nsz Git - cparser/blob - preprocessor.c

   1 #include <config.h>
   2
   3 #include <assert.h>
   4 #include <errno.h>
   5 #include <string.h>
   6 #include <stdbool.h>
   7 #include <ctype.h>
   8
   9 #include "token_t.h"
  10 #include "symbol_t.h"
  11 #include "adt/util.h"
  12 #include "adt/error.h"
  13 #include "adt/strutil.h"
  14 #include "adt/strset.h"
  15 #include "lang_features.h"
  16 #include "diagnostic.h"
  17 #include "string_rep.h"
  18 #include "input.h"
  19
  20 #define MAX_PUTBACK 3
  21 #define INCLUDE_LIMIT 199  /* 199 is for gcc "compatibility" */
  22
  23 struct pp_argument_t {
  24         size_t   list_len;
  25         token_t *token_list;
  26 };
  27
  28 struct pp_definition_t {
  29         symbol_t          *symbol;
  30         source_position_t  source_position;
  31         pp_definition_t   *parent_expansion;
  32         size_t             expand_pos;
  33         bool               is_variadic    : 1;
  34         bool               is_expanding   : 1;
  35         bool               has_parameters : 1;
  36         size_t             n_parameters;
  37         symbol_t          *parameters;
  38
  39         /* replacement */
  40         size_t             list_len;
  41         token_t           *token_list;
  42
  43 };
  44
  45 typedef struct pp_conditional_t pp_conditional_t;
  46 struct pp_conditional_t {
  47         source_position_t  source_position;
  48         bool               condition;
  49         bool               in_else;
  50         bool               skip; /**< conditional in skip mode (then+else gets skipped) */
  51         pp_conditional_t  *parent;
  52 };
  53
  54 typedef struct pp_input_t pp_input_t;
  55 struct pp_input_t {
  56         FILE              *file;
  57         input_t           *input;
  58         utf32              c;
  59         utf32              buf[1024+MAX_PUTBACK];
  60         const utf32       *bufend;
  61         const utf32       *bufpos;
  62         source_position_t  position;
  63         pp_input_t        *parent;
  64         unsigned           output_line;
  65 };
  66
  67 /** additional info about the current token */
  68 typedef struct add_token_info_t {
  69         /** whitespace from beginning of line to the token */
  70         unsigned whitespace;
  71         /** there has been any whitespace before the token */
  72         bool     had_whitespace;
  73         /** the token is at the beginning of the line */
  74         bool     at_line_begin;
  75 } add_token_info_t;
  76
  77 typedef struct searchpath_entry_t searchpath_entry_t;
  78 struct searchpath_entry_t {
  79         const char         *path;
  80         searchpath_entry_t *next;
  81 };
  82
  83 static pp_input_t      input;
  84
  85 static pp_input_t     *input_stack;
  86 static unsigned        n_inputs;
  87 static struct obstack  input_obstack;
  88
  89 static pp_conditional_t *conditional_stack;
  90
  91 static token_t           pp_token;
  92 static bool              resolve_escape_sequences = false;
  93 static bool              ignore_unknown_chars     = true;
  94 static bool              skip_mode;
  95 static FILE             *out;
  96 static struct obstack    pp_obstack;
  97 static struct obstack    config_obstack;
  98 static const char       *printed_input_name = NULL;
  99 static source_position_t expansion_pos;
 100 static pp_definition_t  *current_expansion  = NULL;
 101 static strset_t          stringset;
 102 static token_kind_t      last_token;
 103
 104 static searchpath_entry_t *searchpath;
 105
 106 static add_token_info_t  info;
 107
 108 static inline void next_char(void);
 109 static void next_preprocessing_token(void);
 110 static void print_line_directive(const source_position_t *pos, const char *add);
 111
 112 static void switch_input(FILE *file, const char *filename)
 113 {
 114         input.file                = file;
 115         input.input               = input_from_stream(file, NULL);
 116         input.bufend              = NULL;
 117         input.bufpos              = NULL;
 118         input.output_line         = 0;
 119         input.position.input_name = filename;
 120         input.position.lineno     = 1;
 121
 122         /* indicate that we're at a new input */
 123         print_line_directive(&input.position, input_stack != NULL ? "1" : NULL);
 124
 125         /* place a virtual '\n' so we realize we're at line begin */
 126         input.position.lineno = 0;
 127         input.c               = '\n';
 128         next_preprocessing_token();
 129 }
 130
 131 static void close_input(void)
 132 {
 133         input_free(input.input);
 134         assert(input.file != NULL);
 135
 136         fclose(input.file);
 137         input.input  = NULL;
 138         input.file   = NULL;
 139         input.bufend = NULL;
 140         input.bufpos = NULL;
 141         input.c      = EOF;
 142 }
 143
 144 static void push_input(void)
 145 {
 146         pp_input_t *saved_input
 147                 = obstack_alloc(&input_obstack, sizeof(*saved_input));
 148
 149         memcpy(saved_input, &input, sizeof(*saved_input));
 150
 151         /* adjust buffer positions */
 152         if (input.bufpos != NULL)
 153                 saved_input->bufpos = saved_input->buf + (input.bufpos - input.buf);
 154         if (input.bufend != NULL)
 155                 saved_input->bufend = saved_input->buf + (input.bufend - input.buf);
 156
 157         saved_input->parent = input_stack;
 158         input_stack         = saved_input;
 159         ++n_inputs;
 160 }
 161
 162 static void pop_restore_input(void)
 163 {
 164         assert(n_inputs > 0);
 165         assert(input_stack != NULL);
 166
 167         pp_input_t *saved_input = input_stack;
 168
 169         memcpy(&input, saved_input, sizeof(input));
 170         input.parent = NULL;
 171
 172         /* adjust buffer positions */
 173         if (saved_input->bufpos != NULL)
 174                 input.bufpos = input.buf + (saved_input->bufpos - saved_input->buf);
 175         if (saved_input->bufend != NULL)
 176                 input.bufend = input.buf + (saved_input->bufend - saved_input->buf);
 177
 178         input_stack = saved_input->parent;
 179         obstack_free(&input_obstack, saved_input);
 180         --n_inputs;
 181 }
 182
 183 /**
 184  * Prints a parse error message at the current token.
 185  *
 186  * @param msg   the error message
 187  */
 188 static void parse_error(const char *msg)
 189 {
 190         errorf(&pp_token.base.source_position,  "%s", msg);
 191 }
 192
 193 static inline void next_real_char(void)
 194 {
 195         assert(input.bufpos <= input.bufend);
 196         if (input.bufpos >= input.bufend) {
 197                 size_t const n = decode(input.input, input.buf + MAX_PUTBACK, lengthof(input.buf) - MAX_PUTBACK);
 198                 if (n == 0) {
 199                         input.c = EOF;
 200                         return;
 201                 }
 202                 input.bufpos = input.buf + MAX_PUTBACK;
 203                 input.bufend = input.bufpos + n;
 204         }
 205         input.c = *input.bufpos++;
 206         ++input.position.colno;
 207 }
 208
 209 /**
 210  * Put a character back into the buffer.
 211  *
 212  * @param pc  the character to put back
 213  */
 214 static inline void put_back(utf32 const pc)
 215 {
 216         assert(input.bufpos > input.buf);
 217         *(--input.bufpos - input.buf + input.buf) = (char) pc;
 218         --input.position.colno;
 219 }
 220
 221 #define NEWLINE \
 222         '\r': \
 223                 next_char(); \
 224                 if (input.c == '\n') { \
 225         case '\n': \
 226                         next_char(); \
 227                 } \
 228                 info.whitespace = 0; \
 229                 ++input.position.lineno; \
 230                 input.position.colno = 1; \
 231                 goto newline; \
 232                 newline // Let it look like an ordinary case label.
