rerere: explain the primary codepath
[git/git.git] / rerere.c
CommitLineData
5b2fd956 1#include "cache.h"
697cc8ef 2#include "lockfile.h"
c455c87c 3#include "string-list.h"
5b2fd956 4#include "rerere.h"
5b2fd956 5#include "xdiff-interface.h"
dea4562b
JH
6#include "dir.h"
7#include "resolve-undo.h"
8#include "ll-merge.h"
8588567c 9#include "attr.h"
01a10b0a 10#include "pathspec.h"
5b2fd956 11
ac49f5ca
MZ
12#define RESOLVED 0
13#define PUNTED 1
14#define THREE_STAGED 2
15void *RERERE_RESOLVED = &RERERE_RESOLVED;
16
5b2fd956
SB
17/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
18static int rerere_enabled = -1;
19
20/* automatically update cleanly resolved paths to the index */
21static int rerere_autoupdate;
22
23static char *merge_rr_path;
24
90056966 25const char *rerere_path(const char *hex, const char *file)
5b2fd956 26{
90056966 27 return git_path("rr-cache/%s/%s", hex, file);
5b2fd956
SB
28}
29
7e0d4ab5 30static int has_rerere_resolution(const char *hex)
5b2fd956
SB
31{
32 struct stat st;
90056966 33 return !stat(rerere_path(hex, "postimage"), &st);
5b2fd956
SB
34}
35
4b68c2a0
JH
36/*
37 * $GIT_DIR/MERGE_RR file is a collection of records, each of which is
38 * "conflict ID", a HT and pathname, terminated with a NUL, and is
39 * used to keep track of the set of paths that "rerere" may need to
40 * work on (i.e. what is left by the previous invocation of "git
41 * rerere" during the current conflict resolution session).
42 */
c455c87c 43static void read_rr(struct string_list *rr)
5b2fd956 44{
f5800f6a 45 struct strbuf buf = STRBUF_INIT;
5b2fd956 46 FILE *in = fopen(merge_rr_path, "r");
f5800f6a 47
5b2fd956
SB
48 if (!in)
49 return;
f5800f6a
JH
50 while (!strbuf_getwholeline(&buf, in, '\0')) {
51 char *path;
52 unsigned char sha1[20];
53
54 /* There has to be the hash, tab, path and then NUL */
55 if (buf.len < 42 || get_sha1_hex(buf.buf, sha1))
5b2fd956 56 die("corrupt MERGE_RR");
f5800f6a
JH
57
58 if (buf.buf[40] != '\t')
5b2fd956 59 die("corrupt MERGE_RR");
f5800f6a
JH
60 buf.buf[40] = '\0';
61 path = buf.buf + 41;
62
63 string_list_insert(rr, path)->util = xstrdup(buf.buf);
5b2fd956 64 }
f5800f6a 65 strbuf_release(&buf);
5b2fd956
SB
66 fclose(in);
67}
68
69static struct lock_file write_lock;
70
c455c87c 71static int write_rr(struct string_list *rr, int out_fd)
5b2fd956
SB
72{
73 int i;
74 for (i = 0; i < rr->nr; i++) {
e2cb6a95
JH
75 struct strbuf buf = STRBUF_INIT;
76
77 assert(rr->items[i].util != RERERE_RESOLVED);
5b2fd956
SB
78 if (!rr->items[i].util)
79 continue;
e2cb6a95
JH
80 strbuf_addf(&buf, "%s\t%s%c",
81 (char *)rr->items[i].util,
82 rr->items[i].string, 0);
83 if (write_in_full(out_fd, buf.buf, buf.len) != buf.len)
5b2fd956 84 die("unable to write rerere record");
e2cb6a95
JH
85
86 strbuf_release(&buf);
5b2fd956
SB
87 }
88 if (commit_lock_file(&write_lock) != 0)
89 die("unable to write rerere record");
90 return 0;
91}
92
a96847cc
JH
93/*
94 * "rerere" interacts with conflicted file contents using this I/O
95 * abstraction. It reads a conflicted contents from one place via
96 * "getline()" method, and optionally can write it out after
97 * normalizing the conflicted hunks to the "output". Subclasses of
98 * rerere_io embed this structure at the beginning of their own
99 * rerere_io object.
