Merge branch 'jk/write-file'
[git] / tree-diff.c
1 /*
2  * Helper functions for tree diff generation
3  */
4 #include "cache.h"
5 #include "diff.h"
6 #include "diffcore.h"
7 #include "tree.h"
8
9 /*
10  * internal mode marker, saying a tree entry != entry of tp[imin]
11  * (see ll_diff_tree_paths for what it means there)
12  *
13  * we will update/use/emit entry for diff only with it unset.
14  */
15 #define S_IFXMIN_NEQ    S_DIFFTREE_IFXMIN_NEQ
16
17 #define FAST_ARRAY_ALLOC(x, nr) do { \
18         if ((nr) <= 2) \
19                 (x) = xalloca((nr) * sizeof(*(x))); \
20         else \
21                 ALLOC_ARRAY((x), nr); \
22 } while(0)
23 #define FAST_ARRAY_FREE(x, nr) do { \
24         if ((nr) > 2) \
25                 free((x)); \
26 } while(0)
27
28 static struct combine_diff_path *ll_diff_tree_paths(
29         struct combine_diff_path *p, const unsigned char *sha1,
30         const unsigned char **parents_sha1, int nparent,
31         struct strbuf *base, struct diff_options *opt);
32 static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
33                              struct strbuf *base, struct diff_options *opt);
34
35 /*
36  * Compare two tree entries, taking into account only path/S_ISDIR(mode),
37  * but not their sha1's.
38  *
39  * NOTE files and directories *always* compare differently, even when having
40  *      the same name - thanks to base_name_compare().
41  *
42  * NOTE empty (=invalid) descriptor(s) take part in comparison as +infty,
43  *      so that they sort *after* valid tree entries.
44  *
45  *      Due to this convention, if trees are scanned in sorted order, all
46  *      non-empty descriptors will be processed first.
47  */
48 static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
49 {
50         struct name_entry *e1, *e2;
51         int cmp;
52
53         /* empty descriptors sort after valid tree entries */
54         if (!t1->size)
55                 return t2->size ? 1 : 0;
56         else if (!t2->size)
57                 return -1;
58
59         e1 = &t1->entry;
60         e2 = &t2->entry;
61         cmp = base_name_compare(e1->path, tree_entry_len(e1), e1->mode,
62                                 e2->path, tree_entry_len(e2), e2->mode);
63         return cmp;
64 }
65
66
67 /*
68  * convert path -> opt->diff_*() callbacks
69  *
70  * emits diff to first parent only, and tells diff tree-walker that we are done
71  * with p and it can be freed.
72  */
73 static int emit_diff_first_parent_only(struct diff_options *opt, struct combine_diff_path *p)
74 {
75         struct combine_diff_parent *p0 = &p->parent[0];
76         if (p->mode && p0->mode) {
77                 opt->change(opt, p0->mode, p->mode, p0->oid.hash, p->oid.hash,
78                         1, 1, p->path, 0, 0);
79         }
80         else {
81                 const unsigned char *sha1;
82                 unsigned int mode;
83                 int addremove;
84
85                 if (p->mode) {
86                         addremove = '+';
87                         sha1 = p->oid.hash;
88                         mode = p->mode;
89                 } else {
90                         addremove = '-';
91                         sha1 = p0->oid.hash;
92                         mode = p0->mode;
93                 }
94
95                 opt->add_remove(opt, addremove, mode, sha1, 1, p->path, 0);
96         }
97
98         return 0;       /* we are done with p */
99 }
100
101
102 /*
103  * Make a new combine_diff_path from path/mode/sha1
104  * and append it to paths list tail.
105  *
106  * Memory for created elements could be reused:
107  *
108  *      - if last->next == NULL, the memory is allocated;
109  *
110  *      - if last->next != NULL, it is assumed that p=last->next was returned
111  *        earlier by this function, and p->next was *not* modified.
112  *        The memory is then reused from p.