 233
 234 #define eat(c_type) (assert(input.c == c_type), next_char())
 235
 236 static void maybe_concat_lines(void)
 237 {
 238         eat('\\');
 239
 240         switch (input.c) {
 241         case NEWLINE:
 242                 return;
 243
 244         default:
 245                 break;
 246         }
 247
 248         put_back(input.c);
 249         input.c = '\\';
 250 }
 251
 252 /**
 253  * Set c to the next input character, ie.
 254  * after expanding trigraphs.
 255  */
 256 static inline void next_char(void)
 257 {
 258         next_real_char();
 259
 260         /* filter trigraphs and concatenated lines */
 261         if (UNLIKELY(input.c == '\\')) {
 262                 maybe_concat_lines();
 263                 goto end_of_next_char;
 264         }
 265
 266         if (LIKELY(input.c != '?'))
 267                 goto end_of_next_char;
 268
 269         next_real_char();
 270         if (LIKELY(input.c != '?')) {
 271                 put_back(input.c);
 272                 input.c = '?';
 273                 goto end_of_next_char;
 274         }
 275
 276         next_real_char();
 277         switch (input.c) {
 278         case '=': input.c = '#'; break;
 279         case '(': input.c = '['; break;
 280         case '/': input.c = '\\'; maybe_concat_lines(); break;
 281         case ')': input.c = ']'; break;
 282         case '\'': input.c = '^'; break;
 283         case '<': input.c = '{'; break;
 284         case '!': input.c = '|'; break;
 285         case '>': input.c = '}'; break;
 286         case '-': input.c = '~'; break;
 287         default:
 288                 put_back(input.c);
 289                 put_back('?');
 290                 input.c = '?';
 291                 break;
 292         }
 293
 294 end_of_next_char:;
 295 #ifdef DEBUG_CHARS
 296         printf("nchar '%c'\n", input.c);
 297 #endif
 298 }
 299
 300
 301
 302 /**
 303  * Returns true if the given char is a octal digit.
 304  *
 305  * @param char  the character to check
 306  */
 307 static inline bool is_octal_digit(int chr)
 308 {
 309         switch (chr) {
 310         case '0':
 311         case '1':
 312         case '2':
 313         case '3':
 314         case '4':
 315         case '5':
 316         case '6':
 317         case '7':
 318                 return true;
 319         default:
 320                 return false;
 321         }
 322 }
 323
 324 /**
 325  * Returns the value of a digit.
 326  * The only portable way to do it ...
 327  */
 328 static int digit_value(int digit)
 329 {
 330         switch (digit) {
 331         case '0': return 0;
 332         case '1': return 1;
 333         case '2': return 2;
 334         case '3': return 3;
 335         case '4': return 4;
 336         case '5': return 5;
 337         case '6': return 6;
 338         case '7': return 7;
 339         case '8': return 8;
 340         case '9': return 9;
 341         case 'a':
 342         case 'A': return 10;
 343         case 'b':
 344         case 'B': return 11;
 345         case 'c':
 346         case 'C': return 12;
 347         case 'd':
 348         case 'D': return 13;
 349         case 'e':
 350         case 'E': return 14;
 351         case 'f':
 352         case 'F': return 15;
 353         default:
 354                 panic("wrong character given");
 355         }
 356 }
 357
 358 /**
 359  * Parses an octal character sequence.
 360  *
 361  * @param first_digit  the already read first digit
 362  */
 363 static utf32 parse_octal_sequence(const utf32 first_digit)
 364 {
 365         assert(is_octal_digit(first_digit));
 366         utf32 value = digit_value(first_digit);
 367         if (!is_octal_digit(input.c)) return value;
 368         value = 8 * value + digit_value(input.c);
 369         next_char();
 370         if (!is_octal_digit(input.c)) return value;
 371         value = 8 * value + digit_value(input.c);
 372         next_char();
 373         return value;
 374
 375 }
 376
 377 /**
 378  * Parses a hex character sequence.
 379  */
 380 static utf32 parse_hex_sequence(void)
 381 {
 382         utf32 value = 0;
 383         while (isxdigit(input.c)) {
 384                 value = 16 * value + digit_value(input.c);
 385                 next_char();
 386         }
 387         return value;
 388 }
 389
 390 /**
 391  * Parse an escape sequence.
 392  */
 393 static utf32 parse_escape_sequence(void)
 394 {
 395         eat('\\');
 396
 397         utf32 const ec = input.c;
 398         next_char();
 399
 400         switch (ec) {
 401         case '"':  return '"';
 402         case '\'': return '\'';
 403         case '\\': return '\\';
 404         case '?': return '\?';
 405         case 'a': return '\a';
 406         case 'b': return '\b';
 407         case 'f': return '\f';
 408         case 'n': return '\n';
 409         case 'r': return '\r';
 410         case 't': return '\t';
 411         case 'v': return '\v';
 412         case 'x':
 413                 return parse_hex_sequence();
 414         case '0':
 415         case '1':
 416         case '2':
 417         case '3':
 418         case '4':
 419         case '5':
 420         case '6':
 421         case '7':
 422                 return parse_octal_sequence(ec);
 423         case EOF:
 424                 parse_error("reached end of file while parsing escape sequence");
 425                 return EOF;
 426         /* \E is not documented, but handled, by GCC.  It is acceptable according
 427          * to §6.11.4, whereas \e is not. */
 428         case 'E':
 429         case 'e':
 430                 if (c_mode & _GNUC)
 431                         return 27;   /* hopefully 27 is ALWAYS the code for ESCAPE */
 432                 break;
 433         case 'u':
 434         case 'U':
 435                 parse_error("universal character parsing not implemented yet");
 436                 return EOF;
 437         default:
 438                 break;
 439         }
 440         /* §6.4.4.4:8 footnote 64 */
 441         parse_error("unknown escape sequence");
 442         return EOF;
 443 }
 444
 445 static const char *identify_string(char *string)
 446 {
 447         const char *result = strset_insert(&stringset, string);
 448         if (result != string) {
 449                 obstack_free(&symbol_obstack, string);
 450         }
 451         return result;
 452 }
 453
 454 static string_t sym_make_string(string_encoding_t const enc)
 455 {
 456         obstack_1grow(&symbol_obstack, '\0');
 457         size_t      const len    = obstack_object_size(&symbol_obstack) - 1;
 458         char       *const string = obstack_finish(&symbol_obstack);
 459         char const *const result = identify_string(string);
 460         return (string_t){ result, len, enc };
 461 }
 462
 463 static void parse_string(utf32 const delimiter, token_kind_t const kind,
 464                          string_encoding_t const enc,
 465                          char const *const context)
 466 {
 467         const unsigned start_linenr = input.position.lineno;
 468
 469         eat(delimiter);
 470
 471         while (true) {
 472                 switch (input.c) {
 473                 case '\\': {
 474                         if (resolve_escape_sequences) {
 475                                 utf32 const tc = parse_escape_sequence();
 476                                 if (enc == STRING_ENCODING_CHAR) {
 477                                         if (tc >= 0x100) {
 478                                                 warningf(WARN_OTHER, &pp_token.base.source_position, "escape sequence out of range");
 479                                         }
 480                                         obstack_1grow(&symbol_obstack, tc);
 481                                 } else {
 482                                         obstack_grow_utf8(&symbol_obstack, tc);
 483                                 }
 484                         } else {
 485                                 obstack_1grow(&symbol_obstack, (char)input.c);
 486                                 next_char();
 487                                 obstack_1grow(&symbol_obstack, (char)input.c);
 488                                 next_char();
 489                         }