100 */
101struct rerere_io {
102 int (*getline)(struct strbuf *, struct rerere_io *);
103 FILE *output;
104 int wrerror;
105 /* some more stuff */
106};
107
47d32af2
AR
108static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
109{
110 if (!count || *err)
111 return;
112 if (fwrite(p, count, 1, fp) != 1)
113 *err = errno;
114}
115
116static inline void ferr_puts(const char *s, FILE *fp, int *err)
117{
118 ferr_write(s, strlen(s), fp, err);
119}
120
27d6b085
JH
121static void rerere_io_putstr(const char *str, struct rerere_io *io)
122{
123 if (io->output)
124 ferr_puts(str, io->output, &io->wrerror);
125}
126
a96847cc
JH
127/*
128 * Write a conflict marker to io->output (if defined).
129 */
191f2417
JH
130static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
131{
132 char buf[64];
133
134 while (size) {
d3c2749d 135 if (size <= sizeof(buf) - 2) {
191f2417
JH
136 memset(buf, ch, size);
137 buf[size] = '\n';
138 buf[size + 1] = '\0';
139 size = 0;
140 } else {
141 int sz = sizeof(buf) - 1;
d3c2749d
JH
142
143 /*
144 * Make sure we will not write everything out
145 * in this round by leaving at least 1 byte
146 * for the next round, giving the next round
147 * a chance to add the terminating LF. Yuck.
148 */
191f2417
JH
149 if (size <= sz)
150 sz -= (sz - size) + 1;
151 memset(buf, ch, sz);
152 buf[sz] = '\0';
153 size -= sz;
154 }
155 rerere_io_putstr(buf, io);
156 }
157}
158
27d6b085
JH
159static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
160{
161 if (io->output)
162 ferr_write(mem, sz, io->output, &io->wrerror);
163}
164
a96847cc
JH
165/*
166 * Subclass of rerere_io that reads from an on-disk file
167 */
27d6b085
JH
168struct rerere_io_file {
169 struct rerere_io io;
170 FILE *input;
171};
172
a96847cc
JH
173/*
174 * ... and its getline() method implementation
175 */
27d6b085
JH
176static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
177{
178 struct rerere_io_file *io = (struct rerere_io_file *)io_;
179 return strbuf_getwholeline(sb, io->input, '\n');
180}
181
67711cdc
JH
182/*
183 * Require the exact number of conflict marker letters, no more, no
184 * less, followed by SP or any whitespace
185 * (including LF).
186 */
187static int is_cmarker(char *buf, int marker_char, int marker_size)
191f2417 188{
67711cdc
JH
189 int want_sp;
190
191 /*
192 * The beginning of our version and the end of their version
193 * always are labeled like "<<<<< ours" or ">>>>> theirs",
194 * hence we set want_sp for them. Note that the version from
195 * the common ancestor in diff3-style output is not always
196 * labelled (e.g. "||||| common" is often seen but "|||||"
197 * alone is also valid), so we do not set want_sp.
198 */
199 want_sp = (marker_char == '<') || (marker_char == '>');
200
191f2417
JH
201 while (marker_size--)
202 if (*buf++ != marker_char)
203 return 0;
204 if (want_sp && *buf != ' ')
205 return 0;
206 return isspace(*buf);
207}
208
cc899eca
JH
209/*
210 * Read contents a file with conflicts, normalize the conflicts
211 * by (1) discarding the common ancestor version in diff3-style,
212 * (2) reordering our side and their side so that whichever sorts
213 * alphabetically earlier comes before the other one, while
214 * computing the "conflict ID", which is just an SHA-1 hash of
215 * one side of the conflict, NUL, the other side of the conflict,
216 * and NUL concatenated together.
217 *
218 * Return the number of conflict hunks found.
219 *
220 * NEEDSWORK: the logic and theory of operation behind this conflict
221 * normalization may deserve to be documented somewhere, perhaps in
222 * Documentation/technical/rerere.txt.
