1 /* vi: set sw=4 ts=4: */
2 /*
3 * Mini diff implementation for busybox, adapted from OpenBSD diff.
4 *
5 * Copyright (C) 2010 by Matheus Izvekov <mizvekov@gmail.com>
6 * Copyright (C) 2006 by Robert Sullivan <cogito.ergo.cogito@hotmail.com>
7 * Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
8 *
9 * Sponsored in part by the Defense Advanced Research Projects
10 * Agency (DARPA) and Air Force Research Laboratory, Air Force
11 * Materiel Command, USAF, under agreement number F39502-99-1-0512.
12 *
13 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
14 */
15
16 /*
17 * The following code uses an algorithm due to Harold Stone,
18 * which finds a pair of longest identical subsequences in
19 * the two files.
20 *
21 * The major goal is to generate the match vector J.
22 * J[i] is the index of the line in file1 corresponding
23 * to line i in file0. J[i] = 0 if there is no
24 * such line in file1.
25 *
26 * Lines are hashed so as to work in core. All potential
27 * matches are located by sorting the lines of each file
28 * on the hash (called "value"). In particular, this
29 * collects the equivalence classes in file1 together.
30 * Subroutine equiv replaces the value of each line in
31 * file0 by the index of the first element of its
32 * matching equivalence in (the reordered) file1.
33 * To save space equiv squeezes file1 into a single
34 * array member in which the equivalence classes
35 * are simply concatenated, except that their first
36 * members are flagged by changing sign.
37 *
38 * Next the indices that point into member are unsorted into
39 * array class according to the original order of file0.
40 *
41 * The cleverness lies in routine stone. This marches
42 * through the lines of file0, developing a vector klist
43 * of "k-candidates". At step i a k-candidate is a matched
44 * pair of lines x,y (x in file0, y in file1) such that
45 * there is a common subsequence of length k
46 * between the first i lines of file0 and the first y
47 * lines of file1, but there is no such subsequence for
48 * any smaller y. x is the earliest possible mate to y
49 * that occurs in such a subsequence.
50 *
51 * Whenever any of the members of the equivalence class of
52 * lines in file1 matable to a line in file0 has serial number
53 * less than the y of some k-candidate, that k-candidate
54 * with the smallest such y is replaced. The new
55 * k-candidate is chained (via pred) to the current
56 * k-1 candidate so that the actual subsequence can
57 * be recovered. When a member has serial number greater
58 * that the y of all k-candidates, the klist is extended.
59 * At the end, the longest subsequence is pulled out
60 * and placed in the array J by unravel
61 *
62 * With J in hand, the matches there recorded are
63 * checked against reality to assure that no spurious
64 * matches have crept in due to hashing. If they have,
65 * they are broken, and "jackpot" is recorded--a harmless
66 * matter except that a true match for a spuriously
67 * mated line may now be unnecessarily reported as a change.
68 *
69 * Much of the complexity of the program comes simply
70 * from trying to minimize core utilization and
71 * maximize the range of doable problems by dynamically
72 * allocating what is needed and reusing what is not.
73 * The core requirements for problems larger than somewhat
74 * are (in words) 2*length(file0) + length(file1) +
75 * 3*(number of k-candidates installed), typically about
76 * 6n words for files of length n.
77 */
78
79 //config:config DIFF
80 //config: bool "diff"
81 //config: default y
82 //config: help
83 //config: diff compares two files or directories and outputs the
84 //config: differences between them in a form that can be given to
85 //config: the patch command.
86 //config:
87 //config:config FEATURE_DIFF_LONG_OPTIONS
88 //config: bool "Enable long options"
89 //config: default y
90 //config: depends on DIFF && LONG_OPTS
91 //config: help
92 //config: Enable use of long options.
93 //config:
94 //config:config FEATURE_DIFF_DIR
95 //config: bool "Enable directory support"
96 //config: default y
97 //config: depends on DIFF
98 //config: help
99 //config: This option enables support for directory and subdirectory
100 //config: comparison.