113  *
114  * so for clients,
115  *
116  * - if you do need to keep the element
117  *
118  *      p = path_appendnew(p, ...);
119  *      process(p);
120  *      p->next = NULL;
121  *
122  * - if you don't need to keep the element after processing
123  *
124  *      pprev = p;
125  *      p = path_appendnew(p, ...);
126  *      process(p);
127  *      p = pprev;
128  *      ; don't forget to free tail->next in the end
129  *
130  * p->parent[] remains uninitialized.
131  */
132 static struct combine_diff_path *path_appendnew(struct combine_diff_path *last,
133         int nparent, const struct strbuf *base, const char *path, int pathlen,
134         unsigned mode, const unsigned char *sha1)
135 {
136         struct combine_diff_path *p;
137         size_t len = st_add(base->len, pathlen);
138         size_t alloclen = combine_diff_path_size(nparent, len);
139
140         /* if last->next is !NULL - it is a pre-allocated memory, we can reuse */
141         p = last->next;
142         if (p && (alloclen > (intptr_t)p->next)) {
143                 free(p);
144                 p = NULL;
145         }
146
147         if (!p) {
148                 p = xmalloc(alloclen);
149
150                 /*
151                  * until we go to it next round, .next holds how many bytes we
152                  * allocated (for faster realloc - we don't need copying old data).
153                  */
154                 p->next = (struct combine_diff_path *)(intptr_t)alloclen;
155         }
156
157         last->next = p;
158
159         p->path = (char *)&(p->parent[nparent]);
160         memcpy(p->path, base->buf, base->len);
161         memcpy(p->path + base->len, path, pathlen);
162         p->path[len] = 0;
163         p->mode = mode;
164         hashcpy(p->oid.hash, sha1 ? sha1 : null_sha1);
165
166         return p;
167 }
168
169 /*
170  * new path should be added to combine diff
171  *
172  * 3 cases on how/when it should be called and behaves:
173  *
174  *       t, !tp         -> path added, all parents lack it
175  *      !t,  tp         -> path removed from all parents
176  *       t,  tp         -> path modified/added
177  *                         (M for tp[i]=tp[imin], A otherwise)
178  */
179 static struct combine_diff_path *emit_path(struct combine_diff_path *p,
180         struct strbuf *base, struct diff_options *opt, int nparent,
181         struct tree_desc *t, struct tree_desc *tp,
182         int imin)
183 {
184         unsigned mode;
185         const char *path;
186         const unsigned char *sha1;
187         int pathlen;
188         int old_baselen = base->len;
189         int i, isdir, recurse = 0, emitthis = 1;
190
191         /* at least something has to be valid */
192         assert(t || tp);
193
194         if (t) {
195                 /* path present in resulting tree */
196                 sha1 = tree_entry_extract(t, &path, &mode)->hash;
197                 pathlen = tree_entry_len(&t->entry);
198                 isdir = S_ISDIR(mode);
199         } else {
200                 /*
201                  * a path was removed - take path from imin parent. Also take
202                  * mode from that parent, to decide on recursion(1).
203                  *
204                  * 1) all modes for tp[i]=tp[imin] should be the same wrt
205                  *    S_ISDIR, thanks to base_name_compare().
206                  */
207                 tree_entry_extract(&tp[imin], &path, &mode);
208                 pathlen = tree_entry_len(&tp[imin].entry);
209
210                 isdir = S_ISDIR(mode);
211                 sha1 = NULL;
212                 mode = 0;
213         }
214
215         if (DIFF_OPT_TST(opt, RECURSIVE) && isdir) {
216                 recurse = 1;
217                 emitthis = DIFF_OPT_TST(opt, TREE_IN_RECURSIVE);
218         }
219
220         if (emitthis) {
221                 int keep;
222                 struct combine_diff_path *pprev = p;
223                 p = path_appendnew(p, nparent, base, path, pathlen, mode, sha1);
224
225                 for (i = 0; i < nparent; ++i) {
226                         /*
227                          * tp[i] is valid, if present and if tp[i]==tp[imin] -
228                          * otherwise, we should ignore it.
229                          */
230                         int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
231
232                         const unsigned char *sha1_i;
233                         unsigned mode_i;
234
235                         p->parent[i].status =
236                                 !t ? DIFF_STATUS_DELETED :
237                                         tpi_valid ?
