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TOMOYO Linux Cross Reference
Linux/scripts/unifdef.c

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  1 /*
  2  * Copyright (c) 2002 - 2009 Tony Finch <dot@dotat.at>
  3  *
  4  * Redistribution and use in source and binary forms, with or without
  5  * modification, are permitted provided that the following conditions
  6  * are met:
  7  * 1. Redistributions of source code must retain the above copyright
  8  *    notice, this list of conditions and the following disclaimer.
  9  * 2. Redistributions in binary form must reproduce the above copyright
 10  *    notice, this list of conditions and the following disclaimer in the
 11  *    documentation and/or other materials provided with the distribution.
 12  *
 13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 23  * SUCH DAMAGE.
 24  */
 25 
 26 /*
 27  * This code was derived from software contributed to Berkeley by Dave Yost.
 28  * It was rewritten to support ANSI C by Tony Finch. The original version
 29  * of unifdef carried the 4-clause BSD copyright licence. None of its code
 30  * remains in this version (though some of the names remain) so it now
 31  * carries a more liberal licence.
 32  *
 33  * The latest version is available from http://dotat.at/prog/unifdef
 34  */
 35 
 36 static const char * const copyright[] = {
 37     "@(#) Copyright (c) 2002 - 2009 Tony Finch <dot@dotat.at>\n",
 38     "$dotat: unifdef/unifdef.c,v 1.190 2009/11/27 17:21:26 fanf2 Exp $",
 39 };
 40 
 41 /*
 42  * unifdef - remove ifdef'ed lines
 43  *
 44  *  Wishlist:
 45  *      provide an option which will append the name of the
 46  *        appropriate symbol after #else's and #endif's
 47  *      provide an option which will check symbols after
 48  *        #else's and #endif's to see that they match their
 49  *        corresponding #ifdef or #ifndef
 50  *
 51  *   The first two items above require better buffer handling, which would
 52  *     also make it possible to handle all "dodgy" directives correctly.
 53  */
 54 
 55 #include <ctype.h>
 56 #include <err.h>
 57 #include <stdarg.h>
 58 #include <stdbool.h>
 59 #include <stdio.h>
 60 #include <stdlib.h>
 61 #include <string.h>
 62 #include <unistd.h>
 63 
 64 /* types of input lines: */
 65 typedef enum {
 66         LT_TRUEI,               /* a true #if with ignore flag */
 67         LT_FALSEI,              /* a false #if with ignore flag */
 68         LT_IF,                  /* an unknown #if */
 69         LT_TRUE,                /* a true #if */
 70         LT_FALSE,               /* a false #if */
 71         LT_ELIF,                /* an unknown #elif */
 72         LT_ELTRUE,              /* a true #elif */
 73         LT_ELFALSE,             /* a false #elif */
 74         LT_ELSE,                /* #else */
 75         LT_ENDIF,               /* #endif */
 76         LT_DODGY,               /* flag: directive is not on one line */
 77         LT_DODGY_LAST = LT_DODGY + LT_ENDIF,
 78         LT_PLAIN,               /* ordinary line */
 79         LT_EOF,                 /* end of file */
 80         LT_ERROR,               /* unevaluable #if */
 81         LT_COUNT
 82 } Linetype;
 83 
 84 static char const * const linetype_name[] = {
 85         "TRUEI", "FALSEI", "IF", "TRUE", "FALSE",
 86         "ELIF", "ELTRUE", "ELFALSE", "ELSE", "ENDIF",
 87         "DODGY TRUEI", "DODGY FALSEI",
 88         "DODGY IF", "DODGY TRUE", "DODGY FALSE",
 89         "DODGY ELIF", "DODGY ELTRUE", "DODGY ELFALSE",
 90         "DODGY ELSE", "DODGY ENDIF",
 91         "PLAIN", "EOF", "ERROR"
 92 };
 93 
 94 /* state of #if processing */
 95 typedef enum {
 96         IS_OUTSIDE,
 97         IS_FALSE_PREFIX,        /* false #if followed by false #elifs */
 98         IS_TRUE_PREFIX,         /* first non-false #(el)if is true */
 99         IS_PASS_MIDDLE,         /* first non-false #(el)if is unknown */
100         IS_FALSE_MIDDLE,        /* a false #elif after a pass state */
101         IS_TRUE_MIDDLE,         /* a true #elif after a pass state */
102         IS_PASS_ELSE,           /* an else after a pass state */
103         IS_FALSE_ELSE,          /* an else after a true state */
104         IS_TRUE_ELSE,           /* an else after only false states */
105         IS_FALSE_TRAILER,       /* #elifs after a true are false */
106         IS_COUNT
107 } Ifstate;
108 
109 static char const * const ifstate_name[] = {
110         "OUTSIDE", "FALSE_PREFIX", "TRUE_PREFIX",
111         "PASS_MIDDLE", "FALSE_MIDDLE", "TRUE_MIDDLE",
112         "PASS_ELSE", "FALSE_ELSE", "TRUE_ELSE",
113         "FALSE_TRAILER"
114 };
115 
116 /* state of comment parser */
117 typedef enum {
118         NO_COMMENT = false,     /* outside a comment */
119         C_COMMENT,              /* in a comment like this one */
120         CXX_COMMENT,            /* between // and end of line */
121         STARTING_COMMENT,       /* just after slash-backslash-newline */
122         FINISHING_COMMENT,      /* star-backslash-newline in a C comment */
123         CHAR_LITERAL,           /* inside '' */
124         STRING_LITERAL          /* inside "" */
125 } Comment_state;
126 
127 static char const * const comment_name[] = {
128         "NO", "C", "CXX", "STARTING", "FINISHING", "CHAR", "STRING"
129 };
130 
131 /* state of preprocessor line parser */
132 typedef enum {
133         LS_START,               /* only space and comments on this line */
134         LS_HASH,                /* only space, comments, and a hash */
135         LS_DIRTY                /* this line can't be a preprocessor line */
136 } Line_state;
137 
138 static char const * const linestate_name[] = {
139         "START", "HASH", "DIRTY"
140 };
141 
142 /*
143  * Minimum translation limits from ISO/IEC 9899:1999 5.2.4.1
144  */
145 #define MAXDEPTH        64                      /* maximum #if nesting */
146 #define MAXLINE         4096                    /* maximum length of line */
147 #define MAXSYMS         4096                    /* maximum number of symbols */
148 
149 /*
150  * Sometimes when editing a keyword the replacement text is longer, so
151  * we leave some space at the end of the tline buffer to accommodate this.
