scripts/unifdef.c

   1 /*
   2  * Copyright (c) 2002 - 2009 Tony Finch <dot@dotat.at>
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  */
  25
  26 /*
  27  * This code was derived from software contributed to Berkeley by Dave Yost.
  28  * It was rewritten to support ANSI C by Tony Finch. The original version
  29  * of unifdef carried the 4-clause BSD copyright licence. None of its code
  30  * remains in this version (though some of the names remain) so it now
  31  * carries a more liberal licence.
  32  *
  33  * The latest version is available from http://dotat.at/prog/unifdef
  34  */
  35
  36 static const char * const copyright[] = {
  37     "@(#) Copyright (c) 2002 - 2009 Tony Finch <dot@dotat.at>\n",
  38     "$dotat: unifdef/unifdef.c,v 1.190 2009/11/27 17:21:26 fanf2 Exp $",
  39 };
  40
  41 /*
  42  * unifdef - remove ifdef'ed lines
  43  *
  44  *  Wishlist:
  45  *      provide an option which will append the name of the
  46  *        appropriate symbol after #else's and #endif's
  47  *      provide an option which will check symbols after
  48  *        #else's and #endif's to see that they match their
  49  *        corresponding #ifdef or #ifndef
  50  *
  51  *   The first two items above require better buffer handling, which would
  52  *     also make it possible to handle all "dodgy" directives correctly.
  53  */
  54
  55 #include <ctype.h>
  56 #include <err.h>
  57 #include <stdarg.h>
  58 #include <stdbool.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <unistd.h>
  63
  64 /* types of input lines: */
  65 typedef enum {
  66         LT_TRUEI,               /* a true #if with ignore flag */
  67         LT_FALSEI,              /* a false #if with ignore flag */
  68         LT_IF,                  /* an unknown #if */
  69         LT_TRUE,                /* a true #if */
  70         LT_FALSE,               /* a false #if */
  71         LT_ELIF,                /* an unknown #elif */
  72         LT_ELTRUE,              /* a true #elif */
  73         LT_ELFALSE,             /* a false #elif */
  74         LT_ELSE,                /* #else */
  75         LT_ENDIF,               /* #endif */
  76         LT_DODGY,               /* flag: directive is not on one line */
  77         LT_DODGY_LAST = LT_DODGY + LT_ENDIF,
  78         LT_PLAIN,               /* ordinary line */
  79         LT_EOF,                 /* end of file */
  80         LT_ERROR,               /* unevaluable #if */
  81         LT_COUNT
  82 } Linetype;
  83
  84 static char const * const linetype_name[] = {
  85         "TRUEI", "FALSEI", "IF", "TRUE", "FALSE",
  86         "ELIF", "ELTRUE", "ELFALSE", "ELSE", "ENDIF",
  87         "DODGY TRUEI", "DODGY FALSEI",
  88         "DODGY IF", "DODGY TRUE", "DODGY FALSE",
  89         "DODGY ELIF", "DODGY ELTRUE", "DODGY ELFALSE",
  90         "DODGY ELSE", "DODGY ENDIF",
  91         "PLAIN", "EOF", "ERROR"
  92 };
  93
  94 /* state of #if processing */
  95 typedef enum {
  96         IS_OUTSIDE,
  97         IS_FALSE_PREFIX,        /* false #if followed by false #elifs */
  98         IS_TRUE_PREFIX,         /* first non-false #(el)if is true */
  99         IS_PASS_MIDDLE,         /* first non-false #(el)if is unknown */
 100         IS_FALSE_MIDDLE,        /* a false #elif after a pass state */
 101         IS_TRUE_MIDDLE,         /* a true #elif after a pass state */
 102         IS_PASS_ELSE,           /* an else after a pass state */
 103         IS_FALSE_ELSE,          /* an else after a true state */
 104         IS_TRUE_ELSE,           /* an else after only false states */
 105         IS_FALSE_TRAILER,       /* #elifs after a true are false */
 106         IS_COUNT
 107 } Ifstate;
 108
 109 static char const * const ifstate_name[] = {
 110         "OUTSIDE", "FALSE_PREFIX", "TRUE_PREFIX",
 111         "PASS_MIDDLE", "FALSE_MIDDLE", "TRUE_MIDDLE",
 112         "PASS_ELSE", "FALSE_ELSE", "TRUE_ELSE",
 113         "FALSE_TRAILER"
 114 };
 115
 116 /* state of comment parser */
 117 typedef enum {
 118         NO_COMMENT = false,     /* outside a comment */
 119         C_COMMENT,              /* in a comment like this one */
 120         CXX_COMMENT,            /* between // and end of line */
 121         STARTING_COMMENT,       /* just after slash-backslash-newline */
 122         FINISHING_COMMENT,      /* star-backslash-newline in a C comment */
 123         CHAR_LITERAL,           /* inside '' */
 124         STRING_LITERAL          /* inside "" */
 125 } Comment_state;
 126
 127 static char const * const comment_name[] = {
 128         "NO", "C", "CXX", "STARTING", "FINISHING", "CHAR", "STRING"
 129 };
 130
 131 /* state of preprocessor line parser */
 132 typedef enum {
 133         LS_START,               /* only space and comments on this line */
 134         LS_HASH,                /* only space, comments, and a hash */
 135         LS_DIRTY                /* this line can't be a preprocessor line */
 136 } Line_state;
 137
 138 static char const * const linestate_name[] = {
 139         "START", "HASH", "DIRTY"
 140 };
 141
 142 /*
 143  * Minimum translation limits from ISO/IEC 9899:1999 5.2.4.1
 144  */
 145 #define MAXDEPTH        64                      /* maximum #if nesting */
 146 #define MAXLINE         4096                    /* maximum length of line */
 147 #define MAXSYMS         4096                    /* maximum number of symbols */
 148
 149 /*
 150  * Sometimes when editing a keyword the replacement text is longer, so
 151  * we leave some space at the end of the tline buffer to accommodate this.