223 */
191f2417 224static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
5b2fd956 225{
9126f009 226 git_SHA_CTX ctx;
cc58d7df
JH
227 int hunk_no = 0;
228 enum {
4b05548f 229 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
cc58d7df 230 } hunk = RR_CONTEXT;
f285a2d7 231 struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
d58ee6db 232 struct strbuf buf = STRBUF_INIT;
5b2fd956
SB
233
234 if (sha1)
9126f009 235 git_SHA1_Init(&ctx);
5b2fd956 236
27d6b085 237 while (!io->getline(&buf, io)) {
67711cdc 238 if (is_cmarker(buf.buf, '<', marker_size)) {
cc58d7df 239 if (hunk != RR_CONTEXT)
5b2fd956 240 goto bad;
cc58d7df 241 hunk = RR_SIDE_1;
67711cdc 242 } else if (is_cmarker(buf.buf, '|', marker_size)) {
cc58d7df 243 if (hunk != RR_SIDE_1)
5b2fd956 244 goto bad;
387c9d49 245 hunk = RR_ORIGINAL;
67711cdc 246 } else if (is_cmarker(buf.buf, '=', marker_size)) {
387c9d49 247 if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
5b2fd956 248 goto bad;
cc58d7df 249 hunk = RR_SIDE_2;
67711cdc 250 } else if (is_cmarker(buf.buf, '>', marker_size)) {
cc58d7df 251 if (hunk != RR_SIDE_2)
5b2fd956
SB
252 goto bad;
253 if (strbuf_cmp(&one, &two) > 0)
254 strbuf_swap(&one, &two);
255 hunk_no++;
cc58d7df 256 hunk = RR_CONTEXT;
191f2417 257 rerere_io_putconflict('<', marker_size, io);
27d6b085 258 rerere_io_putmem(one.buf, one.len, io);
191f2417 259 rerere_io_putconflict('=', marker_size, io);
27d6b085 260 rerere_io_putmem(two.buf, two.len, io);
191f2417 261 rerere_io_putconflict('>', marker_size, io);
5b2fd956 262 if (sha1) {
9126f009 263 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
5b2fd956 264 one.len + 1);
9126f009 265 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
5b2fd956
SB
266 two.len + 1);
267 }
268 strbuf_reset(&one);
269 strbuf_reset(&two);
cc58d7df 270 } else if (hunk == RR_SIDE_1)
e992d1eb 271 strbuf_addbuf(&one, &buf);
387c9d49
JH
272 else if (hunk == RR_ORIGINAL)
273 ; /* discard */
cc58d7df 274 else if (hunk == RR_SIDE_2)
e992d1eb 275 strbuf_addbuf(&two, &buf);
27d6b085
JH
276 else
277 rerere_io_putstr(buf.buf, io);
5b2fd956
SB
278 continue;
279 bad:
280 hunk = 99; /* force error exit */
281 break;
282 }
283 strbuf_release(&one);
284 strbuf_release(&two);
d58ee6db 285 strbuf_release(&buf);
5b2fd956 286
5b2fd956 287 if (sha1)
9126f009 288 git_SHA1_Final(sha1, &ctx);
27d6b085
JH
289 if (hunk != RR_CONTEXT)
290 return -1;
291 return hunk_no;
292}
293
cc899eca
JH
294/*
295 * Scan the path for conflicts, do the "handle_path()" thing above, and
296 * return the number of conflict hunks found.
297 */
27d6b085
JH
298static int handle_file(const char *path, unsigned char *sha1, const char *output)
299{
300 int hunk_no = 0;
301 struct rerere_io_file io;
8588567c 302 int marker_size = ll_merge_marker_size(path);
27d6b085
JH
303
304 memset(&io, 0, sizeof(io));
305 io.io.getline = rerere_file_getline;
306 io.input = fopen(path, "r");
307 io.io.wrerror = 0;
308 if (!io.input)
309 return error("Could not open %s", path);
310
311 if (output) {
312 io.io.output = fopen(output, "w");
313 if (!io.io.output) {
314 fclose(io.input);
315 return error("Could not write %s", output);
316 }
317 }
318
191f2417 319 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
27d6b085
JH
320
321 fclose(io.input);
322 if (io.io.wrerror)
323 error("There were errors while writing %s (%s)",
324 path, strerror(io.io.wrerror));
325 if (io.io.output && fclose(io.io.output))
326 io.io.wrerror = error("Failed to flush %s: %s",
327 path, strerror(errno));
328
329 if (hunk_no < 0) {
5b2fd956 330 if (output)
691f1a28 331 unlink_or_warn(output);
5b2fd956
SB
332 return error("Could not parse conflict hunks in %s", path);
333 }
27d6b085 334 if (io.io.wrerror)
47d32af2 335 return -1;
5b2fd956
SB
336 return hunk_no;
337}
338
a96847cc
JH
339/*
340 * Subclass of rerere_io that reads from an in-core buffer that is a
341 * strbuf
342 */
dea4562b
JH
343struct rerere_io_mem {
344 struct rerere_io io;
345 struct strbuf input;
