developer_cmds/unifdef/unifdef.c

   1 /*
   2  * Copyright (c) 2002 - 2011 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  * unifdef - remove ifdef'ed lines
  28  *
  29  * This code was derived from software contributed to Berkeley by Dave Yost.
  30  * It was rewritten to support ANSI C by Tony Finch. The original version
  31  * of unifdef carried the 4-clause BSD copyright licence. None of its code
  32  * remains in this version (though some of the names remain) so it now
  33  * carries a more liberal licence.
  34  *
  35  *  Wishlist:
  36  *      provide an option which will append the name of the
  37  *        appropriate symbol after #else's and #endif's
  38  *      provide an option which will check symbols after
  39  *        #else's and #endif's to see that they match their
  40  *        corresponding #ifdef or #ifndef
  41  *
  42  *   These require better buffer handling, which would also make
  43  *   it possible to handle all "dodgy" directives correctly.
  44  */
  45
  46 #include <sys/types.h>
  47 #include <sys/stat.h>
  48
  49 #include <ctype.h>
  50 #include <err.h>
  51 #include <errno.h>
  52 #include <stdarg.h>
  53 #include <stdbool.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58
  59 const char copyright[] =
  60     "@(#) $Version: unifdef-2.5.6.21f1388 $\n"
  61     "@(#) $FreeBSD: src/usr.bin/unifdef/unifdef.c,v 1.31 2011/01/21 18:10:11 fanf Exp $\n"
  62     "@(#) $Author: Tony Finch (dot@dotat.at) $\n"
  63     "@(#) $URL: http://dotat.at/prog/unifdef $\n"
  64 ;
  65
  66 /* types of input lines: */
  67 typedef enum {
  68         LT_TRUEI,               /* a true #if with ignore flag */
  69         LT_FALSEI,              /* a false #if with ignore flag */
  70         LT_IF,                  /* an unknown #if */
  71         LT_TRUE,                /* a true #if */
  72         LT_FALSE,               /* a false #if */
  73         LT_ELIF,                /* an unknown #elif */
  74         LT_ELTRUE,              /* a true #elif */
  75         LT_ELFALSE,             /* a false #elif */
  76         LT_ELSE,                /* #else */
  77         LT_ENDIF,               /* #endif */
  78         LT_DODGY,               /* flag: directive is not on one line */
  79         LT_DODGY_LAST = LT_DODGY + LT_ENDIF,
  80         LT_PLAIN,               /* ordinary line */
  81         LT_EOF,                 /* end of file */
  82         LT_ERROR,               /* unevaluable #if */
  83         LT_COUNT
  84 } Linetype;
  85
  86 static char const * const linetype_name[] = {
  87         "TRUEI", "FALSEI", "IF", "TRUE", "FALSE",
  88         "ELIF", "ELTRUE", "ELFALSE", "ELSE", "ENDIF",
  89         "DODGY TRUEI", "DODGY FALSEI",
  90         "DODGY IF", "DODGY TRUE", "DODGY FALSE",
  91         "DODGY ELIF", "DODGY ELTRUE", "DODGY ELFALSE",
  92         "DODGY ELSE", "DODGY ENDIF",
  93         "PLAIN", "EOF", "ERROR"
  94 };
  95
  96 /* state of #if processing */
  97 typedef enum {
  98         IS_OUTSIDE,
  99         IS_FALSE_PREFIX,        /* false #if followed by false #elifs */
 100         IS_TRUE_PREFIX,         /* first non-false #(el)if is true */
 101         IS_PASS_MIDDLE,         /* first non-false #(el)if is unknown */
 102         IS_FALSE_MIDDLE,        /* a false #elif after a pass state */
 103         IS_TRUE_MIDDLE,         /* a true #elif after a pass state */
 104         IS_PASS_ELSE,           /* an else after a pass state */
 105         IS_FALSE_ELSE,          /* an else after a true state */
 106         IS_TRUE_ELSE,           /* an else after only false states */
 107         IS_FALSE_TRAILER,       /* #elifs after a true are false */
 108         IS_COUNT
 109 } Ifstate;
 110
 111 static char const * const ifstate_name[] = {
 112         "OUTSIDE", "FALSE_PREFIX", "TRUE_PREFIX",
 113         "PASS_MIDDLE", "FALSE_MIDDLE", "TRUE_MIDDLE",
 114         "PASS_ELSE", "FALSE_ELSE", "TRUE_ELSE",
 115         "FALSE_TRAILER"
 116 };
 117
 118 /* state of comment parser */
 119 typedef enum {
 120         NO_COMMENT = false,     /* outside a comment */
 121         C_COMMENT,              /* in a comment like this one */
 122         CXX_COMMENT,            /* between // and end of line */
 123         STARTING_COMMENT,       /* just after slash-backslash-newline */
 124         FINISHING_COMMENT,      /* star-backslash-newline in a C comment */
 125         CHAR_LITERAL,           /* inside '' */
 126         STRING_LITERAL          /* inside "" */
 127 } Comment_state;
 128
 129 static char const * const comment_name[] = {
 130         "NO", "C", "CXX", "STARTING", "FINISHING", "CHAR", "STRING"
 131 };
 132
 133 /* state of preprocessor line parser */
 134 typedef enum {
 135         LS_START,               /* only space and comments on this line */
 136         LS_HASH,                /* only space, comments, and a hash */
 137         LS_DIRTY                /* this line can't be a preprocessor line */
 138 } Line_state;
 139
 140 static char const * const linestate_name[] = {
 141         "START", "HASH", "DIRTY"
 142 };
 143
 144 /*
 145  * Minimum translation limits from ISO/IEC 9899:1999 5.2.4.1
 146  */
 147 #define MAXDEPTH        64                      /* maximum #if nesting */
 148 #define MAXLINE         4096                    /* maximum length of line */
 149 #define MAXSYMS         4096                    /* maximum number of symbols */
 150
 151 /*
 152  * Sometimes when editing a keyword the replacement text is longer, so
 153  * we leave some space at the end of the tline buffer to accommodate this.
