Merge branch 'rs/opt-updates'
[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 "object-store.h"
13 #include "sha1-lookup.h"
14
15 #define RESOLVED 0
16 #define PUNTED 1
17 #define THREE_STAGED 2
18 void *RERERE_RESOLVED = &RERERE_RESOLVED;
19
20 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
21 static int rerere_enabled = -1;
22
23 /* automatically update cleanly resolved paths to the index */
24 static int rerere_autoupdate;
25
26 static int rerere_dir_nr;
27 static int rerere_dir_alloc;
28
29 #define RR_HAS_POSTIMAGE 1
30 #define RR_HAS_PREIMAGE 2
31 static struct rerere_dir {
32 unsigned char sha1[20];
33 int status_alloc, status_nr;
34 unsigned char *status;
35 } **rerere_dir;
36
37 static void free_rerere_dirs(void)
38 {
39 int i;
40 for (i = 0; i < rerere_dir_nr; i++) {
41 free(rerere_dir[i]->status);
42 free(rerere_dir[i]);
43 }
44 FREE_AND_NULL(rerere_dir);
45 rerere_dir_nr = rerere_dir_alloc = 0;
46 }
47
48 static void free_rerere_id(struct string_list_item *item)
49 {
50 free(item->util);
51 }
52
53 static const char *rerere_id_hex(const struct rerere_id *id)
54 {
55 return sha1_to_hex(id->collection->sha1);
56 }
57
58 static void fit_variant(struct rerere_dir *rr_dir, int variant)
59 {
60 variant++;
61 ALLOC_GROW(rr_dir->status, variant, rr_dir->status_alloc);
62 if (rr_dir->status_nr < variant) {
63 memset(rr_dir->status + rr_dir->status_nr,
64 '\0', variant - rr_dir->status_nr);
65 rr_dir->status_nr = variant;
66 }
67 }
68
69 static void assign_variant(struct rerere_id *id)
70 {
71 int variant;
72 struct rerere_dir *rr_dir = id->collection;
73
74 variant = id->variant;
75 if (variant < 0) {
76 for (variant = 0; variant < rr_dir->status_nr; variant++)
77 if (!rr_dir->status[variant])
78 break;
79 }
80 fit_variant(rr_dir, variant);
81 id->variant = variant;
82 }
83
84 const char *rerere_path(const struct rerere_id *id, const char *file)
85 {
86 if (!file)
87 return git_path("rr-cache/%s", rerere_id_hex(id));
88
89 if (id->variant <= 0)
90 return git_path("rr-cache/%s/%s", rerere_id_hex(id), file);
91
92 return git_path("rr-cache/%s/%s.%d",
93 rerere_id_hex(id), file, id->variant);
94 }
95
96 static int is_rr_file(const char *name, const char *filename, int *variant)
97 {
98 const char *suffix;
99 char *ep;
100
101 if (!strcmp(name, filename)) {
102 *variant = 0;
103 return 1;
104 }
105 if (!skip_prefix(name, filename, &suffix) || *suffix != '.')
106 return 0;
107
108 errno = 0;
109 *variant = strtol(suffix + 1, &ep, 10);
110 if (errno || *ep)
111 return 0;
112 return 1;
113 }
114
115 static void scan_rerere_dir(struct rerere_dir *rr_dir)
116 {
117 struct dirent *de;
118 DIR *dir = opendir(git_path("rr-cache/%s", sha1_to_hex(rr_dir->sha1)));
119
120 if (!dir)
121 return;
122 while ((de = readdir(dir)) != NULL) {
123 int variant;
124
125 if (is_rr_file(de->d_name, "postimage", &variant)) {
126 fit_variant(rr_dir, variant);
127 rr_dir->status[variant] |= RR_HAS_POSTIMAGE;
128 } else if (is_rr_file(de->d_name, "preimage", &variant)) {
129 fit_variant(rr_dir, variant);
130 rr_dir->status[variant] |= RR_HAS_PREIMAGE;
131 }
132 }
133 closedir(dir);
134 }
135
136 static const unsigned char *rerere_dir_sha1(size_t i, void *table)
137 {
138 struct rerere_dir **rr_dir = table;
139 return rr_dir[i]->sha1;
140 }
141
142 static struct rerere_dir *find_rerere_dir(const char *hex)
143 {
144 unsigned char sha1[20];
145 struct rerere_dir *rr_dir;
146 int pos;
147
148 if (get_sha1_hex(hex, sha1))
149 return NULL; /* BUG */
150 pos = sha1_pos(sha1, rerere_dir, rerere_dir_nr, rerere_dir_sha1);
151 if (pos < 0) {
152 rr_dir = xmalloc(sizeof(*rr_dir));
153 hashcpy(rr_dir->sha1, sha1);
154 rr_dir->status = NULL;
155 rr_dir->status_nr = 0;
156 rr_dir->status_alloc = 0;
157 pos = -1 - pos;
158
159 /* Make sure the array is big enough ... */
160 ALLOC_GROW(rerere_dir, rerere_dir_nr + 1, rerere_dir_alloc);
161 /* ... and add it in. */
162 rerere_dir_nr++;
163 MOVE_ARRAY(rerere_dir + pos + 1, rerere_dir + pos,
164 rerere_dir_nr - pos - 1);
165 rerere_dir[pos] = rr_dir;
166 scan_rerere_dir(rr_dir);
167 }
168 return rerere_dir[pos];
169 }
170
171 static int has_rerere_resolution(const struct rerere_id *id)
172 {
173 const int both = RR_HAS_POSTIMAGE|RR_HAS_PREIMAGE;
174 int variant = id->variant;
175
176 if (variant < 0)
177 return 0;
178 return ((id->collection->status[variant] & both) == both);
179 }
180
181 static struct rerere_id *new_rerere_id_hex(char *hex)
182 {
183 struct rerere_id *id = xmalloc(sizeof(*id));
184 id->collection = find_rerere_dir(hex);
185 id->variant = -1; /* not known yet */
186 return id;
187 }
188
189 static struct rerere_id *new_rerere_id(unsigned char *sha1)
190 {
191 return new_rerere_id_hex(sha1_to_hex(sha1));
192 }
193
194 /*
195 * $GIT_DIR/MERGE_RR file is a collection of records, each of which is
196 * "conflict ID", a HT and pathname, terminated with a NUL, and is
197 * used to keep track of the set of paths that "rerere" may need to
198 * work on (i.e. what is left by the previous invocation of "git
199 * rerere" during the current conflict resolution session).