101
102 //kbuild:lib-$(CONFIG_DIFF) += diff.o
103
104 //applet:IF_DIFF(APPLET(diff, BB_DIR_USR_BIN, BB_SUID_DROP))
105
106 //usage:#define diff_trivial_usage
107 //usage: "[-abBdiNqrTstw] [-L LABEL] [-S FILE] [-U LINES] FILE1 FILE2"
108 //usage:#define diff_full_usage "\n\n"
109 //usage: "Compare files line by line and output the differences between them.\n"
110 //usage: "This implementation supports unified diffs only.\n"
111 //usage: "\n -a Treat all files as text"
112 //usage: "\n -b Ignore changes in the amount of whitespace"
113 //usage: "\n -B Ignore changes whose lines are all blank"
114 //usage: "\n -d Try hard to find a smaller set of changes"
115 //usage: "\n -i Ignore case differences"
116 //usage: "\n -L Use LABEL instead of the filename in the unified header"
117 //usage: "\n -N Treat absent files as empty"
118 //usage: "\n -q Output only whether files differ"
119 //usage: "\n -r Recurse"
120 //usage: "\n -S Start with FILE when comparing directories"
121 //usage: "\n -T Make tabs line up by prefixing a tab when necessary"
122 //usage: "\n -s Report when two files are the same"
123 //usage: "\n -t Expand tabs to spaces in output"
124 //usage: "\n -U Output LINES lines of context"
125 //usage: "\n -w Ignore all whitespace"
126
127 #include "libbb.h"
128 #include "common_bufsiz.h"
129
130 #if 0
131 # define dbg_error_msg(...) bb_error_msg(__VA_ARGS__)
132 #else
133 # define dbg_error_msg(...) ((void)0)
134 #endif
135
136 enum { /* print_status() and diffreg() return values */
137 STATUS_SAME, /* files are the same */
138 STATUS_DIFFER, /* files differ */
139 STATUS_BINARY, /* binary files differ */
140 };
141
142 enum { /* Commandline flags */
143 FLAG_a,
144 FLAG_b,
145 FLAG_d,
146 FLAG_i,
147 FLAG_L, /* never used, handled by getopt32 */
148 FLAG_N,
149 FLAG_q,
150 FLAG_r,
151 FLAG_s,
152 FLAG_S, /* never used, handled by getopt32 */
153 FLAG_t,
154 FLAG_T,
155 FLAG_U, /* never used, handled by getopt32 */
156 FLAG_w,
157 FLAG_u, /* ignored, this is the default */
158 FLAG_p, /* not implemented */
159 FLAG_B,
160 FLAG_E, /* not implemented */
161 };
162 #define FLAG(x) (1 << FLAG_##x)
163
164 /* We cache file position to avoid excessive seeking */
165 typedef struct FILE_and_pos_t {
166 FILE *ft_fp;
167 off_t ft_pos;
168 } FILE_and_pos_t;
169
170 struct globals {
171 smallint exit_status;
172 int opt_U_context;
173 const char *other_dir;
174 char *label[2];
175 struct stat stb[2];
176 };
177 #define G (*ptr_to_globals)
178 #define exit_status (G.exit_status )
179 #define opt_U_context (G.opt_U_context )
180 #define label (G.label )
181 #define stb (G.stb )
182 #define INIT_G() do { \
183 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
184 opt_U_context = 3; \
185 } while (0)
186
187 typedef int token_t;
188
189 enum {
190 /* Public */
191 TOK_EMPTY = 1 << 9, /* Line fully processed, you can proceed to the next */
192 TOK_EOF = 1 << 10, /* File ended */
193 /* Private (Only to be used by read_token() */
194 TOK_EOL = 1 << 11, /* we saw EOL (sticky) */
195 TOK_SPACE = 1 << 12, /* used -b code, means we are skipping spaces */
196 SHIFT_EOF = (sizeof(token_t)*8 - 8) - 1,
197 CHAR_MASK = 0x1ff, /* 8th bit is used to distinguish EOF from 0xff */
198 };
199
200 /* Restores full EOF from one 8th bit: */
201 //#define TOK2CHAR(t) (((t) << SHIFT_EOF) >> SHIFT_EOF)
202 /* We don't really need the above, we only need to have EOF != any_real_char: */
203 #define TOK2CHAR(t) ((t) & CHAR_MASK)
204
seek_ft(FILE_and_pos_t * ft,off_t pos)205 static void seek_ft(FILE_and_pos_t *ft, off_t pos)
206 {
207 if (ft->ft_pos != pos) {
208 ft->ft_pos = pos;
209 fseeko(ft->ft_fp, pos, SEEK_SET);
210 }
211 }
212
213 /* Reads tokens from given fp, handling -b and -w flags
214 * The user must reset tok every line start
215 */
read_token(FILE_and_pos_t * ft,token_t tok)216 static int read_token(FILE_and_pos_t *ft, token_t tok)
217 {
218 tok |= TOK_EMPTY;
219 while (!(tok & TOK_EOL)) {
220 bool is_space;
221 int t;
222
223 t = fgetc(ft->ft_fp);
224 if (t != EOF)
225 ft->ft_pos++;
226 is_space = (t == EOF || isspace(t));
227
228 /* If t == EOF (-1), set both TOK_EOF and TOK_EOL */
229 tok |= (t & (TOK_EOF + TOK_EOL));
230 /* Only EOL? */
231 if (t == '\n')
232 tok |= TOK_EOL;
233
234 if (option_mask32 & FLAG(i)) /* Handcoded tolower() */
235 t = (t >= 'A' && t <= 'Z') ? t - ('A' - 'a') : t;
236
237 if ((option_mask32 & FLAG(w)) && is_space)
238 continue;
239
240 /* Trim char value to low 9 bits */
241 t &= CHAR_MASK;
242
243 if (option_mask32 & FLAG(b)) {
244 /* Was prev char whitespace? */
245 if (tok & TOK_SPACE) { /* yes */
246 if (is_space) /* this one too, ignore it */
247 continue;
248 tok &= ~TOK_SPACE;
249 } else if (is_space) {
250 /* 1st whitespace char.