 490                         break;
 491                 }
 492
 493                 case NEWLINE:
 494                         errorf(&pp_token.base.source_position, "newline while parsing %s", context);
 495                         break;
 496
 497                 case EOF: {
 498                         source_position_t source_position;
 499                         source_position.input_name = pp_token.base.source_position.input_name;
 500                         source_position.lineno     = start_linenr;
 501                         errorf(&source_position, "EOF while parsing %s", context);
 502                         goto end_of_string;
 503                 }
 504
 505                 default:
 506                         if (input.c == delimiter) {
 507                                 next_char();
 508                                 goto end_of_string;
 509                         } else {
 510                                 obstack_grow_utf8(&symbol_obstack, input.c);
 511                                 next_char();
 512                                 break;
 513                         }
 514                 }
 515         }
 516
 517 end_of_string:
 518         pp_token.kind           = kind;
 519         pp_token.literal.string = sym_make_string(enc);
 520 }
 521
 522 static void parse_string_literal(string_encoding_t const enc)
 523 {
 524         parse_string('"', T_STRING_LITERAL, enc, "string literal");
 525 }
 526
 527 static void parse_character_constant(string_encoding_t const enc)
 528 {
 529         parse_string('\'', T_CHARACTER_CONSTANT, enc, "character constant");
 530         if (pp_token.literal.string.size == 0) {
 531                 parse_error("empty character constant");
 532         }
 533 }
 534
 535 #define SYMBOL_CASES_WITHOUT_E_P \
 536              'a': \
 537         case 'b': \
 538         case 'c': \
 539         case 'd': \
 540         case 'f': \
 541         case 'g': \
 542         case 'h': \
 543         case 'i': \
 544         case 'j': \
 545         case 'k': \
 546         case 'l': \
 547         case 'm': \
 548         case 'n': \
 549         case 'o': \
 550         case 'q': \
 551         case 'r': \
 552         case 's': \
 553         case 't': \
 554         case 'u': \
 555         case 'v': \
 556         case 'w': \
 557         case 'x': \
 558         case 'y': \
 559         case 'z': \
 560         case 'A': \
 561         case 'B': \
 562         case 'C': \
 563         case 'D': \
 564         case 'F': \
 565         case 'G': \
 566         case 'H': \
 567         case 'I': \
 568         case 'J': \
 569         case 'K': \
 570         case 'L': \
 571         case 'M': \
 572         case 'N': \
 573         case 'O': \
 574         case 'Q': \
 575         case 'R': \
 576         case 'S': \
 577         case 'T': \
 578         case 'U': \
 579         case 'V': \
 580         case 'W': \
 581         case 'X': \
 582         case 'Y': \
 583         case 'Z': \
 584         case '_'
 585
 586 #define SYMBOL_CASES \
 587              SYMBOL_CASES_WITHOUT_E_P: \
 588         case 'e': \
 589         case 'p': \
 590         case 'E': \
 591         case 'P'
 592
 593 #define DIGIT_CASES \
 594              '0':  \
 595         case '1':  \
 596         case '2':  \
 597         case '3':  \
 598         case '4':  \
 599         case '5':  \
 600         case '6':  \
 601         case '7':  \
 602         case '8':  \
 603         case '9'
 604
 605 /**
 606  * returns next final token from a preprocessor macro expansion
 607  */
 608 static void expand_next(void)
 609 {
 610         assert(current_expansion != NULL);
 611
 612         pp_definition_t *definition = current_expansion;
 613
 614 restart:
 615         if (definition->list_len == 0
 616                         || definition->expand_pos >= definition->list_len) {
 617                 /* we're finished with the current macro, move up 1 level in the
 618                  * expansion stack */
 619                 pp_definition_t *parent = definition->parent_expansion;
 620                 definition->parent_expansion = NULL;
 621                 definition->is_expanding     = false;
 622
 623                 /* it was the outermost expansion, parse normal pptoken */
 624                 if (parent == NULL) {
 625                         current_expansion = NULL;
 626                         next_preprocessing_token();
 627                         return;
 628                 }
 629                 definition        = parent;
 630                 current_expansion = definition;
 631                 goto restart;
 632         }
 633         pp_token = definition->token_list[definition->expand_pos];
 634         pp_token.base.source_position = expansion_pos;
 635         ++definition->expand_pos;
 636
 637         if (pp_token.kind != T_IDENTIFIER)
 638                 return;
 639
 640         /* if it was an identifier then we might need to expand again */
 641         pp_definition_t *const symbol_definition = pp_token.base.symbol->pp_definition;
 642         if (symbol_definition != NULL && !symbol_definition->is_expanding) {
 643                 symbol_definition->parent_expansion = definition;
 644                 symbol_definition->expand_pos       = 0;
 645                 symbol_definition->is_expanding     = true;
 646                 definition                          = symbol_definition;
 647                 current_expansion                   = definition;
 648                 goto restart;
 649         }
 650 }
 651
 652 static void skip_line_comment(void)
 653 {
 654         while (true) {
 655                 switch (input.c) {
 656                 case EOF:
 657                         return;
 658
 659                 case '\r':
 660                 case '\n':
 661                         return;
 662
 663                 default:
 664                         next_char();
 665                         break;
 666                 }
 667         }
 668 }
 669
 670 static void skip_multiline_comment(void)
 671 {
 672         unsigned start_linenr = input.position.lineno;
 673         while (true) {
 674                 switch (input.c) {
 675                 case '/':
 676                         next_char();
 677                         if (input.c == '*') {
 678                                 /* TODO: nested comment, warn here */
 679                         }
 680                         break;
 681                 case '*':
 682                         next_char();
 683                         if (input.c == '/') {
 684                                 if (input.position.lineno != input.output_line)
 685                                         info.whitespace = input.position.colno;
 686                                 next_char();
 687                                 return;
 688                         }
 689                         break;
 690
 691                 case NEWLINE:
 692                         break;
 693
 694                 case EOF: {
 695                         source_position_t source_position;
 696                         source_position.input_name = pp_token.base.source_position.input_name;
 697                         source_position.lineno     = start_linenr;
 698                         errorf(&source_position, "at end of file while looking for comment end");
 699                         return;
 700                 }
 701
 702                 default:
 703                         next_char();
 704                         break;
 705                 }
 706         }
 707 }
 708
 709 static void skip_whitespace(void)
 710 {
 711         while (true) {
 712                 switch (input.c) {
 713                 case ' ':
 714                 case '\t':
 715                         next_char();
 716                         continue;
 717
 718                 case NEWLINE:
 719                         info.at_line_begin = true;
 720                         return;
 721
 722                 case '/':
 723                         next_char();
 724                         if (input.c == '/') {
 725                                 next_char();
 726                                 skip_line_comment();