200 */
201 static void read_rr(struct string_list *rr)
202 {
203 struct strbuf buf = STRBUF_INIT;
204 FILE *in = fopen_or_warn(git_path_merge_rr(the_repository), "r");
205
206 if (!in)
207 return;
208 while (!strbuf_getwholeline(&buf, in, '\0')) {
209 char *path;
210 unsigned char sha1[20];
211 struct rerere_id *id;
212 int variant;
213
214 /* There has to be the hash, tab, path and then NUL */
215 if (buf.len < 42 || get_sha1_hex(buf.buf, sha1))
216 die("corrupt MERGE_RR");
217
218 if (buf.buf[40] != '.') {
219 variant = 0;
220 path = buf.buf + 40;
221 } else {
222 errno = 0;
223 variant = strtol(buf.buf + 41, &path, 10);
224 if (errno)
225 die("corrupt MERGE_RR");
226 }
227 if (*(path++) != '\t')
228 die("corrupt MERGE_RR");
229 buf.buf[40] = '\0';
230 id = new_rerere_id_hex(buf.buf);
231 id->variant = variant;
232 string_list_insert(rr, path)->util = id;
233 }
234 strbuf_release(&buf);
235 fclose(in);
236 }
237
238 static struct lock_file write_lock;
239
240 static int write_rr(struct string_list *rr, int out_fd)
241 {
242 int i;
243 for (i = 0; i < rr->nr; i++) {
244 struct strbuf buf = STRBUF_INIT;
245 struct rerere_id *id;
246
247 assert(rr->items[i].util != RERERE_RESOLVED);
248
249 id = rr->items[i].util;
250 if (!id)
251 continue;
252 assert(id->variant >= 0);
253 if (0 < id->variant)
254 strbuf_addf(&buf, "%s.%d\t%s%c",
255 rerere_id_hex(id), id->variant,
256 rr->items[i].string, 0);
257 else
258 strbuf_addf(&buf, "%s\t%s%c",
259 rerere_id_hex(id),
260 rr->items[i].string, 0);
261
262 if (write_in_full(out_fd, buf.buf, buf.len) < 0)
263 die("unable to write rerere record");
264
265 strbuf_release(&buf);
266 }
267 if (commit_lock_file(&write_lock) != 0)
268 die("unable to write rerere record");
269 return 0;
270 }
271
272 /*
273 * "rerere" interacts with conflicted file contents using this I/O
274 * abstraction. It reads a conflicted contents from one place via
275 * "getline()" method, and optionally can write it out after
276 * normalizing the conflicted hunks to the "output". Subclasses of
277 * rerere_io embed this structure at the beginning of their own
278 * rerere_io object.
279 */
280 struct rerere_io {
281 int (*getline)(struct strbuf *, struct rerere_io *);
282 FILE *output;
283 int wrerror;
284 /* some more stuff */
285 };
286
287 static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
288 {
289 if (!count || *err)
290 return;
291 if (fwrite(p, count, 1, fp) != 1)
292 *err = errno;
293 }
294
295 static inline void ferr_puts(const char *s, FILE *fp, int *err)
296 {
297 ferr_write(s, strlen(s), fp, err);
298 }
299
300 static void rerere_io_putstr(const char *str, struct rerere_io *io)
301 {
302 if (io->output)
303 ferr_puts(str, io->output, &io->wrerror);
304 }
305
306 /*
307 * Write a conflict marker to io->output (if defined).
308 */
309 static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
310 {
311 char buf[64];
312
313 while (size) {
314 if (size <= sizeof(buf) - 2) {
315 memset(buf, ch, size);
316 buf[size] = '\n';
317 buf[size + 1] = '\0';
318 size = 0;
319 } else {
320 int sz = sizeof(buf) - 1;
321
322 /*
323 * Make sure we will not write everything out
324 * in this round by leaving at least 1 byte
325 * for the next round, giving the next round
326 * a chance to add the terminating LF. Yuck.