 154  */
 155 #define EDITSLOP        10
 156
 157 /*
 158  * For temporary filenames
 159  */
 160 #define TEMPLATE        "unifdef.XXXXXX"
 161
 162 /*
 163  * Globals.
 164  */
 165
 166 static bool             compblank;              /* -B: compress blank lines */
 167 static bool             lnblank;                /* -b: blank deleted lines */
 168 static bool             complement;             /* -c: do the complement */
 169 static bool             debugging;              /* -d: debugging reports */
 170 static bool             iocccok;                /* -e: fewer IOCCC errors */
 171 static bool             strictlogic;            /* -K: keep ambiguous #ifs */
 172 static bool             killconsts;             /* -k: eval constant #ifs */
 173 static bool             lnnum;                  /* -n: add #line directives */
 174 static bool             symlist;                /* -s: output symbol list */
 175 static bool             symdepth;               /* -S: output symbol depth */
 176 static bool             text;                   /* -t: this is a text file */
 177
 178 static const char      *symname[MAXSYMS];       /* symbol name */
 179 static const char      *value[MAXSYMS];         /* -Dsym=value */
 180 static bool             ignore[MAXSYMS];        /* -iDsym or -iUsym */
 181 static int              nsyms;                  /* number of symbols */
 182
 183 static FILE            *input;                  /* input file pointer */
 184 static const char      *filename;               /* input file name */
 185 static int              linenum;                /* current line number */
 186 static FILE            *output;                 /* output file pointer */
 187 static const char      *ofilename;              /* output file name */
 188 static bool             overwriting;            /* output overwrites input */
 189 static char             tempname[FILENAME_MAX]; /* used when overwriting */
 190
 191 static char             tline[MAXLINE+EDITSLOP];/* input buffer plus space */
 192 static char            *keyword;                /* used for editing #elif's */
 193
 194 static const char      *newline;                /* input file format */
 195 static const char       newline_unix[] = "\n";
 196 static const char       newline_crlf[] = "\r\n";
 197
 198 static Comment_state    incomment;              /* comment parser state */
 199 static Line_state       linestate;              /* #if line parser state */
 200 static Ifstate          ifstate[MAXDEPTH];      /* #if processor state */
 201 static bool             ignoring[MAXDEPTH];     /* ignore comments state */
 202 static int              stifline[MAXDEPTH];     /* start of current #if */
 203 static int              depth;                  /* current #if nesting */
 204 static int              delcount;               /* count of deleted lines */
 205 static unsigned         blankcount;             /* count of blank lines */
 206 static unsigned         blankmax;               /* maximum recent blankcount */
 207 static bool             constexpr;              /* constant #if expression */
 208 static bool             zerosyms = true;        /* to format symdepth output */
 209 static bool             firstsym;               /* ditto */
 210
 211 static int              exitstat;               /* program exit status */
 212
 213 static void             addsym(bool, bool, char *);
 214 static void             closeout(void);
 215 static void             debug(const char *, ...);
 216 static void             done(void);
 217 static void             error(const char *);
 218 static int              findsym(const char *);
 219 static void             flushline(bool);
 220 static Linetype         parseline(void);
 221 static Linetype         ifeval(const char **);
 222 static void             ignoreoff(void);
 223 static void             ignoreon(void);
 224 static void             keywordedit(const char *);
 225 static void             nest(void);
 226 static void             process(void);
 227 static const char      *skipargs(const char *);
 228 static const char      *skipcomment(const char *);
 229 static const char      *skipsym(const char *);
 230 static void             state(Ifstate);
 231 static int              strlcmp(const char *, const char *, size_t);
 232 static void             unnest(void);
 233 static void             usage(void);
 234 static void             version(void);
 235
 236 #define endsym(c) (!isalnum((unsigned char)c) && c != '_')
 237
 238 /*
 239  * The main program.
 240  */
 241 int
 242 main(int argc, char *argv[])
 243 {
 244         int opt;
 245
 246         while ((opt = getopt(argc, argv, "i:D:U:I:o:bBcdeKklnsStV")) != -1)
 247                 switch (opt) {
 248                 case 'i': /* treat stuff controlled by these symbols as text */
 249                         /*
 250                          * For strict backwards-compatibility the U or D
 251                          * should be immediately after the -i but it doesn't
 252                          * matter much if we relax that requirement.
