Root/scripts/unifdef.c

1/*
2 * Copyright (c) 2002 - 2009 Tony Finch <dot@dotat.at>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26/*
27 * This code was derived from software contributed to Berkeley by Dave Yost.
28 * It was rewritten to support ANSI C by Tony Finch. The original version
29 * of unifdef carried the 4-clause BSD copyright licence. None of its code
30 * remains in this version (though some of the names remain) so it now
31 * carries a more liberal licence.
32 *
33 * The latest version is available from http://dotat.at/prog/unifdef
34 */
35
36static 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: */
65typedef 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
84static 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 */
95typedef 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
109static 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 */
117typedef 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
127static char const * const comment_name[] = {
128    "NO", "C", "CXX", "STARTING", "FINISHING", "CHAR", "STRING"
129};
130
131/* state of preprocessor line parser */
132typedef 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
138static 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
159static bool compblank; /* -B: compress blank lines */
160static bool lnblank; /* -b: blank deleted lines */
161static bool complement; /* -c: do the complement */
162static bool debugging; /* -d: debugging reports */
163static bool iocccok; /* -e: fewer IOCCC errors */
164static bool strictlogic; /* -K: keep ambiguous #ifs */
165static bool killconsts; /* -k: eval constant #ifs */
166static bool lnnum; /* -n: add #line directives */
167static bool symlist; /* -s: output symbol list */
168static bool text; /* -t: this is a text file */
169
170static const char *symname[MAXSYMS]; /* symbol name */
171static const char *value[MAXSYMS]; /* -Dsym=value */
172static bool ignore[MAXSYMS]; /* -iDsym or -iUsym */
173static int nsyms; /* number of symbols */
174
175static FILE *input; /* input file pointer */
176static const char *filename; /* input file name */
177static int linenum; /* current line number */
178
179static char tline[MAXLINE+EDITSLOP];/* input buffer plus space */
180static char *keyword; /* used for editing #elif's */
181
182static Comment_state incomment; /* comment parser state */
183static Line_state linestate; /* #if line parser state */
184static Ifstate ifstate[MAXDEPTH]; /* #if processor state */
185static bool ignoring[MAXDEPTH]; /* ignore comments state */
186static int stifline[MAXDEPTH]; /* start of current #if */
187static int depth; /* current #if nesting */
188static int delcount; /* count of deleted lines */
189static unsigned blankcount; /* count of blank lines */
190static unsigned blankmax; /* maximum recent blankcount */
191static bool constexpr; /* constant #if expression */
192
193static int exitstat; /* program exit status */
194
195static void addsym(bool, bool, char *);
196static void debug(const char *, ...);
197static void done(void);
198static void error(const char *);
199static int findsym(const char *);
200static void flushline(bool);
201static Linetype parseline(void);
202static Linetype ifeval(const char **);
203static void ignoreoff(void);
204static void ignoreon(void);
205static void keywordedit(const char *);
206static void nest(void);
207static void process(void);
208static const char *skipargs(const char *);
209static const char *skipcomment(const char *);
210static const char *skipsym(const char *);
211static void state(Ifstate);
212static int strlcmp(const char *, const char *, size_t);
213static void unnest(void);
214static void usage(void);
215
216#define endsym(c) (!isalnum((unsigned char)c) && c != '_')
217
218/*
219 * The main program.