327 */
328 if (size <= sz)
329 sz -= (sz - size) + 1;
330 memset(buf, ch, sz);
331 buf[sz] = '\0';
332 size -= sz;
333 }
334 rerere_io_putstr(buf, io);
335 }
336 }
337
338 static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
339 {
340 if (io->output)
341 ferr_write(mem, sz, io->output, &io->wrerror);
342 }
343
344 /*
345 * Subclass of rerere_io that reads from an on-disk file
346 */
347 struct rerere_io_file {
348 struct rerere_io io;
349 FILE *input;
350 };
351
352 /*
353 * ... and its getline() method implementation
354 */
355 static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
356 {
357 struct rerere_io_file *io = (struct rerere_io_file *)io_;
358 return strbuf_getwholeline(sb, io->input, '\n');
359 }
360
361 /*
362 * Require the exact number of conflict marker letters, no more, no
363 * less, followed by SP or any whitespace
364 * (including LF).
365 */
366 static int is_cmarker(char *buf, int marker_char, int marker_size)
367 {
368 int want_sp;
369
370 /*
371 * The beginning of our version and the end of their version
372 * always are labeled like "<<<<< ours" or ">>>>> theirs",
373 * hence we set want_sp for them. Note that the version from
374 * the common ancestor in diff3-style output is not always
375 * labelled (e.g. "||||| common" is often seen but "|||||"
376 * alone is also valid), so we do not set want_sp.
377 */
378 want_sp = (marker_char == '<') || (marker_char == '>');
379
380 while (marker_size--)
381 if (*buf++ != marker_char)
382 return 0;
383 if (want_sp && *buf != ' ')
384 return 0;
385 return isspace(*buf);
386 }
387
388 /*
389 * Read contents a file with conflicts, normalize the conflicts
390 * by (1) discarding the common ancestor version in diff3-style,
391 * (2) reordering our side and their side so that whichever sorts
392 * alphabetically earlier comes before the other one, while
393 * computing the "conflict ID", which is just an SHA-1 hash of
394 * one side of the conflict, NUL, the other side of the conflict,
395 * and NUL concatenated together.
396 *
397 * Return the number of conflict hunks found.
398 *
399 * NEEDSWORK: the logic and theory of operation behind this conflict
400 * normalization may deserve to be documented somewhere, perhaps in
401 * Documentation/technical/rerere.txt.
402 */
403 static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
404 {
405 git_SHA_CTX ctx;
406 int hunk_no = 0;
407 enum {
408 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
409 } hunk = RR_CONTEXT;
410 struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
411 struct strbuf buf = STRBUF_INIT;
412
413 if (sha1)
414 git_SHA1_Init(&ctx);
415
416 while (!io->getline(&buf, io)) {
417 if (is_cmarker(buf.buf, '<', marker_size)) {
418 if (hunk != RR_CONTEXT)
419 goto bad;
420 hunk = RR_SIDE_1;
421 } else if (is_cmarker(buf.buf, '|', marker_size)) {
422 if (hunk != RR_SIDE_1)
423 goto bad;
424 hunk = RR_ORIGINAL;
425 } else if (is_cmarker(buf.buf, '=', marker_size)) {
426 if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
427 goto bad;
428 hunk = RR_SIDE_2;
429 } else if (is_cmarker(buf.buf, '>', marker_size)) {
430 if (hunk != RR_SIDE_2)
431 goto bad;
432 if (strbuf_cmp(&one, &two) > 0)
433 strbuf_swap(&one, &two);
434 hunk_no++;
435 hunk = RR_CONTEXT;
436 rerere_io_putconflict('<', marker_size, io);
437 rerere_io_putmem(one.buf, one.len, io);
438 rerere_io_putconflict('=', marker_size, io);
439 rerere_io_putmem(two.buf, two.len, io);
440 rerere_io_putconflict('>', marker_size, io);
441 if (sha1) {
442 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
443 one.len + 1);
444 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
445 two.len + 1);
446 }
447 strbuf_reset(&one);
448 strbuf_reset(&two);
449 } else if (hunk == RR_SIDE_1)
450 strbuf_addbuf(&one, &buf);
451 else if (hunk == RR_ORIGINAL)
452 ; /* discard */
453 else if (hunk == RR_SIDE_2)
454 strbuf_addbuf(&two, &buf);
455 else
456 rerere_io_putstr(buf.buf, io);
457 continue;
458 bad:
459 hunk = 99; /* force error exit */
460 break;
461 }
462 strbuf_release(&one);
463 strbuf_release(&two);
464 strbuf_release(&buf);
465
466 if (sha1)
467 git_SHA1_Final(sha1, &ctx);
468 if (hunk != RR_CONTEXT)
469 return -1;
470 return hunk_no;
471 }
472
473 /*
474 * Scan the path for conflicts, do the "handle_path()" thing above, and
475 * return the number of conflict hunks found.
