be98c0afcb9fa48ae9d637046c50774889af385f
[git/git.git] / rerere.c
1 #include "cache.h"
2 #include "config.h"
3 #include "lockfile.h"
4 #include "string-list.h"
5 #include "rerere.h"
6 #include "xdiff-interface.h"
7 #include "dir.h"
8 #include "resolve-undo.h"
9 #include "ll-merge.h"
10 #include "attr.h"
11 #include "pathspec.h"
12 #include "sha1-lookup.h"
13
14 #define RESOLVED 0
15 #define PUNTED 1
16 #define THREE_STAGED 2
17 void *RERERE_RESOLVED = &RERERE_RESOLVED;
18
19 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
20 static int rerere_enabled = -1;
21
22 /* automatically update cleanly resolved paths to the index */
23 static int rerere_autoupdate;
24
25 static int rerere_dir_nr;
26 static int rerere_dir_alloc;
27
28 #define RR_HAS_POSTIMAGE 1
29 #define RR_HAS_PREIMAGE 2
30 static struct rerere_dir {
31 unsigned char sha1[20];
32 int status_alloc, status_nr;
33 unsigned char *status;
34 } **rerere_dir;
35
36 static void free_rerere_dirs(void)
37 {
38 int i;
39 for (i = 0; i < rerere_dir_nr; i++) {
40 free(rerere_dir[i]->status);
41 free(rerere_dir[i]);
42 }
43 FREE_AND_NULL(rerere_dir);
44 rerere_dir_nr = rerere_dir_alloc = 0;
45 }
46
47 static void free_rerere_id(struct string_list_item *item)
48 {
49 free(item->util);
50 }
51
52 static const char *rerere_id_hex(const struct rerere_id *id)
53 {
54 return sha1_to_hex(id->collection->sha1);
55 }
56
57 static void fit_variant(struct rerere_dir *rr_dir, int variant)
58 {
59 variant++;
60 ALLOC_GROW(rr_dir->status, variant, rr_dir->status_alloc);
61 if (rr_dir->status_nr < variant) {
62 memset(rr_dir->status + rr_dir->status_nr,
63 '\0', variant - rr_dir->status_nr);
64 rr_dir->status_nr = variant;
65 }
66 }
67
68 static void assign_variant(struct rerere_id *id)
69 {
70 int variant;
71 struct rerere_dir *rr_dir = id->collection;
72
73 variant = id->variant;
74 if (variant < 0) {
75 for (variant = 0; variant < rr_dir->status_nr; variant++)
76 if (!rr_dir->status[variant])
77 break;
78 }
79 fit_variant(rr_dir, variant);
80 id->variant = variant;
81 }
82
83 const char *rerere_path(const struct rerere_id *id, const char *file)
84 {
85 if (!file)
86 return git_path("rr-cache/%s", rerere_id_hex(id));
87
88 if (id->variant <= 0)
89 return git_path("rr-cache/%s/%s", rerere_id_hex(id), file);
90
91 return git_path("rr-cache/%s/%s.%d",
92 rerere_id_hex(id), file, id->variant);
93 }
94
95 static int is_rr_file(const char *name, const char *filename, int *variant)
96 {
97 const char *suffix;
98 char *ep;
99
100 if (!strcmp(name, filename)) {
101 *variant = 0;
102 return 1;
103 }
104 if (!skip_prefix(name, filename, &suffix) || *suffix != '.')
105 return 0;
106
107 errno = 0;
108 *variant = strtol(suffix + 1, &ep, 10);
109 if (errno || *ep)
110 return 0;
111 return 1;
112 }
113
114 static void scan_rerere_dir(struct rerere_dir *rr_dir)
115 {
116 struct dirent *de;
117 DIR *dir = opendir(git_path("rr-cache/%s", sha1_to_hex(rr_dir->sha1)));
118
119 if (!dir)
120 return;
121 while ((de = readdir(dir)) != NULL) {
122 int variant;
123
124 if (is_rr_file(de->d_name, "postimage", &variant)) {
125 fit_variant(rr_dir, variant);
126 rr_dir->status[variant] |= RR_HAS_POSTIMAGE;
127 } else if (is_rr_file(de->d_name, "preimage", &variant)) {
128 fit_variant(rr_dir, variant);
129 rr_dir->status[variant] |= RR_HAS_PREIMAGE;
130 }
131 }
132 closedir(dir);
133 }
134
135 static const unsigned char *rerere_dir_sha1(size_t i, void *table)
136 {
137 struct rerere_dir **rr_dir = table;
138 return rr_dir[i]->sha1;
139 }
140
141 static struct rerere_dir *find_rerere_dir(const char *hex)
142 {
143 unsigned char sha1[20];
144 struct rerere_dir *rr_dir;
145 int pos;
146
147 if (get_sha1_hex(hex, sha1))
148 return NULL; /* BUG */
149 pos = sha1_pos(sha1, rerere_dir, rerere_dir_nr, rerere_dir_sha1);
150 if (pos < 0) {
151 rr_dir = xmalloc(sizeof(*rr_dir));
152 hashcpy(rr_dir->sha1, sha1);
153 rr_dir->status = NULL;
154 rr_dir->status_nr = 0;
155 rr_dir->status_alloc = 0;
156 pos = -1 - pos;
157
158 /* Make sure the array is big enough ... */