346};
347
a96847cc
JH
348/*
349 * ... and its getline() method implementation
350 */
dea4562b
JH
351static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
352{
353 struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
354 char *ep;
355 size_t len;
356
357 strbuf_release(sb);
358 if (!io->input.len)
359 return -1;
53d8afaf
JS
360 ep = memchr(io->input.buf, '\n', io->input.len);
361 if (!ep)
362 ep = io->input.buf + io->input.len;
363 else if (*ep == '\n')
dea4562b
JH
364 ep++;
365 len = ep - io->input.buf;
366 strbuf_add(sb, io->input.buf, len);
367 strbuf_remove(&io->input, 0, len);
368 return 0;
369}
370
371static int handle_cache(const char *path, unsigned char *sha1, const char *output)
372{
b9e31f59 373 mmfile_t mmfile[3] = {{NULL}};
dea4562b 374 mmbuffer_t result = {NULL, 0};
9c5e6c80 375 const struct cache_entry *ce;
dea4562b
JH
376 int pos, len, i, hunk_no;
377 struct rerere_io_mem io;
8588567c 378 int marker_size = ll_merge_marker_size(path);
dea4562b
JH
379
380 /*
381 * Reproduce the conflicted merge in-core
382 */
383 len = strlen(path);
384 pos = cache_name_pos(path, len);
385 if (0 <= pos)
47d32af2 386 return -1;
dea4562b
JH
387 pos = -pos - 1;
388
74444d4e 389 while (pos < active_nr) {
dea4562b
JH
390 enum object_type type;
391 unsigned long size;
392
dea4562b 393 ce = active_cache[pos++];
b9e31f59 394 if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
74444d4e
JH
395 break;
396 i = ce_stage(ce) - 1;
7d4053b6
JH
397 if (!mmfile[i].ptr) {
398 mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
399 mmfile[i].size = size;
400 }
dea4562b 401 }
74444d4e 402 for (i = 0; i < 3; i++)
dea4562b
JH
403 if (!mmfile[i].ptr && !mmfile[i].size)
404 mmfile[i].ptr = xstrdup("");
74444d4e 405
18b037a5
JN
406 /*
407 * NEEDSWORK: handle conflicts from merges with
408 * merge.renormalize set, too
409 */
f01de62e 410 ll_merge(&result, path, &mmfile[0], NULL,
dea4562b 411 &mmfile[1], "ours",
712516bc 412 &mmfile[2], "theirs", NULL);
dea4562b
JH
413 for (i = 0; i < 3; i++)
414 free(mmfile[i].ptr);
415
af86debc 416 memset(&io, 0, sizeof(io));
dea4562b
JH
417 io.io.getline = rerere_mem_getline;
418 if (output)
419 io.io.output = fopen(output, "w");
420 else
421 io.io.output = NULL;
422 strbuf_init(&io.input, 0);
423 strbuf_attach(&io.input, result.ptr, result.size, result.size);
424
191f2417 425 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
dea4562b
JH
426 strbuf_release(&io.input);
427 if (io.io.output)
428 fclose(io.io.output);
5b2fd956
SB
429 return hunk_no;
430}
431
4b68c2a0
JH
432/*
433 * Look at a cache entry at "i" and see if it is not conflicting,
434 * conflicting and we are willing to handle, or conflicting and
435 * we are unable to handle, and return the determination in *type.
436 * Return the cache index to be looked at next, by skipping the
437 * stages we have already looked at in this invocation of this
438 * function.
439 */
ac49f5ca 440static int check_one_conflict(int i, int *type)
5b2fd956 441{
9c5e6c80 442 const struct cache_entry *e = active_cache[i];
ac49f5ca
MZ
443
444 if (!ce_stage(e)) {
445 *type = RESOLVED;
446 return i + 1;
447 }
448
449 *type = PUNTED;
5eda906b 450 while (ce_stage(active_cache[i]) == 1)
fb70a06d 451 i++;
ac49f5ca
MZ
452
453 /* Only handle regular files with both stages #2 and #3 */
454 if (i + 1 < active_nr) {
9c5e6c80
NTND
455 const struct cache_entry *e2 = active_cache[i];
456 const struct cache_entry *e3 = active_cache[i + 1];
5b2fd956
SB
457 if (ce_stage(e2) == 2 &&
458 ce_stage(e3) == 3 &&
ac49f5ca 459 ce_same_name(e, e3) &&
5b2fd956 460 S_ISREG(e2->ce_mode) &&
ac49f5ca
MZ
461 S_ISREG(e3->ce_mode))
462 *type = THREE_STAGED;
463 }
464
465 /* Skip the entries with the same name */
466 while (i < active_nr && ce_same_name(e, active_cache[i]))
467 i++;
468 return i;
469}
470
4b68c2a0
JH
471/*
472 * Scan the index and find paths that have conflicts that rerere can
473 * handle, i.e. the ones that has both stages #2 and #3.