 253                          */
 254                         opt = *optarg++;
 255                         if (opt == 'D')
 256                                 addsym(true, true, optarg);
 257                         else if (opt == 'U')
 258                                 addsym(true, false, optarg);
 259                         else
 260                                 usage();
 261                         break;
 262                 case 'D': /* define a symbol */
 263                         addsym(false, true, optarg);
 264                         break;
 265                 case 'U': /* undef a symbol */
 266                         addsym(false, false, optarg);
 267                         break;
 268                 case 'I': /* no-op for compatibility with cpp */
 269                         break;
 270                 case 'b': /* blank deleted lines instead of omitting them */
 271                 case 'l': /* backwards compatibility */
 272                         lnblank = true;
 273                         break;
 274                 case 'B': /* compress blank lines around removed section */
 275                         compblank = true;
 276                         break;
 277                 case 'c': /* treat -D as -U and vice versa */
 278                         complement = true;
 279                         break;
 280                 case 'd':
 281                         debugging = true;
 282                         break;
 283                 case 'e': /* fewer errors from dodgy lines */
 284                         iocccok = true;
 285                         break;
 286                 case 'K': /* keep ambiguous #ifs */
 287                         strictlogic = true;
 288                         break;
 289                 case 'k': /* process constant #ifs */
 290                         killconsts = true;
 291                         break;
 292                 case 'n': /* add #line directive after deleted lines */
 293                         lnnum = true;
 294                         break;
 295                 case 'o': /* output to a file */
 296                         ofilename = optarg;
 297                         break;
 298                 case 's': /* only output list of symbols that control #ifs */
 299                         symlist = true;
 300                         break;
 301                 case 'S': /* list symbols with their nesting depth */
 302                         symlist = symdepth = true;
 303                         break;
 304                 case 't': /* don't parse C comments */
 305                         text = true;
 306                         break;
 307                 case 'V': /* print version */
 308                         version();
 309                 default:
 310                         usage();
 311                 }
 312         argc -= optind;
 313         argv += optind;
 314         if (compblank && lnblank)
 315                 errx(2, "-B and -b are mutually exclusive");
 316         if (argc > 1) {
 317                 errx(2, "can only do one file");
 318         } else if (argc == 1 && strcmp(*argv, "-") != 0) {
 319                 filename = *argv;
 320                 input = fopen(filename, "rb");
 321                 if (input == NULL)
 322                         err(2, "can't open %s", filename);
 323         } else {
 324                 filename = "[stdin]";
 325                 input = stdin;
 326         }
 327         if (ofilename == NULL) {
 328                 ofilename = "[stdout]";
 329                 output = stdout;
 330         } else {
 331                 struct stat ist, ost;
 332                 if (stat(ofilename, &ost) == 0 &&
 333                     fstat(fileno(input), &ist) == 0)
 334                         overwriting = (ist.st_dev == ost.st_dev
 335                                     && ist.st_ino == ost.st_ino);
 336                 if (overwriting) {
 337                         const char *dirsep;
 338                         int ofd;
 339
 340                         dirsep = strrchr(ofilename, '/');
 341                         if (dirsep != NULL)
 342                                 snprintf(tempname, sizeof(tempname),
 343                                     "%.*s/" TEMPLATE,
 344                                     (int)(dirsep - ofilename), ofilename);
 345                         else
 346                                 snprintf(tempname, sizeof(tempname),
 347                                     TEMPLATE);
 348                         ofd = mkstemp(tempname);
 349                         if (ofd != -1)
 350                                 output = fdopen(ofd, "wb+");
 351                         if (output == NULL)
 352                                 err(2, "can't create temporary file");
 353                         fchmod(ofd, ist.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO));
 354                 } else {
 355                         output = fopen(ofilename, "wb");
 356                         if (output == NULL)
 357                                 err(2, "can't open %s", ofilename);
 358                 }
 359         }
 360         process();
 361         abort(); /* bug */
 362 }
 363
 364 static void
 365 version(void)
 366 {
 367         const char *c = copyright;
 368         for (;;) {
 369                 while (*++c != '$')
 370                         if (*c == '\0')
 371                                 exit(0);
 372                 while (*++c != '$')
 373                         putc(*c, stderr);
 374                 putc('\n', stderr);
 375         }
 376 }
 377
 378 static void
 379 usage(void)
 380 {
 381         fprintf(stderr, "usage: unifdef [-bBcdeKknsStV] [-Ipath]"
 382             " [-Dsym[=val]] [-Usym] [-iDsym[=val]] [-iUsym] ... [file]\n");
 383         exit(2);
 384 }
 385
 386 /*
 387  * A state transition function alters the global #if processing state
 388  * in a particular way. The table below is indexed by the current
 389  * processing state and the type of the current line.
 390  *
 391  * Nesting is handled by keeping a stack of states; some transition
 392  * functions increase or decrease the depth. They also maintain the
 393  * ignore state on a stack. In some complicated cases they have to
 394  * alter the preprocessor directive, as follows.
 395  *
 396  * When we have processed a group that starts off with a known-false
 397  * #if/#elif sequence (which has therefore been deleted) followed by a
 398  * #elif that we don't understand and therefore must keep, we edit the
 399  * latter into a #if to keep the nesting correct. We use strncpy() to
 400  * overwrite the 4 byte token "elif" with "if  " without a '\0' byte.
 401  *
 402  * When we find a true #elif in a group, the following block will
 403  * always be kept and the rest of the sequence after the next #elif or
 404  * #else will be discarded. We edit the #elif into a #else and the
 405  * following directive to #endif since this has the desired behaviour.
 406  *
 407  * "Dodgy" directives are split across multiple lines, the most common
 408  * example being a multi-line comment hanging off the right of the
 409  * directive. We can handle them correctly only if there is no change
 410  * from printing to dropping (or vice versa) caused by that directive.
 411  * If the directive is the first of a group we have a choice between
 412  * failing with an error, or passing it through unchanged instead of
 413  * evaluating it. The latter is not the default to avoid questions from
 414  * users about unifdef unexpectedly leaving behind preprocessor directives.