 152  */
 153 #define EDITSLOP        10
 154
 155 /*
 156  * Globals.
 157  */
 158
 159 static bool             compblank;              /* -B: compress blank lines */
 160 static bool             lnblank;                /* -b: blank deleted lines */
 161 static bool             complement;             /* -c: do the complement */
 162 static bool             debugging;              /* -d: debugging reports */
 163 static bool             iocccok;                /* -e: fewer IOCCC errors */
 164 static bool             strictlogic;            /* -K: keep ambiguous #ifs */
 165 static bool             killconsts;             /* -k: eval constant #ifs */
 166 static bool             lnnum;                  /* -n: add #line directives */
 167 static bool             symlist;                /* -s: output symbol list */
 168 static bool             text;                   /* -t: this is a text file */
 169
 170 static const char      *symname[MAXSYMS];       /* symbol name */
 171 static const char      *value[MAXSYMS];         /* -Dsym=value */
 172 static bool             ignore[MAXSYMS];        /* -iDsym or -iUsym */
 173 static int              nsyms;                  /* number of symbols */
 174
 175 static FILE            *input;                  /* input file pointer */
 176 static const char      *filename;               /* input file name */
 177 static int              linenum;                /* current line number */
 178
 179 static char             tline[MAXLINE+EDITSLOP];/* input buffer plus space */
 180 static char            *keyword;                /* used for editing #elif's */
 181
 182 static Comment_state    incomment;              /* comment parser state */
 183 static Line_state       linestate;              /* #if line parser state */
 184 static Ifstate          ifstate[MAXDEPTH];      /* #if processor state */
 185 static bool             ignoring[MAXDEPTH];     /* ignore comments state */
 186 static int              stifline[MAXDEPTH];     /* start of current #if */
 187 static int              depth;                  /* current #if nesting */
 188 static int              delcount;               /* count of deleted lines */
 189 static unsigned         blankcount;             /* count of blank lines */
 190 static unsigned         blankmax;               /* maximum recent blankcount */
 191 static bool             constexpr;              /* constant #if expression */
 192
 193 static int              exitstat;               /* program exit status */
 194
 195 static void             addsym(bool, bool, char *);
 196 static void             debug(const char *, ...);
 197 static void             done(void);
 198 static void             error(const char *);
 199 static int              findsym(const char *);
 200 static void             flushline(bool);
 201 static Linetype         parseline(void);
 202 static Linetype         ifeval(const char **);
 203 static void             ignoreoff(void);
 204 static void             ignoreon(void);
 205 static void             keywordedit(const char *);
 206 static void             nest(void);
 207 static void             process(void);
 208 static const char      *skipargs(const char *);
 209 static const char      *skipcomment(const char *);
 210 static const char      *skipsym(const char *);
 211 static void             state(Ifstate);
 212 static int              strlcmp(const char *, const char *, size_t);
 213 static void             unnest(void);
 214 static void             usage(void);
 215
 216 #define endsym(c) (!isalnum((unsigned char)c) && c != '_')
 217
 218 /*
 219  * The main program.
 220  */
 221 int
 222 main(int argc, char *argv[])
 223 {
 224         int opt;
 225
 226         while ((opt = getopt(argc, argv, "i:D:U:I:BbcdeKklnst")) != -1)
 227                 switch (opt) {
 228                 case 'i': /* treat stuff controlled by these symbols as text */
 229                         /*
 230                          * For strict backwards-compatibility the U or D
 231                          * should be immediately after the -i but it doesn't
 232                          * matter much if we relax that requirement.