476 */
477 static int handle_file(const char *path, unsigned char *sha1, const char *output)
478 {
479 int hunk_no = 0;
480 struct rerere_io_file io;
481 int marker_size = ll_merge_marker_size(path);
482
483 memset(&io, 0, sizeof(io));
484 io.io.getline = rerere_file_getline;
485 io.input = fopen(path, "r");
486 io.io.wrerror = 0;
487 if (!io.input)
488 return error_errno("Could not open %s", path);
489
490 if (output) {
491 io.io.output = fopen(output, "w");
492 if (!io.io.output) {
493 error_errno("Could not write %s", output);
494 fclose(io.input);
495 return -1;
496 }
497 }
498
499 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
500
501 fclose(io.input);
502 if (io.io.wrerror)
503 error("There were errors while writing %s (%s)",
504 path, strerror(io.io.wrerror));
505 if (io.io.output && fclose(io.io.output))
506 io.io.wrerror = error_errno("Failed to flush %s", path);
507
508 if (hunk_no < 0) {
509 if (output)
510 unlink_or_warn(output);
511 return error("Could not parse conflict hunks in %s", path);
512 }
513 if (io.io.wrerror)
514 return -1;
515 return hunk_no;
516 }
517
518 /*
519 * Look at a cache entry at "i" and see if it is not conflicting,
520 * conflicting and we are willing to handle, or conflicting and
521 * we are unable to handle, and return the determination in *type.
522 * Return the cache index to be looked at next, by skipping the
523 * stages we have already looked at in this invocation of this
524 * function.
525 */
526 static int check_one_conflict(int i, int *type)
527 {
528 const struct cache_entry *e = active_cache[i];
529
530 if (!ce_stage(e)) {
531 *type = RESOLVED;
532 return i + 1;
533 }
534
535 *type = PUNTED;
536 while (ce_stage(active_cache[i]) == 1)
537 i++;
538
539 /* Only handle regular files with both stages #2 and #3 */
540 if (i + 1 < active_nr) {
541 const struct cache_entry *e2 = active_cache[i];
542 const struct cache_entry *e3 = active_cache[i + 1];
543 if (ce_stage(e2) == 2 &&
544 ce_stage(e3) == 3 &&
545 ce_same_name(e, e3) &&
546 S_ISREG(e2->ce_mode) &&
547 S_ISREG(e3->ce_mode))
548 *type = THREE_STAGED;
549 }
550
551 /* Skip the entries with the same name */
552 while (i < active_nr && ce_same_name(e, active_cache[i]))
553 i++;
554 return i;
555 }
556
557 /*
558 * Scan the index and find paths that have conflicts that rerere can
559 * handle, i.e. the ones that has both stages #2 and #3.
560 *
561 * NEEDSWORK: we do not record or replay a previous "resolve by
562 * deletion" for a delete-modify conflict, as that is inherently risky
563 * without knowing what modification is being discarded. The only
564 * safe case, i.e. both side doing the deletion and modification that
565 * are identical to the previous round, might want to be handled,
566 * though.
567 */
568 static int find_conflict(struct string_list *conflict)
569 {
570 int i;
571 if (read_cache() < 0)
572 return error("Could not read index");
573
574 for (i = 0; i < active_nr;) {
575 int conflict_type;
576 const struct cache_entry *e = active_cache[i];
577 i = check_one_conflict(i, &conflict_type);
578 if (conflict_type == THREE_STAGED)
579 string_list_insert(conflict, (const char *)e->name);
580 }
581 return 0;
582 }
583
584 /*
585 * The merge_rr list is meant to hold outstanding conflicted paths
586 * that rerere could handle. Abuse the list by adding other types of
587 * entries to allow the caller to show "rerere remaining".
588 *
589 * - Conflicted paths that rerere does not handle are added
590 * - Conflicted paths that have been resolved are marked as such
591 * by storing RERERE_RESOLVED to .util field (where conflict ID
592 * is expected to be stored).
593 *
594 * Do *not* write MERGE_RR file out after calling this function.
595 *
596 * NEEDSWORK: we may want to fix the caller that implements "rerere
597 * remaining" to do this without abusing merge_rr.
598 */
599 int rerere_remaining(struct string_list *merge_rr)
600 {
601 int i;
602 if (setup_rerere(merge_rr, RERERE_READONLY))
603 return 0;
604 if (read_cache() < 0)
605 return error("Could not read index");
606
607 for (i = 0; i < active_nr;) {
608 int conflict_type;
609 const struct cache_entry *e = active_cache[i];
610 i = check_one_conflict(i, &conflict_type);
611 if (conflict_type == PUNTED)
612 string_list_insert(merge_rr, (const char *)e->name);
613 else if (conflict_type == RESOLVED) {
614 struct string_list_item *it;
615 it = string_list_lookup(merge_rr, (const char *)e->name);
616 if (it != NULL) {
617 free_rerere_id(it);
618 it->util = RERERE_RESOLVED;
619 }
620 }
621 }
622 return 0;
623 }
624
625 /*
626 * Try using the given conflict resolution "ID" to see
627 * if that recorded conflict resolves cleanly what we
628 * got in the "cur".