251 * Set TOK_SPACE and replace char by ' ' */
252 t = TOK_SPACE + ' ';
253 }
254 }
255 /* Clear EMPTY */
256 tok &= ~(TOK_EMPTY + CHAR_MASK);
257 /* Assign char value (low 9 bits) and maybe set TOK_SPACE */
258 tok |= t;
259 break;
260 }
261 #if 0
262 bb_error_msg("fp:%p tok:%x '%c'%s%s%s%s", fp, tok, tok & 0xff
263 , tok & TOK_EOF ? " EOF" : ""
264 , tok & TOK_EOL ? " EOL" : ""
265 , tok & TOK_EMPTY ? " EMPTY" : ""
266 , tok & TOK_SPACE ? " SPACE" : ""
267 );
268 #endif
269 return tok;
270 }
271
272 struct cand {
273 int x;
274 int y;
275 int pred;
276 };
277
search(const int * c,int k,int y,const struct cand * list)278 static int search(const int *c, int k, int y, const struct cand *list)
279 {
280 int i, j;
281
282 if (list[c[k]].y < y) /* quick look for typical case */
283 return k + 1;
284
285 for (i = 0, j = k + 1;;) {
286 const int l = (i + j) >> 1;
287 if (l > i) {
288 const int t = list[c[l]].y;
289 if (t > y)
290 j = l;
291 else if (t < y)
292 i = l;
293 else
294 return l;
295 } else
296 return l + 1;
297 }
298 }
299
isqrt(unsigned n)300 static unsigned isqrt(unsigned n)
301 {
302 unsigned x = 1;
303 while (1) {
304 const unsigned y = x;
305 x = ((n / x) + x) >> 1;
306 if (x <= (y + 1) && x >= (y - 1))
307 return x;
308 }
309 }
310
stone(const int * a,int n,const int * b,int * J,int pref)311 static void stone(const int *a, int n, const int *b, int *J, int pref)
312 {
313 const unsigned isq = isqrt(n);
314 const unsigned bound =
315 (option_mask32 & FLAG(d)) ? UINT_MAX : MAX(256, isq);
316 int clen = 1;
317 int clistlen = 100;
318 int k = 0;
319 struct cand *clist = xzalloc(clistlen * sizeof(clist[0]));
320 struct cand cand;
321 struct cand *q;
322 int *klist = xzalloc((n + 2) * sizeof(klist[0]));
323 /*clist[0] = (struct cand){0}; - xzalloc did it */
324 /*klist[0] = 0; */
325
326 for (cand.x = 1; cand.x <= n; cand.x++) {
327 int j = a[cand.x], oldl = 0;
328 unsigned numtries = 0;
329 if (j == 0)
330 continue;
331 cand.y = -b[j];
332 cand.pred = klist[0];
333 do {
334 int l, tc;
335 if (cand.y <= clist[cand.pred].y)
336 continue;
337 l = search(klist, k, cand.y, clist);
338 if (l != oldl + 1)
339 cand.pred = klist[l - 1];
340 if (l <= k && clist[klist[l]].y <= cand.y)
341 continue;
342 if (clen == clistlen) {
343 clistlen = clistlen * 11 / 10;
344 clist = xrealloc(clist, clistlen * sizeof(clist[0]));
345 }
346 clist[clen] = cand;
347 tc = klist[l];
348 klist[l] = clen++;
349 if (l <= k) {
350 cand.pred = tc;
351 oldl = l;
352 numtries++;
353 } else {
354 k++;
355 break;
356 }
357 } while ((cand.y = b[++j]) > 0 && numtries < bound);
358 }
359 /* Unravel */
360 for (q = clist + klist[k]; q->y; q = clist + q->pred)
361 J[q->x + pref] = q->y + pref;
362 free(klist);
363 free(clist);
364 }
365
366 struct line {
367 /* 'serial' is not used in the beginning, so we reuse it
368 * to store line offsets, thus reducing memory pressure
369 */
370 union {
371 unsigned serial;
372 off_t offset;
373 };
374 unsigned value;
375 };
376
equiv(struct line * a,int n,struct line * b,int m,int * c)377 static void equiv(struct line *a, int n, struct line *b, int m, int *c)
378 {
379 int i = 1, j = 1;
380
381 while (i <= n && j <= m) {
382 if (a[i].value < b[j].value)
383 a[i++].value = 0;
384 else if (a[i].value == b[j].value)
385 a[i++].value = j;
386 else
387 j++;
388 }
389 while (i <= n)
390 a[i++].value = 0;
391 b[m + 1].value = 0;
392 j = 0;
393 while (++j <= m) {
394 c[j] = -b[j].serial;
395 while (b[j + 1].value == b[j].value) {
396 j++;
397 c[j] = b[j].serial;
398 }
399 }
400 c[j] = -1;
401 }
402
unsort(const struct line * f,int l,int * b)403 static void unsort(const struct line *f, int l, int *b)
404 {
405 int i;
406 int *a = xmalloc((l + 1) * sizeof(a[0]));
407 for (i = 1; i <= l; i++)
408 a[f[i].serial] = f[i].value;
409 for (i = 1; i <= l; i++)
410 b[i] = a[i];
411 free(a);
412 }
413
line_compar(const void * a,const void * b)414 static int line_compar(const void *a, const void *b)
415 {
416 #define l0 ((const struct line*)a)
417 #define l1 ((const struct line*)b)
418 int r = l0->value - l1->value;
419 if (r)
420 return r;
421 return l0->serial - l1->serial;
422 #undef l0
423 #undef l1
424 }
425
fetch(FILE_and_pos_t * ft,const off_t * ix,int a,int b,int ch)426 static void fetch(FILE_and_pos_t *ft, const off_t *ix, int a, int b, int ch)
427 {
428 int i, j, col;
429 for (i = a; i <= b; i++) {
430 seek_ft(ft, ix[i - 1]);
431 putchar(ch);
432 if (option_mask32 & FLAG(T))
433 putchar('\t');
434 for (j = 0, col = 0; j < ix[i] - ix[i - 1]; j++) {
435 int c = fgetc(ft->ft_fp);
436 if (c == EOF) {
437 puts("\n\\ No newline at end of file");
438 return;
439 }
440 ft->ft_pos++;
441 if (c == '\t' && (option_mask32 & FLAG(t)))
442 do putchar(' '); while (++col & 7);
443 else {
444 putchar(c);
445 col++;
446 }
447 }
448 }
449 }
450
451 /* Creates the match vector J, where J[i] is the index
452 * of the line in the new file corresponding to the line i
453 * in the old file. Lines start at 1 instead of 0, that value
454 * being used instead to denote no corresponding line.