159 ALLOC_GROW(rerere_dir, rerere_dir_nr + 1, rerere_dir_alloc);
160 /* ... and add it in. */
161 rerere_dir_nr++;
162 MOVE_ARRAY(rerere_dir + pos + 1, rerere_dir + pos,
163 rerere_dir_nr - pos - 1);
164 rerere_dir[pos] = rr_dir;
165 scan_rerere_dir(rr_dir);
166 }
167 return rerere_dir[pos];
168 }
169
170 static int has_rerere_resolution(const struct rerere_id *id)
171 {
172 const int both = RR_HAS_POSTIMAGE|RR_HAS_PREIMAGE;
173 int variant = id->variant;
174
175 if (variant < 0)
176 return 0;
177 return ((id->collection->status[variant] & both) == both);
178 }
179
180 static struct rerere_id *new_rerere_id_hex(char *hex)
181 {
182 struct rerere_id *id = xmalloc(sizeof(*id));
183 id->collection = find_rerere_dir(hex);
184 id->variant = -1; /* not known yet */
185 return id;
186 }
187
188 static struct rerere_id *new_rerere_id(unsigned char *sha1)
189 {
190 return new_rerere_id_hex(sha1_to_hex(sha1));
191 }
192
193 /*
194 * $GIT_DIR/MERGE_RR file is a collection of records, each of which is
195 * "conflict ID", a HT and pathname, terminated with a NUL, and is
196 * used to keep track of the set of paths that "rerere" may need to
197 * work on (i.e. what is left by the previous invocation of "git
198 * rerere" during the current conflict resolution session).
199 */
200 static void read_rr(struct string_list *rr)
201 {
202 struct strbuf buf = STRBUF_INIT;
203 FILE *in = fopen_or_warn(git_path_merge_rr(), "r");
204
205 if (!in)
206 return;
207 while (!strbuf_getwholeline(&buf, in, '\0')) {
208 char *path;
209 unsigned char sha1[20];
210 struct rerere_id *id;
211 int variant;
212
213 /* There has to be the hash, tab, path and then NUL */
214 if (buf.len < 42 || get_sha1_hex(buf.buf, sha1))
215 die(_("corrupt MERGE_RR"));
216
217 if (buf.buf[40] != '.') {
218 variant = 0;
219 path = buf.buf + 40;
220 } else {
221 errno = 0;
222 variant = strtol(buf.buf + 41, &path, 10);
223 if (errno)
224 die(_("corrupt MERGE_RR"));
225 }
226 if (*(path++) != '\t')
227 die(_("corrupt MERGE_RR"));
228 buf.buf[40] = '\0';
229 id = new_rerere_id_hex(buf.buf);
230 id->variant = variant;
231 string_list_insert(rr, path)->util = id;
232 }
233 strbuf_release(&buf);
234 fclose(in);
235 }
236
237 static struct lock_file write_lock;
238
239 static int write_rr(struct string_list *rr, int out_fd)
240 {
241 int i;
242 for (i = 0; i < rr->nr; i++) {
243 struct strbuf buf = STRBUF_INIT;
244 struct rerere_id *id;
245
246 assert(rr->items[i].util != RERERE_RESOLVED);
247
248 id = rr->items[i].util;
249 if (!id)
250 continue;
251 assert(id->variant >= 0);
252 if (0 < id->variant)
253 strbuf_addf(&buf, "%s.%d\t%s%c",
254 rerere_id_hex(id), id->variant,
255 rr->items[i].string, 0);
256 else
257 strbuf_addf(&buf, "%s\t%s%c",
258 rerere_id_hex(id),
259 rr->items[i].string, 0);
260
261 if (write_in_full(out_fd, buf.buf, buf.len) < 0)
262 die(_("unable to write rerere record"));
263
264 strbuf_release(&buf);
265 }
266 if (commit_lock_file(&write_lock) != 0)
267 die(_("unable to write rerere record"));
268 return 0;
269 }
270
271 /*
272 * "rerere" interacts with conflicted file contents using this I/O
273 * abstraction. It reads a conflicted contents from one place via
274 * "getline()" method, and optionally can write it out after
275 * normalizing the conflicted hunks to the "output". Subclasses of
276 * rerere_io embed this structure at the beginning of their own
277 * rerere_io object.
278 */
279 struct rerere_io {
280 int (*getline)(struct strbuf *, struct rerere_io *);
281 FILE *output;
282 int wrerror;
283 /* some more stuff */
284 };
285
286 static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
287 {
288 if (!count || *err)
289 return;
290 if (fwrite(p, count, 1, fp) != 1)
291 *err = errno;
292 }
293
294 static inline void ferr_puts(const char *s, FILE *fp, int *err)
295 {
296 ferr_write(s, strlen(s), fp, err);
297 }
298
299 static void rerere_io_putstr(const char *str, struct rerere_io *io)
300 {
301 if (io->output)
302 ferr_puts(str, io->output, &io->wrerror);
303 }
304
305 /*
306 * Write a conflict marker to io->output (if defined).