238                                                 DIFF_STATUS_MODIFIED :
239                                                 DIFF_STATUS_ADDED;
240
241                         if (tpi_valid) {
242                                 sha1_i = tp[i].entry.oid->hash;
243                                 mode_i = tp[i].entry.mode;
244                         }
245                         else {
246                                 sha1_i = NULL;
247                                 mode_i = 0;
248                         }
249
250                         p->parent[i].mode = mode_i;
251                         hashcpy(p->parent[i].oid.hash, sha1_i ? sha1_i : null_sha1);
252                 }
253
254                 keep = 1;
255                 if (opt->pathchange)
256                         keep = opt->pathchange(opt, p);
257
258                 /*
259                  * If a path was filtered or consumed - we don't need to add it
260                  * to the list and can reuse its memory, leaving it as
261                  * pre-allocated element on the tail.
262                  *
263                  * On the other hand, if path needs to be kept, we need to
264                  * correct its .next to NULL, as it was pre-initialized to how
265                  * much memory was allocated.
266                  *
267                  * see path_appendnew() for details.
268                  */
269                 if (!keep)
270                         p = pprev;
271                 else
272                         p->next = NULL;
273         }
274
275         if (recurse) {
276                 const unsigned char **parents_sha1;
277
278                 FAST_ARRAY_ALLOC(parents_sha1, nparent);
279                 for (i = 0; i < nparent; ++i) {
280                         /* same rule as in emitthis */
281                         int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
282
283                         parents_sha1[i] = tpi_valid ? tp[i].entry.oid->hash
284                                                     : NULL;
285                 }
286
287                 strbuf_add(base, path, pathlen);
288                 strbuf_addch(base, '/');
289                 p = ll_diff_tree_paths(p, sha1, parents_sha1, nparent, base, opt);
290                 FAST_ARRAY_FREE(parents_sha1, nparent);
291         }
292
293         strbuf_setlen(base, old_baselen);
294         return p;
295 }
296
297 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
298                                struct diff_options *opt)
299 {
300         enum interesting match;
301
302         while (t->size) {
303                 match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
304                 if (match) {
305                         if (match == all_entries_not_interesting)
306                                 t->size = 0;
307                         break;
308                 }
309                 update_tree_entry(t);
310         }
311 }
312
313
314 /*
315  * generate paths for combined diff D(sha1,parents_sha1[])
316  *
317  * Resulting paths are appended to combine_diff_path linked list, and also, are
318  * emitted on the go via opt->pathchange() callback, so it is possible to
319  * process the result as batch or incrementally.
320  *
321  * The paths are generated scanning new tree and all parents trees
322  * simultaneously, similarly to what diff_tree() was doing for 2 trees.
323  * The theory behind such scan is as follows:
324  *
325  *
326  * D(T,P1...Pn) calculation scheme
327  * -------------------------------
328  *
329  * D(T,P1...Pn) = D(T,P1) ^ ... ^ D(T,Pn)       (regarding resulting paths set)
330  *
331  *      D(T,Pj)         - diff between T..Pj
332  *      D(T,P1...Pn)    - combined diff from T to parents P1,...,Pn
333  *
334  *
335  * We start from all trees, which are sorted, and compare their entries in
336  * lock-step:
337  *
338  *       T     P1       Pn
339  *       -     -        -
340  *      |t|   |p1|     |pn|
341  *      |-|   |--| ... |--|      imin = argmin(p1...pn)
342  *      | |   |  |     |  |
343  *      |-|   |--|     |--|
344  *      |.|   |. |     |. |
345  *       .     .        .
346  *       .     .        .
347  *
348  * at any time there could be 3 cases:
349  *
350  *      1)  t < p[imin];
351  *      2)  t > p[imin];
352  *      3)  t = p[imin].