629 */
630 static int try_merge(const struct rerere_id *id, const char *path,
631 mmfile_t *cur, mmbuffer_t *result)
632 {
633 int ret;
634 mmfile_t base = {NULL, 0}, other = {NULL, 0};
635
636 if (read_mmfile(&base, rerere_path(id, "preimage")) ||
637 read_mmfile(&other, rerere_path(id, "postimage")))
638 ret = 1;
639 else
640 /*
641 * A three-way merge. Note that this honors user-customizable
642 * low-level merge driver settings.
643 */
644 ret = ll_merge(result, path, &base, NULL, cur, "", &other, "", NULL);
645
646 free(base.ptr);
647 free(other.ptr);
648
649 return ret;
650 }
651
652 /*
653 * Find the conflict identified by "id"; the change between its
654 * "preimage" (i.e. a previous contents with conflict markers) and its
655 * "postimage" (i.e. the corresponding contents with conflicts
656 * resolved) may apply cleanly to the contents stored in "path", i.e.
657 * the conflict this time around.
658 *
659 * Returns 0 for successful replay of recorded resolution, or non-zero
660 * for failure.
661 */
662 static int merge(const struct rerere_id *id, const char *path)
663 {
664 FILE *f;
665 int ret;
666 mmfile_t cur = {NULL, 0};
667 mmbuffer_t result = {NULL, 0};
668
669 /*
670 * Normalize the conflicts in path and write it out to
671 * "thisimage" temporary file.
672 */
673 if ((handle_file(path, NULL, rerere_path(id, "thisimage")) < 0) ||
674 read_mmfile(&cur, rerere_path(id, "thisimage"))) {
675 ret = 1;
676 goto out;
677 }
678
679 ret = try_merge(id, path, &cur, &result);
680 if (ret)
681 goto out;
682
683 /*
684 * A successful replay of recorded resolution.
685 * Mark that "postimage" was used to help gc.
686 */
687 if (utime(rerere_path(id, "postimage"), NULL) < 0)
688 warning_errno("failed utime() on %s",
689 rerere_path(id, "postimage"));
690
691 /* Update "path" with the resolution */
692 f = fopen(path, "w");
693 if (!f)
694 return error_errno("Could not open %s", path);
695 if (fwrite(result.ptr, result.size, 1, f) != 1)
696 error_errno("Could not write %s", path);
697 if (fclose(f))
698 return error_errno("Writing %s failed", path);
699
700 out:
701 free(cur.ptr);
702 free(result.ptr);
703
704 return ret;
705 }
706
707 static void update_paths(struct string_list *update)
708 {
709 struct lock_file index_lock = LOCK_INIT;
710 int i;
711
712 hold_locked_index(&index_lock, LOCK_DIE_ON_ERROR);
713
714 for (i = 0; i < update->nr; i++) {
715 struct string_list_item *item = &update->items[i];
716 if (add_file_to_cache(item->string, 0))
717 exit(128);
718 fprintf(stderr, "Staged '%s' using previous resolution.\n",
719 item->string);
720 }
721
722 if (write_locked_index(&the_index, &index_lock,
723 COMMIT_LOCK | SKIP_IF_UNCHANGED))
724 die("Unable to write new index file");
725 }
726
727 static void remove_variant(struct rerere_id *id)
728 {
729 unlink_or_warn(rerere_path(id, "postimage"));
730 unlink_or_warn(rerere_path(id, "preimage"));
731 id->collection->status[id->variant] = 0;
732 }
733
734 /*
735 * The path indicated by rr_item may still have conflict for which we
736 * have a recorded resolution, in which case replay it and optionally
737 * update it. Or it may have been resolved by the user and we may
738 * only have the preimage for that conflict, in which case the result
739 * needs to be recorded as a resolution in a postimage file.
740 */
741 static void do_rerere_one_path(struct string_list_item *rr_item,
742 struct string_list *update)
743 {
744 const char *path = rr_item->string;
745 struct rerere_id *id = rr_item->util;
746 struct rerere_dir *rr_dir = id->collection;
747 int variant;
748
749 variant = id->variant;
750
751 /* Has the user resolved it already? */
752 if (variant >= 0) {
753 if (!handle_file(path, NULL, NULL)) {
754 copy_file(rerere_path(id, "postimage"), path, 0666);
755 id->collection->status[variant] |= RR_HAS_POSTIMAGE;
756 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
757 free_rerere_id(rr_item);
758 rr_item->util = NULL;
759 return;
760 }
761 /*
762 * There may be other variants that can cleanly
763 * replay. Try them and update the variant number for
764 * this one.
765 */
766 }
767
768 /* Does any existing resolution apply cleanly? */
769 for (variant = 0; variant < rr_dir->status_nr; variant++) {
770 const int both = RR_HAS_PREIMAGE | RR_HAS_POSTIMAGE;
771 struct rerere_id vid = *id;
772
773 if ((rr_dir->status[variant] & both) != both)
774 continue;
775
776 vid.variant = variant;
777 if (merge(&vid, path))
778 continue; /* failed to replay */
779
780 /*
781 * If there already is a different variant that applies
782 * cleanly, there is no point maintaining our own variant.