152  */
153 #define EDITSLOP        10
154 
155 /*
156  * Globals.
157  */
158 
159 static bool             compblank;              /* -B: compress blank lines */
160 static bool             lnblank;                /* -b: blank deleted lines */
161 static bool             complement;             /* -c: do the complement */
162 static bool             debugging;              /* -d: debugging reports */
163 static bool             iocccok;                /* -e: fewer IOCCC errors */
164 static bool             strictlogic;            /* -K: keep ambiguous #ifs */
165 static bool             killconsts;             /* -k: eval constant #ifs */
166 static bool             lnnum;                  /* -n: add #line directives */
167 static bool             symlist;                /* -s: output symbol list */
168 static bool             text;                   /* -t: this is a text file */
169 
170 static const char      *symname[MAXSYMS];       /* symbol name */
171 static const char      *value[MAXSYMS];         /* -Dsym=value */
172 static bool             ignore[MAXSYMS];        /* -iDsym or -iUsym */
173 static int              nsyms;                  /* number of symbols */
174 
175 static FILE            *input;                  /* input file pointer */
176 static const char      *filename;               /* input file name */
177 static int              linenum;                /* current line number */
178 
179 static char             tline[MAXLINE+EDITSLOP];/* input buffer plus space */
180 static char            *keyword;                /* used for editing #elif's */
181 
182 static Comment_state    incomment;              /* comment parser state */
183 static Line_state       linestate;              /* #if line parser state */
184 static Ifstate          ifstate[MAXDEPTH];      /* #if processor state */
185 static bool             ignoring[MAXDEPTH];     /* ignore comments state */
186 static int              stifline[MAXDEPTH];     /* start of current #if */
187 static int              depth;                  /* current #if nesting */
188 static int              delcount;               /* count of deleted lines */
189 static unsigned         blankcount;             /* count of blank lines */
190 static unsigned         blankmax;               /* maximum recent blankcount */
191 static bool             constexpr;              /* constant #if expression */
192 
193 static int              exitstat;               /* program exit status */
194 
195 static void             addsym(bool, bool, char *);
196 static void             debug(const char *, ...);
197 static void             done(void);
198 static void             error(const char *);
199 static int              findsym(const char *);
200 static void             flushline(bool);
201 static Linetype         parseline(void);
202 static Linetype         ifeval(const char **);
203 static void             ignoreoff(void);
204 static void             ignoreon(void);
205 static void             keywordedit(const char *);
206 static void             nest(void);
207 static void             process(void);
208 static const char      *skipargs(const char *);
209 static const char      *skipcomment(const char *);
210 static const char      *skipsym(const char *);
211 static void             state(Ifstate);
212 static int              strlcmp(const char *, const char *, size_t);
213 static void             unnest(void);
214 static void             usage(void);
215 
216 #define endsym(c) (!isalnum((unsigned char)c) && c != '_')
217 
218 /*
219  * The main program.
220  */
221 int
222 main(int argc, char *argv[])
223 {
224         int opt;
225 
226         while ((opt = getopt(argc, argv, "i:D:U:I:BbcdeKklnst")) != -1)
227                 switch (opt) {
228                 case 'i': /* treat stuff controlled by these symbols as text */
229                         /*
230                          * For strict backwards-compatibility the U or D
231                          * should be immediately after the -i but it doesn't
232                          * matter much if we relax that requirement.