 727                                 continue;
 728                         } else if (input.c == '*') {
 729                                 next_char();
 730                                 skip_multiline_comment();
 731                                 continue;
 732                         } else {
 733                                 put_back(input.c);
 734                                 input.c = '/';
 735                         }
 736                         return;
 737                 default:
 738                         return;
 739                 }
 740         }
 741 }
 742
 743 static inline void eat_pp(pp_token_kind_t const kind)
 744 {
 745         assert(pp_token.base.symbol->pp_ID == kind);
 746         (void) kind;
 747         next_preprocessing_token();
 748 }
 749
 750 static void parse_symbol(void)
 751 {
 752         obstack_1grow(&symbol_obstack, (char) input.c);
 753         next_char();
 754
 755         while (true) {
 756                 switch (input.c) {
 757                 case DIGIT_CASES:
 758                 case SYMBOL_CASES:
 759                         obstack_1grow(&symbol_obstack, (char) input.c);
 760                         next_char();
 761                         break;
 762
 763                 default:
 764                         goto end_symbol;
 765                 }
 766         }
 767
 768 end_symbol:
 769         obstack_1grow(&symbol_obstack, '\0');
 770         char *string = obstack_finish(&symbol_obstack);
 771
 772         /* might be a wide string or character constant ( L"string"/L'c' ) */
 773         if (input.c == '"' && string[0] == 'L' && string[1] == '\0') {
 774                 obstack_free(&symbol_obstack, string);
 775                 parse_string_literal(STRING_ENCODING_WIDE);
 776                 return;
 777         } else if (input.c == '\'' && string[0] == 'L' && string[1] == '\0') {
 778                 obstack_free(&symbol_obstack, string);
 779                 parse_character_constant(STRING_ENCODING_WIDE);
 780                 return;
 781         }
 782
 783         symbol_t *symbol = symbol_table_insert(string);
 784
 785         pp_token.kind        = symbol->ID;
 786         pp_token.base.symbol = symbol;
 787
 788         /* we can free the memory from symbol obstack if we already had an entry in
 789          * the symbol table */
 790         if (symbol->string != string) {
 791                 obstack_free(&symbol_obstack, string);
 792         }
 793 }
 794
 795 static void parse_number(void)
 796 {
 797         obstack_1grow(&symbol_obstack, (char) input.c);
 798         next_char();
 799
 800         while (true) {
 801                 switch (input.c) {
 802                 case '.':
 803                 case DIGIT_CASES:
 804                 case SYMBOL_CASES_WITHOUT_E_P:
 805                         obstack_1grow(&symbol_obstack, (char) input.c);
 806                         next_char();
 807                         break;
 808
 809                 case 'e':
 810                 case 'p':
 811                 case 'E':
 812                 case 'P':
 813                         obstack_1grow(&symbol_obstack, (char) input.c);
 814                         next_char();
 815                         if (input.c == '+' || input.c == '-') {
 816                                 obstack_1grow(&symbol_obstack, (char) input.c);
 817                                 next_char();
 818                         }
 819                         break;
 820
 821                 default:
 822                         goto end_number;
 823                 }
 824         }
 825
 826 end_number:
 827         pp_token.kind           = T_NUMBER;
 828         pp_token.literal.string = sym_make_string(STRING_ENCODING_CHAR);
 829 }
 830
 831
 832 #define MAYBE_PROLOG                                       \
 833                         next_char();                                   \
 834                         while (true) {                                 \
 835                                 switch (input.c) {
 836
 837 #define MAYBE(ch, set_type)                                \
 838                                 case ch:                                   \
 839                                         next_char();                           \
 840                                         pp_token.kind = set_type;              \
 841                                         return;
 842
 843 #define ELSE_CODE(code)                                    \
 844                                 default:                                   \
 845                                         code                                   \
 846                                         return;                                \
 847                                 }                                          \
 848                         }
 849
 850 #define ELSE(set_type)                                     \
 851                 ELSE_CODE(                                         \
 852                         pp_token.kind = set_type;                      \
 853                 )
 854
 855 static void next_preprocessing_token(void)
 856 {
 857         if (current_expansion != NULL) {
 858                 expand_next();
 859                 return;
 860         }
 861
 862         info.at_line_begin  = false;
 863         info.had_whitespace = false;
 864 restart:
 865         pp_token.base.source_position = input.position;
 866         pp_token.base.symbol          = NULL;
 867
 868         switch (input.c) {
 869         case ' ':
 870         case '\t':
 871                 ++info.whitespace;
 872                 info.had_whitespace = true;
 873                 next_char();
 874                 goto restart;
 875
 876         case NEWLINE:
 877                 info.at_line_begin = true;
 878                 info.had_whitespace = true;
 879                 goto restart;
 880
 881         case SYMBOL_CASES:
 882                 parse_symbol();
 883                 return;
 884
 885         case DIGIT_CASES:
 886                 parse_number();
 887                 return;
 888
 889         case '"':
 890                 parse_string_literal(STRING_ENCODING_CHAR);
 891                 return;
 892
 893         case '\'':
 894                 parse_character_constant(STRING_ENCODING_CHAR);
 895                 return;
 896
 897         case '.':
 898                 MAYBE_PROLOG
 899                         case '0':
 900                         case '1':
 901                         case '2':
 902                         case '3':
 903                         case '4':
 904                         case '5':
 905                         case '6':
 906                         case '7':
 907                         case '8':
 908                         case '9':
 909                                 put_back(input.c);
 910                                 input.c = '.';
 911                                 parse_number();
 912                                 return;
 913
 914                         case '.':
 915                                 MAYBE_PROLOG
 916                                 MAYBE('.', T_DOTDOTDOT)
 917                                 ELSE_CODE(
 918                                         put_back(input.c);
 919                                         input.c = '.';
 920                                         pp_token.kind = '.';
 921                                 )
 922                 ELSE('.')
 923         case '&':
 924                 MAYBE_PROLOG
 925                 MAYBE('&', T_ANDAND)
 926                 MAYBE('=', T_ANDEQUAL)
 927                 ELSE('&')
 928         case '*':
 929                 MAYBE_PROLOG
 930                 MAYBE('=', T_ASTERISKEQUAL)
 931                 ELSE('*')
 932         case '+':
 933                 MAYBE_PROLOG
 934                 MAYBE('+', T_PLUSPLUS)
 935                 MAYBE('=', T_PLUSEQUAL)
 936                 ELSE('+')
 937         case '-':
 938                 MAYBE_PROLOG
 939                 MAYBE('>', T_MINUSGREATER)
 940                 MAYBE('-', T_MINUSMINUS)
 941                 MAYBE('=', T_MINUSEQUAL)
 942                 ELSE('-')
 943         case '!':