783 */
784 if (0 <= id->variant && id->variant != variant)
785 remove_variant(id);
786
787 if (rerere_autoupdate)
788 string_list_insert(update, path);
789 else
790 fprintf(stderr,
791 "Resolved '%s' using previous resolution.\n",
792 path);
793 free_rerere_id(rr_item);
794 rr_item->util = NULL;
795 return;
796 }
797
798 /* None of the existing one applies; we need a new variant */
799 assign_variant(id);
800
801 variant = id->variant;
802 handle_file(path, NULL, rerere_path(id, "preimage"));
803 if (id->collection->status[variant] & RR_HAS_POSTIMAGE) {
804 const char *path = rerere_path(id, "postimage");
805 if (unlink(path))
806 die_errno("cannot unlink stray '%s'", path);
807 id->collection->status[variant] &= ~RR_HAS_POSTIMAGE;
808 }
809 id->collection->status[variant] |= RR_HAS_PREIMAGE;
810 fprintf(stderr, "Recorded preimage for '%s'\n", path);
811 }
812
813 static int do_plain_rerere(struct string_list *rr, int fd)
814 {
815 struct string_list conflict = STRING_LIST_INIT_DUP;
816 struct string_list update = STRING_LIST_INIT_DUP;
817 int i;
818
819 find_conflict(&conflict);
820
821 /*
822 * MERGE_RR records paths with conflicts immediately after
823 * merge failed. Some of the conflicted paths might have been
824 * hand resolved in the working tree since then, but the
825 * initial run would catch all and register their preimages.
826 */
827 for (i = 0; i < conflict.nr; i++) {
828 struct rerere_id *id;
829 unsigned char sha1[20];
830 const char *path = conflict.items[i].string;
831 int ret;
832
833 if (string_list_has_string(rr, path))
834 continue;
835
836 /*
837 * Ask handle_file() to scan and assign a
838 * conflict ID. No need to write anything out
839 * yet.
840 */
841 ret = handle_file(path, sha1, NULL);
842 if (ret < 1)
843 continue;
844
845 id = new_rerere_id(sha1);
846 string_list_insert(rr, path)->util = id;
847
848 /* Ensure that the directory exists. */
849 mkdir_in_gitdir(rerere_path(id, NULL));
850 }
851
852 for (i = 0; i < rr->nr; i++)
853 do_rerere_one_path(&rr->items[i], &update);
854
855 if (update.nr)
856 update_paths(&update);
857
858 return write_rr(rr, fd);
859 }
860
861 static void git_rerere_config(void)
862 {
863 git_config_get_bool("rerere.enabled", &rerere_enabled);
864 git_config_get_bool("rerere.autoupdate", &rerere_autoupdate);
865 git_config(git_default_config, NULL);
866 }
867
868 static GIT_PATH_FUNC(git_path_rr_cache, "rr-cache")
869
870 static int is_rerere_enabled(void)
871 {
872 int rr_cache_exists;
873
874 if (!rerere_enabled)
875 return 0;
876
877 rr_cache_exists = is_directory(git_path_rr_cache());
878 if (rerere_enabled < 0)
879 return rr_cache_exists;
880
881 if (!rr_cache_exists && mkdir_in_gitdir(git_path_rr_cache()))
882 die("Could not create directory %s", git_path_rr_cache());
883 return 1;
884 }
885
886 int setup_rerere(struct string_list *merge_rr, int flags)
887 {
888 int fd;
889
890 git_rerere_config();
891 if (!is_rerere_enabled())
892 return -1;
893
894 if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
895 rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
896 if (flags & RERERE_READONLY)
897 fd = 0;
898 else
899 fd = hold_lock_file_for_update(&write_lock,
900 git_path_merge_rr(the_repository),
901 LOCK_DIE_ON_ERROR);
902 read_rr(merge_rr);
903 return fd;
904 }
905
906 /*
907 * The main entry point that is called internally from codepaths that
908 * perform mergy operations, possibly leaving conflicted index entries
909 * and working tree files.