 415  */
 416 typedef void state_fn(void);
 417
 418 /* report an error */
 419 static void Eelif (void) { error("Inappropriate #elif"); }
 420 static void Eelse (void) { error("Inappropriate #else"); }
 421 static void Eendif(void) { error("Inappropriate #endif"); }
 422 static void Eeof  (void) { error("Premature EOF"); }
 423 static void Eioccc(void) { error("Obfuscated preprocessor control line"); }
 424 /* plain line handling */
 425 static void print (void) { flushline(true); }
 426 static void drop  (void) { flushline(false); }
 427 /* output lacks group's start line */
 428 static void Strue (void) { drop();  ignoreoff(); state(IS_TRUE_PREFIX); }
 429 static void Sfalse(void) { drop();  ignoreoff(); state(IS_FALSE_PREFIX); }
 430 static void Selse (void) { drop();               state(IS_TRUE_ELSE); }
 431 /* print/pass this block */
 432 static void Pelif (void) { print(); ignoreoff(); state(IS_PASS_MIDDLE); }
 433 static void Pelse (void) { print();              state(IS_PASS_ELSE); }
 434 static void Pendif(void) { print(); unnest(); }
 435 /* discard this block */
 436 static void Dfalse(void) { drop();  ignoreoff(); state(IS_FALSE_TRAILER); }
 437 static void Delif (void) { drop();  ignoreoff(); state(IS_FALSE_MIDDLE); }
 438 static void Delse (void) { drop();               state(IS_FALSE_ELSE); }
 439 static void Dendif(void) { drop();  unnest(); }
 440 /* first line of group */
 441 static void Fdrop (void) { nest();  Dfalse(); }
 442 static void Fpass (void) { nest();  Pelif(); }
 443 static void Ftrue (void) { nest();  Strue(); }
 444 static void Ffalse(void) { nest();  Sfalse(); }
 445 /* variable pedantry for obfuscated lines */
 446 static void Oiffy (void) { if (!iocccok) Eioccc(); Fpass(); ignoreon(); }
 447 static void Oif   (void) { if (!iocccok) Eioccc(); Fpass(); }
 448 static void Oelif (void) { if (!iocccok) Eioccc(); Pelif(); }
 449 /* ignore comments in this block */
 450 static void Idrop (void) { Fdrop();  ignoreon(); }
 451 static void Itrue (void) { Ftrue();  ignoreon(); }
 452 static void Ifalse(void) { Ffalse(); ignoreon(); }
 453 /* modify this line */
 454 static void Mpass (void) { strncpy(keyword, "if  ", 4); Pelif(); }
 455 static void Mtrue (void) { keywordedit("else");  state(IS_TRUE_MIDDLE); }
 456 static void Melif (void) { keywordedit("endif"); state(IS_FALSE_TRAILER); }
 457 static void Melse (void) { keywordedit("endif"); state(IS_FALSE_ELSE); }
 458
 459 static state_fn * const trans_table[IS_COUNT][LT_COUNT] = {
 460 /* IS_OUTSIDE */
 461 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Eendif,
 462   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eendif,
 463   print, done,  abort },
 464 /* IS_FALSE_PREFIX */
 465 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Strue, Sfalse,Selse, Dendif,
 466   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Eioccc,Eioccc,Eioccc,Eioccc,
 467   drop,  Eeof,  abort },
 468 /* IS_TRUE_PREFIX */
 469 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Dfalse,Dfalse,Dfalse,Delse, Dendif,
 470   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
 471   print, Eeof,  abort },
 472 /* IS_PASS_MIDDLE */
 473 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Pelif, Mtrue, Delif, Pelse, Pendif,
 474   Oiffy, Oiffy, Fpass, Oif,   Oif,   Pelif, Oelif, Oelif, Pelse, Pendif,
 475   print, Eeof,  abort },
 476 /* IS_FALSE_MIDDLE */
 477 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Pelif, Mtrue, Delif, Pelse, Pendif,
 478   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
 479   drop,  Eeof,  abort },
 480 /* IS_TRUE_MIDDLE */
 481 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Melif, Melif, Melif, Melse, Pendif,
 482   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Pendif,
 483   print, Eeof,  abort },
 484 /* IS_PASS_ELSE */
 485 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Pendif,
 486   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Pendif,
 487   print, Eeof,  abort },
 488 /* IS_FALSE_ELSE */
 489 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Dendif,
 490   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Eioccc,
 491   drop,  Eeof,  abort },
 492 /* IS_TRUE_ELSE */
 493 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Dendif,
 494   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eioccc,
 495   print, Eeof,  abort },
 496 /* IS_FALSE_TRAILER */
 497 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Dendif,
 498   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Eioccc,
 499   drop,  Eeof,  abort }
 500 /*TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF
 501   TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF (DODGY)
 502   PLAIN  EOF    ERROR */
 503 };
 504
 505 /*
 506  * State machine utility functions
 507  */
 508 static void
 509 ignoreoff(void)
 510 {
 511         if (depth == 0)
 512                 abort(); /* bug */
 513         ignoring[depth] = ignoring[depth-1];
 514 }
 515 static void
 516 ignoreon(void)
 517 {
 518         ignoring[depth] = true;
 519 }
 520 static void
 521 keywordedit(const char *replacement)
 522 {
 523         snprintf(keyword, tline + sizeof(tline) - keyword,
 524             "%s%s", replacement, newline);
 525         print();
 526 }
 527 static void
 528 nest(void)
 529 {
 530         if (depth > MAXDEPTH-1)
 531                 abort(); /* bug */
 532         if (depth == MAXDEPTH-1)
 533                 error("Too many levels of nesting");
 534         depth += 1;
 535         stifline[depth] = linenum;
 536 }
 537 static void
 538 unnest(void)
 539 {
 540         if (depth == 0)
 541                 abort(); /* bug */
 542         depth -= 1;
 543 }
 544 static void
 545 state(Ifstate is)
 546 {
 547         ifstate[depth] = is;
 548 }
 549
 550 /*
 551  * Write a line to the output or not, according to command line options.
 552  * If writing fails, closeout() will print the error and exit.
 553  */
 554 static void
 555 flushline(bool keep)
 556 {
 557         if (symlist)
 558                 return;
 559         if (keep ^ complement) {
 560                 bool blankline = tline[strspn(tline, " \t\r\n")] == '\0';
 561                 if (blankline && compblank && blankcount != blankmax) {
 562                         delcount += 1;
 563                         blankcount += 1;
 564                 } else {
 565                         if (lnnum && delcount > 0 &&
 566                             fprintf(output, "#line %d%s", linenum, newline) < 0)
 567                                 closeout();
 568                         if (fputs(tline, output) == EOF)
 569                                 closeout();
 570                         delcount = 0;
 571                         blankmax = blankcount = blankline ? blankcount + 1 : 0;
 572                 }
 573         } else {
 574                 if (lnblank && fputs(newline, output) == EOF)
 575                         closeout();
 576                 exitstat = 1;
 577                 delcount += 1;
 578                 blankcount = 0;
 579         }
 580         if (debugging && fflush(output) == EOF)
 581                 closeout();
 582 }
 583
 584 /*
 585  * The driver for the state machine.
 586  */
 587 static void
 588 process(void)
 589 {
 590         /* When compressing blank lines, act as if the file
 591            is preceded by a large number of blank lines. */
 592         blankmax = blankcount = 1000;
 593         for (;;) {
 594                 Linetype lineval = parseline();
 595                 trans_table[ifstate[depth]][lineval]();
 596                 debug("process line %d %s -> %s depth %d",
 597                     linenum, linetype_name[lineval],
 598                     ifstate_name[ifstate[depth]], depth);
 599         }
 600 }
 601
 602 /*
 603  * Flush the output and handle errors.