233                          */
234                         opt = *optarg++;
235                         if (opt == 'D')
236                                 addsym(true, true, optarg);
237                         else if (opt == 'U')
238                                 addsym(true, false, optarg);
239                         else
240                                 usage();
241                         break;
242                 case 'D': /* define a symbol */
243                         addsym(false, true, optarg);
244                         break;
245                 case 'U': /* undef a symbol */
246                         addsym(false, false, optarg);
247                         break;
248                 case 'I':
249                         /* no-op for compatibility with cpp */
250                         break;
251                 case 'B': /* compress blank lines around removed section */
252                         compblank = true;
253                         break;
254                 case 'b': /* blank deleted lines instead of omitting them */
255                 case 'l': /* backwards compatibility */
256                         lnblank = true;
257                         break;
258                 case 'c': /* treat -D as -U and vice versa */
259                         complement = true;
260                         break;
261                 case 'd':
262                         debugging = true;
263                         break;
264                 case 'e': /* fewer errors from dodgy lines */
265                         iocccok = true;
266                         break;
267                 case 'K': /* keep ambiguous #ifs */
268                         strictlogic = true;
269                         break;
270                 case 'k': /* process constant #ifs */
271                         killconsts = true;
272                         break;
273                 case 'n': /* add #line directive after deleted lines */
274                         lnnum = true;
275                         break;
276                 case 's': /* only output list of symbols that control #ifs */
277                         symlist = true;
278                         break;
279                 case 't': /* don't parse C comments */
280                         text = true;
281                         break;
282                 default:
283                         usage();
284                 }
285         argc -= optind;
286         argv += optind;
287         if (compblank && lnblank)
288                 errx(2, "-B and -b are mutually exclusive");
289         if (argc > 1) {
290                 errx(2, "can only do one file");
291         } else if (argc == 1 && strcmp(*argv, "-") != 0) {
292                 filename = *argv;
293                 input = fopen(filename, "r");
294                 if (input == NULL)
295                         err(2, "can't open %s", filename);
296         } else {
297                 filename = "[stdin]";
298                 input = stdin;
299         }
300         process();
301         abort(); /* bug */
302 }
303 
304 static void
305 usage(void)
306 {
307         fprintf(stderr, "usage: unifdef [-BbcdeKknst] [-Ipath]"
308             " [-Dsym[=val]] [-Usym] [-iDsym[=val]] [-iUsym] ... [file]\n");
309         exit(2);
310 }
311 
312 /*
313  * A state transition function alters the global #if processing state
314  * in a particular way. The table below is indexed by the current
315  * processing state and the type of the current line.
316  *
317  * Nesting is handled by keeping a stack of states; some transition
318  * functions increase or decrease the depth. They also maintain the
319  * ignore state on a stack. In some complicated cases they have to
320  * alter the preprocessor directive, as follows.
321  *
322  * When we have processed a group that starts off with a known-false
323  * #if/#elif sequence (which has therefore been deleted) followed by a
324  * #elif that we don't understand and therefore must keep, we edit the
325  * latter into a #if to keep the nesting correct.
326  *
327  * When we find a true #elif in a group, the following block will
328  * always be kept and the rest of the sequence after the next #elif or
329  * #else will be discarded. We edit the #elif into a #else and the
330  * following directive to #endif since this has the desired behaviour.
331  *
332  * "Dodgy" directives are split across multiple lines, the most common
333  * example being a multi-line comment hanging off the right of the
334  * directive. We can handle them correctly only if there is no change
335  * from printing to dropping (or vice versa) caused by that directive.
336  * If the directive is the first of a group we have a choice between
337  * failing with an error, or passing it through unchanged instead of
338  * evaluating it. The latter is not the default to avoid questions from
339  * users about unifdef unexpectedly leaving behind preprocessor directives.
340  */
341 typedef void state_fn(void);
342 
343 /* report an error */
344 static void Eelif (void) { error("Inappropriate #elif"); }
345 static void Eelse (void) { error("Inappropriate #else"); }
346 static void Eendif(void) { error("Inappropriate #endif"); }
347 static void Eeof  (void) { error("Premature EOF"); }
348 static void Eioccc(void) { error("Obfuscated preprocessor control line"); }
349 /* plain line handling */
350 static void print (void) { flushline(true); }
351 static void drop  (void) { flushline(false); }
352 /* output lacks group's start line */
353 static void Strue (void) { drop();  ignoreoff(); state(IS_TRUE_PREFIX); }
354 static void Sfalse(void) { drop();  ignoreoff(); state(IS_FALSE_PREFIX); }
355 static void Selse (void) { drop();               state(IS_TRUE_ELSE); }
356 /* print/pass this block */
357 static void Pelif (void) { print(); ignoreoff(); state(IS_PASS_MIDDLE); }
358 static void Pelse (void) { print();              state(IS_PASS_ELSE); }
359 static void Pendif(void) { print(); unnest(); }
360 /* discard this block */
361 static void Dfalse(void) { drop();  ignoreoff(); state(IS_FALSE_TRAILER); }