 944                 MAYBE_PROLOG
 945                 MAYBE('=', T_EXCLAMATIONMARKEQUAL)
 946                 ELSE('!')
 947         case '/':
 948                 MAYBE_PROLOG
 949                 MAYBE('=', T_SLASHEQUAL)
 950                         case '*':
 951                                 next_char();
 952                                 info.had_whitespace = true;
 953                                 skip_multiline_comment();
 954                                 goto restart;
 955                         case '/':
 956                                 next_char();
 957                                 info.had_whitespace = true;
 958                                 skip_line_comment();
 959                                 goto restart;
 960                 ELSE('/')
 961         case '%':
 962                 MAYBE_PROLOG
 963                 MAYBE('>', '}')
 964                 MAYBE('=', T_PERCENTEQUAL)
 965                         case ':':
 966                                 MAYBE_PROLOG
 967                                         case '%':
 968                                                 MAYBE_PROLOG
 969                                                 MAYBE(':', T_HASHHASH)
 970                                                 ELSE_CODE(
 971                                                         put_back(input.c);
 972                                                         input.c = '%';
 973                                                         pp_token.kind = '#';
 974                                                 )
 975                                 ELSE('#')
 976                 ELSE('%')
 977         case '<':
 978                 MAYBE_PROLOG
 979                 MAYBE(':', '[')
 980                 MAYBE('%', '{')
 981                 MAYBE('=', T_LESSEQUAL)
 982                         case '<':
 983                                 MAYBE_PROLOG
 984                                 MAYBE('=', T_LESSLESSEQUAL)
 985                                 ELSE(T_LESSLESS)
 986                 ELSE('<')
 987         case '>':
 988                 MAYBE_PROLOG
 989                 MAYBE('=', T_GREATEREQUAL)
 990                         case '>':
 991                                 MAYBE_PROLOG
 992                                 MAYBE('=', T_GREATERGREATEREQUAL)
 993                                 ELSE(T_GREATERGREATER)
 994                 ELSE('>')
 995         case '^':
 996                 MAYBE_PROLOG
 997                 MAYBE('=', T_CARETEQUAL)
 998                 ELSE('^')
 999         case '|':
1000                 MAYBE_PROLOG
1001                 MAYBE('=', T_PIPEEQUAL)
1002                 MAYBE('|', T_PIPEPIPE)
1003                 ELSE('|')
1004         case ':':
1005                 MAYBE_PROLOG
1006                 MAYBE('>', ']')
1007                 ELSE(':')
1008         case '=':
1009                 MAYBE_PROLOG
1010                 MAYBE('=', T_EQUALEQUAL)
1011                 ELSE('=')
1012         case '#':
1013                 MAYBE_PROLOG
1014                 MAYBE('#', T_HASHHASH)
1015                 ELSE_CODE(
1016                         pp_token.kind = '#';
1017                 )
1018
1019         case '?':
1020         case '[':
1021         case ']':
1022         case '(':
1023         case ')':
1024         case '{':
1025         case '}':
1026         case '~':
1027         case ';':
1028         case ',':
1029                 pp_token.kind = input.c;
1030                 next_char();
1031                 return;
1032
1033         case EOF:
1034                 if (input_stack != NULL) {
1035                         close_input();
1036                         pop_restore_input();
1037                         fputc('\n', out);
1038                         print_line_directive(&input.position, "2");
1039                         goto restart;
1040                 } else {
1041                         pp_token.base.source_position.lineno++;
1042                         info.at_line_begin = true;
1043                         pp_token.kind      = T_EOF;
1044                 }
1045                 return;
1046
1047         default:
1048                 next_char();
1049                 if (!ignore_unknown_chars) {
1050                         errorf(&pp_token.base.source_position,
1051                                "unknown character '%lc' found\n", input.c);
1052                         goto restart;
1053                 } else {
1054                         pp_token.kind = input.c;
1055                         return;
1056                 }
1057         }
1058 }
1059
1060 static void print_quoted_string(const char *const string)
1061 {
1062         fputc('"', out);
1063         for (const char *c = string; *c != 0; ++c) {
1064                 switch (*c) {
1065                 case '"': fputs("\\\"", out); break;
1066                 case '\\':  fputs("\\\\", out); break;
1067                 case '\a':  fputs("\\a", out); break;
1068                 case '\b':  fputs("\\b", out); break;
1069                 case '\f':  fputs("\\f", out); break;
1070                 case '\n':  fputs("\\n", out); break;
1071                 case '\r':  fputs("\\r", out); break;
1072                 case '\t':  fputs("\\t", out); break;
1073                 case '\v':  fputs("\\v", out); break;
1074                 case '\?':  fputs("\\?", out); break;
1075                 default:
1076                         if (!isprint(*c)) {
1077                                 fprintf(out, "\\%03o", (unsigned)*c);
1078                                 break;
1079                         }
1080                         fputc(*c, out);
1081                         break;
1082                 }
1083         }
1084         fputc('"', out);
1085 }
1086
1087 static void print_line_directive(const source_position_t *pos, const char *add)
1088 {
1089         fprintf(out, "# %u ", pos->lineno);
1090         print_quoted_string(pos->input_name);
1091         if (add != NULL) {
1092                 fputc(' ', out);
1093                 fputs(add, out);
1094         }
1095
1096         printed_input_name = pos->input_name;
1097         input.output_line  = pos->lineno-1;
1098 }
1099
1100 static bool emit_newlines(void)
1101 {
1102         unsigned delta = pp_token.base.source_position.lineno - input.output_line;
1103         if (delta == 0)
1104                 return false;
1105
1106         if (delta >= 9) {
1107                 fputc('\n', out);
1108                 print_line_directive(&pp_token.base.source_position, NULL);
1109                 fputc('\n', out);
1110         } else {
1111                 for (unsigned i = 0; i < delta; ++i) {
1112                         fputc('\n', out);
1113                 }
1114         }
1115         input.output_line = pp_token.base.source_position.lineno;
1116
1117         for (unsigned i = 0; i < info.whitespace; ++i)
1118                 fputc(' ', out);
1119
1120         return true;
1121 }
1122
1123 static void emit_pp_token(void)
1124 {
1125         if (skip_mode)
1126                 return;
1127
1128         if (!emit_newlines() &&
1129             (info.had_whitespace || tokens_would_paste(last_token, pp_token.kind)))
1130                 fputc(' ', out);
1131
1132         switch (pp_token.kind) {
1133         case T_NUMBER:
1134                 fputs(pp_token.literal.string.begin, out);
1135                 break;
1136
1137         case T_STRING_LITERAL:
1138                 fputs(get_string_encoding_prefix(pp_token.literal.string.encoding), out);
1139                 fputc('"', out);
1140                 fputs(pp_token.literal.string.begin, out);
1141                 fputc('"', out);
1142                 break;
1143
1144         case T_CHARACTER_CONSTANT:
1145                 fputs(get_string_encoding_prefix(pp_token.literal.string.encoding), out);
1146                 fputc('\'', out);
1147                 fputs(pp_token.literal.string.begin, out);
1148                 fputc('\'', out);
1149                 break;
1150
1151         default:
1152                 if (pp_token.base.symbol) {
1153                         fputs(pp_token.base.symbol->string, out);
1154                 } else {