 604  */
 605 static void
 606 closeout(void)
 607 {
 608         if (symdepth && !zerosyms)
 609                 printf("\n");
 610         if (ferror(output) || fclose(output) == EOF) {
 611                 if (overwriting) {
 612                         warn("couldn't write to temporary file");
 613                         unlink(tempname);
 614                         errx(2, "%s unchanged", ofilename);
 615                 } else {
 616                         err(2, "couldn't write to %s", ofilename);
 617                 }
 618         }
 619 }
 620
 621 /*
 622  * Clean up and exit.
 623  */
 624 static void
 625 done(void)
 626 {
 627         if (incomment)
 628                 error("EOF in comment");
 629         closeout();
 630         if (overwriting && rename(tempname, ofilename) == -1) {
 631                 warn("couldn't rename temporary file");
 632                 unlink(tempname);
 633                 errx(2, "%s unchanged", ofilename);
 634         }
 635         exit(exitstat);
 636 }
 637
 638 /*
 639  * Parse a line and determine its type. We keep the preprocessor line
 640  * parser state between calls in the global variable linestate, with
 641  * help from skipcomment().
 642  */
 643 static Linetype
 644 parseline(void)
 645 {
 646         const char *cp;
 647         int cursym;
 648         int kwlen;
 649         Linetype retval;
 650         Comment_state wascomment;
 651
 652         linenum++;
 653         if (fgets(tline, MAXLINE, input) == NULL) {
 654                 if (ferror(input))
 655                         error(strerror(errno));
 656                 else
 657                         return (LT_EOF);
 658         }
 659         if (newline == NULL) {
 660                 if (strrchr(tline, '\n') == strrchr(tline, '\r') + 1)
 661                         newline = newline_crlf;
 662                 else
 663                         newline = newline_unix;
 664         }
 665         retval = LT_PLAIN;
 666         wascomment = incomment;
 667         cp = skipcomment(tline);
 668         if (linestate == LS_START) {
 669                 if (*cp == '#') {
 670                         linestate = LS_HASH;
 671                         firstsym = true;
 672                         cp = skipcomment(cp + 1);
 673                 } else if (*cp != '\0')
 674                         linestate = LS_DIRTY;
 675         }
 676         if (!incomment && linestate == LS_HASH) {
 677                 keyword = tline + (cp - tline);
 678                 cp = skipsym(cp);
 679                 kwlen = cp - keyword;
 680                 /* no way can we deal with a continuation inside a keyword */
 681                 if (strncmp(cp, "\\\r\n", 3) == 0 ||
 682                     strncmp(cp, "\\\n", 2) == 0)
 683                         Eioccc();
 684                 if (strlcmp("ifdef", keyword, kwlen) == 0 ||
 685                     strlcmp("ifndef", keyword, kwlen) == 0) {
 686                         cp = skipcomment(cp);
 687                         if ((cursym = findsym(cp)) < 0)
 688                                 retval = LT_IF;
 689                         else {
 690                                 retval = (keyword[2] == 'n')
 691                                     ? LT_FALSE : LT_TRUE;
 692                                 if (value[cursym] == NULL)
 693                                         retval = (retval == LT_TRUE)
 694                                             ? LT_FALSE : LT_TRUE;
 695                                 if (ignore[cursym])
 696                                         retval = (retval == LT_TRUE)
 697                                             ? LT_TRUEI : LT_FALSEI;
 698                         }
 699                         cp = skipsym(cp);
 700                 } else if (strlcmp("if", keyword, kwlen) == 0)
 701                         retval = ifeval(&cp);
 702                 else if (strlcmp("elif", keyword, kwlen) == 0)
 703                         retval = ifeval(&cp) - LT_IF + LT_ELIF;
 704                 else if (strlcmp("else", keyword, kwlen) == 0)
 705                         retval = LT_ELSE;
 706                 else if (strlcmp("endif", keyword, kwlen) == 0)
 707                         retval = LT_ENDIF;
 708                 else {
 709                         linestate = LS_DIRTY;
 710                         retval = LT_PLAIN;
 711                 }
 712                 cp = skipcomment(cp);
 713                 if (*cp != '\0') {
 714                         linestate = LS_DIRTY;
 715                         if (retval == LT_TRUE || retval == LT_FALSE ||
 716                             retval == LT_TRUEI || retval == LT_FALSEI)
 717                                 retval = LT_IF;
 718                         if (retval == LT_ELTRUE || retval == LT_ELFALSE)
 719                                 retval = LT_ELIF;
 720                 }
 721                 if (retval != LT_PLAIN && (wascomment || incomment)) {
 722                         retval += LT_DODGY;
 723                         if (incomment)
 724                                 linestate = LS_DIRTY;
 725                 }
 726                 /* skipcomment normally changes the state, except
 727                    if the last line of the file lacks a newline, or
 728                    if there is too much whitespace in a directive */
 729                 if (linestate == LS_HASH) {
 730                         size_t len = cp - tline;
 731                         if (fgets(tline + len, MAXLINE - len, input) == NULL) {
 732                                 if (ferror(input))
 733                                         error(strerror(errno));
 734                                 /* append the missing newline at eof */
 735                                 strcpy(tline + len, newline);
 736                                 cp += strlen(newline);
 737                                 linestate = LS_START;
 738                         } else {
 739                                 linestate = LS_DIRTY;
 740                         }
 741                 }
 742         }
 743         if (linestate == LS_DIRTY) {
 744                 while (*cp != '\0')
 745                         cp = skipcomment(cp + 1);
 746         }
 747         debug("parser line %d state %s comment %s line", linenum,
 748             comment_name[incomment], linestate_name[linestate]);
 749         return (retval);
 750 }
 751
 752 /*
 753  * These are the binary operators that are supported by the expression
 754  * evaluator.