362 static void Delif (void) { drop();  ignoreoff(); state(IS_FALSE_MIDDLE); }
363 static void Delse (void) { drop();               state(IS_FALSE_ELSE); }
364 static void Dendif(void) { drop();  unnest(); }
365 /* first line of group */
366 static void Fdrop (void) { nest();  Dfalse(); }
367 static void Fpass (void) { nest();  Pelif(); }
368 static void Ftrue (void) { nest();  Strue(); }
369 static void Ffalse(void) { nest();  Sfalse(); }
370 /* variable pedantry for obfuscated lines */
371 static void Oiffy (void) { if (!iocccok) Eioccc(); Fpass(); ignoreon(); }
372 static void Oif   (void) { if (!iocccok) Eioccc(); Fpass(); }
373 static void Oelif (void) { if (!iocccok) Eioccc(); Pelif(); }
374 /* ignore comments in this block */
375 static void Idrop (void) { Fdrop();  ignoreon(); }
376 static void Itrue (void) { Ftrue();  ignoreon(); }
377 static void Ifalse(void) { Ffalse(); ignoreon(); }
378 /* edit this line */
379 static void Mpass (void) { strncpy(keyword, "if  ", 4); Pelif(); }
380 static void Mtrue (void) { keywordedit("else\n");  state(IS_TRUE_MIDDLE); }
381 static void Melif (void) { keywordedit("endif\n"); state(IS_FALSE_TRAILER); }
382 static void Melse (void) { keywordedit("endif\n"); state(IS_FALSE_ELSE); }
383 
384 static state_fn * const trans_table[IS_COUNT][LT_COUNT] = {
385 /* IS_OUTSIDE */
386 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Eendif,
387   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eendif,
388   print, done,  abort },
389 /* IS_FALSE_PREFIX */
390 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Strue, Sfalse,Selse, Dendif,
391   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Mpass, Eioccc,Eioccc,Eioccc,Eioccc,
392   drop,  Eeof,  abort },
393 /* IS_TRUE_PREFIX */
394 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Dfalse,Dfalse,Dfalse,Delse, Dendif,
395   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
396   print, Eeof,  abort },
397 /* IS_PASS_MIDDLE */
398 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Pelif, Mtrue, Delif, Pelse, Pendif,
399   Oiffy, Oiffy, Fpass, Oif,   Oif,   Pelif, Oelif, Oelif, Pelse, Pendif,
400   print, Eeof,  abort },
401 /* IS_FALSE_MIDDLE */
402 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Pelif, Mtrue, Delif, Pelse, Pendif,
403   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eioccc,Eioccc,Eioccc,Eioccc,Eioccc,
404   drop,  Eeof,  abort },
405 /* IS_TRUE_MIDDLE */
406 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Melif, Melif, Melif, Melse, Pendif,
407   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eioccc,Eioccc,Eioccc,Eioccc,Pendif,
408   print, Eeof,  abort },
409 /* IS_PASS_ELSE */
410 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Pendif,
411   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Pendif,
412   print, Eeof,  abort },
413 /* IS_FALSE_ELSE */
414 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Dendif,
415   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Eelif, Eelif, Eelif, Eelse, Eioccc,
416   drop,  Eeof,  abort },
417 /* IS_TRUE_ELSE */
418 { Itrue, Ifalse,Fpass, Ftrue, Ffalse,Eelif, Eelif, Eelif, Eelse, Dendif,
419   Oiffy, Oiffy, Fpass, Oif,   Oif,   Eelif, Eelif, Eelif, Eelse, Eioccc,
420   print, Eeof,  abort },
421 /* IS_FALSE_TRAILER */
422 { Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Dendif,
423   Idrop, Idrop, Fdrop, Fdrop, Fdrop, Dfalse,Dfalse,Dfalse,Delse, Eioccc,
424   drop,  Eeof,  abort }
425 /*TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF
426   TRUEI  FALSEI IF     TRUE   FALSE  ELIF   ELTRUE ELFALSE ELSE  ENDIF (DODGY)
427   PLAIN  EOF    ERROR */
428 };
429 
430 /*
431  * State machine utility functions
432  */
433 static void
434 done(void)
435 {
436         if (incomment)
437                 error("EOF in comment");
438         exit(exitstat);
439 }
440 static void
441 ignoreoff(void)
442 {
443         if (depth == 0)
444                 abort(); /* bug */
445         ignoring[depth] = ignoring[depth-1];
446 }
447 static void
448 ignoreon(void)
449 {
450         ignoring[depth] = true;
451 }
452 static void
453 keywordedit(const char *replacement)
454 {
455         size_t size = tline + sizeof(tline) - keyword;
456         char *dst = keyword;
457         const char *src = replacement;
458         if (size != 0) {
459                 while ((--size != 0) && (*src != '\0'))
460                         *dst++ = *src++;
461                 *dst = '\0';
462         }
463         print();
464 }
465 static void
466 nest(void)
467 {
468         if (depth > MAXDEPTH-1)
469                 abort(); /* bug */
470         if (depth == MAXDEPTH-1)
471                 error("Too many levels of nesting");
472         depth += 1;
473         stifline[depth] = linenum;
474 }
475 static void
476 unnest(void)
477 {
478         if (depth == 0)
479                 abort(); /* bug */
480         depth -= 1;
481 }
482 static void
483 state(Ifstate is)
484 {
485         ifstate[depth] = is;
486 }
487 
488 /*
489  * Write a line to the output or not, according to command line options.
490  */
491 static void
492 flushline(bool keep)
493 {
494         if (symlist)
495                 return;
496         if (keep ^ complement) {
497                 bool blankline = tline[strspn(tline, " \t\n")] == '\0';
498                 if (blankline && compblank && blankcount != blankmax) {
499                         delcount += 1;
500                         blankcount += 1;
501                 } else {
502                         if (lnnum && delcount > 0)
503                                 printf("#line %d\n", linenum);
504                         fputs(tline, stdout);
505                         delcount = 0;
506                         blankmax = blankcount = blankline ? blankcount + 1 : 0;
507                 }
508         } else {
509                 if (lnblank)
510                         putc('\n', stdout);
511                 exitstat = 1;
512                 delcount += 1;
513                 blankcount = 0;
514         }
515 }
516 
517 /*
518  * The driver for the state machine.