307 */
308 static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
309 {
310 char buf[64];
311
312 while (size) {
313 if (size <= sizeof(buf) - 2) {
314 memset(buf, ch, size);
315 buf[size] = '\n';
316 buf[size + 1] = '\0';
317 size = 0;
318 } else {
319 int sz = sizeof(buf) - 1;
320
321 /*
322 * Make sure we will not write everything out
323 * in this round by leaving at least 1 byte
324 * for the next round, giving the next round
325 * a chance to add the terminating LF. Yuck.
326 */
327 if (size <= sz)
328 sz -= (sz - size) + 1;
329 memset(buf, ch, sz);
330 buf[sz] = '\0';
331 size -= sz;
332 }
333 rerere_io_putstr(buf, io);
334 }
335 }
336
337 static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
338 {
339 if (io->output)
340 ferr_write(mem, sz, io->output, &io->wrerror);
341 }
342
343 /*
344 * Subclass of rerere_io that reads from an on-disk file
345 */
346 struct rerere_io_file {
347 struct rerere_io io;
348 FILE *input;
349 };
350
351 /*
352 * ... and its getline() method implementation
353 */
354 static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
355 {
356 struct rerere_io_file *io = (struct rerere_io_file *)io_;
357 return strbuf_getwholeline(sb, io->input, '\n');
358 }
359
360 /*
361 * Require the exact number of conflict marker letters, no more, no
362 * less, followed by SP or any whitespace
363 * (including LF).
364 */
365 static int is_cmarker(char *buf, int marker_char, int marker_size)
366 {
367 int want_sp;
368
369 /*
370 * The beginning of our version and the end of their version
371 * always are labeled like "<<<<< ours" or ">>>>> theirs",
372 * hence we set want_sp for them. Note that the version from
373 * the common ancestor in diff3-style output is not always
374 * labelled (e.g. "||||| common" is often seen but "|||||"
375 * alone is also valid), so we do not set want_sp.
376 */
377 want_sp = (marker_char == '<') || (marker_char == '>');
378
379 while (marker_size--)
380 if (*buf++ != marker_char)
381 return 0;
382 if (want_sp && *buf != ' ')
383 return 0;
384 return isspace(*buf);
385 }
386
387 /*
388 * Read contents a file with conflicts, normalize the conflicts
389 * by (1) discarding the common ancestor version in diff3-style,
390 * (2) reordering our side and their side so that whichever sorts
391 * alphabetically earlier comes before the other one, while
392 * computing the "conflict ID", which is just an SHA-1 hash of
393 * one side of the conflict, NUL, the other side of the conflict,
394 * and NUL concatenated together.
395 *
396 * Return the number of conflict hunks found.
397 *
398 * NEEDSWORK: the logic and theory of operation behind this conflict
399 * normalization may deserve to be documented somewhere, perhaps in
400 * Documentation/technical/rerere.txt.
401 */
402 static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
403 {
404 git_SHA_CTX ctx;
405 int hunk_no = 0;
406 enum {
407 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
408 } hunk = RR_CONTEXT;
409 struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
410 struct strbuf buf = STRBUF_INIT;
411
412 if (sha1)
413 git_SHA1_Init(&ctx);
414
415 while (!io->getline(&buf, io)) {
416 if (is_cmarker(buf.buf, '<', marker_size)) {
417 if (hunk != RR_CONTEXT)
418 goto bad;
419 hunk = RR_SIDE_1;
420 } else if (is_cmarker(buf.buf, '|', marker_size)) {
421 if (hunk != RR_SIDE_1)
422 goto bad;
423 hunk = RR_ORIGINAL;
424 } else if (is_cmarker(buf.buf, '=', marker_size)) {
425 if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
426 goto bad;
427 hunk = RR_SIDE_2;
428 } else if (is_cmarker(buf.buf, '>', marker_size)) {
429 if (hunk != RR_SIDE_2)
430 goto bad;
431 if (strbuf_cmp(&one, &two) > 0)
432 strbuf_swap(&one, &two);
433 hunk_no++;
434 hunk = RR_CONTEXT;
435 rerere_io_putconflict('<', marker_size, io);
436 rerere_io_putmem(one.buf, one.len, io);
437 rerere_io_putconflict('=', marker_size, io);
438 rerere_io_putmem(two.buf, two.len, io);
439 rerere_io_putconflict('>', marker_size, io);
440 if (sha1) {
441 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
442 one.len + 1);
443 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
444 two.len + 1);
445 }
446 strbuf_reset(&one);
447 strbuf_reset(&two);
448 } else if (hunk == RR_SIDE_1)
449 strbuf_addbuf(&one, &buf);
450 else if (hunk == RR_ORIGINAL)
451 ; /* discard */
452 else if (hunk == RR_SIDE_2)
453 strbuf_addbuf(&two, &buf);
454 else
455 rerere_io_putstr(buf.buf, io);
456 continue;
457 bad:
458 hunk = 99; /* force error exit */
459 break;
460 }
461 strbuf_release(&one);
462 strbuf_release(&two);
463 strbuf_release(&buf);
464
465 if (sha1)
466 git_SHA1_Final(sha1, &ctx);
467 if (hunk != RR_CONTEXT)
468 return -1;
469 return hunk_no;
470 }
471
472 /*
473 * Scan the path for conflicts, do the "handle_path()" thing above, and
474 * return the number of conflict hunks found.