455 * This vector is dynamically allocated and must be freed by the caller.
456 *
457 * * fp is an input parameter, where fp[0] and fp[1] are the open
458 * old file and new file respectively.
459 * * nlen is an output variable, where nlen[0] and nlen[1]
460 * gets the number of lines in the old and new file respectively.
461 * * ix is an output variable, where ix[0] and ix[1] gets
462 * assigned dynamically allocated vectors of the offsets of the lines
463 * of the old and new file respectively. These must be freed by the caller.
464 */
create_J(FILE_and_pos_t ft[2],int nlen[2],off_t * ix[2])465 static NOINLINE int *create_J(FILE_and_pos_t ft[2], int nlen[2], off_t *ix[2])
466 {
467 int *J, slen[2], *class, *member;
468 struct line *nfile[2], *sfile[2];
469 int pref = 0, suff = 0, i, j, delta;
470
471 /* Lines of both files are hashed, and in the process
472 * their offsets are stored in the array ix[fileno]
473 * where fileno == 0 points to the old file, and
474 * fileno == 1 points to the new one.
475 */
476 for (i = 0; i < 2; i++) {
477 unsigned hash;
478 token_t tok;
479 size_t sz = 100;
480 nfile[i] = xmalloc((sz + 3) * sizeof(nfile[i][0]));
481 /* ft gets here without the correct position, cant use seek_ft */
482 ft[i].ft_pos = 0;
483 fseeko(ft[i].ft_fp, 0, SEEK_SET);
484
485 nlen[i] = 0;
486 /* We could zalloc nfile, but then zalloc starts showing in gprof at ~1% */
487 nfile[i][0].offset = 0;
488 goto start; /* saves code */
489 while (1) {
490 tok = read_token(&ft[i], tok);
491 if (!(tok & TOK_EMPTY)) {
492 /* Hash algorithm taken from Robert Sedgewick, Algorithms in C, 3d ed., p 578. */
493 /*hash = hash * 128 - hash + TOK2CHAR(tok);
494 * gcc insists on optimizing above to "hash * 127 + ...", thus... */
495 unsigned o = hash - TOK2CHAR(tok);
496 hash = hash * 128 - o; /* we want SPEED here */
497 continue;
498 }
499 if (nlen[i]++ == sz) {
500 sz = sz * 3 / 2;
501 nfile[i] = xrealloc(nfile[i], (sz + 3) * sizeof(nfile[i][0]));
502 }
503 /* line_compar needs hashes fit into positive int */
504 nfile[i][nlen[i]].value = hash & INT_MAX;
505 /* like ftello(ft[i].ft_fp) but faster (avoids lseek syscall) */
506 nfile[i][nlen[i]].offset = ft[i].ft_pos;
507 if (tok & TOK_EOF) {
508 /* EOF counts as a token, so we have to adjust it here */
509 nfile[i][nlen[i]].offset++;
510 break;
511 }
512 start:
513 hash = tok = 0;
514 }
515 /* Exclude lone EOF line from the end of the file, to make fetch()'s job easier */
516 if (nfile[i][nlen[i]].offset - nfile[i][nlen[i] - 1].offset == 1)
517 nlen[i]--;
518 /* Now we copy the line offsets into ix */
519 ix[i] = xmalloc((nlen[i] + 2) * sizeof(ix[i][0]));
520 for (j = 0; j < nlen[i] + 1; j++)
521 ix[i][j] = nfile[i][j].offset;
522 }
523
524 /* length of prefix and suffix is calculated */
525 for (; pref < nlen[0] && pref < nlen[1] &&
526 nfile[0][pref + 1].value == nfile[1][pref + 1].value;
527 pref++);
528 for (; suff < nlen[0] - pref && suff < nlen[1] - pref &&
529 nfile[0][nlen[0] - suff].value == nfile[1][nlen[1] - suff].value;
530 suff++);
531 /* Arrays are pruned by the suffix and prefix length,
532 * the result being sorted and stored in sfile[fileno],
533 * and their sizes are stored in slen[fileno]
534 */
535 for (j = 0; j < 2; j++) {
536 sfile[j] = nfile[j] + pref;
537 slen[j] = nlen[j] - pref - suff;
538 for (i = 0; i <= slen[j]; i++)
539 sfile[j][i].serial = i;
540 qsort(sfile[j] + 1, slen[j], sizeof(*sfile[j]), line_compar);
541 }
542 /* nfile arrays are reused to reduce memory pressure
543 * The #if zeroed out section performs the same task as the
544 * one in the #else section.