220 */
221int
222main(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
304static void
305usage(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 */
341typedef void state_fn(void);
342
343/* report an error */
344static void Eelif (void) { error("Inappropriate #elif"); }
345static void Eelse (void) { error("Inappropriate #else"); }
346static void Eendif(void) { error("Inappropriate #endif"); }
347static void Eeof (void) { error("Premature EOF"); }
348static void Eioccc(void) { error("Obfuscated preprocessor control line"); }
349/* plain line handling */
350static void print (void) { flushline(true); }
351static void drop (void) { flushline(false); }
352/* output lacks group's start line */
353static void Strue (void) { drop(); ignoreoff(); state(IS_TRUE_PREFIX); }
354static void Sfalse(void) { drop(); ignoreoff(); state(IS_FALSE_PREFIX); }
355static void Selse (void) { drop(); state(IS_TRUE_ELSE); }
356/* print/pass this block */
357static void Pelif (void) { print(); ignoreoff(); state(IS_PASS_MIDDLE); }
358static void Pelse (void) { print(); state(IS_PASS_ELSE); }
359static void Pendif(void) { print(); unnest(); }
360/* discard this block */
361static void Dfalse(void) { drop(); ignoreoff(); state(IS_FALSE_TRAILER); }
362static void Delif (void) { drop(); ignoreoff(); state(IS_FALSE_MIDDLE); }
363static void Delse (void) { drop(); state(IS_FALSE_ELSE); }
364static void Dendif(void) { drop(); unnest(); }
365/* first line of group */
366static void Fdrop (void) { nest(); Dfalse(); }
367static void Fpass (void) { nest(); Pelif(); }
368static void Ftrue (void) { nest(); Strue(); }
369static void Ffalse(void) { nest(); Sfalse(); }
370/* variable pedantry for obfuscated lines */
371static void Oiffy (void) { if (!iocccok) Eioccc(); Fpass(); ignoreon(); }
372static void Oif (void) { if (!iocccok) Eioccc(); Fpass(); }
373static void Oelif (void) { if (!iocccok) Eioccc(); Pelif(); }
374/* ignore comments in this block */
375static void Idrop (void) { Fdrop(); ignoreon(); }
376static void Itrue (void) { Ftrue(); ignoreon(); }
377static void Ifalse(void) { Ffalse(); ignoreon(); }
378/* edit this line */
379static void Mpass (void) { strncpy(keyword, "if ", 4); Pelif(); }
380static void Mtrue (void) { keywordedit("else\n"); state(IS_TRUE_MIDDLE); }
381static void Melif (void) { keywordedit("endif\n"); state(IS_FALSE_TRAILER); }
382static void Melse (void) { keywordedit("endif\n"); state(IS_FALSE_ELSE); }
383
384static 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 */
433static void
434done(void)
435{
436    if (incomment)
437        error("EOF in comment");
438    exit(exitstat);
439}
440static void
441ignoreoff(void)
442{
443    if (depth == 0)
444        abort(); /* bug */
445    ignoring[depth] = ignoring[depth-1];
446}
447static void
448ignoreon(void)
449{
450    ignoring[depth] = true;
451}
452static void
453keywordedit(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}
465static void
466nest(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}
475static void
476unnest(void)
477{
478    if (depth == 0)
479        abort(); /* bug */
480    depth -= 1;
481}
482static void
483state(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 */
491static void
492flushline(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 */
520static void
521process(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 */
543static Linetype
544parseline(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 */
642static 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}
646static Linetype op_lt(int *p, Linetype at, int a, Linetype bt, int b) {
647    return op_strict(p, a < b, at, bt);
648}
649static Linetype op_gt(int *p, Linetype at, int a, Linetype bt, int b) {
650    return op_strict(p, a > b, at, bt);
651}
652static Linetype op_le(int *p, Linetype at, int a, Linetype bt, int b) {
653    return op_strict(p, a <= b, at, bt);
654}
655static Linetype op_ge(int *p, Linetype at, int a, Linetype bt, int b) {
656    return op_strict(p, a >= b, at, bt);
657}
658static Linetype op_eq(int *p, Linetype at, int a, Linetype bt, int b) {
659    return op_strict(p, a == b, at, bt);
660}
661static Linetype op_ne(int *p, Linetype at, int a, Linetype bt, int b) {
662    return op_strict(p, a != b, at, bt);
663}
664static 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}
669static 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 */
685struct ops;
686
687typedef Linetype eval_fn(const struct ops *, int *, const char **);
688
689static 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 */
698static 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 */
720static Linetype
721eval_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 */
808static Linetype
809eval_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 */
847static Linetype
848ifeval(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 */
867static const char *
868skipcomment(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 */
971static const char *
972skipargs(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 */
996static const char *
997skipsym(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 */
1008static int
1009findsym(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 */
1035static void
1036addsym(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 */
1069static int
1070strlcmp(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 */
1083static void
1084debug(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
1095static void
1096error(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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