 755  */
 756 static Linetype op_strict(int *p, int v, Linetype at, Linetype bt) {
 757         if(at == LT_IF || bt == LT_IF) return (LT_IF);
 758         return (*p = v, v ? LT_TRUE : LT_FALSE);
 759 }
 760 static Linetype op_lt(int *p, Linetype at, int a, Linetype bt, int b) {
 761         return op_strict(p, a < b, at, bt);
 762 }
 763 static Linetype op_gt(int *p, Linetype at, int a, Linetype bt, int b) {
 764         return op_strict(p, a > b, at, bt);
 765 }
 766 static Linetype op_le(int *p, Linetype at, int a, Linetype bt, int b) {
 767         return op_strict(p, a <= b, at, bt);
 768 }
 769 static Linetype op_ge(int *p, Linetype at, int a, Linetype bt, int b) {
 770         return op_strict(p, a >= b, at, bt);
 771 }
 772 static Linetype op_eq(int *p, Linetype at, int a, Linetype bt, int b) {
 773         return op_strict(p, a == b, at, bt);
 774 }
 775 static Linetype op_ne(int *p, Linetype at, int a, Linetype bt, int b) {
 776         return op_strict(p, a != b, at, bt);
 777 }
 778 static Linetype op_or(int *p, Linetype at, int a, Linetype bt, int b) {
 779         if (!strictlogic && (at == LT_TRUE || bt == LT_TRUE))
 780                 return (*p = 1, LT_TRUE);
 781         return op_strict(p, a || b, at, bt);
 782 }
 783 static Linetype op_and(int *p, Linetype at, int a, Linetype bt, int b) {
 784         if (!strictlogic && (at == LT_FALSE || bt == LT_FALSE))
 785                 return (*p = 0, LT_FALSE);
 786         return op_strict(p, a && b, at, bt);
 787 }
 788
 789 /*
 790  * An evaluation function takes three arguments, as follows: (1) a pointer to
 791  * an element of the precedence table which lists the operators at the current
 792  * level of precedence; (2) a pointer to an integer which will receive the
 793  * value of the expression; and (3) a pointer to a char* that points to the
 794  * expression to be evaluated and that is updated to the end of the expression
 795  * when evaluation is complete. The function returns LT_FALSE if the value of
 796  * the expression is zero, LT_TRUE if it is non-zero, LT_IF if the expression
 797  * depends on an unknown symbol, or LT_ERROR if there is a parse failure.
 798  */
 799 struct ops;
 800
 801 typedef Linetype eval_fn(const struct ops *, int *, const char **);
 802
 803 static eval_fn eval_table, eval_unary;
 804
 805 /*
 806  * The precedence table. Expressions involving binary operators are evaluated
 807  * in a table-driven way by eval_table. When it evaluates a subexpression it
 808  * calls the inner function with its first argument pointing to the next
 809  * element of the table. Innermost expressions have special non-table-driven
 810  * handling.
 811  */
 812 static const struct ops {
 813         eval_fn *inner;
 814         struct op {
 815                 const char *str;
 816                 Linetype (*fn)(int *, Linetype, int, Linetype, int);
 817         } op[5];
 818 } eval_ops[] = {
 819         { eval_table, { { "||", op_or } } },
 820         { eval_table, { { "&&", op_and } } },
 821         { eval_table, { { "==", op_eq },
 822                         { "!=", op_ne } } },
 823         { eval_unary, { { "<=", op_le },
 824                         { ">=", op_ge },
 825                         { "<", op_lt },
 826                         { ">", op_gt } } }
 827 };
 828
 829 /*
 830  * Function for evaluating the innermost parts of expressions,
 831  * viz. !expr (expr) number defined(symbol) symbol
 832  * We reset the constexpr flag in the last two cases.
 833  */
 834 static Linetype
 835 eval_unary(const struct ops *ops, int *valp, const char **cpp)
 836 {
 837         const char *cp;
 838         char *ep;
 839         int sym;
 840         bool defparen;
 841         Linetype lt;
 842
 843         cp = skipcomment(*cpp);
 844         if (*cp == '!') {
 845                 debug("eval%d !", ops - eval_ops);
 846                 cp++;
 847                 lt = eval_unary(ops, valp, &cp);
 848                 if (lt == LT_ERROR)
 849                         return (LT_ERROR);
 850                 if (lt != LT_IF) {
 851                         *valp = !*valp;
 852                         lt = *valp ? LT_TRUE : LT_FALSE;
 853                 }
 854         } else if (*cp == '(') {
 855                 cp++;
 856                 debug("eval%d (", ops - eval_ops);
 857                 lt = eval_table(eval_ops, valp, &cp);
 858                 if (lt == LT_ERROR)
 859                         return (LT_ERROR);
 860                 cp = skipcomment(cp);
 861                 if (*cp++ != ')')
 862                         return (LT_ERROR);
 863         } else if (isdigit((unsigned char)*cp)) {
 864                 debug("eval%d number", ops - eval_ops);
 865                 *valp = strtol(cp, &ep, 0);
 866                 if (ep == cp)
 867                         return (LT_ERROR);
 868                 lt = *valp ? LT_TRUE : LT_FALSE;
 869                 cp = skipsym(cp);
 870         } else if (strncmp(cp, "defined", 7) == 0 && endsym(cp[7])) {
 871                 cp = skipcomment(cp+7);
 872                 debug("eval%d defined", ops - eval_ops);
 873                 if (*cp == '(') {
 874                         cp = skipcomment(cp+1);
 875                         defparen = true;
 876                 } else {
 877                         defparen = false;
 878                 }
 879                 sym = findsym(cp);
 880                 if (sym < 0) {
 881                         lt = LT_IF;
 882                 } else {
 883                         *valp = (value[sym] != NULL);
 884                         lt = *valp ? LT_TRUE : LT_FALSE;
 885                 }
 886                 cp = skipsym(cp);
 887                 cp = skipcomment(cp);
 888                 if (defparen && *cp++ != ')')
 889                         return (LT_ERROR);
 890                 constexpr = false;
 891         } else if (!endsym(*cp)) {
 892                 debug("eval%d symbol", ops - eval_ops);
 893                 sym = findsym(cp);
 894                 cp = skipsym(cp);
 895                 if (sym < 0) {
 896                         lt = LT_IF;
 897                         cp = skipargs(cp);
 898                 } else if (value[sym] == NULL) {
 899                         *valp = 0;
 900                         lt = LT_FALSE;
 901                 } else {
 902                         *valp = strtol(value[sym], &ep, 0);
 903                         if (*ep != '\0' || ep == value[sym])
 904                                 return (LT_ERROR);
 905                         lt = *valp ? LT_TRUE : LT_FALSE;
 906                         cp = skipargs(cp);
 907                 }
 908                 constexpr = false;
 909         } else {
 910                 debug("eval%d bad expr", ops - eval_ops);
 911                 return (LT_ERROR);
 912         }
 913
 914         *cpp = cp;
 915         debug("eval%d = %d", ops - eval_ops, *valp);
 916         return (lt);
 917 }
 918
 919 /*
 920  * Table-driven evaluation of binary operators.