545 * Peak memory usage is higher, but one array copy is avoided
546 * by not using unsort()
547 */
548 #if 0
549 member = xmalloc((slen[1] + 2) * sizeof(member[0]));
550 equiv(sfile[0], slen[0], sfile[1], slen[1], member);
551 free(nfile[1]);
552
553 class = xmalloc((slen[0] + 1) * sizeof(class[0]));
554 for (i = 1; i <= slen[0]; i++) /* Unsorting */
555 class[sfile[0][i].serial] = sfile[0][i].value;
556 free(nfile[0]);
557 #else
558 member = (int *)nfile[1];
559 equiv(sfile[0], slen[0], sfile[1], slen[1], member);
560 member = xrealloc(member, (slen[1] + 2) * sizeof(member[0]));
561
562 class = (int *)nfile[0];
563 unsort(sfile[0], slen[0], (int *)nfile[0]);
564 class = xrealloc(class, (slen[0] + 2) * sizeof(class[0]));
565 #endif
566 J = xmalloc((nlen[0] + 2) * sizeof(J[0]));
567 /* The elements of J which fall inside the prefix and suffix regions
568 * are marked as unchanged, while the ones which fall outside
569 * are initialized with 0 (no matches), so that function stone can
570 * then assign them their right values
571 */
572 for (i = 0, delta = nlen[1] - nlen[0]; i <= nlen[0]; i++)
573 J[i] = i <= pref ? i :
574 i > (nlen[0] - suff) ? (i + delta) : 0;
575 /* Here the magic is performed */
576 stone(class, slen[0], member, J, pref);
577 J[nlen[0] + 1] = nlen[1] + 1;
578
579 free(class);
580 free(member);
581
582 /* Both files are rescanned, in an effort to find any lines
583 * which, due to limitations intrinsic to any hashing algorithm,
584 * are different but ended up confounded as the same
585 */
586 for (i = 1; i <= nlen[0]; i++) {
587 if (!J[i])
588 continue;
589
590 seek_ft(&ft[0], ix[0][i - 1]);
591 seek_ft(&ft[1], ix[1][J[i] - 1]);
592
593 for (j = J[i]; i <= nlen[0] && J[i] == j; i++, j++) {
594 token_t tok0 = 0, tok1 = 0;
595 do {
596 tok0 = read_token(&ft[0], tok0);
597 tok1 = read_token(&ft[1], tok1);
598
599 if (((tok0 ^ tok1) & TOK_EMPTY) != 0 /* one is empty (not both) */
600 || (!(tok0 & TOK_EMPTY) && TOK2CHAR(tok0) != TOK2CHAR(tok1))
601 ) {
602 J[i] = 0; /* Break the correspondence */
603 }
604 } while (!(tok0 & tok1 & TOK_EMPTY));
605 }
606 }
607
608 return J;
609 }
610
diff(FILE * fp[2],char * file[2])611 static bool diff(FILE* fp[2], char *file[2])
612 {
613 int nlen[2];
614 off_t *ix[2];
615 FILE_and_pos_t ft[2];
616 typedef struct { int a, b; } vec_t[2];
617 vec_t *vec = NULL;
618 int i = 1, j, k, idx = -1;
619 bool anychange = false;
620 int *J;
621
622 ft[0].ft_fp = fp[0];
623 ft[1].ft_fp = fp[1];
624 /* note that ft[i].ft_pos is unintitalized, create_J()
625 * must not assume otherwise */
626 J = create_J(ft, nlen, ix);
627
628 do {
629 bool nonempty = false;
630
631 while (1) {
632 vec_t v;
633
634 for (v[0].a = i; v[0].a <= nlen[0] && J[v[0].a] == J[v[0].a - 1] + 1; v[0].a++)
635 continue;
636 v[1].a = J[v[0].a - 1] + 1;
637
638 for (v[0].b = v[0].a - 1; v[0].b < nlen[0] && !J[v[0].b + 1]; v[0].b++)
639 continue;
640 v[1].b = J[v[0].b + 1] - 1;
641 /*
642 * Indicate that there is a difference between lines a and b of the 'from' file
643 * to get to lines c to d of the 'to' file. If a is greater than b then there
644 * are no lines in the 'from' file involved and this means that there were
645 * lines appended (beginning at b). If c is greater than d then there are
646 * lines missing from the 'to' file.
647 */
648 if (v[0].a <= v[0].b || v[1].a <= v[1].b) {
649 /*
650 * If this change is more than 'context' lines from the
651 * previous change, dump the record and reset it.