353  *
354  * Schematic deduction of what every case means, and what to do, follows:
355  *
356  * 1)  t < p[imin]  ->  ∀j t ∉ Pj  ->  "+t" ∈ D(T,Pj)  ->  D += "+t";  t↓
357  *
358  * 2)  t > p[imin]
359  *
360  *     2.1) ∃j: pj > p[imin]  ->  "-p[imin]" ∉ D(T,Pj)  ->  D += ø;  ∀ pi=p[imin]  pi↓
361  *     2.2) ∀i  pi = p[imin]  ->  pi ∉ T  ->  "-pi" ∈ D(T,Pi)  ->  D += "-p[imin]";  ∀i pi↓
362  *
363  * 3)  t = p[imin]
364  *
365  *     3.1) ∃j: pj > p[imin]  ->  "+t" ∈ D(T,Pj)  ->  only pi=p[imin] remains to investigate
366  *     3.2) pi = p[imin]  ->  investigate δ(t,pi)
367  *      |
368  *      |
369  *      v
370  *
371  *     3.1+3.2) looking at δ(t,pi) ∀i: pi=p[imin] - if all != ø  ->
372  *
373  *                       ⎧δ(t,pi)  - if pi=p[imin]
374  *              ->  D += ⎨
375  *                       ⎩"+t"     - if pi>p[imin]
376  *
377  *
378  *     in any case t↓  ∀ pi=p[imin]  pi↓
379  *
380  *
381  * ~~~~~~~~
382  *
383  * NOTE
384  *
385  *      Usual diff D(A,B) is by definition the same as combined diff D(A,[B]),
386  *      so this diff paths generator can, and is used, for plain diffs
387  *      generation too.
388  *
389  *      Please keep attention to the common D(A,[B]) case when working on the
390  *      code, in order not to slow it down.
391  *
392  * NOTE
393  *      nparent must be > 0.
394  */
395
396
397 /* ∀ pi=p[imin]  pi↓ */
398 static inline void update_tp_entries(struct tree_desc *tp, int nparent)
399 {
400         int i;
401         for (i = 0; i < nparent; ++i)
402                 if (!(tp[i].entry.mode & S_IFXMIN_NEQ))
403                         update_tree_entry(&tp[i]);
404 }
405
406 static struct combine_diff_path *ll_diff_tree_paths(
407         struct combine_diff_path *p, const unsigned char *sha1,
408         const unsigned char **parents_sha1, int nparent,
409         struct strbuf *base, struct diff_options *opt)
410 {
411         struct tree_desc t, *tp;
412         void *ttree, **tptree;
413         int i;
414
415         FAST_ARRAY_ALLOC(tp, nparent);
416         FAST_ARRAY_ALLOC(tptree, nparent);
417
418         /*
419          * load parents first, as they are probably already cached.
420          *
421          * ( log_tree_diff() parses commit->parent before calling here via
422          *   diff_tree_sha1(parent, commit) )
423          */
424         for (i = 0; i < nparent; ++i)
425                 tptree[i] = fill_tree_descriptor(&tp[i], parents_sha1[i]);
426         ttree = fill_tree_descriptor(&t, sha1);
427
428         /* Enable recursion indefinitely */
429         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
430
431         for (;;) {
432                 int imin, cmp;
433
434                 if (diff_can_quit_early(opt))
435                         break;
436
437                 if (opt->pathspec.nr) {
438                         skip_uninteresting(&t, base, opt);
439                         for (i = 0; i < nparent; i++)
440                                 skip_uninteresting(&tp[i], base, opt);
441                 }
442
443                 /* comparing is finished when all trees are done */
444                 if (!t.size) {
445                         int done = 1;
446                         for (i = 0; i < nparent; ++i)
447                                 if (tp[i].size) {
448                                         done = 0;
449                                         break;
450                                 }
451                         if (done)
452                                 break;
453                 }
454
455                 /*
456                  * lookup imin = argmin(p1...pn),
457                  * mark entries whether they =p[imin] along the way
458                  */
459                 imin = 0;
460                 tp[0].entry.mode &= ~S_IFXMIN_NEQ;
461
462                 for (i = 1; i < nparent; ++i) {
463                         cmp = tree_entry_pathcmp(&tp[i], &tp[imin]);
464                         if (cmp < 0) {
465                                 imin = i;
466                                 tp[i].entry.mode &= ~S_IFXMIN_NEQ;
467                         }
468                         else if (cmp == 0) {
469                                 tp[i].entry.mode &= ~S_IFXMIN_NEQ;
470                         }
471                         else {
472                                 tp[i].entry.mode |= S_IFXMIN_NEQ;
473                         }
474                 }
475
476                 /* fixup markings for entries before imin */