519  */
520 static void
521 process(void)
522 {
523         Linetype lineval;
524 
525         /* When compressing blank lines, act as if the file
526            is preceded by a large number of blank lines. */
527         blankmax = blankcount = 1000;
528         for (;;) {
529                 linenum++;
530                 lineval = parseline();
531                 trans_table[ifstate[depth]][lineval]();
532                 debug("process %s -> %s depth %d",
533                     linetype_name[lineval],
534                     ifstate_name[ifstate[depth]], depth);
535         }
536 }
537 
538 /*
539  * Parse a line and determine its type. We keep the preprocessor line
540  * parser state between calls in the global variable linestate, with
541  * help from skipcomment().
542  */
543 static Linetype
544 parseline(void)
545 {
546         const char *cp;
547         int cursym;
548         int kwlen;
549         Linetype retval;
550         Comment_state wascomment;
551 
552         if (fgets(tline, MAXLINE, input) == NULL)
553                 return (LT_EOF);
554         retval = LT_PLAIN;
555         wascomment = incomment;
556         cp = skipcomment(tline);
557         if (linestate == LS_START) {
558                 if (*cp == '#') {
559                         linestate = LS_HASH;
560                         cp = skipcomment(cp + 1);
561                 } else if (*cp != '\0')
562                         linestate = LS_DIRTY;
563         }
564         if (!incomment && linestate == LS_HASH) {
565                 keyword = tline + (cp - tline);
566                 cp = skipsym(cp);
567                 kwlen = cp - keyword;
568                 /* no way can we deal with a continuation inside a keyword */
569                 if (strncmp(cp, "\\\n", 2) == 0)
570                         Eioccc();
571                 if (strlcmp("ifdef", keyword, kwlen) == 0 ||
572                     strlcmp("ifndef", keyword, kwlen) == 0) {
573                         cp = skipcomment(cp);
574                         if ((cursym = findsym(cp)) < 0)
575                                 retval = LT_IF;
576                         else {
577                                 retval = (keyword[2] == 'n')
578                                     ? LT_FALSE : LT_TRUE;
579                                 if (value[cursym] == NULL)
580                                         retval = (retval == LT_TRUE)
581                                             ? LT_FALSE : LT_TRUE;
582                                 if (ignore[cursym])
583                                         retval = (retval == LT_TRUE)
584                                             ? LT_TRUEI : LT_FALSEI;
585                         }
586                         cp = skipsym(cp);
587                 } else if (strlcmp("if", keyword, kwlen) == 0)
588                         retval = ifeval(&cp);
589                 else if (strlcmp("elif", keyword, kwlen) == 0)
590                         retval = ifeval(&cp) - LT_IF + LT_ELIF;
591                 else if (strlcmp("else", keyword, kwlen) == 0)
592                         retval = LT_ELSE;
593                 else if (strlcmp("endif", keyword, kwlen) == 0)
594                         retval = LT_ENDIF;
595                 else {
596                         linestate = LS_DIRTY;
597                         retval = LT_PLAIN;
598                 }
599                 cp = skipcomment(cp);
600                 if (*cp != '\0') {
601                         linestate = LS_DIRTY;
602                         if (retval == LT_TRUE || retval == LT_FALSE ||
603                             retval == LT_TRUEI || retval == LT_FALSEI)
604                                 retval = LT_IF;
605                         if (retval == LT_ELTRUE || retval == LT_ELFALSE)
606                                 retval = LT_ELIF;
607                 }
608                 if (retval != LT_PLAIN && (wascomment || incomment)) {
609                         retval += LT_DODGY;
610                         if (incomment)
611                                 linestate = LS_DIRTY;
612                 }
613                 /* skipcomment normally changes the state, except
614                    if the last line of the file lacks a newline, or
615                    if there is too much whitespace in a directive */
616                 if (linestate == LS_HASH) {
617                         size_t len = cp - tline;
618                         if (fgets(tline + len, MAXLINE - len, input) == NULL) {
619                                 /* append the missing newline */
620                                 tline[len+0] = '\n';
621                                 tline[len+1] = '\0';
622                                 cp++;
623                                 linestate = LS_START;
624                         } else {
625                                 linestate = LS_DIRTY;
626                         }
627                 }
628         }
629         if (linestate == LS_DIRTY) {
630                 while (*cp != '\0')
631                         cp = skipcomment(cp + 1);
632         }
633         debug("parser %s comment %s line",
634             comment_name[incomment], linestate_name[linestate]);
635         return (retval);
636 }
637 
638 /*
639  * These are the binary operators that are supported by the expression
640  * evaluator.