475 */
476 static int handle_file(const char *path, unsigned char *sha1, const char *output)
477 {
478 int hunk_no = 0;
479 struct rerere_io_file io;
480 int marker_size = ll_merge_marker_size(path);
481
482 memset(&io, 0, sizeof(io));
483 io.io.getline = rerere_file_getline;
484 io.input = fopen(path, "r");
485 io.io.wrerror = 0;
486 if (!io.input)
487 return error_errno(_("could not open '%s'"), path);
488
489 if (output) {
490 io.io.output = fopen(output, "w");
491 if (!io.io.output) {
492 error_errno(_("could not write '%s'"), output);
493 fclose(io.input);
494 return -1;
495 }
496 }
497
498 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
499
500 fclose(io.input);
501 if (io.io.wrerror)
502 error(_("there were errors while writing '%s' (%s)"),
503 path, strerror(io.io.wrerror));
504 if (io.io.output && fclose(io.io.output))
505 io.io.wrerror = error_errno(_("failed to flush '%s'"), path);
506
507 if (hunk_no < 0) {
508 if (output)
509 unlink_or_warn(output);
510 return error(_("could not parse conflict hunks in '%s'"), path);
511 }
512 if (io.io.wrerror)
513 return -1;
514 return hunk_no;
515 }
516
517 /*
518 * Look at a cache entry at "i" and see if it is not conflicting,
519 * conflicting and we are willing to handle, or conflicting and
520 * we are unable to handle, and return the determination in *type.
521 * Return the cache index to be looked at next, by skipping the
522 * stages we have already looked at in this invocation of this
523 * function.
524 */
525 static int check_one_conflict(int i, int *type)
526 {
527 const struct cache_entry *e = active_cache[i];
528
529 if (!ce_stage(e)) {
530 *type = RESOLVED;
531 return i + 1;
532 }
533
534 *type = PUNTED;
535 while (ce_stage(active_cache[i]) == 1)
536 i++;
537
538 /* Only handle regular files with both stages #2 and #3 */
539 if (i + 1 < active_nr) {
540 const struct cache_entry *e2 = active_cache[i];
541 const struct cache_entry *e3 = active_cache[i + 1];
542 if (ce_stage(e2) == 2 &&
543 ce_stage(e3) == 3 &&
544 ce_same_name(e, e3) &&
545 S_ISREG(e2->ce_mode) &&
546 S_ISREG(e3->ce_mode))
547 *type = THREE_STAGED;
548 }
549
550 /* Skip the entries with the same name */
551 while (i < active_nr && ce_same_name(e, active_cache[i]))
552 i++;
553 return i;
554 }
555
556 /*
557 * Scan the index and find paths that have conflicts that rerere can
558 * handle, i.e. the ones that has both stages #2 and #3.
559 *
560 * NEEDSWORK: we do not record or replay a previous "resolve by
561 * deletion" for a delete-modify conflict, as that is inherently risky
562 * without knowing what modification is being discarded. The only
563 * safe case, i.e. both side doing the deletion and modification that
564 * are identical to the previous round, might want to be handled,
565 * though.
566 */
567 static int find_conflict(struct string_list *conflict)
568 {
569 int i;
570 if (read_cache() < 0)
571 return error(_("index file corrupt"));
572
573 for (i = 0; i < active_nr;) {
574 int conflict_type;
575 const struct cache_entry *e = active_cache[i];
576 i = check_one_conflict(i, &conflict_type);
577 if (conflict_type == THREE_STAGED)
578 string_list_insert(conflict, (const char *)e->name);
579 }
580 return 0;
581 }
582
583 /*
584 * The merge_rr list is meant to hold outstanding conflicted paths
585 * that rerere could handle. Abuse the list by adding other types of
586 * entries to allow the caller to show "rerere remaining".
587 *
588 * - Conflicted paths that rerere does not handle are added
589 * - Conflicted paths that have been resolved are marked as such
590 * by storing RERERE_RESOLVED to .util field (where conflict ID
591 * is expected to be stored).
592 *
593 * Do *not* write MERGE_RR file out after calling this function.
594 *
595 * NEEDSWORK: we may want to fix the caller that implements "rerere
596 * remaining" to do this without abusing merge_rr.
597 */
598 int rerere_remaining(struct string_list *merge_rr)
599 {
600 int i;
601 if (setup_rerere(merge_rr, RERERE_READONLY))
602 return 0;
603 if (read_cache() < 0)
604 return error(_("index file corrupt"));
605
606 for (i = 0; i < active_nr;) {
607 int conflict_type;
608 const struct cache_entry *e = active_cache[i];
609 i = check_one_conflict(i, &conflict_type);
610 if (conflict_type == PUNTED)
611 string_list_insert(merge_rr, (const char *)e->name);
612 else if (conflict_type == RESOLVED) {
613 struct string_list_item *it;
614 it = string_list_lookup(merge_rr, (const char *)e->name);
615 if (it != NULL) {
616 free_rerere_id(it);
617 it->util = RERERE_RESOLVED;
618 }
619 }
620 }
621 return 0;
622 }
623
624 /*
625 * Try using the given conflict resolution "ID" to see
626 * if that recorded conflict resolves cleanly what we
627 * got in the "cur".