 233                          */
 234                         opt = *optarg++;
 235                         if (opt == 'D')
 236                                 addsym(true, true, optarg);
 237                         else if (opt == 'U')
 238                                 addsym(true, false, optarg);
 239                         else
 240                                 usage();
 241                         break;
 242                 case 'D': /* define a symbol */
 243                         addsym(false, true, optarg);
 244                         break;
 245                 case 'U': /* undef a symbol */
 246                         addsym(false, false, optarg);
 247                         break;
 248                 case 'I':
 249                         /* no-op for compatibility with cpp */
 250                         break;
 251                 case 'B': /* compress blank lines around removed section */
 252                         compblank = true;
 253                         break;
 254                 case 'b': /* blank deleted lines instead of omitting them */
 255                 case 'l': /* backwards compatibility */
 256                         lnblank = true;
 257                         break;
 258                 case 'c': /* treat -D as -U and vice versa */
 259                         complement = true;
 260                         break;
 261                 case 'd':
 262                         debugging = true;
 263                         break;
 264                 case 'e': /* fewer errors from dodgy lines */
 265                         iocccok = true;
 266                         break;
 267                 case 'K': /* keep ambiguous #ifs */
 268                         strictlogic = true;
 269                         break;
 270                 case 'k': /* process constant #ifs */
 271                         killconsts = true;
 272                         break;
 273                 case 'n': /* add #line directive after deleted lines */
 274                         lnnum = true;
 275                         break;
 276                 case 's': /* only output list of symbols that control #ifs */
 277                         symlist = true;
 278                         break;
 279                 case 't': /* don't parse C comments */
 280                         text = true;
 281                         break;
 282                 default:
 283                         usage();
 284                 }
 285         argc -= optind;
 286         argv += optind;
 287         if (compblank && lnblank)
 288                 errx(2, "-B and -b are mutually exclusive");
 289         if (argc > 1) {
 290                 errx(2, "can only do one file");
 291         } else if (argc == 1 && strcmp(*argv, "-") != 0) {
 292                 filename = *argv;
 293                 input = fopen(filename, "r");
 294                 if (input == NULL)
 295                         err(2, "can't open %s", filename);
 296         } else {
 297                 filename = "[stdin]";
 298                 input = stdin;
 299         }
 300         process();
 301         abort(); /* bug */
 302 }
 303
 304 static void
 305 usage(void)
 306 {
 307         fprintf(stderr, "usage: unifdef [-BbcdeKknst] [-Ipath]"
 308             " [-Dsym[=val]] [-Usym] [-iDsym[=val]] [-iUsym] ... [file]\n");
 309         exit(2);
 310 }
 311
 312 /*
 313  * A state transition function alters the global #if processing state
 314  * in a particular way. The table below is indexed by the current
 315  * processing state and the type of the current line.
 316  *
 317  * Nesting is handled by keeping a stack of states; some transition
 318  * functions increase or decrease the depth. They also maintain the
 319  * ignore state on a stack. In some complicated cases they have to
 320  * alter the preprocessor directive, as follows.
 321  *
 322  * When we have processed a group that starts off with a known-false
 323  * #if/#elif sequence (which has therefore been deleted) followed by a
 324  * #elif that we don't understand and therefore must keep, we edit the
 325  * latter into a #if to keep the nesting correct.
 326  *
 327  * When we find a true #elif in a group, the following block will
 328  * always be kept and the rest of the sequence after the next #elif or
 329  * #else will be discarded. We edit the #elif into a #else and the
 330  * following directive to #endif since this has the desired behaviour.
 331  *
 332  * "Dodgy" directives are split across multiple lines, the most common
 333  * example being a multi-line comment hanging off the right of the
 334  * directive. We can handle them correctly only if there is no change
 335  * from printing to dropping (or vice versa) caused by that directive.
 336  * If the directive is the first of a group we have a choice between
 337  * failing with an error, or passing it through unchanged instead of
 338  * evaluating it. The latter is not the default to avoid questions from
 339  * users about unifdef unexpectedly leaving behind preprocessor directives.
 340  */
 341 typedef void state_fn(void);
 342
 343 /* report an error */
 344 static void Eelif (void) { error("Inappropriate #elif"); }
 345 static void Eelse (void) { error("Inappropriate #else"); }
 346 static void Eendif(void) { error("Inappropriate #endif"); }
 347 static void Eeof  (void) { error("Premature EOF"); }
 348 static void Eioccc(void) { error("Obfuscated preprocessor control line"); }
 349 /* plain line handling */
 350 static void print (void) { flushline(true); }
 351 static void drop  (void) { flushline(false); }
 352 /* output lacks group's start line */
 353 static void Strue (void) { drop();  ignoreoff(); state(IS_TRUE_PREFIX); }
 354 static void Sfalse(void) { drop();  ignoreoff(); state(IS_FALSE_PREFIX); }
 355 static void Selse (void) { drop();               state(IS_TRUE_ELSE); }
 356 /* print/pass this block */
 357 static void Pelif (void) { print(); ignoreoff(); state(IS_PASS_MIDDLE); }
 358 static void Pelse (void) { print();              state(IS_PASS_ELSE); }
 359 static void Pendif(void) { print(); unnest(); }
 360 /* discard this block */
 361 static void Dfalse(void) { drop();  ignoreoff(); state(IS_FALSE_TRAILER); }
 362 static void Delif (void) { drop();  ignoreoff(); state(IS_FALSE_MIDDLE); }
 363 static void Delse (void) { drop();               state(IS_FALSE_ELSE); }
 364 static void Dendif(void) { drop();  unnest(); }
 365 /* first line of group */
 366 static void Fdrop (void) { nest();  Dfalse(); }
