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unifdef.c
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1 /*
2  * Copyright (c) 2002 - 2011 Tony Finch <[email protected]>
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 ([email protected]) $\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 strncpy() 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) { strncpy(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 }
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