628 */
629 static int try_merge(const struct rerere_id *id, const char *path,
630 mmfile_t *cur, mmbuffer_t *result)
631 {
632 int ret;
633 mmfile_t base = {NULL, 0}, other = {NULL, 0};
634
635 if (read_mmfile(&base, rerere_path(id, "preimage")) ||
636 read_mmfile(&other, rerere_path(id, "postimage")))
637 ret = 1;
638 else
639 /*
640 * A three-way merge. Note that this honors user-customizable
641 * low-level merge driver settings.
642 */
643 ret = ll_merge(result, path, &base, NULL, cur, "", &other, "", NULL);
644
645 free(base.ptr);
646 free(other.ptr);
647
648 return ret;
649 }
650
651 /*
652 * Find the conflict identified by "id"; the change between its
653 * "preimage" (i.e. a previous contents with conflict markers) and its
654 * "postimage" (i.e. the corresponding contents with conflicts
655 * resolved) may apply cleanly to the contents stored in "path", i.e.
656 * the conflict this time around.
657 *
658 * Returns 0 for successful replay of recorded resolution, or non-zero
659 * for failure.
660 */
661 static int merge(const struct rerere_id *id, const char *path)
662 {
663 FILE *f;
664 int ret;
665 mmfile_t cur = {NULL, 0};
666 mmbuffer_t result = {NULL, 0};
667
668 /*
669 * Normalize the conflicts in path and write it out to
670 * "thisimage" temporary file.
671 */
672 if ((handle_file(path, NULL, rerere_path(id, "thisimage")) < 0) ||
673 read_mmfile(&cur, rerere_path(id, "thisimage"))) {
674 ret = 1;
675 goto out;
676 }
677
678 ret = try_merge(id, path, &cur, &result);
679 if (ret)
680 goto out;
681
682 /*
683 * A successful replay of recorded resolution.
684 * Mark that "postimage" was used to help gc.
685 */
686 if (utime(rerere_path(id, "postimage"), NULL) < 0)
687 warning_errno(_("failed utime() on '%s'"),
688 rerere_path(id, "postimage"));
689
690 /* Update "path" with the resolution */
691 f = fopen(path, "w");
692 if (!f)
693 return error_errno(_("could not open '%s'"), path);
694 if (fwrite(result.ptr, result.size, 1, f) != 1)
695 error_errno(_("could not write '%s'"), path);
696 if (fclose(f))
697 return error_errno(_("writing '%s' failed"), path);
698
699 out:
700 free(cur.ptr);
701 free(result.ptr);
702
703 return ret;
704 }
705
706 static void update_paths(struct string_list *update)
707 {
708 struct lock_file index_lock = LOCK_INIT;
709 int i;
710
711 hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
712
713 for (i = 0; i < update->nr; i++) {
714 struct string_list_item *item = &update->items[i];
715 if (add_file_to_cache(item->string, 0))
716 exit(128);
717 fprintf_ln(stderr, _("Staged '%s' using previous resolution."),
718 item->string);
719 }
720
721 if (write_locked_index(&the_index, &index_lock,
722 COMMIT_LOCK | SKIP_IF_UNCHANGED))
723 die(_("unable to write new index file"));
724 }
725
726 static void remove_variant(struct rerere_id *id)
727 {
728 unlink_or_warn(rerere_path(id, "postimage"));
729 unlink_or_warn(rerere_path(id, "preimage"));
730 id->collection->status[id->variant] = 0;
731 }
732
733 /*
734 * The path indicated by rr_item may still have conflict for which we
735 * have a recorded resolution, in which case replay it and optionally
736 * update it. Or it may have been resolved by the user and we may
737 * only have the preimage for that conflict, in which case the result
738 * needs to be recorded as a resolution in a postimage file.
739 */
740 static void do_rerere_one_path(struct string_list_item *rr_item,
741 struct string_list *update)
742 {
743 const char *path = rr_item->string;
744 struct rerere_id *id = rr_item->util;
745 struct rerere_dir *rr_dir = id->collection;
746 int variant;
747
748 variant = id->variant;
749
750 /* Has the user resolved it already? */
751 if (variant >= 0) {
752 if (!handle_file(path, NULL, NULL)) {
753 copy_file(rerere_path(id, "postimage"), path, 0666);
754 id->collection->status[variant] |= RR_HAS_POSTIMAGE;
755 fprintf_ln(stderr, _("Recorded resolution for '%s'."), path);
756 free_rerere_id(rr_item);
757 rr_item->util = NULL;
758 return;
759 }
760 /*
761 * There may be other variants that can cleanly
762 * replay. Try them and update the variant number for
763 * this one.
764 */
765 }
766
767 /* Does any existing resolution apply cleanly? */
768 for (variant = 0; variant < rr_dir->status_nr; variant++) {
769 const int both = RR_HAS_PREIMAGE | RR_HAS_POSTIMAGE;
770 struct rerere_id vid = *id;
771
772 if ((rr_dir->status[variant] & both) != both)
773 continue;
774
775 vid.variant = variant;
776 if (merge(&vid, path))
777 continue; /* failed to replay */
778
779 /*
780 * If there already is a different variant that applies
781 * cleanly, there is no point maintaining our own variant.