 367 static void Fpass (void) { nest();  Pelif(); }
 368 static void Ftrue (void) { nest();  Strue(); }
 369 static void Ffalse(void) { nest();  Sfalse(); }
 370 /* variable pedantry for obfuscated lines */
 371 static void Oiffy (void) { if (!iocccok) Eioccc(); Fpass(); ignoreon(); }
 372 static void Oif   (void) { if (!iocccok) Eioccc(); Fpass(); }
 373 static void Oelif (void) { if (!iocccok) Eioccc(); Pelif(); }
 374 /* ignore comments in this block */
 375 static void Idrop (void) { Fdrop();  ignoreon(); }
 376 static void Itrue (void) { Ftrue();  ignoreon(); }
 377 static void Ifalse(void) { Ffalse(); ignoreon(); }
 378 /* edit this line */
 379 static void Mpass (void) { strncpy(keyword, "if  ", 4); Pelif(); }
 380 static void Mtrue (void) { keywordedit("else\n");  state(IS_TRUE_MIDDLE); }
 381 static void Melif (void) { keywordedit("endif\n"); state(IS_FALSE_TRAILER); }
 382 static void Melse (void) { keywordedit("endif\n"); state(IS_FALSE_ELSE); }
 383
 384 static state_fn * const trans_table[IS_COUNT][LT_COUNT] = {
 385 /* IS_OUTSIDE */
 386 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Eendif,
 387   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eendif,
 388   print, done,  abort },
 389 /* IS_FALSE_PREFIX */
 390 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Strue, Sfalse,Selse, Dendif,
 391   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Eioccc,Eioccc,Eioccc,Eioccc,
 392   drop,  Eeof,  abort },
 393 /* IS_TRUE_PREFIX */
 394 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Dfalse,Dfalse,Dfalse,Delse, Dendif,
 395   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
 396   print, Eeof,  abort },
 397 /* IS_PASS_MIDDLE */
 398 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Pelif, Mtrue, Delif, Pelse, Pendif,
 399   Oiffy, Oiffy, Fpass, Oif,   Oif,   Pelif, Oelif, Oelif, Pelse, Pendif,
 400   print, Eeof,  abort },
 401 /* IS_FALSE_MIDDLE */
 402 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Pelif, Mtrue, Delif, Pelse, Pendif,
 403   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
 404   drop,  Eeof,  abort },
 405 /* IS_TRUE_MIDDLE */
 406 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Melif, Melif, Melif, Melse, Pendif,
 407   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Pendif,
 408   print, Eeof,  abort },
 409 /* IS_PASS_ELSE */
 410 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Pendif,
 411   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Pendif,
 412   print, Eeof,  abort },
 413 /* IS_FALSE_ELSE */
 414 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Dendif,
 415   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Eioccc,
 416   drop,  Eeof,  abort },
 417 /* IS_TRUE_ELSE */
 418 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Dendif,
 419   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eioccc,
 420   print, Eeof,  abort },
 421 /* IS_FALSE_TRAILER */
 422 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Dendif,
 423   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Eioccc,
 424   drop,  Eeof,  abort }
 425 /*TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF
 426   TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF (DODGY)
 427   PLAIN  EOF    ERROR */
 428 };
 429
 430 /*
 431  * State machine utility functions
 432  */
 433 static void
 434 done(void)
 435 {
 436         if (incomment)
 437                 error("EOF in comment");
 438         exit(exitstat);
 439 }
 440 static void
 441 ignoreoff(void)
 442 {
 443         if (depth == 0)
 444                 abort(); /* bug */
 445         ignoring[depth] = ignoring[depth-1];
 446 }
 447 static void
 448 ignoreon(void)
 449 {
 450         ignoring[depth] = true;
 451 }
 452 static void
 453 keywordedit(const char *replacement)
 454 {
 455         size_t size = tline + sizeof(tline) - keyword;
 456         char *dst = keyword;
 457         const char *src = replacement;
 458         if (size != 0) {
 459                 while ((--size != 0) && (*src != '\0'))
 460                         *dst++ = *src++;
 461                 *dst = '\0';
 462         }
 463         print();
 464 }
 465 static void
 466 nest(void)
 467 {
 468         if (depth > MAXDEPTH-1)
 469                 abort(); /* bug */
 470         if (depth == MAXDEPTH-1)
 471                 error("Too many levels of nesting");
 472         depth += 1;
 473         stifline[depth] = linenum;
 474 }
 475 static void
 476 unnest(void)
 477 {
 478         if (depth == 0)
 479                 abort(); /* bug */
 480         depth -= 1;
 481 }
 482 static void
 483 state(Ifstate is)
 484 {
 485         ifstate[depth] = is;
 486 }
 487
 488 /*
 489  * Write a line to the output or not, according to command line options.
 490  */
 491 static void
 492 flushline(bool keep)
 493 {
 494         if (symlist)
 495                 return;
 496         if (keep ^ complement) {
 497                 bool blankline = tline[strspn(tline, " \t\n")] == '\0';
 498                 if (blankline && compblank && blankcount != blankmax) {
 499                         delcount += 1;
 500                         blankcount += 1;
 501                 } else {
 502                         if (lnnum && delcount > 0)
 503                                 printf("#line %d\n", linenum);
 504                         fputs(tline, stdout);
 505                         delcount = 0;
 506                         blankmax = blankcount = blankline ? blankcount + 1 : 0;
 507                 }
 508         } else {
 509                 if (lnblank)
 510                         putc('\n', stdout);
 511                 exitstat = 1;
 512                 delcount += 1;
 513                 blankcount = 0;
 514         }
 515 }
 516
 517 /*
 518  * The driver for the state machine.
 519  */
 520 static void
 521 process(void)
 522 {
 523         Linetype lineval;
 524
 525         /* When compressing blank lines, act as if the file
 526            is preceded by a large number of blank lines. */
 527         blankmax = blankcount = 1000;
 528         for (;;) {
 529                 linenum++;
 530                 lineval = parseline();
 531                 trans_table[ifstate[depth]][lineval]();
 532                 debug("process %s -> %s depth %d",
 533                     linetype_name[lineval],
 534                     ifstate_name[ifstate[depth]], depth);
 535         }
 536 }
 537
 538 /*
 539  * Parse a line and determine its type. We keep the preprocessor line
 540  * parser state between calls in the global variable linestate, with
 541  * help from skipcomment().