652 */
653 int ct = (2 * opt_U_context) + 1;
654 if (idx >= 0
655 && v[0].a > vec[idx][0].b + ct
656 && v[1].a > vec[idx][1].b + ct
657 ) {
658 break;
659 }
660
661 for (j = 0; j < 2; j++)
662 for (k = v[j].a; k <= v[j].b; k++)
663 nonempty |= (ix[j][k] - ix[j][k - 1] != 1);
664
665 vec = xrealloc_vector(vec, 6, ++idx);
666 memcpy(vec[idx], v, sizeof(v));
667 }
668
669 i = v[0].b + 1;
670 if (i > nlen[0])
671 break;
672 J[v[0].b] = v[1].b;
673 }
674 if (idx < 0 || ((option_mask32 & FLAG(B)) && !nonempty))
675 goto cont;
676 if (!(option_mask32 & FLAG(q))) {
677 int lowa;
678 vec_t span, *cvp = vec;
679
680 if (!anychange) {
681 /* Print the context/unidiff header first time through */
682 printf("--- %s\n", label[0] ? label[0] : file[0]);
683 printf("+++ %s\n", label[1] ? label[1] : file[1]);
684 }
685
686 printf("@@");
687 for (j = 0; j < 2; j++) {
688 int a = span[j].a = MAX(1, (*cvp)[j].a - opt_U_context);
689 int b = span[j].b = MIN(nlen[j], vec[idx][j].b + opt_U_context);
690
691 printf(" %c%d", j ? '+' : '-', MIN(a, b));
692 if (a == b)
693 continue;
694 printf(",%d", (a < b) ? b - a + 1 : 0);
695 }
696 puts(" @@");
697 /*
698 * Output changes in "unified" diff format--the old and new lines
699 * are printed together.
700 */
701 for (lowa = span[0].a; ; lowa = (*cvp++)[0].b + 1) {
702 bool end = cvp > &vec[idx];
703 fetch(&ft[0], ix[0], lowa, end ? span[0].b : (*cvp)[0].a - 1, ' ');
704 if (end)
705 break;
706 for (j = 0; j < 2; j++)
707 fetch(&ft[j], ix[j], (*cvp)[j].a, (*cvp)[j].b, j ? '+' : '-');
708 }
709 }
710 anychange = true;
711 cont:
712 idx = -1;
713 } while (i <= nlen[0]);
714
715 free(vec);
716 free(ix[0]);
717 free(ix[1]);
718 free(J);
719 return anychange;
720 }
721
diffreg(char * file[2])722 static int diffreg(char *file[2])
723 {
724 FILE *fp[2];
725 bool binary = false, differ = false;
726 int status = STATUS_SAME, i;
727
728 fp[0] = stdin;
729 fp[1] = stdin;
730 for (i = 0; i < 2; i++) {
731 int fd = open_or_warn_stdin(file[i]);
732 if (fd == -1)
733 goto out;
734 /* Our diff implementation is using seek.
735 * When we meet non-seekable file, we must make a temp copy.
736 */
737 if (lseek(fd, 0, SEEK_SET) == -1 && errno == ESPIPE) {
738 char name[] = "/tmp/difXXXXXX";
739 int fd_tmp = xmkstemp(name);
740
741 unlink(name);
742 if (bb_copyfd_eof(fd, fd_tmp) < 0)
743 xfunc_die();
744 if (fd != STDIN_FILENO)
745 close(fd);
746 fd = fd_tmp;
747 xlseek(fd, 0, SEEK_SET);
748 }
749 fp[i] = fdopen(fd, "r");
750 }
751
752 setup_common_bufsiz();
753 while (1) {
754 const size_t sz = COMMON_BUFSIZE / 2;
755 char *const buf0 = bb_common_bufsiz1;
756 char *const buf1 = buf0 + sz;
757 int j, k;
758 i = fread(buf0, 1, sz, fp[0]);
759 j = fread(buf1, 1, sz, fp[1]);
760 if (i != j) {
761 differ = true;
762 i = MIN(i, j);
763 }
764 if (i == 0)
765 break;
766 for (k = 0; k < i; k++) {
767 if (!buf0[k] || !buf1[k])
768 binary = true;
769 if (buf0[k] != buf1[k])
770 differ = true;
771 }
772 }
773 if (differ) {
774 if (binary && !(option_mask32 & FLAG(a)))
775 status = STATUS_BINARY;
776 else if (diff(fp, file))
777 status = STATUS_DIFFER;
778 }
779 if (status != STATUS_SAME)
780 exit_status |= 1;
781 out:
782 fclose_if_not_stdin(fp[0]);
783 fclose_if_not_stdin(fp[1]);
784
785 return status;
786 }
787
print_status(int status,char * path[2])788 static void print_status(int status, char *path[2])
789 {
790 switch (status) {
791 case STATUS_BINARY:
792 case STATUS_DIFFER:
793 if ((option_mask32 & FLAG(q)) || status == STATUS_BINARY)
794 printf("Files %s and %s differ\n", path[0], path[1]);
795 break;
796 case STATUS_SAME:
797 if (option_mask32 & FLAG(s))
798 printf("Files %s and %s are identical\n", path[0], path[1]);
799 break;
800 }
801 }
802
803 #if ENABLE_FEATURE_DIFF_DIR
804 struct dlist {
805 size_t len;
806 int s, e;
807 char **dl;
808 };
809
810 /* This function adds a filename to dl, the directory listing. */
add_to_dirlist(const char * filename,struct stat * sb UNUSED_PARAM,void * userdata,int depth UNUSED_PARAM)811 static int FAST_FUNC add_to_dirlist(const char *filename,
812 struct stat *sb UNUSED_PARAM,
813 void *userdata, int depth UNUSED_PARAM)
814 {
815 struct dlist *const l = userdata;
816 const char *file = filename + l->len;
817 while (*file == '/')
818 file++;
819 l->dl = xrealloc_vector(l->dl, 6, l->e);
820 l->dl[l->e] = xstrdup(file);
821 l->e++;
822 return TRUE;
823 }
824
825 /* If recursion is not set, this function adds the directory
826 * to the list and prevents recursive_action from recursing into it.