477                 for (i = 0; i < imin; ++i)
478                         tp[i].entry.mode |= S_IFXMIN_NEQ;       /* pi > p[imin] */
479
480
481
482                 /* compare t vs p[imin] */
483                 cmp = tree_entry_pathcmp(&t, &tp[imin]);
484
485                 /* t = p[imin] */
486                 if (cmp == 0) {
487                         /* are either pi > p[imin] or diff(t,pi) != ø ? */
488                         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER)) {
489                                 for (i = 0; i < nparent; ++i) {
490                                         /* p[i] > p[imin] */
491                                         if (tp[i].entry.mode & S_IFXMIN_NEQ)
492                                                 continue;
493
494                                         /* diff(t,pi) != ø */
495                                         if (oidcmp(t.entry.oid, tp[i].entry.oid) ||
496                                             (t.entry.mode != tp[i].entry.mode))
497                                                 continue;
498
499                                         goto skip_emit_t_tp;
500                                 }
501                         }
502
503                         /* D += {δ(t,pi) if pi=p[imin];  "+a" if pi > p[imin]} */
504                         p = emit_path(p, base, opt, nparent,
505                                         &t, tp, imin);
506
507                 skip_emit_t_tp:
508                         /* t↓,  ∀ pi=p[imin]  pi↓ */
509                         update_tree_entry(&t);
510                         update_tp_entries(tp, nparent);
511                 }
512
513                 /* t < p[imin] */
514                 else if (cmp < 0) {
515                         /* D += "+t" */
516                         p = emit_path(p, base, opt, nparent,
517                                         &t, /*tp=*/NULL, -1);
518
519                         /* t↓ */
520                         update_tree_entry(&t);
521                 }
522
523                 /* t > p[imin] */
524                 else {
525                         /* ∀i pi=p[imin] -> D += "-p[imin]" */
526                         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER)) {
527                                 for (i = 0; i < nparent; ++i)
528                                         if (tp[i].entry.mode & S_IFXMIN_NEQ)
529                                                 goto skip_emit_tp;
530                         }
531
532                         p = emit_path(p, base, opt, nparent,
533                                         /*t=*/NULL, tp, imin);
534
535                 skip_emit_tp:
536                         /* ∀ pi=p[imin]  pi↓ */
537                         update_tp_entries(tp, nparent);
538                 }
539         }
540
541         free(ttree);
542         for (i = nparent-1; i >= 0; i--)
543                 free(tptree[i]);
544         FAST_ARRAY_FREE(tptree, nparent);
545         FAST_ARRAY_FREE(tp, nparent);
546
547         return p;
548 }
549
550 struct combine_diff_path *diff_tree_paths(
551         struct combine_diff_path *p, const unsigned char *sha1,
552         const unsigned char **parents_sha1, int nparent,
553         struct strbuf *base, struct diff_options *opt)
554 {
555         p = ll_diff_tree_paths(p, sha1, parents_sha1, nparent, base, opt);
556
557         /*
558          * free pre-allocated last element, if any
559          * (see path_appendnew() for details about why)
560          */
561         if (p->next) {
562                 free(p->next);
563                 p->next = NULL;
564         }
565
566         return p;
567 }
568
569 /*
570  * Does it look like the resulting diff might be due to a rename?
571  *  - single entry
572  *  - not a valid previous file
573  */
574 static inline int diff_might_be_rename(void)
575 {
576         return diff_queued_diff.nr == 1 &&
577                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
578 }
579
580 static void try_to_follow_renames(const unsigned char *old, const unsigned char *new, struct strbuf *base, struct diff_options *opt)
581 {
582         struct diff_options diff_opts;
583         struct diff_queue_struct *q = &diff_queued_diff;
584         struct diff_filepair *choice;
585         int i;
586
587         /*
588          * follow-rename code is very specific, we need exactly one
589          * path. Magic that matches more than one path is not
590          * supported.