 542  */
 543 static Linetype
 544 parseline(void)
 545 {
 546         const char *cp;
 547         int cursym;
 548         int kwlen;
 549         Linetype retval;
 550         Comment_state wascomment;
 551
 552         if (fgets(tline, MAXLINE, input) == NULL)
 553                 return (LT_EOF);
 554         retval = LT_PLAIN;
 555         wascomment = incomment;
 556         cp = skipcomment(tline);
 557         if (linestate == LS_START) {
 558                 if (*cp == '#') {
 559                         linestate = LS_HASH;
 560                         cp = skipcomment(cp + 1);
 561                 } else if (*cp != '\0')
 562                         linestate = LS_DIRTY;
 563         }
 564         if (!incomment && linestate == LS_HASH) {
 565                 keyword = tline + (cp - tline);
 566                 cp = skipsym(cp);
 567                 kwlen = cp - keyword;
 568                 /* no way can we deal with a continuation inside a keyword */
 569                 if (strncmp(cp, "\\\n", 2) == 0)
 570                         Eioccc();
 571                 if (strlcmp("ifdef", keyword, kwlen) == 0 ||
 572                     strlcmp("ifndef", keyword, kwlen) == 0) {
 573                         cp = skipcomment(cp);
 574                         if ((cursym = findsym(cp)) < 0)
 575                                 retval = LT_IF;
 576                         else {
 577                                 retval = (keyword[2] == 'n')
 578                                     ? LT_FALSE : LT_TRUE;
 579                                 if (value[cursym] == NULL)
 580                                         retval = (retval == LT_TRUE)
 581                                             ? LT_FALSE : LT_TRUE;
 582                                 if (ignore[cursym])
 583                                         retval = (retval == LT_TRUE)
 584                                             ? LT_TRUEI : LT_FALSEI;
 585                         }
 586                         cp = skipsym(cp);
 587                 } else if (strlcmp("if", keyword, kwlen) == 0)
 588                         retval = ifeval(&cp);
 589                 else if (strlcmp("elif", keyword, kwlen) == 0)
 590                         retval = ifeval(&cp) - LT_IF + LT_ELIF;
 591                 else if (strlcmp("else", keyword, kwlen) == 0)
 592                         retval = LT_ELSE;
 593                 else if (strlcmp("endif", keyword, kwlen) == 0)
 594                         retval = LT_ENDIF;
 595                 else {
 596                         linestate = LS_DIRTY;
 597                         retval = LT_PLAIN;
 598                 }
 599                 cp = skipcomment(cp);
 600                 if (*cp != '\0') {
 601                         linestate = LS_DIRTY;
 602                         if (retval == LT_TRUE || retval == LT_FALSE ||
 603                             retval == LT_TRUEI || retval == LT_FALSEI)
 604                                 retval = LT_IF;
 605                         if (retval == LT_ELTRUE || retval == LT_ELFALSE)
 606                                 retval = LT_ELIF;
 607                 }
 608                 if (retval != LT_PLAIN && (wascomment || incomment)) {
 609                         retval += LT_DODGY;
 610                         if (incomment)
 611                                 linestate = LS_DIRTY;
 612                 }
 613                 /* skipcomment normally changes the state, except
 614                    if the last line of the file lacks a newline, or
 615                    if there is too much whitespace in a directive */
 616                 if (linestate == LS_HASH) {
 617                         size_t len = cp - tline;
 618                         if (fgets(tline + len, MAXLINE - len, input) == NULL) {
 619                                 /* append the missing newline */
 620                                 tline[len+0] = '\n';
 621                                 tline[len+1] = '\0';
 622                                 cp++;
 623                                 linestate = LS_START;
 624                         } else {
 625                                 linestate = LS_DIRTY;
 626                         }
 627                 }
 628         }
 629         if (linestate == LS_DIRTY) {
 630                 while (*cp != '\0')
 631                         cp = skipcomment(cp + 1);
 632         }
 633         debug("parser %s comment %s line",
 634             comment_name[incomment], linestate_name[linestate]);
 635         return (retval);
 636 }
 637
 638 /*
 639  * These are the binary operators that are supported by the expression
 640  * evaluator.