474 *
475 * NEEDSWORK: we do not record or replay a previous "resolve by
476 * deletion" for a delete-modify conflict, as that is inherently risky
477 * without knowing what modification is being discarded. The only
478 * safe case, i.e. both side doing the deletion and modification that
479 * are identical to the previous round, might want to be handled,
480 * though.
481 */
ac49f5ca
MZ
482static int find_conflict(struct string_list *conflict)
483{
484 int i;
485 if (read_cache() < 0)
486 return error("Could not read index");
487
488 for (i = 0; i < active_nr;) {
489 int conflict_type;
9c5e6c80 490 const struct cache_entry *e = active_cache[i];
ac49f5ca
MZ
491 i = check_one_conflict(i, &conflict_type);
492 if (conflict_type == THREE_STAGED)
493 string_list_insert(conflict, (const char *)e->name);
494 }
495 return 0;
496}
497
4b68c2a0
JH
498/*
499 * The merge_rr list is meant to hold outstanding conflicted paths
500 * that rerere could handle. Abuse the list by adding other types of
501 * entries to allow the caller to show "rerere remaining".
502 *
503 * - Conflicted paths that rerere does not handle are added
504 * - Conflicted paths that have been resolved are marked as such
505 * by storing RERERE_RESOLVED to .util field (where conflict ID
506 * is expected to be stored).
507 *
508 * Do *not* write MERGE_RR file out after calling this function.
509 *
510 * NEEDSWORK: we may want to fix the caller that implements "rerere
511 * remaining" to do this without abusing merge_rr.
512 */
ac49f5ca
MZ
513int rerere_remaining(struct string_list *merge_rr)
514{
515 int i;
516 if (read_cache() < 0)
517 return error("Could not read index");
518
519 for (i = 0; i < active_nr;) {
520 int conflict_type;
9c5e6c80 521 const struct cache_entry *e = active_cache[i];
ac49f5ca
MZ
522 i = check_one_conflict(i, &conflict_type);
523 if (conflict_type == PUNTED)
524 string_list_insert(merge_rr, (const char *)e->name);
525 else if (conflict_type == RESOLVED) {
526 struct string_list_item *it;
527 it = string_list_lookup(merge_rr, (const char *)e->name);
528 if (it != NULL) {
529 free(it->util);
530 it->util = RERERE_RESOLVED;
531 }
5b2fd956
SB
532 }
533 }
534 return 0;
535}
536
cc899eca
JH
537/*
538 * Find the conflict identified by "name"; the change between its
539 * "preimage" (i.e. a previous contents with conflict markers) and its
540 * "postimage" (i.e. the corresponding contents with conflicts
541 * resolved) may apply cleanly to the contents stored in "path", i.e.
542 * the conflict this time around.
543 *
544 * Returns 0 for successful replay of recorded resolution, or non-zero
545 * for failure.
546 */
5b2fd956
SB
547static int merge(const char *name, const char *path)
548{
549 int ret;
689b8c29 550 mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
5b2fd956 551 mmbuffer_t result = {NULL, 0};
5b2fd956 552
cc899eca
JH
553 /*
554 * Normalize the conflicts in path and write it out to
555 * "thisimage" temporary file.
556 */
90056966 557 if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
5b2fd956
SB
558 return 1;
559
90056966 560 if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
cc899eca
JH
561 read_mmfile(&base, rerere_path(name, "preimage")) ||
562 read_mmfile(&other, rerere_path(name, "postimage"))) {
689b8c29
BW
563 ret = 1;
564 goto out;
565 }
cc899eca
JH
566
567 /*
568 * A three-way merge. Note that this honors user-customizable
569 * low-level merge driver settings.