 921  */
 922 static Linetype
 923 eval_table(const struct ops *ops, int *valp, const char **cpp)
 924 {
 925         const struct op *op;
 926         const char *cp;
 927         int val;
 928         Linetype lt, rt;
 929
 930         debug("eval%d", ops - eval_ops);
 931         cp = *cpp;
 932         lt = ops->inner(ops+1, valp, &cp);
 933         if (lt == LT_ERROR)
 934                 return (LT_ERROR);
 935         for (;;) {
 936                 cp = skipcomment(cp);
 937                 for (op = ops->op; op->str != NULL; op++)
 938                         if (strncmp(cp, op->str, strlen(op->str)) == 0)
 939                                 break;
 940                 if (op->str == NULL)
 941                         break;
 942                 cp += strlen(op->str);
 943                 debug("eval%d %s", ops - eval_ops, op->str);
 944                 rt = ops->inner(ops+1, &val, &cp);
 945                 if (rt == LT_ERROR)
 946                         return (LT_ERROR);
 947                 lt = op->fn(valp, lt, *valp, rt, val);
 948         }
 949
 950         *cpp = cp;
 951         debug("eval%d = %d", ops - eval_ops, *valp);
 952         debug("eval%d lt = %s", ops - eval_ops, linetype_name[lt]);
 953         return (lt);
 954 }
 955
 956 /*
 957  * Evaluate the expression on a #if or #elif line. If we can work out
 958  * the result we return LT_TRUE or LT_FALSE accordingly, otherwise we
 959  * return just a generic LT_IF.
 960  */
 961 static Linetype
 962 ifeval(const char **cpp)
 963 {
 964         int ret;
 965         int val = 0;
 966
 967         debug("eval %s", *cpp);
 968         constexpr = killconsts ? false : true;
 969         ret = eval_table(eval_ops, &val, cpp);
 970         debug("eval = %d", val);
 971         return (constexpr ? LT_IF : ret == LT_ERROR ? LT_IF : ret);
 972 }
 973
 974 /*
 975  * Skip over comments, strings, and character literals and stop at the
 976  * next character position that is not whitespace. Between calls we keep
 977  * the comment state in the global variable incomment, and we also adjust
 978  * the global variable linestate when we see a newline.
 979  * XXX: doesn't cope with the buffer splitting inside a state transition.
 980  */
 981 static const char *
 982 skipcomment(const char *cp)
 983 {
 984         if (text || ignoring[depth]) {
 985                 for (; isspace((unsigned char)*cp); cp++)
 986                         if (*cp == '\n')
 987                                 linestate = LS_START;
 988                 return (cp);
 989         }
 990         while (*cp != '\0')
 991                 /* don't reset to LS_START after a line continuation */
 992                 if (strncmp(cp, "\\\r\n", 3) == 0)
 993                         cp += 3;
 994                 else if (strncmp(cp, "\\\n", 2) == 0)
 995                         cp += 2;
 996                 else switch (incomment) {
 997                 case NO_COMMENT:
 998                         if (strncmp(cp, "/\\\r\n", 4) == 0) {
 999                                 incomment = STARTING_COMMENT;
1000                                 cp += 4;
1001                         } else if (strncmp(cp, "/\\\n", 3) == 0) {
1002                                 incomment = STARTING_COMMENT;
1003                                 cp += 3;
1004                         } else if (strncmp(cp, "/*", 2) == 0) {
1005                                 incomment = C_COMMENT;
1006                                 cp += 2;
1007                         } else if (strncmp(cp, "//", 2) == 0) {
1008                                 incomment = CXX_COMMENT;
1009                                 cp += 2;
1010                         } else if (strncmp(cp, "\'", 1) == 0) {
1011                                 incomment = CHAR_LITERAL;
1012                                 linestate = LS_DIRTY;
1013                                 cp += 1;
1014                         } else if (strncmp(cp, "\"", 1) == 0) {
1015                                 incomment = STRING_LITERAL;
1016                                 linestate = LS_DIRTY;
1017                                 cp += 1;
1018                         } else if (strncmp(cp, "\n", 1) == 0) {
1019                                 linestate = LS_START;
1020                                 cp += 1;
1021                         } else if (strchr(" \r\t", *cp) != NULL) {
1022                                 cp += 1;
1023                         } else
1024                                 return (cp);
1025                         continue;
1026                 case CXX_COMMENT:
1027                         if (strncmp(cp, "\n", 1) == 0) {
1028                                 incomment = NO_COMMENT;
1029                                 linestate = LS_START;
1030                         }
1031                         cp += 1;
1032                         continue;
1033                 case CHAR_LITERAL:
1034                 case STRING_LITERAL:
1035                         if ((incomment == CHAR_LITERAL && cp[0] == '\'') ||
1036                             (incomment == STRING_LITERAL && cp[0] == '\"')) {
1037                                 incomment = NO_COMMENT;
1038                                 cp += 1;
1039                         } else if (cp[0] == '\\') {
1040                                 if (cp[1] == '\0')
1041                                         cp += 1;
1042                                 else
1043                                         cp += 2;
1044                         } else if (strncmp(cp, "\n", 1) == 0) {
1045                                 if (incomment == CHAR_LITERAL)
1046                                         error("unterminated char literal");
1047                                 else
1048                                         error("unterminated string literal");
1049                         } else
1050                                 cp += 1;
1051                         continue;
1052                 case C_COMMENT:
1053                         if (strncmp(cp, "*\\\r\n", 4) == 0) {
1054                                 incomment = FINISHING_COMMENT;
1055                                 cp += 4;
1056                         } else if (strncmp(cp, "*\\\n", 3) == 0) {
1057                                 incomment = FINISHING_COMMENT;
1058                                 cp += 3;
1059                         } else if (strncmp(cp, "*/", 2) == 0) {
1060                                 incomment = NO_COMMENT;
1061                                 cp += 2;
1062                         } else
1063                                 cp += 1;
1064                         continue;
1065                 case STARTING_COMMENT:
1066                         if (*cp == '*') {
1067                                 incomment = C_COMMENT;
1068                                 cp += 1;
1069                         } else if (*cp == '/') {
1070                                 incomment = CXX_COMMENT;
1071                                 cp += 1;
1072                         } else {
1073                                 incomment = NO_COMMENT;
1074                                 linestate = LS_DIRTY;
1075                         }
1076                         continue;
1077                 case FINISHING_COMMENT:
1078                         if (*cp == '/') {
1079                                 incomment = NO_COMMENT;
1080                                 cp += 1;
1081                         } else
1082                                 incomment = C_COMMENT;
1083                         continue;
1084                 default:
1085                         abort(); /* bug */
1086                 }
1087         return (cp);
1088 }
1089
1090 /*
1091  * Skip macro arguments.