 641  */
 642 static Linetype op_strict(int *p, int v, Linetype at, Linetype bt) {
 643         if(at == LT_IF || bt == LT_IF) return (LT_IF);
 644         return (*p = v, v ? LT_TRUE : LT_FALSE);
 645 }
 646 static Linetype op_lt(int *p, Linetype at, int a, Linetype bt, int b) {
 647         return op_strict(p, a < b, at, bt);
 648 }
 649 static Linetype op_gt(int *p, Linetype at, int a, Linetype bt, int b) {
 650         return op_strict(p, a > b, at, bt);
 651 }
 652 static Linetype op_le(int *p, Linetype at, int a, Linetype bt, int b) {
 653         return op_strict(p, a <= b, at, bt);
 654 }
 655 static Linetype op_ge(int *p, Linetype at, int a, Linetype bt, int b) {
 656         return op_strict(p, a >= b, at, bt);
 657 }
 658 static Linetype op_eq(int *p, Linetype at, int a, Linetype bt, int b) {
 659         return op_strict(p, a == b, at, bt);
 660 }
 661 static Linetype op_ne(int *p, Linetype at, int a, Linetype bt, int b) {
 662         return op_strict(p, a != b, at, bt);
 663 }
 664 static Linetype op_or(int *p, Linetype at, int a, Linetype bt, int b) {
 665         if (!strictlogic && (at == LT_TRUE || bt == LT_TRUE))
 666                 return (*p = 1, LT_TRUE);
 667         return op_strict(p, a || b, at, bt);
 668 }
 669 static Linetype op_and(int *p, Linetype at, int a, Linetype bt, int b) {
 670         if (!strictlogic && (at == LT_FALSE || bt == LT_FALSE))
 671                 return (*p = 0, LT_FALSE);
 672         return op_strict(p, a && b, at, bt);
 673 }
 674
 675 /*
 676  * An evaluation function takes three arguments, as follows: (1) a pointer to
 677  * an element of the precedence table which lists the operators at the current
 678  * level of precedence; (2) a pointer to an integer which will receive the
 679  * value of the expression; and (3) a pointer to a char* that points to the
 680  * expression to be evaluated and that is updated to the end of the expression
 681  * when evaluation is complete. The function returns LT_FALSE if the value of
 682  * the expression is zero, LT_TRUE if it is non-zero, LT_IF if the expression
 683  * depends on an unknown symbol, or LT_ERROR if there is a parse failure.
 684  */
 685 struct ops;
 686
 687 typedef Linetype eval_fn(const struct ops *, int *, const char **);
 688
 689 static eval_fn eval_table, eval_unary;
 690
 691 /*
 692  * The precedence table. Expressions involving binary operators are evaluated
 693  * in a table-driven way by eval_table. When it evaluates a subexpression it
 694  * calls the inner function with its first argument pointing to the next
 695  * element of the table. Innermost expressions have special non-table-driven
 696  * handling.
 697  */
 698 static const struct ops {
 699         eval_fn *inner;
 700         struct op {
 701                 const char *str;
 702                 Linetype (*fn)(int *, Linetype, int, Linetype, int);
 703         } op[5];
 704 } eval_ops[] = {
 705         { eval_table, { { "||", op_or } } },
 706         { eval_table, { { "&&", op_and } } },
 707         { eval_table, { { "==", op_eq },
 708                         { "!=", op_ne } } },
 709         { eval_unary, { { "<=", op_le },
 710                         { ">=", op_ge },
 711                         { "<", op_lt },
 712                         { ">", op_gt } } }
 713 };
 714
 715 /*
 716  * Function for evaluating the innermost parts of expressions,
 717  * viz. !expr (expr) number defined(symbol) symbol
 718  * We reset the constexpr flag in the last two cases.
 719  */
 720 static Linetype
 721 eval_unary(const struct ops *ops, int *valp, const char **cpp)
 722 {
 723         const char *cp;
 724         char *ep;
 725         int sym;
 726         bool defparen;
 727         Linetype lt;
 728
 729         cp = skipcomment(*cpp);
 730         if (*cp == '!') {
 731                 debug("eval%d !", ops - eval_ops);
 732                 cp++;
 733                 lt = eval_unary(ops, valp, &cp);
 734                 if (lt == LT_ERROR)
 735                         return (LT_ERROR);
 736                 if (lt != LT_IF) {
 737                         *valp = !*valp;
 738                         lt = *valp ? LT_TRUE : LT_FALSE;
 739                 }
 740         } else if (*cp == '(') {
 741                 cp++;
 742                 debug("eval%d (", ops - eval_ops);
 743                 lt = eval_table(eval_ops, valp, &cp);
 744                 if (lt == LT_ERROR)
 745                         return (LT_ERROR);
 746                 cp = skipcomment(cp);
 747                 if (*cp++ != ')')
 748                         return (LT_ERROR);
 749         } else if (isdigit((unsigned char)*cp)) {
 750                 debug("eval%d number", ops - eval_ops);
 751                 *valp = strtol(cp, &ep, 0);
 752                 if (ep == cp)
 753                         return (LT_ERROR);
 754                 lt = *valp ? LT_TRUE : LT_FALSE;
 755                 cp = skipsym(cp);
 756         } else if (strncmp(cp, "defined", 7) == 0 && endsym(cp[7])) {
 757                 cp = skipcomment(cp+7);
 758                 debug("eval%d defined", ops - eval_ops);
 759                 if (*cp == '(') {
 760                         cp = skipcomment(cp+1);
 761                         defparen = true;
 762                 } else {
 763                         defparen = false;
 764                 }
 765                 sym = findsym(cp);
 766                 if (sym < 0) {
 767                         lt = LT_IF;
 768                 } else {
 769                         *valp = (value[sym] != NULL);
 770                         lt = *valp ? LT_TRUE : LT_FALSE;
 771                 }
 772                 cp = skipsym(cp);
 773                 cp = skipcomment(cp);
 774                 if (defparen && *cp++ != ')')
 775                         return (LT_ERROR);
 776                 constexpr = false;
 777         } else if (!endsym(*cp)) {
 778                 debug("eval%d symbol", ops - eval_ops);
 779                 sym = findsym(cp);
 780                 cp = skipsym(cp);
 781                 if (sym < 0) {
 782                         lt = LT_IF;
 783                         cp = skipargs(cp);
 784                 } else if (value[sym] == NULL) {
 785                         *valp = 0;
 786                         lt = LT_FALSE;
 787                 } else {
 788                         *valp = strtol(value[sym], &ep, 0);
 789                         if (*ep != '\0' || ep == value[sym])
 790                                 return (LT_ERROR);
 791                         lt = *valp ? LT_TRUE : LT_FALSE;
 792                         cp = skipargs(cp);
 793                 }
 794                 constexpr = false;
 795         } else {
 796                 debug("eval%d bad expr", ops - eval_ops);
 797                 return (LT_ERROR);
 798         }
 799
 800         *cpp = cp;
 801         debug("eval%d = %d", ops - eval_ops, *valp);
 802         return (lt);
 803 }
 804
 805 /*
 806  * Table-driven evaluation of binary operators.