641  */
642 static Linetype op_strict(int *p, int v, Linetype at, Linetype bt) {
643         if(at == LT_IF || bt == LT_IF) return (LT_IF);
644         return (*p = v, v ? LT_TRUE : LT_FALSE);
645 }
646 static Linetype op_lt(int *p, Linetype at, int a, Linetype bt, int b) {
647         return op_strict(p, a < b, at, bt);
648 }
649 static Linetype op_gt(int *p, Linetype at, int a, Linetype bt, int b) {
650         return op_strict(p, a > b, at, bt);
651 }
652 static Linetype op_le(int *p, Linetype at, int a, Linetype bt, int b) {
653         return op_strict(p, a <= b, at, bt);
654 }
655 static Linetype op_ge(int *p, Linetype at, int a, Linetype bt, int b) {
656         return op_strict(p, a >= b, at, bt);
657 }
658 static Linetype op_eq(int *p, Linetype at, int a, Linetype bt, int b) {
659         return op_strict(p, a == b, at, bt);
660 }
661 static Linetype op_ne(int *p, Linetype at, int a, Linetype bt, int b) {
662         return op_strict(p, a != b, at, bt);
663 }
664 static Linetype op_or(int *p, Linetype at, int a, Linetype bt, int b) {
665         if (!strictlogic && (at == LT_TRUE || bt == LT_TRUE))
666                 return (*p = 1, LT_TRUE);
667         return op_strict(p, a || b, at, bt);
668 }
669 static Linetype op_and(int *p, Linetype at, int a, Linetype bt, int b) {
670         if (!strictlogic && (at == LT_FALSE || bt == LT_FALSE))
671                 return (*p = 0, LT_FALSE);
672         return op_strict(p, a && b, at, bt);
673 }
674 
675 /*
676  * An evaluation function takes three arguments, as follows: (1) a pointer to
677  * an element of the precedence table which lists the operators at the current
678  * level of precedence; (2) a pointer to an integer which will receive the
679  * value of the expression; and (3) a pointer to a char* that points to the
680  * expression to be evaluated and that is updated to the end of the expression
681  * when evaluation is complete. The function returns LT_FALSE if the value of
682  * the expression is zero, LT_TRUE if it is non-zero, LT_IF if the expression
683  * depends on an unknown symbol, or LT_ERROR if there is a parse failure.
684  */
685 struct ops;
686 
687 typedef Linetype eval_fn(const struct ops *, int *, const char **);
688 
689 static eval_fn eval_table, eval_unary;
690 
691 /*
692  * The precedence table. Expressions involving binary operators are evaluated
693  * in a table-driven way by eval_table. When it evaluates a subexpression it
694  * calls the inner function with its first argument pointing to the next
695  * element of the table. Innermost expressions have special non-table-driven
696  * handling.
697  */
698 static const struct ops {
699         eval_fn *inner;
700         struct op {
701                 const char *str;
702                 Linetype (*fn)(int *, Linetype, int, Linetype, int);
703         } op[5];
704 } eval_ops[] = {
705         { eval_table, { { "||", op_or } } },
706         { eval_table, { { "&&", op_and } } },
707         { eval_table, { { "==", op_eq },
708                         { "!=", op_ne } } },
709         { eval_unary, { { "<=", op_le },
710                         { ">=", op_ge },
711                         { "<", op_lt },
712                         { ">", op_gt } } }
713 };
714 
715 /*
716  * Function for evaluating the innermost parts of expressions,
717  * viz. !expr (expr) number defined(symbol) symbol
718  * We reset the constexpr flag in the last two cases.
719  */
720 static Linetype
721 eval_unary(const struct ops *ops, int *valp, const char **cpp)
722 {
723         const char *cp;
724         char *ep;
725         int sym;
726         bool defparen;
727         Linetype lt;
728 
729         cp = skipcomment(*cpp);
730         if (*cp == '!') {
731                 debug("eval%d !", ops - eval_ops);
732                 cp++;
733                 lt = eval_unary(ops, valp, &cp);
734                 if (lt == LT_ERROR)
735                         return (LT_ERROR);
736                 if (lt != LT_IF) {
737                         *valp = !*valp;
738                         lt = *valp ? LT_TRUE : LT_FALSE;
739                 }
740         } else if (*cp == '(') {
741                 cp++;
742                 debug("eval%d (", ops - eval_ops);
743                 lt = eval_table(eval_ops, valp, &cp);
744                 if (lt == LT_ERROR)
745                         return (LT_ERROR);
746                 cp = skipcomment(cp);
747                 if (*cp++ != ')')
748                         return (LT_ERROR);
749         } else if (isdigit((unsigned char)*cp)) {
750                 debug("eval%d number", ops - eval_ops);
751                 *valp = strtol(cp, &ep, 0);
752                 if (ep == cp)
753                         return (LT_ERROR);
754                 lt = *valp ? LT_TRUE : LT_FALSE;
755                 cp = skipsym(cp);
756         } else if (strncmp(cp, "defined", 7) == 0 && endsym(cp[7])) {
757                 cp = skipcomment(cp+7);
758                 debug("eval%d defined", ops - eval_ops);
759                 if (*cp == '(') {
760                         cp = skipcomment(cp+1);
761                         defparen = true;
762                 } else {
763                         defparen = false;
764                 }
765                 sym = findsym(cp);
766                 if (sym < 0) {
767                         lt = LT_IF;
768                 } else {
769                         *valp = (value[sym] != NULL);
770                         lt = *valp ? LT_TRUE : LT_FALSE;
771                 }
772                 cp = skipsym(cp);
773                 cp = skipcomment(cp);
774                 if (defparen && *cp++ != ')')
775                         return (LT_ERROR);
776                 constexpr = false;
777         } else if (!endsym(*cp)) {
778                 debug("eval%d symbol", ops - eval_ops);
779                 sym = findsym(cp);
780                 cp = skipsym(cp);
781                 if (sym < 0) {
782                         lt = LT_IF;
783                         cp = skipargs(cp);
784                 } else if (value[sym] == NULL) {
785                         *valp = 0;
786                         lt = LT_FALSE;
787                 } else {
788                         *valp = strtol(value[sym], &ep, 0);
789                         if (*ep != '\0' || ep == value[sym])
790                                 return (LT_ERROR);
791                         lt = *valp ? LT_TRUE : LT_FALSE;
792                         cp = skipargs(cp);
793                 }
794                 constexpr = false;
795         } else {
796                 debug("eval%d bad expr", ops - eval_ops);
797                 return (LT_ERROR);
798         }
799 
800         *cpp = cp;
801         debug("eval%d = %d", ops - eval_ops, *valp);
802         return (lt);
803 }
804 
805 /*
806  * Table-driven evaluation of binary operators.
