         deps_phony_targets (pfile->deps, deps_stream);
 689     }
 690
 691   /* Report on headers that could use multiple include guards.  */
 692   if (CPP_OPTION (pfile, print_include_names))
 693     _cpp_report_missing_guards (pfile);
 694 }
 695
 696 static void
 697 post_options (cpp_reader *pfile)
 698 {
 699   /* -Wtraditional is not useful in C++ mode.  */
 700   if (CPP_OPTION (pfile, cplusplus))
 701     CPP_OPTION (pfile, cpp_warn_traditional) = 0;
 702
 703   /* Permanently disable macro expansion if we are rescanning
 704      preprocessed text.  Read preprocesed source in ISO mode.  */
 705   if (CPP_OPTION (pfile, preprocessed))
 706     {
 707       if (!CPP_OPTION (pfile, directives_only))
 708         pfile->state.prevent_expansion = 1;
 709       CPP_OPTION (pfile, traditional) = 0;
 710     }
 711
 712   if (CPP_OPTION (pfile, warn_trigraphs) == 2)
 713     CPP_OPTION (pfile, warn_trigraphs) = !CPP_OPTION (pfile, trigraphs);
 714
 715   if (CPP_OPTION (pfile, traditional))
 716     {
 717       CPP_OPTION (pfile, cplusplus_comments) = 0;
 718
 719       CPP_OPTION (pfile, trigraphs) = 0;
 720       CPP_OPTION (pfile, warn_trigraphs) = 0;
 721     }
 722 }