570 */
1e4cd68c 571 ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", NULL);
5b2fd956 572 if (!ret) {
7d7ff15b
SG
573 FILE *f;
574
cc899eca
JH
575 /*
576 * A successful replay of recorded resolution.
577 * Mark that "postimage" was used to help gc.
578 */
7d7ff15b
SG
579 if (utime(rerere_path(name, "postimage"), NULL) < 0)
580 warning("failed utime() on %s: %s",
581 rerere_path(name, "postimage"),
582 strerror(errno));
cc899eca
JH
583
584 /* Update "path" with the resolution */
7d7ff15b 585 f = fopen(path, "w");
5b2fd956 586 if (!f)
47d32af2
AR
587 return error("Could not open %s: %s", path,
588 strerror(errno));
589 if (fwrite(result.ptr, result.size, 1, f) != 1)
590 error("Could not write %s: %s", path, strerror(errno));
591 if (fclose(f))
592 return error("Writing %s failed: %s", path,
593 strerror(errno));
5b2fd956
SB
594 }
595
689b8c29 596out:
5b2fd956
SB
597 free(cur.ptr);
598 free(base.ptr);
599 free(other.ptr);
600 free(result.ptr);
601
602 return ret;
603}
604
605static struct lock_file index_lock;
606
89ea9035 607static void update_paths(struct string_list *update)
5b2fd956
SB
608{
609 int i;
5b2fd956 610
89ea9035 611 hold_locked_index(&index_lock, 1);
5b2fd956
SB
612
613 for (i = 0; i < update->nr; i++) {
c455c87c 614 struct string_list_item *item = &update->items[i];
89ea9035
JN
615 if (add_file_to_cache(item->string, 0))
616 exit(128);
a14c7ab8
JH
617 fprintf(stderr, "Staged '%s' using previous resolution.\n",
618 item->string);
5b2fd956
SB
619 }
620
89ea9035 621 if (active_cache_changed) {
03b86647 622 if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
5b2fd956 623 die("Unable to write new index file");
89ea9035 624 } else
5b2fd956 625 rollback_lock_file(&index_lock);
5b2fd956
SB
626}
627
c455c87c 628static int do_plain_rerere(struct string_list *rr, int fd)
5b2fd956 629{
183113a5
TF
630 struct string_list conflict = STRING_LIST_INIT_DUP;
631 struct string_list update = STRING_LIST_INIT_DUP;
5b2fd956
SB
632 int i;
633
634 find_conflict(&conflict);
635
636 /*
cc899eca
JH
637 * MERGE_RR records paths with conflicts immediately after
638 * merge failed. Some of the conflicted paths might have been
639 * hand resolved in the working tree since then, but the
640 * initial run would catch all and register their preimages.
5b2fd956 641 */
5b2fd956 642 for (i = 0; i < conflict.nr; i++) {
c455c87c
JS
643 const char *path = conflict.items[i].string;
644 if (!string_list_has_string(rr, path)) {
5b2fd956
SB
645 unsigned char sha1[20];
646 char *hex;
647 int ret;
cc899eca
JH
648
649 /*
650 * Ask handle_file() to scan and assign a
651 * conflict ID. No need to write anything out
652 * yet.
653 */
5b2fd956
SB
654 ret = handle_file(path, sha1, NULL);
655 if (ret < 1)
656 continue;
657 hex = xstrdup(sha1_to_hex(sha1));
78a395d3 658 string_list_insert(rr, path)->util = hex;
cc899eca
JH
659
660 /*
661 * If the directory does not exist, create
662 * it. mkdir_in_gitdir() will fail with
663 * EEXIST if there already is one.
664 *
665 * NEEDSWORK: make sure "gc" does not remove
666 * preimage without removing the directory.
667 */
fd956338 668 if (mkdir_in_gitdir(git_path("rr-cache/%s", hex)))
ba19a808 669 continue;
cc899eca
JH
670
671 /*
672 * We are the first to encounter this
673 * conflict. Ask handle_file() to write the
674 * normalized contents to the "preimage" file.
675 */
90056966 676 handle_file(path, NULL, rerere_path(hex, "preimage"));
5b2fd956
SB
677 fprintf(stderr, "Recorded preimage for '%s'\n", path);
678 }
679 }
680
681 /*
cc899eca
JH
682 * Some of the paths that had conflicts earlier might have
683 * been resolved by the user. Others may be similar to a
684 * conflict already that was resolved before.