807  */
808 static Linetype
809 eval_table(const struct ops *ops, int *valp, const char **cpp)
810 {
811         const struct op *op;
812         const char *cp;
813         int val;
814         Linetype lt, rt;
815 
816         debug("eval%d", ops - eval_ops);
817         cp = *cpp;
818         lt = ops->inner(ops+1, valp, &cp);
819         if (lt == LT_ERROR)
820                 return (LT_ERROR);
821         for (;;) {
822                 cp = skipcomment(cp);
823                 for (op = ops->op; op->str != NULL; op++)
824                         if (strncmp(cp, op->str, strlen(op->str)) == 0)
825                                 break;
826                 if (op->str == NULL)
827                         break;
828                 cp += strlen(op->str);
829                 debug("eval%d %s", ops - eval_ops, op->str);
830                 rt = ops->inner(ops+1, &val, &cp);
831                 if (rt == LT_ERROR)
832                         return (LT_ERROR);
833                 lt = op->fn(valp, lt, *valp, rt, val);
834         }
835 
836         *cpp = cp;
837         debug("eval%d = %d", ops - eval_ops, *valp);
838         debug("eval%d lt = %s", ops - eval_ops, linetype_name[lt]);
839         return (lt);
840 }
841 
842 /*
843  * Evaluate the expression on a #if or #elif line. If we can work out
844  * the result we return LT_TRUE or LT_FALSE accordingly, otherwise we
845  * return just a generic LT_IF.
846  */
847 static Linetype
848 ifeval(const char **cpp)
849 {
850         int ret;
851         int val = 0;
852 
853         debug("eval %s", *cpp);
854         constexpr = killconsts ? false : true;
855         ret = eval_table(eval_ops, &val, cpp);
856         debug("eval = %d", val);
857         return (constexpr ? LT_IF : ret == LT_ERROR ? LT_IF : ret);
858 }
859 
860 /*
861  * Skip over comments, strings, and character literals and stop at the
862  * next character position that is not whitespace. Between calls we keep
863  * the comment state in the global variable incomment, and we also adjust
864  * the global variable linestate when we see a newline.
865  * XXX: doesn't cope with the buffer splitting inside a state transition.
866  */
867 static const char *
868 skipcomment(const char *cp)
869 {
870         if (text || ignoring[depth]) {
871                 for (; isspace((unsigned char)*cp); cp++)
872                         if (*cp == '\n')
873                                 linestate = LS_START;
874                 return (cp);
875         }
876         while (*cp != '\0')
877                 /* don't reset to LS_START after a line continuation */
878                 if (strncmp(cp, "\\\n", 2) == 0)
879                         cp += 2;
880                 else switch (incomment) {
881                 case NO_COMMENT:
882                         if (strncmp(cp, "/\\\n", 3) == 0) {
883                                 incomment = STARTING_COMMENT;
884                                 cp += 3;
885                         } else if (strncmp(cp, "/*", 2) == 0) {
886                                 incomment = C_COMMENT;
887                                 cp += 2;
888                         } else if (strncmp(cp, "//", 2) == 0) {
889                                 incomment = CXX_COMMENT;
890                                 cp += 2;
891                         } else if (strncmp(cp, "\'", 1) == 0) {
892                                 incomment = CHAR_LITERAL;
893                                 linestate = LS_DIRTY;
894                                 cp += 1;
895                         } else if (strncmp(cp, "\"", 1) == 0) {
896                                 incomment = STRING_LITERAL;
897                                 linestate = LS_DIRTY;
898                                 cp += 1;
899                         } else if (strncmp(cp, "\n", 1) == 0) {
900                                 linestate = LS_START;
901                                 cp += 1;
902                         } else if (strchr(" \t", *cp) != NULL) {
903                                 cp += 1;
904                         } else
905                                 return (cp);
906                         continue;
907                 case CXX_COMMENT:
908                         if (strncmp(cp, "\n", 1) == 0) {
909                                 incomment = NO_COMMENT;
910                                 linestate = LS_START;
911                         }
912                         cp += 1;
913                         continue;
914                 case CHAR_LITERAL:
915                 case STRING_LITERAL:
916                         if ((incomment == CHAR_LITERAL && cp[0] == '\'') ||
917                             (incomment == STRING_LITERAL && cp[0] == '\"')) {
918                                 incomment = NO_COMMENT;
919                                 cp += 1;
920                         } else if (cp[0] == '\\') {
921                                 if (cp[1] == '\0')
922                                         cp += 1;
923                                 else
924                                         cp += 2;
925                         } else if (strncmp(cp, "\n", 1) == 0) {
926                                 if (incomment == CHAR_LITERAL)
927                                         error("unterminated char literal");
928                                 else
929                                         error("unterminated string literal");
930                         } else
931                                 cp += 1;
932                         continue;
933                 case C_COMMENT:
934                         if (strncmp(cp, "*\\\n", 3) == 0) {
935                                 incomment = FINISHING_COMMENT;
936                                 cp += 3;
937                         } else if (strncmp(cp, "*/", 2) == 0) {
938                                 incomment = NO_COMMENT;
939                                 cp += 2;
940                         } else
941                                 cp += 1;
942                         continue;
943                 case STARTING_COMMENT:
944                         if (*cp == '*') {
945                                 incomment = C_COMMENT;
946                                 cp += 1;
947                         } else if (*cp == '/') {
948                                 incomment = CXX_COMMENT;
949                                 cp += 1;
950                         } else {
951                                 incomment = NO_COMMENT;
952                                 linestate = LS_DIRTY;
953                         }
954                         continue;
955                 case FINISHING_COMMENT:
956                         if (*cp == '/') {
957                                 incomment = NO_COMMENT;
958                                 cp += 1;
959                         } else
960                                 incomment = C_COMMENT;
961                         continue;
962                 default:
963                         abort(); /* bug */
964                 }
965         return (cp);
966 }
967 
968 /*
969  * Skip macro arguments.