910 */
911 int rerere(int flags)
912 {
913 struct string_list merge_rr = STRING_LIST_INIT_DUP;
914 int fd, status;
915
916 fd = setup_rerere(&merge_rr, flags);
917 if (fd < 0)
918 return 0;
919 status = do_plain_rerere(&merge_rr, fd);
920 free_rerere_dirs();
921 return status;
922 }
923
924 /*
925 * Subclass of rerere_io that reads from an in-core buffer that is a
926 * strbuf
927 */
928 struct rerere_io_mem {
929 struct rerere_io io;
930 struct strbuf input;
931 };
932
933 /*
934 * ... and its getline() method implementation
935 */
936 static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
937 {
938 struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
939 char *ep;
940 size_t len;
941
942 strbuf_release(sb);
943 if (!io->input.len)
944 return -1;
945 ep = memchr(io->input.buf, '\n', io->input.len);
946 if (!ep)
947 ep = io->input.buf + io->input.len;
948 else if (*ep == '\n')
949 ep++;
950 len = ep - io->input.buf;
951 strbuf_add(sb, io->input.buf, len);
952 strbuf_remove(&io->input, 0, len);
953 return 0;
954 }
955
956 static int handle_cache(const char *path, unsigned char *sha1, const char *output)
957 {
958 mmfile_t mmfile[3] = {{NULL}};
959 mmbuffer_t result = {NULL, 0};
960 const struct cache_entry *ce;
961 int pos, len, i, hunk_no;
962 struct rerere_io_mem io;
963 int marker_size = ll_merge_marker_size(path);
964
965 /*
966 * Reproduce the conflicted merge in-core
967 */
968 len = strlen(path);
969 pos = cache_name_pos(path, len);
970 if (0 <= pos)
971 return -1;
972 pos = -pos - 1;
973
974 while (pos < active_nr) {
975 enum object_type type;
976 unsigned long size;
977
978 ce = active_cache[pos++];
979 if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
980 break;
981 i = ce_stage(ce) - 1;
982 if (!mmfile[i].ptr) {
983 mmfile[i].ptr = read_object_file(&ce->oid, &type,
984 &size);
985 mmfile[i].size = size;
986 }
987 }
988 for (i = 0; i < 3; i++)
989 if (!mmfile[i].ptr && !mmfile[i].size)
990 mmfile[i].ptr = xstrdup("");
991
992 /*
993 * NEEDSWORK: handle conflicts from merges with
994 * merge.renormalize set, too?
995 */
996 ll_merge(&result, path, &mmfile[0], NULL,
997 &mmfile[1], "ours",
998 &mmfile[2], "theirs", NULL);
999 for (i = 0; i < 3; i++)
1000 free(mmfile[i].ptr);
1001
1002 memset(&io, 0, sizeof(io));
1003 io.io.getline = rerere_mem_getline;
1004 if (output)
1005 io.io.output = fopen(output, "w");
1006 else
1007 io.io.output = NULL;
1008 strbuf_init(&io.input, 0);
1009 strbuf_attach(&io.input, result.ptr, result.size, result.size);
1010
1011 /*
1012 * Grab the conflict ID and optionally write the original
1013 * contents with conflict markers out.
1014 */
1015 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
1016 strbuf_release(&io.input);
1017 if (io.io.output)
1018 fclose(io.io.output);
1019 return hunk_no;
1020 }
1021
1022 static int rerere_forget_one_path(const char *path, struct string_list *rr)
1023 {
1024 const char *filename;
1025 struct rerere_id *id;
1026 unsigned char sha1[20];
1027 int ret;
1028 struct string_list_item *item;
1029
1030 /*
1031 * Recreate the original conflict from the stages in the
1032 * index and compute the conflict ID
1033 */
1034 ret = handle_cache(path, sha1, NULL);
1035 if (ret < 1)
1036 return error("Could not parse conflict hunks in '%s'", path);
1037
1038 /* Nuke the recorded resolution for the conflict */
1039 id = new_rerere_id(sha1);
1040
1041 for (id->variant = 0;
1042 id->variant < id->collection->status_nr;
1043 id->variant++) {
1044 mmfile_t cur = { NULL, 0 };
1045 mmbuffer_t result = {NULL, 0};
1046 int cleanly_resolved;
1047
1048 if (!has_rerere_resolution(id))
1049 continue;
1050
1051 handle_cache(path, sha1, rerere_path(id, "thisimage"));
1052 if (read_mmfile(&cur, rerere_path(id, "thisimage"))) {
1053 free(cur.ptr);
1054 error("Failed to update conflicted state in '%s'", path);
1055 goto fail_exit;
1056 }
1057 cleanly_resolved = !try_merge(id, path, &cur, &result);
1058 free(result.ptr);
1059 free(cur.ptr);
1060 if (cleanly_resolved)
1061 break;
1062 }
1063
1064 if (id->collection->status_nr <= id->variant) {
1065 error("no remembered resolution for '%s'", path);
1066 goto fail_exit;
1067 }
1068
1069 filename = rerere_path(id, "postimage");
1070 if (unlink(filename)) {
1071 if (errno == ENOENT)
1072 error("no remembered resolution for %s", path);
1073 else
1074 error_errno("cannot unlink %s", filename);
1075 goto fail_exit;
1076 }
1077
1078 /*
1079 * Update the preimage so that the user can resolve the
1080 * conflict in the working tree, run us again to record
1081 * the postimage.
1082 */
1083 handle_cache(path, sha1, rerere_path(id, "preimage"));
1084 fprintf(stderr, "Updated preimage for '%s'\n", path);
1085
1086 /*
1087 * And remember that we can record resolution for this
1088 * conflict when the user is done.
1089 */
1090 item = string_list_insert(rr, path);
1091 free_rerere_id(item);
1092 item->util = id;
1093 fprintf(stderr, "Forgot resolution for %s\n", path);
1094 return 0;
1095
1096 fail_exit:
1097 free(id);
1098 return -1;
1099 }
1100
1101 int rerere_forget(struct pathspec *pathspec)
1102 {
1103 int i, fd;
1104 struct string_list conflict = STRING_LIST_INIT_DUP;
1105 struct string_list merge_rr = STRING_LIST_INIT_DUP;
1106
1107 if (read_cache() < 0)
1108 return error("Could not read index");
1109
1110 fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
1111 if (fd < 0)
1112 return 0;
1113
1114 /*
1115 * The paths may have been resolved (incorrectly);
1116 * recover the original conflicted state and then
1117 * find the conflicted paths.