827 */
skip_dir(const char * filename,struct stat * sb,void * userdata,int depth)828 static int FAST_FUNC skip_dir(const char *filename,
829 struct stat *sb, void *userdata,
830 int depth)
831 {
832 if (!(option_mask32 & FLAG(r)) && depth) {
833 add_to_dirlist(filename, sb, userdata, depth);
834 return SKIP;
835 }
836 if (!(option_mask32 & FLAG(N))) {
837 /* -r without -N: no need to recurse into dirs
838 * which do not exist on the "other side".
839 * Testcase: diff -r /tmp /
840 * (it would recurse deep into /proc without this code) */
841 struct dlist *const l = userdata;
842 filename += l->len;
843 if (filename[0]) {
844 struct stat osb;
845 char *othername = concat_path_file(G.other_dir, filename);
846 int r = stat(othername, &osb);
847 free(othername);
848 if (r != 0 || !S_ISDIR(osb.st_mode)) {
849 /* other dir doesn't have similarly named
850 * directory, don't recurse; return 1 upon
851 * exit, just like diffutils' diff */
852 exit_status |= 1;
853 return SKIP;
854 }
855 }
856 }
857 return TRUE;
858 }
859
diffdir(char * p[2],const char * s_start)860 static void diffdir(char *p[2], const char *s_start)
861 {
862 struct dlist list[2];
863 int i;
864
865 memset(&list, 0, sizeof(list));
866 for (i = 0; i < 2; i++) {
867 /*list[i].s = list[i].e = 0; - memset did it */
868 /*list[i].dl = NULL; */
869
870 G.other_dir = p[1 - i];
871 /* We need to trim root directory prefix.
872 * Using list.len to specify its length,
873 * add_to_dirlist will remove it. */
874 list[i].len = strlen(p[i]);
875 recursive_action(p[i], ACTION_RECURSE | ACTION_FOLLOWLINKS,
876 add_to_dirlist, skip_dir, &list[i], 0);
877 /* Sort dl alphabetically.
878 * GNU diff does this ignoring any number of trailing dots.
879 * We don't, so for us dotted files almost always are
880 * first on the list.
881 */
882 qsort_string_vector(list[i].dl, list[i].e);
883 /* If -S was set, find the starting point. */
884 if (!s_start)
885 continue;
886 while (list[i].s < list[i].e && strcmp(list[i].dl[list[i].s], s_start) < 0)
887 list[i].s++;
888 }
889 /* Now that both dirlist1 and dirlist2 contain sorted directory
890 * listings, we can start to go through dirlist1. If both listings
891 * contain the same file, then do a normal diff. Otherwise, behaviour
892 * is determined by whether the -N flag is set. */
893 while (1) {
894 char *dp[2];
895 int pos;
896 int k;
897
898 dp[0] = list[0].s < list[0].e ? list[0].dl[list[0].s] : NULL;
899 dp[1] = list[1].s < list[1].e ? list[1].dl[list[1].s] : NULL;
900 if (!dp[0] && !dp[1])
901 break;
902 pos = !dp[0] ? 1 : (!dp[1] ? -1 : strcmp(dp[0], dp[1]));
903 k = pos > 0;
904 if (pos && !(option_mask32 & FLAG(N))) {
905 printf("Only in %s: %s\n", p[k], dp[k]);
906 exit_status |= 1;
907 } else {
908 char *fullpath[2], *path[2]; /* if -N */
909
910 for (i = 0; i < 2; i++) {
911 if (pos == 0 || i == k) {
912 path[i] = fullpath[i] = concat_path_file(p[i], dp[i]);
913 stat(fullpath[i], &stb[i]);
914 } else {
915 fullpath[i] = concat_path_file(p[i], dp[1 - i]);
916 path[i] = (char *)bb_dev_null;
917 }
918 }
919 if (pos)
920 stat(fullpath[k], &stb[1 - k]);
921
922 if (S_ISDIR(stb[0].st_mode) && S_ISDIR(stb[1].st_mode))
923 printf("Common subdirectories: %s and %s\n", fullpath[0], fullpath[1]);
924 else if (!S_ISREG(stb[0].st_mode) && !S_ISDIR(stb[0].st_mode))
925 printf("File %s is not a regular file or directory and was skipped\n", fullpath[0]);
926 else if (!S_ISREG(stb[1].st_mode) && !S_ISDIR(stb[1].st_mode))
927 printf("File %s is not a regular file or directory and was skipped\n", fullpath[1]);
928 else if (S_ISDIR(stb[0].st_mode) != S_ISDIR(stb[1].st_mode)) {
929 if (S_ISDIR(stb[0].st_mode))
930 printf("File %s is a %s while file %s is a %s\n", fullpath[0], "directory", fullpath[1], "regular file");
931 else
932 printf("File %s is a %s while file %s is a %s\n", fullpath[0], "regular file", fullpath[1], "directory");
933 } else
934 print_status(diffreg(path), fullpath);