970  */
971 static const char *
972 skipargs(const char *cp)
973 {
974         const char *ocp = cp;
975         int level = 0;
976         cp = skipcomment(cp);
977         if (*cp != '(')
978                 return (cp);
979         do {
980                 if (*cp == '(')
981                         level++;
982                 if (*cp == ')')
983                         level--;
984                 cp = skipcomment(cp+1);
985         } while (level != 0 && *cp != '\0');
986         if (level == 0)
987                 return (cp);
988         else
989         /* Rewind and re-detect the syntax error later. */
990                 return (ocp);
991 }
992 
993 /*
994  * Skip over an identifier.
995  */
996 static const char *
997 skipsym(const char *cp)
998 {
999         while (!endsym(*cp))
1000                 ++cp;
1001         return (cp);
1002 }
1003 
1004 /*
1005  * Look for the symbol in the symbol table. If it is found, we return
1006  * the symbol table index, else we return -1.
1007  */
1008 static int
1009 findsym(const char *str)
1010 {
1011         const char *cp;
1012         int symind;
1013 
1014         cp = skipsym(str);
1015         if (cp == str)
1016                 return (-1);
1017         if (symlist) {
1018                 printf("%.*s\n", (int)(cp-str), str);
1019                 /* we don't care about the value of the symbol */
1020                 return (0);
1021         }
1022         for (symind = 0; symind < nsyms; ++symind) {
1023                 if (strlcmp(symname[symind], str, cp-str) == 0) {
1024                         debug("findsym %s %s", symname[symind],
1025                             value[symind] ? value[symind] : "");
1026                         return (symind);
1027                 }
1028         }
1029         return (-1);
1030 }
1031 
1032 /*
1033  * Add a symbol to the symbol table.
1034  */
1035 static void
1036 addsym(bool ignorethis, bool definethis, char *sym)
1037 {
1038         int symind;
1039         char *val;
1040 
1041         symind = findsym(sym);
1042         if (symind < 0) {
1043                 if (nsyms >= MAXSYMS)
1044                         errx(2, "too many symbols");
1045                 symind = nsyms++;
1046         }
1047         symname[symind] = sym;
1048         ignore[symind] = ignorethis;
1049         val = sym + (skipsym(sym) - sym);
1050         if (definethis) {
1051                 if (*val == '=') {
1052                         value[symind] = val+1;
1053                         *val = '\0';
1054                 } else if (*val == '\0')
1055                         value[symind] = "";
1056                 else
1057                         usage();
1058         } else {
1059                 if (*val != '\0')
1060                         usage();
1061                 value[symind] = NULL;
1062         }
1063 }
1064 
1065 /*
1066  * Compare s with n characters of t.
1067  * The same as strncmp() except that it checks that s[n] == '\0'.
1068  */
1069 static int
1070 strlcmp(const char *s, const char *t, size_t n)
1071 {
1072         while (n-- && *t != '\0')
1073                 if (*s != *t)
1074                         return ((unsigned char)*s - (unsigned char)*t);
1075                 else
1076                         ++s, ++t;
1077         return ((unsigned char)*s);
1078 }
1079 
1080 /*
1081  * Diagnostics.
1082  */
1083 static void
1084 debug(const char *msg, ...)
1085 {
1086         va_list ap;
1087 
1088         if (debugging) {
1089                 va_start(ap, msg);
1090                 vwarnx(msg, ap);
1091                 va_end(ap);
1092         }
1093 }
1094 
1095 static void
1096 error(const char *msg)
1097 {
1098         if (depth == 0)
1099                 warnx("%s: %d: %s", filename, linenum, msg);
1100         else
1101                 warnx("%s: %d: %s (#if line %d depth %d)",
1102                     filename, linenum, msg, stifline[depth], depth);
1103         errx(2, "output may be truncated");
1104 }
1105 

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