1155                         print_token_kind(out, pp_token.kind);
1156                 }
1157                 break;
1158         }
1159         last_token = pp_token.kind;
1160 }
1161
1162 static void eat_pp_directive(void)
1163 {
1164         while (!info.at_line_begin) {
1165                 next_preprocessing_token();
1166         }
1167 }
1168
1169 static bool strings_equal(const string_t *string1, const string_t *string2)
1170 {
1171         size_t size = string1->size;
1172         if (size != string2->size)
1173                 return false;
1174
1175         const char *c1 = string1->begin;
1176         const char *c2 = string2->begin;
1177         for (size_t i = 0; i < size; ++i, ++c1, ++c2) {
1178                 if (*c1 != *c2)
1179                         return false;
1180         }
1181         return true;
1182 }
1183
1184 static bool pp_tokens_equal(const token_t *token1, const token_t *token2)
1185 {
1186         if (token1->kind != token2->kind)
1187                 return false;
1188
1189         switch (token1->kind) {
1190         case T_IDENTIFIER:
1191                 return token1->base.symbol == token2->base.symbol;
1192
1193         case T_NUMBER:
1194         case T_CHARACTER_CONSTANT:
1195         case T_STRING_LITERAL:
1196                 return strings_equal(&token1->literal.string, &token2->literal.string);
1197
1198         default:
1199                 return true;
1200         }
1201 }
1202
1203 static bool pp_definitions_equal(const pp_definition_t *definition1,
1204                                  const pp_definition_t *definition2)
1205 {
1206         if (definition1->list_len != definition2->list_len)
1207                 return false;
1208
1209         size_t         len = definition1->list_len;
1210         const token_t *t1  = definition1->token_list;
1211         const token_t *t2  = definition2->token_list;
1212         for (size_t i = 0; i < len; ++i, ++t1, ++t2) {
1213                 if (!pp_tokens_equal(t1, t2))
1214                         return false;
1215         }
1216         return true;
1217 }
1218
1219 static void parse_define_directive(void)
1220 {
1221         eat_pp(TP_define);
1222         if (skip_mode) {
1223                 eat_pp_directive();
1224                 return;
1225         }
1226
1227         assert(obstack_object_size(&pp_obstack) == 0);
1228
1229         if (pp_token.kind != T_IDENTIFIER || info.at_line_begin) {
1230                 errorf(&pp_token.base.source_position,
1231                        "expected identifier after #define, got %K", &pp_token);
1232                 goto error_out;
1233         }
1234         symbol_t *const symbol = pp_token.base.symbol;
1235
1236         pp_definition_t *new_definition
1237                 = obstack_alloc(&pp_obstack, sizeof(new_definition[0]));
1238         memset(new_definition, 0, sizeof(new_definition[0]));
1239         new_definition->source_position = input.position;
1240
1241         /* this is probably the only place where spaces are significant in the
1242          * lexer (except for the fact that they separate tokens). #define b(x)
1243          * is something else than #define b (x) */
1244         if (input.c == '(') {
1245                 /* eat the '(' */
1246                 next_preprocessing_token();
1247                 /* get next token after '(' */
1248                 next_preprocessing_token();
1249
1250                 while (true) {
1251                         switch (pp_token.kind) {
1252                         case T_DOTDOTDOT:
1253                                 new_definition->is_variadic = true;
1254                                 next_preprocessing_token();
1255                                 if (pp_token.kind != ')') {
1256                                         errorf(&input.position,
1257                                                         "'...' not at end of macro argument list");
1258                                         goto error_out;
1259                                 }
1260                                 break;
1261                         case T_IDENTIFIER:
1262                                 obstack_ptr_grow(&pp_obstack, pp_token.base.symbol);
1263                                 next_preprocessing_token();
1264
1265                                 if (pp_token.kind == ',') {
1266                                         next_preprocessing_token();
1267                                         break;
1268                                 }
1269
1270                                 if (pp_token.kind != ')') {
1271                                         errorf(&pp_token.base.source_position,
1272                                                "expected ',' or ')' after identifier, got %K",
1273                                                &pp_token);
1274                                         goto error_out;
1275                                 }
1276                                 break;
1277                         case ')':
1278                                 next_preprocessing_token();
1279                                 goto finish_argument_list;
1280                         default:
1281                                 errorf(&pp_token.base.source_position,
1282                                        "expected identifier, '...' or ')' in #define argument list, got %K",
1283                                        &pp_token);
1284                                 goto error_out;
1285                         }
1286                 }
1287
1288         finish_argument_list:
1289                 new_definition->has_parameters = true;
1290                 new_definition->n_parameters
1291                         = obstack_object_size(&pp_obstack) / sizeof(new_definition->parameters[0]);
1292                 new_definition->parameters = obstack_finish(&pp_obstack);
1293         } else {
1294                 next_preprocessing_token();
1295         }
1296
1297         /* construct a new pp_definition on the obstack */
1298         assert(obstack_object_size(&pp_obstack) == 0);
1299         size_t list_len = 0;
1300         while (!info.at_line_begin) {
1301                 obstack_grow(&pp_obstack, &pp_token, sizeof(pp_token));
1302                 ++list_len;
1303                 next_preprocessing_token();
1304         }
1305
1306         new_definition->list_len   = list_len;
1307         new_definition->token_list = obstack_finish(&pp_obstack);
1308
1309         pp_definition_t *old_definition = symbol->pp_definition;
1310         if (old_definition != NULL) {
1311                 if (!pp_definitions_equal(old_definition, new_definition)) {
1312                         warningf(WARN_OTHER, &input.position, "multiple definition of macro '%Y' (first defined %P)", symbol, &old_definition->source_position);
1313                 } else {
1314                         /* reuse the old definition */
1315                         obstack_free(&pp_obstack, new_definition);
1316                         new_definition = old_definition;
1317                 }
1318         }
1319
1320         symbol->pp_definition = new_definition;
1321         return;
1322
1323 error_out:
1324         if (obstack_object_size(&pp_obstack) > 0) {
1325                 char *ptr = obstack_finish(&pp_obstack);
1326                 obstack_free(&pp_obstack, ptr);
1327         }
1328         eat_pp_directive();
1329 }
1330
1331 static void parse_undef_directive(void)
1332 {
1333         eat_pp(TP_undef);
1334         if (skip_mode) {
1335                 eat_pp_directive();
1336                 return;
1337         }
1338
1339         if (pp_token.kind != T_IDENTIFIER) {
1340                 errorf(&input.position,
1341                        "expected identifier after #undef, got %K", &pp_token);
1342                 eat_pp_directive();
1343                 return;
1344         }
1345
1346         pp_token.base.symbol->pp_definition = NULL;
1347         next_preprocessing_token();
1348
1349         if (!info.at_line_begin) {
1350                 warningf(WARN_OTHER, &input.position, "extra tokens at end of #undef directive");
1351         }
1352         eat_pp_directive();
1353 }
1354
1355 /** behind an #include we can have the special headername lexems.