782 */
783 if (0 <= id->variant && id->variant != variant)
784 remove_variant(id);
785
786 if (rerere_autoupdate)
787 string_list_insert(update, path);
788 else
789 fprintf_ln(stderr,
790 _("Resolved '%s' using previous resolution."),
791 path);
792 free_rerere_id(rr_item);
793 rr_item->util = NULL;
794 return;
795 }
796
797 /* None of the existing one applies; we need a new variant */
798 assign_variant(id);
799
800 variant = id->variant;
801 handle_file(path, NULL, rerere_path(id, "preimage"));
802 if (id->collection->status[variant] & RR_HAS_POSTIMAGE) {
803 const char *path = rerere_path(id, "postimage");
804 if (unlink(path))
805 die_errno(_("cannot unlink stray '%s'"), path);
806 id->collection->status[variant] &= ~RR_HAS_POSTIMAGE;
807 }
808 id->collection->status[variant] |= RR_HAS_PREIMAGE;
809 fprintf_ln(stderr, _("Recorded preimage for '%s'"), path);
810 }
811
812 static int do_plain_rerere(struct string_list *rr, int fd)
813 {
814 struct string_list conflict = STRING_LIST_INIT_DUP;
815 struct string_list update = STRING_LIST_INIT_DUP;
816 int i;
817
818 find_conflict(&conflict);
819
820 /*
821 * MERGE_RR records paths with conflicts immediately after
822 * merge failed. Some of the conflicted paths might have been
823 * hand resolved in the working tree since then, but the
824 * initial run would catch all and register their preimages.
825 */
826 for (i = 0; i < conflict.nr; i++) {
827 struct rerere_id *id;
828 unsigned char sha1[20];
829 const char *path = conflict.items[i].string;
830 int ret;
831
832 if (string_list_has_string(rr, path))
833 continue;
834
835 /*
836 * Ask handle_file() to scan and assign a
837 * conflict ID. No need to write anything out
838 * yet.
839 */
840 ret = handle_file(path, sha1, NULL);
841 if (ret < 1)
842 continue;
843
844 id = new_rerere_id(sha1);
845 string_list_insert(rr, path)->util = id;
846
847 /* Ensure that the directory exists. */
848 mkdir_in_gitdir(rerere_path(id, NULL));
849 }
850
851 for (i = 0; i < rr->nr; i++)
852 do_rerere_one_path(&rr->items[i], &update);
853
854 if (update.nr)
855 update_paths(&update);
856
857 return write_rr(rr, fd);
858 }
859
860 static void git_rerere_config(void)
861 {
862 git_config_get_bool("rerere.enabled", &rerere_enabled);
863 git_config_get_bool("rerere.autoupdate", &rerere_autoupdate);
864 git_config(git_default_config, NULL);
865 }
866
867 static GIT_PATH_FUNC(git_path_rr_cache, "rr-cache")
868
869 static int is_rerere_enabled(void)
870 {
871 int rr_cache_exists;
872
873 if (!rerere_enabled)
874 return 0;
875
876 rr_cache_exists = is_directory(git_path_rr_cache());
877 if (rerere_enabled < 0)
878 return rr_cache_exists;
879
880 if (!rr_cache_exists && mkdir_in_gitdir(git_path_rr_cache()))
881 die(_("could not create directory '%s'"), git_path_rr_cache());
882 return 1;
883 }
884
885 int setup_rerere(struct string_list *merge_rr, int flags)
886 {
887 int fd;
888
889 git_rerere_config();
890 if (!is_rerere_enabled())
891 return -1;
892
893 if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
894 rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
895 if (flags & RERERE_READONLY)
896 fd = 0;
897 else
898 fd = hold_lock_file_for_update(&write_lock, git_path_merge_rr(),
899 LOCK_DIE_ON_ERROR);
900 read_rr(merge_rr);
901 return fd;
902 }
903
904 /*
905 * The main entry point that is called internally from codepaths that
906 * perform mergy operations, possibly leaving conflicted index entries
907 * and working tree files.