1092  */
1093 static const char *
1094 skipargs(const char *cp)
1095 {
1096         const char *ocp = cp;
1097         int level = 0;
1098         cp = skipcomment(cp);
1099         if (*cp != '(')
1100                 return (cp);
1101         do {
1102                 if (*cp == '(')
1103                         level++;
1104                 if (*cp == ')')
1105                         level--;
1106                 cp = skipcomment(cp+1);
1107         } while (level != 0 && *cp != '\0');
1108         if (level == 0)
1109                 return (cp);
1110         else
1111         /* Rewind and re-detect the syntax error later. */
1112                 return (ocp);
1113 }
1114
1115 /*
1116  * Skip over an identifier.
1117  */
1118 static const char *
1119 skipsym(const char *cp)
1120 {
1121         while (!endsym(*cp))
1122                 ++cp;
1123         return (cp);
1124 }
1125
1126 /*
1127  * Look for the symbol in the symbol table. If it is found, we return
1128  * the symbol table index, else we return -1.
1129  */
1130 static int
1131 findsym(const char *str)
1132 {
1133         const char *cp;
1134         int symind;
1135
1136         cp = skipsym(str);
1137         if (cp == str)
1138                 return (-1);
1139         if (symlist) {
1140                 if (symdepth && firstsym)
1141                         printf("%s%3d", zerosyms ? "" : "\n", depth);
1142                 firstsym = zerosyms = false;
1143                 printf("%s%.*s%s",
1144                     symdepth ? " " : "",
1145                     (int)(cp-str), str,
1146                     symdepth ? "" : "\n");
1147                 /* we don't care about the value of the symbol */
1148                 return (0);
1149         }
1150         for (symind = 0; symind < nsyms; ++symind) {
1151                 if (strlcmp(symname[symind], str, cp-str) == 0) {
1152                         debug("findsym %s %s", symname[symind],
1153                             value[symind] ? value[symind] : "");
1154                         return (symind);
1155                 }
1156         }
1157         return (-1);
1158 }
1159
1160 /*
1161  * Add a symbol to the symbol table.
1162  */
1163 static void
1164 addsym(bool ignorethis, bool definethis, char *sym)
1165 {
1166         int symind;
1167         char *val;
1168
1169         symind = findsym(sym);
1170         if (symind < 0) {
1171                 if (nsyms >= MAXSYMS)
1172                         errx(2, "too many symbols");
1173                 symind = nsyms++;
1174         }
1175         symname[symind] = sym;
1176         ignore[symind] = ignorethis;
1177         val = sym + (skipsym(sym) - sym);
1178         if (definethis) {
1179                 if (*val == '=') {
1180                         value[symind] = val+1;
1181                         *val = '\0';
1182                 } else if (*val == '\0')
1183                         value[symind] = "1";
1184                 else
1185                         usage();
1186         } else {
1187                 if (*val != '\0')
1188                         usage();
1189                 value[symind] = NULL;
1190         }
1191         debug("addsym %s=%s", symname[symind],
1192             value[symind] ? value[symind] : "undef");
1193 }
1194
1195 /*
1196  * Compare s with n characters of t.
1197  * The same as strncmp() except that it checks that s[n] == '\0'.
1198  */
1199 static int
1200 strlcmp(const char *s, const char *t, size_t n)
1201 {
1202         while (n-- && *t != '\0')
1203                 if (*s != *t)
1204                         return ((unsigned char)*s - (unsigned char)*t);
1205                 else
1206                         ++s, ++t;
1207         return ((unsigned char)*s);
1208 }
1209
1210 /*
1211  * Diagnostics.
1212  */
1213 static void
1214 debug(const char *msg, ...)
1215 {
1216         va_list ap;
1217
1218         if (debugging) {
1219                 va_start(ap, msg);
1220                 vwarnx(msg, ap);
1221                 va_end(ap);
1222         }
1223 }
1224
1225 static void
1226 error(const char *msg)
1227 {
1228         if (depth == 0)
1229                 warnx("%s: %d: %s", filename, linenum, msg);
1230         else
1231                 warnx("%s: %d: %s (#if line %d depth %d)",
1232                     filename, linenum, msg, stifline[depth], depth);
1233         closeout();
1234         errx(2, "output may be truncated");
1235 }