935
936 free(fullpath[0]);
937 free(fullpath[1]);
938 }
939 free(dp[k]);
940 list[k].s++;
941 if (pos == 0) {
942 free(dp[1 - k]);
943 list[1 - k].s++;
944 }
945 }
946 if (ENABLE_FEATURE_CLEAN_UP) {
947 free(list[0].dl);
948 free(list[1].dl);
949 }
950 }
951 #endif
952
953 #if ENABLE_FEATURE_DIFF_LONG_OPTIONS
954 static const char diff_longopts[] ALIGN1 =
955 "ignore-case\0" No_argument "i"
956 "ignore-tab-expansion\0" No_argument "E"
957 "ignore-space-change\0" No_argument "b"
958 "ignore-all-space\0" No_argument "w"
959 "ignore-blank-lines\0" No_argument "B"
960 "text\0" No_argument "a"
961 "unified\0" Required_argument "U"
962 "label\0" Required_argument "L"
963 "show-c-function\0" No_argument "p"
964 "brief\0" No_argument "q"
965 "expand-tabs\0" No_argument "t"
966 "initial-tab\0" No_argument "T"
967 "recursive\0" No_argument "r"
968 "new-file\0" No_argument "N"
969 "report-identical-files\0" No_argument "s"
970 "starting-file\0" Required_argument "S"
971 "minimal\0" No_argument "d"
972 ;
973 #endif
974
975 int diff_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
diff_main(int argc UNUSED_PARAM,char ** argv)976 int diff_main(int argc UNUSED_PARAM, char **argv)
977 {
978 int gotstdin = 0, i;
979 char *file[2], *s_start = NULL;
980 llist_t *L_arg = NULL;
981
982 INIT_G();
983
984 /* exactly 2 params; collect multiple -L <label>; -U N */
985 opt_complementary = "=2";
986 #if ENABLE_FEATURE_DIFF_LONG_OPTIONS
987 applet_long_options = diff_longopts;
988 #endif
989 getopt32(argv, "abdiL:*NqrsS:tTU:+wupBE",
990 &L_arg, &s_start, &opt_U_context);
991 argv += optind;
992 while (L_arg)
993 label[!!label[0]] = llist_pop(&L_arg);
994 xfunc_error_retval = 2;
995 for (i = 0; i < 2; i++) {
996 file[i] = argv[i];
997 /* Compat: "diff file name_which_doesnt_exist" exits with 2 */
998 if (LONE_DASH(file[i])) {
999 fstat(STDIN_FILENO, &stb[i]);
1000 gotstdin++;
1001 } else
1002 xstat(file[i], &stb[i]);
1003 }
1004 xfunc_error_retval = 1;
1005 if (gotstdin && (S_ISDIR(stb[0].st_mode) || S_ISDIR(stb[1].st_mode)))
1006 bb_error_msg_and_die("can't compare stdin to a directory");
1007
1008 /* Compare metadata to check if the files are the same physical file.
1009 *
1010 * Comment from diffutils source says:
1011 * POSIX says that two files are identical if st_ino and st_dev are
1012 * the same, but many file systems incorrectly assign the same (device,
1013 * inode) pair to two distinct files, including:
1014 * GNU/Linux NFS servers that export all local file systems as a
1015 * single NFS file system, if a local device number (st_dev) exceeds
1016 * 255, or if a local inode number (st_ino) exceeds 16777215.
1017 */
1018 if (ENABLE_DESKTOP
1019 && stb[0].st_ino == stb[1].st_ino
1020 && stb[0].st_dev == stb[1].st_dev
1021 && stb[0].st_size == stb[1].st_size
1022 && stb[0].st_mtime == stb[1].st_mtime
1023 && stb[0].st_ctime == stb[1].st_ctime
1024 && stb[0].st_mode == stb[1].st_mode
1025 && stb[0].st_nlink == stb[1].st_nlink
1026 && stb[0].st_uid == stb[1].st_uid
1027 && stb[0].st_gid == stb[1].st_gid
1028 ) {
1029 /* files are physically the same; no need to compare them */
1030 return STATUS_SAME;
1031 }
1032
1033 if (S_ISDIR(stb[0].st_mode) && S_ISDIR(stb[1].st_mode)) {
1034 #if ENABLE_FEATURE_DIFF_DIR
1035 diffdir(file, s_start);
1036 #else
1037 bb_error_msg_and_die("no support for directory comparison");
1038 #endif
1039 } else {
1040 bool dirfile = S_ISDIR(stb[0].st_mode) || S_ISDIR(stb[1].st_mode);
1041 bool dir = S_ISDIR(stb[1].st_mode);
1042 if (dirfile) {
1043 const char *slash = strrchr(file[!dir], '/');
1044 file[dir] = concat_path_file(file[dir], slash ? slash + 1 : file[!dir]);
1045 xstat(file[dir], &stb[dir]);
1046 }
1047 /* diffreg can get non-regular files here */
1048 print_status(gotstdin > 1 ? STATUS_SAME : diffreg(file), file);
1049
1050 if (dirfile)
1051 free(file[dir]);
1052 }
1053
1054 return exit_status;
1055 }
1056