908 */
909 int rerere(int flags)
910 {
911 struct string_list merge_rr = STRING_LIST_INIT_DUP;
912 int fd, status;
913
914 fd = setup_rerere(&merge_rr, flags);
915 if (fd < 0)
916 return 0;
917 status = do_plain_rerere(&merge_rr, fd);
918 free_rerere_dirs();
919 return status;
920 }
921
922 /*
923 * Subclass of rerere_io that reads from an in-core buffer that is a
924 * strbuf
925 */
926 struct rerere_io_mem {
927 struct rerere_io io;
928 struct strbuf input;
929 };
930
931 /*
932 * ... and its getline() method implementation
933 */
934 static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
935 {
936 struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
937 char *ep;
938 size_t len;
939
940 strbuf_release(sb);
941 if (!io->input.len)
942 return -1;
943 ep = memchr(io->input.buf, '\n', io->input.len);
944 if (!ep)
945 ep = io->input.buf + io->input.len;
946 else if (*ep == '\n')
947 ep++;
948 len = ep - io->input.buf;
949 strbuf_add(sb, io->input.buf, len);
950 strbuf_remove(&io->input, 0, len);
951 return 0;
952 }
953
954 static int handle_cache(const char *path, unsigned char *sha1, const char *output)
955 {
956 mmfile_t mmfile[3] = {{NULL}};
957 mmbuffer_t result = {NULL, 0};
958 const struct cache_entry *ce;
959 int pos, len, i, hunk_no;
960 struct rerere_io_mem io;
961 int marker_size = ll_merge_marker_size(path);
962
963 /*
964 * Reproduce the conflicted merge in-core
965 */
966 len = strlen(path);
967 pos = cache_name_pos(path, len);
968 if (0 <= pos)
969 return -1;
970 pos = -pos - 1;
971
972 while (pos < active_nr) {
973 enum object_type type;
974 unsigned long size;
975
976 ce = active_cache[pos++];
977 if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
978 break;
979 i = ce_stage(ce) - 1;
980 if (!mmfile[i].ptr) {
981 mmfile[i].ptr = read_object_file(&ce->oid, &type,
982 &size);
983 mmfile[i].size = size;
984 }
985 }
986 for (i = 0; i < 3; i++)
987 if (!mmfile[i].ptr && !mmfile[i].size)
988 mmfile[i].ptr = xstrdup("");
989
990 /*
991 * NEEDSWORK: handle conflicts from merges with
992 * merge.renormalize set, too?
993 */
994 ll_merge(&result, path, &mmfile[0], NULL,
995 &mmfile[1], "ours",
996 &mmfile[2], "theirs", NULL);
997 for (i = 0; i < 3; i++)
998 free(mmfile[i].ptr);
999
1000 memset(&io, 0, sizeof(io));
1001 io.io.getline = rerere_mem_getline;
1002 if (output)
1003 io.io.output = fopen(output, "w");
1004 else
1005 io.io.output = NULL;
1006 strbuf_init(&io.input, 0);
1007 strbuf_attach(&io.input, result.ptr, result.size, result.size);
1008
1009 /*
1010 * Grab the conflict ID and optionally write the original
1011 * contents with conflict markers out.
1012 */
1013 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
1014 strbuf_release(&io.input);
1015 if (io.io.output)
1016 fclose(io.io.output);
1017 return hunk_no;
1018 }
1019
1020 static int rerere_forget_one_path(const char *path, struct string_list *rr)
1021 {
1022 const char *filename;
1023 struct rerere_id *id;
1024 unsigned char sha1[20];
1025 int ret;
1026 struct string_list_item *item;
1027
1028 /*
1029 * Recreate the original conflict from the stages in the
1030 * index and compute the conflict ID
1031 */
1032 ret = handle_cache(path, sha1, NULL);
1033 if (ret < 1)
1034 return error(_("could not parse conflict hunks in '%s'"), path);
1035
1036 /* Nuke the recorded resolution for the conflict */
1037 id = new_rerere_id(sha1);
1038
1039 for (id->variant = 0;
1040 id->variant < id->collection->status_nr;
1041 id->variant++) {
1042 mmfile_t cur = { NULL, 0 };
1043 mmbuffer_t result = {NULL, 0};
1044 int cleanly_resolved;
1045
1046 if (!has_rerere_resolution(id))
1047 continue;
1048
1049 handle_cache(path, sha1, rerere_path(id, "thisimage"));
1050 if (read_mmfile(&cur, rerere_path(id, "thisimage"))) {
1051 free(cur.ptr);
1052 error(_("failed to update conflicted state in '%s'"), path);
1053 goto fail_exit;
1054 }
1055 cleanly_resolved = !try_merge(id, path, &cur, &result);
1056 free(result.ptr);
1057 free(cur.ptr);
1058 if (cleanly_resolved)
1059 break;
1060 }
1061
1062 if (id->collection->status_nr <= id->variant) {
1063 error(_("no remembered resolution for '%s'"), path);
1064 goto fail_exit;
1065 }
1066
1067 filename = rerere_path(id, "postimage");
1068 if (unlink(filename)) {
1069 if (errno == ENOENT)
1070 error(_("no remembered resolution for '%s'"), path);
1071 else
1072 error_errno(_("cannot unlink '%s'"), filename);
1073 goto fail_exit;
1074 }
1075
1076 /*
1077 * Update the preimage so that the user can resolve the
1078 * conflict in the working tree, run us again to record
1079 * the postimage.
1080 */
1081 handle_cache(path, sha1, rerere_path(id, "preimage"));
1082 fprintf_ln(stderr, _("Updated preimage for '%s'"), path);
1083
1084 /*
1085 * And remember that we can record resolution for this
1086 * conflict when the user is done.
1087 */
1088 item = string_list_insert(rr, path);
1089 free_rerere_id(item);
1090 item->util = id;
1091 fprintf(stderr, _("Forgot resolution for '%s'\n"), path);
1092 return 0;
1093
1094 fail_exit:
1095 free(id);
1096 return -1;
1097 }
1098
1099 int rerere_forget(struct pathspec *pathspec)
1100 {
1101 int i, fd;
1102 struct string_list conflict = STRING_LIST_INIT_DUP;
1103 struct string_list merge_rr = STRING_LIST_INIT_DUP;
1104
1105 if (read_cache() < 0)
1106 return error(_("index file corrupt"));
1107
1108 fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
1109 if (fd < 0)
1110 return 0;
1111
1112 /*
1113 * The paths may have been resolved (incorrectly);
1114 * recover the original conflicted state and then
1115 * find the conflicted paths.