1356  * They're only allowed behind an #include so they're not recognized
1357  * by the normal next_preprocessing_token. We handle them as a special
1358  * exception here */
1359 static void parse_headername(void)
1360 {
1361         const source_position_t start_position = input.position;
1362         string_t                string         = { NULL, 0, STRING_ENCODING_CHAR };
1363         assert(obstack_object_size(&symbol_obstack) == 0);
1364
1365         if (info.at_line_begin) {
1366                 parse_error("expected headername after #include");
1367                 goto finish_error;
1368         }
1369
1370         /* check wether we have a "... or <... headername */
1371         switch (input.c) {
1372         {
1373                 utf32 delimiter;
1374         case '<': delimiter = '>'; goto parse_name;
1375         case '"': delimiter = '"'; goto parse_name;
1376 parse_name:
1377                 next_char();
1378                 while (true) {
1379                         switch (input.c) {
1380                         case NEWLINE:
1381                         case EOF:
1382                                 errorf(&pp_token.base.source_position, "header name without closing '%c'", (char)delimiter);
1383                                 goto finish_error;
1384
1385                         default:
1386                                 if (input.c == delimiter) {
1387                                         next_char();
1388                                         goto finished_headername;
1389                                 } else {
1390                                         obstack_1grow(&symbol_obstack, (char)input.c);
1391                                         next_char();
1392                                 }
1393                                 break;
1394                         }
1395                 }
1396                 /* we should never be here */
1397         }
1398
1399         default:
1400                 /* TODO: do normal pp_token parsing and concatenate results */
1401                 panic("pp_token concat include not implemented yet");
1402         }
1403
1404 finished_headername:
1405         string = sym_make_string(STRING_ENCODING_CHAR);
1406
1407 finish_error:
1408         pp_token.base.source_position = start_position;
1409         pp_token.kind                 = T_HEADERNAME;
1410         pp_token.literal.string       = string;
1411 }
1412
1413 static bool do_include(bool system_include, const char *headername)
1414 {
1415         size_t headername_len = strlen(headername);
1416         if (!system_include) {
1417                 /* put dirname of current input on obstack */
1418                 const char *filename   = input.position.input_name;
1419                 const char *last_slash = strrchr(filename, '/');
1420                 if (last_slash != NULL) {
1421                         size_t len = last_slash - filename;
1422                         obstack_grow(&symbol_obstack, filename, len + 1);
1423                         obstack_grow0(&symbol_obstack, headername, headername_len);
1424                         char *complete_path = obstack_finish(&symbol_obstack);
1425                         headername = identify_string(complete_path);
1426                 }
1427
1428                 FILE *file = fopen(headername, "r");
1429                 if (file != NULL) {
1430                         switch_input(file, headername);
1431                         return true;
1432                 }
1433         }
1434
1435         assert(obstack_object_size(&symbol_obstack) == 0);
1436         /* check searchpath */
1437         for (searchpath_entry_t *entry = searchpath; entry != NULL;
1438              entry = entry->next) {
1439             const char *path = entry->path;
1440             size_t      len  = strlen(path);
1441                 obstack_grow(&symbol_obstack, path, len);
1442                 if (path[len-1] != '/')
1443                         obstack_1grow(&symbol_obstack, '/');
1444                 obstack_grow(&symbol_obstack, headername, headername_len+1);
1445
1446                 char *complete_path = obstack_finish(&symbol_obstack);
1447                 FILE *file          = fopen(complete_path, "r");
1448                 if (file != NULL) {
1449                         const char *filename = identify_string(complete_path);
1450                         switch_input(file, filename);
1451                         return true;
1452                 } else {
1453                         obstack_free(&symbol_obstack, complete_path);
1454                 }
1455         }
1456
1457         return false;
1458 }
1459
1460 /* read till next newline character, only for parse_include_directive(),
1461  * use eat_pp_directive() in all other cases */
1462 static void skip_till_newline(void)
1463 {
1464         /* skip till newline */
1465         while (true) {
1466                 switch (input.c) {
1467                 case NEWLINE:
1468                 case EOF:
1469                         return;
1470                 }
1471                 next_char();
1472         }
1473 }
1474
1475 static bool parse_include_directive(void)
1476 {
1477         if (skip_mode) {
1478                 eat_pp_directive();
1479                 return;
1480         }
1481
1482         /* don't eat the TP_include here!
1483          * we need an alternative parsing for the next token */
1484         skip_whitespace();
1485         bool system_include = input.c == '<';
1486         parse_headername();
1487         string_t headername = pp_token.literal.string;
1488         if (headername.begin == NULL) {
1489                 eat_pp_directive();
1490                 return false;
1491         }
1492
1493         skip_whitespace();
1494         if (!info.at_line_begin) {
1495                 warningf(WARN_OTHER, &pp_token.base.source_position,
1496                          "extra tokens at end of #include directive");
1497                 skip_till_newline();
1498         }
1499
1500         if (n_inputs > INCLUDE_LIMIT) {
1501                 errorf(&pp_token.base.source_position, "#include nested too deeply");
1502                 /* eat \n or EOF */
1503                 next_preprocessing_token();
1504                 return false;
1505         }
1506
1507         /* switch inputs */
1508         emit_newlines();
1509         push_input();
1510         bool res = do_include(system_include, pp_token.literal.string.begin);
1511         if (!res) {
1512                 errorf(&pp_token.base.source_position, "failed including '%S': %s", &pp_token.literal, strerror(errno));
1513                 pop_restore_input();
1514                 return false;
1515         }
1516
1517         return true;
1518 }
1519
1520 static pp_conditional_t *push_conditional(void)
1521 {
1522         pp_conditional_t *conditional
1523                 = obstack_alloc(&pp_obstack, sizeof(*conditional));
1524         memset(conditional, 0, sizeof(*conditional));
1525
1526         conditional->parent = conditional_stack;
1527         conditional_stack   = conditional;
1528
1529         return conditional;
1530 }
1531
1532 static void pop_conditional(void)
1533 {
1534         assert(conditional_stack != NULL);
1535         conditional_stack = conditional_stack->parent;
1536 }
1537
1538 static void check_unclosed_conditionals(void)
1539 {
1540         while (conditional_stack != NULL) {
1541                 pp_conditional_t *conditional = conditional_stack;
1542
1543                 if (conditional->in_else) {
1544                         errorf(&conditional->source_position, "unterminated #else");
1545                 } else {
1546                         errorf(&conditional->source_position, "unterminated condition");
1547                 }
1548                 pop_conditional();
1549         }
1550 }
1551
1552 static void parse_ifdef_ifndef_directive(void)
1553 {
1554         bool is_ifndef = pp_token.base.symbol->pp_ID == TP_ifndef;
1555         bool condition;
1556         next_preprocessing_token();
1557
1558         if (skip_mode) {
1559                 eat_pp_directive();
1560                 pp_conditional_t *conditional = push_conditional();
1561                 conditional->source_position  = pp_token.base.source_position;
1562                 conditional->skip             = true;
1563                 return;
1564         }
1565
1566         if (pp_token.kind != T_IDENTIFIER || info.at_line_begin) {
1567                 errorf(&pp_token.base.source_position,
1568                        "expected identifier after #%s, got %K",
1569                        is_ifndef ? "ifndef" : "ifdef", &pp_token);
1570                 eat_pp_directive();
1571
1572                 /* just take the true case in the hope to avoid further errors */
1573                 condition = true;
1574         } else {
1575                 /* evaluate wether we are in true or false case */
1576                 condition = (bool)!pp_token.base.symbol->pp_definition == is_ifndef;
1577
1578                 next_preprocessing_token();
1579
1580                 if (!info.at_line_begin) {
1581                         errorf(&pp_token.base.source_position,
1582                                "extra tokens at end of #%s",
1583                                is_ifndef ? "ifndef" : "ifdef");
1584                         eat_pp_directive();
1585                 }
1586         }
1587
1588         pp_conditional_t *conditional = push_conditional();
1589         conditional->source_position  = pp_token.base.source_position;
1590         conditional->condition        = condition;
1591
1592         if (!condition) {
1593                 skip_mode = true;
1594         }
1595 }
1596
1597 static void parse_else_directive(void)
1598 {
1599         eat_pp(TP_else);
1600
1601         if (!info.at_line_begin) {
1602                 if (!skip_mode) {
1603                         warningf(WARN_OTHER, &pp_token.base.source_position, "extra tokens at end of #else");
1604                 }
1605                 eat_pp_directive();
1606         }
1607
1608         pp_conditional_t *conditional = conditional_stack;
1609         if (conditional == NULL) {
1610                 errorf(&pp_token.base.source_position, "#else without prior #if");
1611                 return;
1612         }