591          */
592         GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
593 #if 0
594         /*
595          * We should reject wildcards as well. Unfortunately we
596          * haven't got a reliable way to detect that 'foo\*bar' in
597          * fact has no wildcards. nowildcard_len is merely a hint for
598          * optimization. Let it slip for now until wildmatch is taught
599          * about dry-run mode and returns wildcard info.
600          */
601         if (opt->pathspec.has_wildcard)
602                 die("BUG:%s:%d: wildcards are not supported",
603                     __FILE__, __LINE__);
604 #endif
605
606         /* Remove the file creation entry from the diff queue, and remember it */
607         choice = q->queue[0];
608         q->nr = 0;
609
610         diff_setup(&diff_opts);
611         DIFF_OPT_SET(&diff_opts, RECURSIVE);
612         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
613         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
614         diff_opts.single_follow = opt->pathspec.items[0].match;
615         diff_opts.break_opt = opt->break_opt;
616         diff_opts.rename_score = opt->rename_score;
617         diff_setup_done(&diff_opts);
618         ll_diff_tree_sha1(old, new, base, &diff_opts);
619         diffcore_std(&diff_opts);
620         clear_pathspec(&diff_opts.pathspec);
621
622         /* Go through the new set of filepairing, and see if we find a more interesting one */
623         opt->found_follow = 0;
624         for (i = 0; i < q->nr; i++) {
625                 struct diff_filepair *p = q->queue[i];
626
627                 /*
628                  * Found a source? Not only do we use that for the new
629                  * diff_queued_diff, we will also use that as the path in
630                  * the future!
631                  */
632                 if ((p->status == 'R' || p->status == 'C') &&
633                     !strcmp(p->two->path, opt->pathspec.items[0].match)) {
634                         const char *path[2];
635
636                         /* Switch the file-pairs around */
637                         q->queue[i] = choice;
638                         choice = p;
639
640                         /* Update the path we use from now on.. */
641                         path[0] = p->one->path;
642                         path[1] = NULL;
643                         clear_pathspec(&opt->pathspec);
644                         parse_pathspec(&opt->pathspec,
645                                        PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
646                                        PATHSPEC_LITERAL_PATH, "", path);
647
648                         /*
649                          * The caller expects us to return a set of vanilla
650                          * filepairs to let a later call to diffcore_std()
651                          * it makes to sort the renames out (among other
652                          * things), but we already have found renames
653                          * ourselves; signal diffcore_std() not to muck with
654                          * rename information.
655                          */
656                         opt->found_follow = 1;
657                         break;
658                 }
659         }
660
661         /*
662          * Then, discard all the non-relevant file pairs...
663          */
664         for (i = 0; i < q->nr; i++) {
665                 struct diff_filepair *p = q->queue[i];
666                 diff_free_filepair(p);
667         }
668
669         /*
670          * .. and re-instate the one we want (which might be either the
671          * original one, or the rename/copy we found)
672          */
673         q->queue[0] = choice;
674         q->nr = 1;
675 }
676
677 static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
678                              struct strbuf *base, struct diff_options *opt)
679 {
680         struct combine_diff_path phead, *p;
681         pathchange_fn_t pathchange_old = opt->pathchange;
682
683         phead.next = NULL;
684         opt->pathchange = emit_diff_first_parent_only;
685         diff_tree_paths(&phead, new, &old, 1, base, opt);
686
687         for (p = phead.next; p;) {
688                 struct combine_diff_path *pprev = p;
689                 p = p->next;
690                 free(pprev);
691         }
692
693         opt->pathchange = pathchange_old;
694         return 0;
695 }
696
697 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base_str, struct diff_options *opt)
698 {
699         struct strbuf base;
700         int retval;
701
702         strbuf_init(&base, PATH_MAX);
703         strbuf_addstr(&base, base_str);
704
705         retval = ll_diff_tree_sha1(old, new, &base, opt);
706         if (!*base_str && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename())
707                 try_to_follow_renames(old, new, &base, opt);
708
709         strbuf_release(&base);
710
711         return retval;
712 }
713
714 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
715 {
716         return diff_tree_sha1(NULL, new, base, opt);
717 }