1116 */
1117 unmerge_cache(pathspec);
1118 find_conflict(&conflict);
1119 for (i = 0; i < conflict.nr; i++) {
1120 struct string_list_item *it = &conflict.items[i];
1121 if (!match_pathspec(pathspec, it->string,
1122 strlen(it->string), 0, NULL, 0))
1123 continue;
1124 rerere_forget_one_path(it->string, &merge_rr);
1125 }
1126 return write_rr(&merge_rr, fd);
1127 }
1128
1129 /*
1130 * Garbage collection support
1131 */
1132
1133 static timestamp_t rerere_created_at(struct rerere_id *id)
1134 {
1135 struct stat st;
1136
1137 return stat(rerere_path(id, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
1138 }
1139
1140 static timestamp_t rerere_last_used_at(struct rerere_id *id)
1141 {
1142 struct stat st;
1143
1144 return stat(rerere_path(id, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
1145 }
1146
1147 /*
1148 * Remove the recorded resolution for a given conflict ID
1149 */
1150 static void unlink_rr_item(struct rerere_id *id)
1151 {
1152 unlink_or_warn(rerere_path(id, "thisimage"));
1153 remove_variant(id);
1154 id->collection->status[id->variant] = 0;
1155 }
1156
1157 static void prune_one(struct rerere_id *id,
1158 timestamp_t cutoff_resolve, timestamp_t cutoff_noresolve)
1159 {
1160 timestamp_t then;
1161 timestamp_t cutoff;
1162
1163 then = rerere_last_used_at(id);
1164 if (then)
1165 cutoff = cutoff_resolve;
1166 else {
1167 then = rerere_created_at(id);
1168 if (!then)
1169 return;
1170 cutoff = cutoff_noresolve;
1171 }
1172 if (then < cutoff)
1173 unlink_rr_item(id);
1174 }
1175
1176 void rerere_gc(struct string_list *rr)
1177 {
1178 struct string_list to_remove = STRING_LIST_INIT_DUP;
1179 DIR *dir;
1180 struct dirent *e;
1181 int i;
1182 timestamp_t now = time(NULL);
1183 timestamp_t cutoff_noresolve = now - 15 * 86400;
1184 timestamp_t cutoff_resolve = now - 60 * 86400;
1185
1186 if (setup_rerere(rr, 0) < 0)
1187 return;
1188
1189 git_config_get_expiry_in_days("gc.rerereresolved", &cutoff_resolve, now);
1190 git_config_get_expiry_in_days("gc.rerereunresolved", &cutoff_noresolve, now);
1191 git_config(git_default_config, NULL);
1192 dir = opendir(git_path("rr-cache"));
1193 if (!dir)
1194 die_errno(_("unable to open rr-cache directory"));
1195 /* Collect stale conflict IDs ... */
1196 while ((e = readdir(dir))) {
1197 struct rerere_dir *rr_dir;
1198 struct rerere_id id;
1199 int now_empty;
1200
1201 if (is_dot_or_dotdot(e->d_name))
1202 continue;
1203 rr_dir = find_rerere_dir(e->d_name);
1204 if (!rr_dir)
1205 continue; /* or should we remove e->d_name? */
1206
1207 now_empty = 1;
1208 for (id.variant = 0, id.collection = rr_dir;
1209 id.variant < id.collection->status_nr;
1210 id.variant++) {
1211 prune_one(&id, cutoff_resolve, cutoff_noresolve);
1212 if (id.collection->status[id.variant])
1213 now_empty = 0;
1214 }
1215 if (now_empty)
1216 string_list_append(&to_remove, e->d_name);
1217 }
1218 closedir(dir);
1219
1220 /* ... and then remove the empty directories */
1221 for (i = 0; i < to_remove.nr; i++)
1222 rmdir(git_path("rr-cache/%s", to_remove.items[i].string));
1223 string_list_clear(&to_remove, 0);
1224 rollback_lock_file(&write_lock);
1225 }
1226
1227 /*
1228 * During a conflict resolution, after "rerere" recorded the
1229 * preimages, abandon them if the user did not resolve them or
1230 * record their resolutions. And drop $GIT_DIR/MERGE_RR.
1231 *
1232 * NEEDSWORK: shouldn't we be calling this from "reset --hard"?
1233 */
1234 void rerere_clear(struct string_list *merge_rr)
1235 {
1236 int i;
1237
1238 if (setup_rerere(merge_rr, 0) < 0)
1239 return;
1240
1241 for (i = 0; i < merge_rr->nr; i++) {
1242 struct rerere_id *id = merge_rr->items[i].util;
1243 if (!has_rerere_resolution(id)) {
1244 unlink_rr_item(id);
1245 rmdir(rerere_path(id, NULL));
1246 }
1247 }
1248 unlink_or_warn(git_path_merge_rr());
1249 rollback_lock_file(&write_lock);
1250 }