1118 */
1119 unmerge_cache(pathspec);
1120 find_conflict(&conflict);
1121 for (i = 0; i < conflict.nr; i++) {
1122 struct string_list_item *it = &conflict.items[i];
1123 if (!match_pathspec(&the_index, pathspec, it->string,
1124 strlen(it->string), 0, NULL, 0))
1125 continue;
1126 rerere_forget_one_path(it->string, &merge_rr);
1127 }
1128 return write_rr(&merge_rr, fd);
1129 }
1130
1131 /*
1132 * Garbage collection support
1133 */
1134
1135 static timestamp_t rerere_created_at(struct rerere_id *id)
1136 {
1137 struct stat st;
1138
1139 return stat(rerere_path(id, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
1140 }
1141
1142 static timestamp_t rerere_last_used_at(struct rerere_id *id)
1143 {
1144 struct stat st;
1145
1146 return stat(rerere_path(id, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
1147 }
1148
1149 /*
1150 * Remove the recorded resolution for a given conflict ID
1151 */
1152 static void unlink_rr_item(struct rerere_id *id)
1153 {
1154 unlink_or_warn(rerere_path(id, "thisimage"));
1155 remove_variant(id);
1156 id->collection->status[id->variant] = 0;
1157 }
1158
1159 static void prune_one(struct rerere_id *id,
1160 timestamp_t cutoff_resolve, timestamp_t cutoff_noresolve)
1161 {
1162 timestamp_t then;
1163 timestamp_t cutoff;
1164
1165 then = rerere_last_used_at(id);
1166 if (then)
1167 cutoff = cutoff_resolve;
1168 else {
1169 then = rerere_created_at(id);
1170 if (!then)
1171 return;
1172 cutoff = cutoff_noresolve;
1173 }
1174 if (then < cutoff)
1175 unlink_rr_item(id);
1176 }
1177
1178 void rerere_gc(struct string_list *rr)
1179 {
1180 struct string_list to_remove = STRING_LIST_INIT_DUP;
1181 DIR *dir;
1182 struct dirent *e;
1183 int i;
1184 timestamp_t now = time(NULL);
1185 timestamp_t cutoff_noresolve = now - 15 * 86400;
1186 timestamp_t cutoff_resolve = now - 60 * 86400;
1187
1188 if (setup_rerere(rr, 0) < 0)
1189 return;
1190
1191 git_config_get_expiry_in_days("gc.rerereresolved", &cutoff_resolve, now);
1192 git_config_get_expiry_in_days("gc.rerereunresolved", &cutoff_noresolve, now);
1193 git_config(git_default_config, NULL);
1194 dir = opendir(git_path("rr-cache"));
1195 if (!dir)
1196 die_errno("unable to open rr-cache directory");
1197 /* Collect stale conflict IDs ... */
1198 while ((e = readdir(dir))) {
1199 struct rerere_dir *rr_dir;
1200 struct rerere_id id;
1201 int now_empty;
1202
1203 if (is_dot_or_dotdot(e->d_name))
1204 continue;
1205 rr_dir = find_rerere_dir(e->d_name);
1206 if (!rr_dir)
1207 continue; /* or should we remove e->d_name? */
1208
1209 now_empty = 1;
1210 for (id.variant = 0, id.collection = rr_dir;
1211 id.variant < id.collection->status_nr;
1212 id.variant++) {
1213 prune_one(&id, cutoff_resolve, cutoff_noresolve);
1214 if (id.collection->status[id.variant])
1215 now_empty = 0;
1216 }
1217 if (now_empty)
1218 string_list_append(&to_remove, e->d_name);
1219 }
1220 closedir(dir);
1221
1222 /* ... and then remove the empty directories */
1223 for (i = 0; i < to_remove.nr; i++)
1224 rmdir(git_path("rr-cache/%s", to_remove.items[i].string));
1225 string_list_clear(&to_remove, 0);
1226 rollback_lock_file(&write_lock);
1227 }
1228
1229 /*
1230 * During a conflict resolution, after "rerere" recorded the
1231 * preimages, abandon them if the user did not resolve them or
1232 * record their resolutions. And drop $GIT_DIR/MERGE_RR.
1233 *
1234 * NEEDSWORK: shouldn't we be calling this from "reset --hard"?
1235 */
1236 void rerere_clear(struct string_list *merge_rr)
1237 {
1238 int i;
1239
1240 if (setup_rerere(merge_rr, 0) < 0)
1241 return;
1242
1243 for (i = 0; i < merge_rr->nr; i++) {
1244 struct rerere_id *id = merge_rr->items[i].util;
1245 if (!has_rerere_resolution(id)) {
1246 unlink_rr_item(id);
1247 rmdir(rerere_path(id, NULL));
1248 }
1249 }
1250 unlink_or_warn(git_path_merge_rr(the_repository));
1251 rollback_lock_file(&write_lock);
1252 }