1613
1614         if (conditional->in_else) {
1615                 errorf(&pp_token.base.source_position,
1616                        "#else after #else (condition started %P)",
1617                        &conditional->source_position);
1618                 skip_mode = true;
1619                 return;
1620         }
1621
1622         conditional->in_else = true;
1623         if (!conditional->skip) {
1624                 skip_mode = conditional->condition;
1625         }
1626         conditional->source_position = pp_token.base.source_position;
1627 }
1628
1629 static void parse_endif_directive(void)
1630 {
1631         eat_pp(TP_endif);
1632
1633         if (!info.at_line_begin) {
1634                 if (!skip_mode) {
1635                         warningf(WARN_OTHER, &pp_token.base.source_position, "extra tokens at end of #endif");
1636                 }
1637                 eat_pp_directive();
1638         }
1639
1640         pp_conditional_t *conditional = conditional_stack;
1641         if (conditional == NULL) {
1642                 errorf(&pp_token.base.source_position, "#endif without prior #if");
1643                 return;
1644         }
1645
1646         if (!conditional->skip) {
1647                 skip_mode = false;
1648         }
1649         pop_conditional();
1650 }
1651
1652 static void parse_preprocessing_directive(void)
1653 {
1654         next_preprocessing_token(); /* Eat '#'. */
1655
1656         if (info.at_line_begin) {
1657                 /* empty directive */
1658                 return;
1659         }
1660
1661         if (pp_token.base.symbol) {
1662                 switch (pp_token.base.symbol->pp_ID) {
1663                 case TP_define:  parse_define_directive();       break;
1664                 case TP_else:    parse_else_directive();         break;
1665                 case TP_endif:   parse_endif_directive();        break;
1666                 case TP_ifdef:
1667                 case TP_ifndef:  parse_ifdef_ifndef_directive(); break;
1668                 case TP_include: parse_include_directive();      break;
1669                 case TP_undef:   parse_undef_directive();        break;
1670                 default:         goto skip;
1671                 }
1672         } else {
1673 skip:
1674                 if (!skip_mode) {
1675                         errorf(&pp_token.base.source_position, "invalid preprocessing directive #%K", &pp_token);
1676                 }
1677                 eat_pp_directive();
1678         }
1679
1680         assert(info.at_line_begin);
1681 }
1682
1683 static void prepend_include_path(const char *path)
1684 {
1685         searchpath_entry_t *entry = OALLOCZ(&config_obstack, searchpath_entry_t);
1686         entry->path = path;
1687         entry->next = searchpath;
1688         searchpath  = entry;
1689 }
1690
1691 static void setup_include_path(void)
1692 {
1693         /* built-in paths */
1694         prepend_include_path("/usr/include");
1695
1696         /* parse environment variable */
1697         const char *cpath = getenv("CPATH");
1698         if (cpath != NULL && *cpath != '\0') {
1699                 const char *begin = cpath;
1700                 const char *c;
1701                 do {
1702                         c = begin;
1703                         while (*c != '\0' && *c != ':')
1704                                 ++c;
1705
1706                         size_t len = c-begin;
1707                         if (len == 0) {
1708                                 /* for gcc compatibility (Matze: I would expect that
1709                                  * nothing happens for an empty entry...) */
1710                                 prepend_include_path(".");
1711                         } else {
1712                                 char *string = obstack_alloc(&config_obstack, len+1);
1713                                 memcpy(string, begin, len);
1714                                 string[len] = '\0';
1715
1716                                 prepend_include_path(string);
1717                         }
1718
1719                         begin = c+1;
1720                         /* skip : */
1721                         if (*begin == ':')
1722                                 ++begin;
1723                 } while(*c != '\0');
1724         }
1725 }
1726
1727 int pptest_main(int argc, char **argv);
1728 int pptest_main(int argc, char **argv)
1729 {
1730         init_symbol_table();
1731         init_tokens();
1732
1733         obstack_init(&config_obstack);
1734         obstack_init(&pp_obstack);
1735         obstack_init(&input_obstack);
1736         strset_init(&stringset);
1737
1738         setup_include_path();
1739
1740         /* simplistic commandline parser */
1741         const char *filename = NULL;
1742         const char *output = NULL;
1743         for (int i = 1; i < argc; ++i) {
1744                 const char *opt = argv[i];
1745                 if (streq(opt, "-I")) {
1746                         prepend_include_path(argv[++i]);
1747                         continue;
1748                 } else if (streq(opt, "-E")) {
1749                         /* ignore */
1750                 } else if (streq(opt, "-o")) {
1751                         output = argv[++i];
1752                         continue;
1753                 } else if (opt[0] == '-') {
1754                         fprintf(stderr, "Unknown option '%s'\n", opt);
1755                 } else {
1756                         if (filename != NULL)
1757                                 fprintf(stderr, "Multiple inputs not supported\n");
1758                         filename = argv[i];
1759                 }
1760         }
1761         if (filename == NULL) {
1762                 fprintf(stderr, "No input specified\n");
1763                 return 1;
1764         }
1765
1766         if (output == NULL) {
1767                 out = stdout;
1768         } else {
1769                 out = fopen(output, "w");
1770                 if (out == NULL) {
1771                         fprintf(stderr, "Couldn't open output '%s'\n", output);
1772                         return 1;
1773                 }
1774         }
1775
1776         /* just here for gcc compatibility */
1777         fprintf(out, "# 1 \"%s\"\n", filename);
1778         fprintf(out, "# 1 \"<built-in>\"\n");
1779         fprintf(out, "# 1 \"<command-line>\"\n");
1780
1781         FILE *file = fopen(filename, "r");
1782         if (file == NULL) {
1783                 fprintf(stderr, "Couldn't open input '%s'\n", filename);
1784                 return 1;
1785         }
1786         switch_input(file, filename);
1787
1788         while (true) {
1789                 if (pp_token.kind == '#' && info.at_line_begin) {
1790                         parse_preprocessing_directive();
1791                         continue;
1792                 } else if (pp_token.kind == T_EOF) {
1793                         goto end_of_main_loop;
1794                 } else if (pp_token.kind == T_IDENTIFIER) {
1795                         symbol_t        *const symbol        = pp_token.base.symbol;
1796                         pp_definition_t *const pp_definition = symbol->pp_definition;
1797                         if (pp_definition != NULL && !pp_definition->is_expanding) {
1798                                 expansion_pos = pp_token.base.source_position;
1799                                 if (pp_definition->has_parameters) {
1800                                         source_position_t position = pp_token.base.source_position;
1801                                         add_token_info_t old_info = info;
1802                                         next_preprocessing_token();
1803                                         add_token_info_t new_info = info;
1804
1805                                         /* no opening brace -> no expansion */
1806                                         if (pp_token.kind == '(') {
1807                                                 next_preprocessing_token(); /* Eat '('. */
1808
1809                                                 /* parse arguments (TODO) */
1810                                                 while (pp_token.kind != T_EOF && pp_token.kind != ')')
1811                                                         next_preprocessing_token();
1812                                         } else {
1813                                                 token_t next_token = pp_token;
1814                                                 /* restore identifier token */
1815                                                 pp_token.kind                 = T_IDENTIFIER;
1816                                                 pp_token.base.symbol          = symbol;
1817                                                 pp_token.base.source_position = position;
1818                                                 info = old_info;
1819                                                 emit_pp_token();
1820
1821                                                 info = new_info;
1822                                                 pp_token = next_token;
1823                                                 continue;
1824                                         }
1825                                         info = old_info;
1826                                 }
1827                                 pp_definition->expand_pos   = 0;
1828                                 pp_definition->is_expanding = true;
1829                                 current_expansion           = pp_definition;
1830                                 expand_next();
1831                                 continue;
1832                         }
1833                 }
1834
1835                 emit_pp_token();
1836                 next_preprocessing_token();
1837         }
1838 end_of_main_loop:
1839
1840         fputc('\n', out);
1841         check_unclosed_conditionals();
1842         close_input();
1843         if (out != stdout)
1844                 fclose(out);
1845
1846         obstack_free(&input_obstack, NULL);
1847         obstack_free(&pp_obstack, NULL);
1848         obstack_free(&config_obstack, NULL);
1849
1850         strset_destroy(&stringset);
1851
1852         exit_tokens();
1853         exit_symbol_table();
1854
1855         return 0;
1856 }