root/scripts/unifdef.c

DEFINITIONS

1. main
2. version
3. usage
4. Eelif
5. Eelse
6. Eendif
7. Eeof
8. Eioccc
9. print
10. drop
11. Strue
12. Sfalse
13. Selse
14. Pelif
15. Pelse
16. Pendif
17. Dfalse
18. Delif
19. Delse
20. Dendif
21. Fdrop
22. Fpass
23. Ftrue
24. Ffalse
25. Oiffy
26. Oif
27. Oelif
28. Idrop
29. Itrue
30. Ifalse
31. Mpass
32. Mtrue
33. Melif
34. Melse
35. ignoreoff
36. ignoreon
37. keywordedit
38. nest
39. unnest
40. state
41. flushline
42. process
43. closeout
44. done
45. parseline
46. op_strict
47. op_lt
48. op_gt
49. op_le
50. op_ge
51. op_eq
52. op_ne
53. op_or
54. op_and
55. eval_unary
56. eval_table
57. ifeval
58. skipcomment
59. skipargs
60. skipsym
61. findsym
62. addsym
63. strlcmp
64. debug
65. error

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