 807  */
 808 static Linetype
 809 eval_table(const struct ops *ops, int *valp, const char **cpp)
 810 {
 811         const struct op *op;
 812         const char *cp;
 813         int val;
 814         Linetype lt, rt;
 815
 816         debug("eval%d", ops - eval_ops);
 817         cp = *cpp;
 818         lt = ops->inner(ops+1, valp, &cp);
 819         if (lt == LT_ERROR)
 820                 return (LT_ERROR);
 821         for (;;) {
 822                 cp = skipcomment(cp);
 823                 for (op = ops->op; op->str != NULL; op++)
 824                         if (strncmp(cp, op->str, strlen(op->str)) == 0)
 825                                 break;
 826                 if (op->str == NULL)
 827                         break;
 828                 cp += strlen(op->str);
 829                 debug("eval%d %s", ops - eval_ops, op->str);
 830                 rt = ops->inner(ops+1, &val, &cp);
 831                 if (rt == LT_ERROR)
 832                         return (LT_ERROR);
 833                 lt = op->fn(valp, lt, *valp, rt, val);
 834         }
 835
 836         *cpp = cp;
 837         debug("eval%d = %d", ops - eval_ops, *valp);
 838         debug("eval%d lt = %s", ops - eval_ops, linetype_name[lt]);
 839         return (lt);
 840 }
 841
 842 /*
 843  * Evaluate the expression on a #if or #elif line. If we can work out
 844  * the result we return LT_TRUE or LT_FALSE accordingly, otherwise we
 845  * return just a generic LT_IF.
 846  */
 847 static Linetype
 848 ifeval(const char **cpp)
 849 {
 850         int ret;
 851         int val = 0;
 852
 853         debug("eval %s", *cpp);
 854         constexpr = killconsts ? false : true;
 855         ret = eval_table(eval_ops, &val, cpp);
 856         debug("eval = %d", val);
 857         return (constexpr ? LT_IF : ret == LT_ERROR ? LT_IF : ret);
 858 }
 859
 860 /*
 861  * Skip over comments, strings, and character literals and stop at the
 862  * next character position that is not whitespace. Between calls we keep
 863  * the comment state in the global variable incomment, and we also adjust
 864  * the global variable linestate when we see a newline.
 865  * XXX: doesn't cope with the buffer splitting inside a state transition.
 866  */
 867 static const char *
 868 skipcomment(const char *cp)
 869 {
 870         if (text || ignoring[depth]) {
 871                 for (; isspace((unsigned char)*cp); cp++)
 872                         if (*cp == '\n')
 873                                 linestate = LS_START;
 874                 return (cp);
 875         }
 876         while (*cp != '\0')
 877                 /* don't reset to LS_START after a line continuation */
 878                 if (strncmp(cp, "\\\n", 2) == 0)
 879                         cp += 2;
 880                 else switch (incomment) {
 881                 case NO_COMMENT:
 882                         if (strncmp(cp, "/\\\n", 3) == 0) {
 883                                 incomment = STARTING_COMMENT;
 884                                 cp += 3;
 885                         } else if (strncmp(cp, "/*", 2) == 0) {
 886                                 incomment = C_COMMENT;
 887                                 cp += 2;
 888                         } else if (strncmp(cp, "//", 2) == 0) {
 889                                 incomment = CXX_COMMENT;
 890                                 cp += 2;
 891                         } else if (strncmp(cp, "\'", 1) == 0) {
 892                                 incomment = CHAR_LITERAL;
 893                                 linestate = LS_DIRTY;
 894                                 cp += 1;
 895                         } else if (strncmp(cp, "\"", 1) == 0) {
 896                                 incomment = STRING_LITERAL;
 897                                 linestate = LS_DIRTY;
 898                                 cp += 1;
 899                         } else if (strncmp(cp, "\n", 1) == 0) {
 900                                 linestate = LS_START;
 901                                 cp += 1;
 902                         } else if (strchr(" \t", *cp) != NULL) {
 903                                 cp += 1;
 904                         } else
 905                                 return (cp);
 906                         continue;
 907                 case CXX_COMMENT:
 908                         if (strncmp(cp, "\n", 1) == 0) {
 909                                 incomment = NO_COMMENT;
 910                                 linestate = LS_START;
 911                         }
 912                         cp += 1;
 913                         continue;
 914                 case CHAR_LITERAL:
 915                 case STRING_LITERAL:
 916                         if ((incomment == CHAR_LITERAL && cp[0] == '\'') ||
 917                             (incomment == STRING_LITERAL && cp[0] == '\"')) {
 918                                 incomment = NO_COMMENT;
 919                                 cp += 1;
 920                         } else if (cp[0] == '\\') {
 921                                 if (cp[1] == '\0')
 922                                         cp += 1;
 923                                 else
 924                                         cp += 2;
 925                         } else if (strncmp(cp, "\n", 1) == 0) {
 926                                 if (incomment == CHAR_LITERAL)
 927                                         error("unterminated char literal");
 928                                 else
 929                                         error("unterminated string literal");
 930                         } else
 931                                 cp += 1;
 932                         continue;
 933                 case C_COMMENT:
 934                         if (strncmp(cp, "*\\\n", 3) == 0) {
 935                                 incomment = FINISHING_COMMENT;
 936                                 cp += 3;
 937                         } else if (strncmp(cp, "*/", 2) == 0) {
 938                                 incomment = NO_COMMENT;
 939                                 cp += 2;
 940                         } else
 941                                 cp += 1;
 942                         continue;
 943                 case STARTING_COMMENT:
 944                         if (*cp == '*') {
 945                                 incomment = C_COMMENT;
 946                                 cp += 1;
 947                         } else if (*cp == '/') {
 948                                 incomment = CXX_COMMENT;
 949                                 cp += 1;
 950                         } else {
 951                                 incomment = NO_COMMENT;
 952                                 linestate = LS_DIRTY;
 953                         }
 954                         continue;
 955                 case FINISHING_COMMENT:
 956                         if (*cp == '/') {
 957                                 incomment = NO_COMMENT;
 958                                 cp += 1;
 959                         } else
 960                                 incomment = C_COMMENT;
 961                         continue;
 962                 default:
 963                         abort(); /* bug */
 964                 }
 965         return (cp);
 966 }
 967
 968 /*
 969  * Skip macro arguments.
 970  */
 971 static const char *
 972 skipargs(const char *cp)
 973 {
 974         const char *ocp = cp;
 975         int level = 0;
 976         cp = skipcomment(cp);
 977         if (*cp != '(')
 978                 return (cp);
 979         do {
 980                 if (*cp == '(')
 981                         level++;
 982                 if (*cp == ')')
 983                         level--;
 984                 cp = skipcomment(cp+1);
 985         } while (level != 0 && *cp != '\0');
 986         if (level == 0)
 987                 return (cp);
 988         else
 989         /* Rewind and re-detect the syntax error later. */
 990                 return (ocp);
 991 }
 992
 993 /*
 994  * Skip over an identifier.
 995  */
 996 static const char *
 997 skipsym(const char *cp)
 998 {
 999         while (!endsym(*cp))
1000                 ++cp;
1001         return (cp);
1002 }
1003
1004 /*
1005  * Look for the symbol in the symbol table. If it is found, we return
1006  * the symbol table index, else we return -1.
1007  */
1008 static int
1009 findsym(const char *str)
1010 {
1011         const char *cp;
1012         int symind;
1013
1014         cp = skipsym(str);
1015         if (cp == str)
1016                 return (-1);
1017         if (symlist) {
1018                 printf("%.*s\n", (int)(cp-str), str);
1019                 /* we don't care about the value of the symbol */
1020                 return (0);
1021         }
1022         for (symind = 0; symind < nsyms; ++symind) {
1023                 if (strlcmp(symname[symind], str, cp-str) == 0) {
1024                         debug("findsym %s %s", symname[symind],
1025                             value[symind] ? value[symind] : "");
1026                         return (symind);
1027                 }
1028         }
1029         return (-1);
1030 }
1031
1032 /*
1033  * Add a symbol to the symbol table.
1034  */
1035 static void
1036 addsym(bool ignorethis, bool definethis, char *sym)
1037 {
1038         int symind;
1039         char *val;
1040
1041         symind = findsym(sym);
1042         if (symind < 0) {
1043                 if (nsyms >= MAXSYMS)
1044                         errx(2, "too many symbols");
1045                 symind = nsyms++;
1046         }
1047         symname[symind] = sym;
1048         ignore[symind] = ignorethis;
1049         val = sym + (skipsym(sym) - sym);
1050         if (definethis) {
1051                 if (*val == '=') {
1052                         value[symind] = val+1;
1053                         *val = '\0';
1054                 } else if (*val == '\0')
1055                         value[symind] = "";
1056                 else
1057                         usage();
1058         } else {
1059                 if (*val != '\0')
1060                         usage();
1061                 value[symind] = NULL;
1062         }
1063 }
1064
1065 /*
1066  * Compare s with n characters of t.
1067  * The same as strncmp() except that it checks that s[n] == '\0'.
1068  */
1069 static int
1070 strlcmp(const char *s, const char *t, size_t n)
1071 {
1072         while (n-- && *t != '\0')
1073                 if (*s != *t)
1074                         return ((unsigned char)*s - (unsigned char)*t);
1075                 else
1076                         ++s, ++t;
1077         return ((unsigned char)*s);
1078 }
1079
1080 /*
1081  * Diagnostics.
1082  */
1083 static void
1084 debug(const char *msg, ...)
1085 {
1086         va_list ap;
1087
1088         if (debugging) {
1089                 va_start(ap, msg);
1090                 vwarnx(msg, ap);
1091                 va_end(ap);
1092         }
1093 }
1094
1095 static void
1096 error(const char *msg)
1097 {
1098         if (depth == 0)
1099                 warnx("%s: %d: %s", filename, linenum, msg);
1100         else
1101                 warnx("%s: %d: %s (#if line %d depth %d)",
1102                     filename, linenum, msg, stifline[depth], depth);
1103         errx(2, "output may be truncated");
1104 }