5b2fd956 685 */
5b2fd956
SB
686 for (i = 0; i < rr->nr; i++) {
687 int ret;
c455c87c 688 const char *path = rr->items[i].string;
5b2fd956
SB
689 const char *name = (const char *)rr->items[i].util;
690
cc899eca 691 /* Is there a recorded resolution we could attempt to apply? */
90056966 692 if (has_rerere_resolution(name)) {
a14c7ab8
JH
693 if (merge(name, path))
694 continue;
695
696 if (rerere_autoupdate)
697 string_list_insert(&update, path);
698 else
699 fprintf(stderr,
700 "Resolved '%s' using previous resolution.\n",
701 path);
702 goto mark_resolved;
5b2fd956
SB
703 }
704
cc899eca 705 /* Let's see if the user has resolved it. */
5b2fd956
SB
706 ret = handle_file(path, NULL, NULL);
707 if (ret)
708 continue;
709
90056966 710 copy_file(rerere_path(name, "postimage"), path, 0666);
cc899eca 711 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
5b2fd956 712 mark_resolved:
8d9b5a4a 713 free(rr->items[i].util);
5b2fd956
SB
714 rr->items[i].util = NULL;
715 }
716
717 if (update.nr)
718 update_paths(&update);
719
720 return write_rr(rr, fd);
721}
722
633e5ad3 723static void git_rerere_config(void)
5b2fd956 724{
633e5ad3
TA
725 git_config_get_bool("rerere.enabled", &rerere_enabled);
726 git_config_get_bool("rerere.autoupdate", &rerere_autoupdate);
727 git_config(git_default_config, NULL);
5b2fd956
SB
728}
729
730static int is_rerere_enabled(void)
731{
5b2fd956
SB
732 const char *rr_cache;
733 int rr_cache_exists;
734
735 if (!rerere_enabled)
736 return 0;
737
738 rr_cache = git_path("rr-cache");
90b4a71c 739 rr_cache_exists = is_directory(rr_cache);
5b2fd956
SB
740 if (rerere_enabled < 0)
741 return rr_cache_exists;
742
90a6464b 743 if (!rr_cache_exists && mkdir_in_gitdir(rr_cache))
5b2fd956
SB
744 die("Could not create directory %s", rr_cache);
745 return 1;
746}
747
cb6020bb 748int setup_rerere(struct string_list *merge_rr, int flags)
5b2fd956
SB
749{
750 int fd;
751
633e5ad3 752 git_rerere_config();
5b2fd956
SB
753 if (!is_rerere_enabled())
754 return -1;
755
cb6020bb
JH
756 if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
757 rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
a4f34cbb 758 merge_rr_path = git_pathdup("MERGE_RR");
acd3b9ec
JH
759 fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
760 LOCK_DIE_ON_ERROR);
5b2fd956
SB
761 read_rr(merge_rr);
762 return fd;
763}
764
cc899eca
JH
765/*
766 * The main entry point that is called internally from codepaths that
767 * perform mergy operations, possibly leaving conflicted index entries
768 * and working tree files.
769 */
cb6020bb 770int rerere(int flags)
5b2fd956 771{
183113a5 772 struct string_list merge_rr = STRING_LIST_INIT_DUP;
5b2fd956
SB
773 int fd;
774
cb6020bb 775 fd = setup_rerere(&merge_rr, flags);
5b2fd956
SB
776 if (fd < 0)
777 return 0;
778 return do_plain_rerere(&merge_rr, fd);
779}
dea4562b
JH
780
781static int rerere_forget_one_path(const char *path, struct string_list *rr)
782{
783 const char *filename;
784 char *hex;
785 unsigned char sha1[20];
786 int ret;
8d9b5a4a 787 struct string_list_item *item;
dea4562b
JH
788
789 ret = handle_cache(path, sha1, NULL);
790 if (ret < 1)
791 return error("Could not parse conflict hunks in '%s'", path);
792 hex = xstrdup(sha1_to_hex(sha1));
793 filename = rerere_path(hex, "postimage");
794 if (unlink(filename))
795 return (errno == ENOENT
796 ? error("no remembered resolution for %s", path)
797 : error("cannot unlink %s: %s", filename, strerror(errno)));
798
799 handle_cache(path, sha1, rerere_path(hex, "preimage"));
800 fprintf(stderr, "Updated preimage for '%s'\n", path);
801
8d9b5a4a
JH
802 item = string_list_insert(rr, path);
803 free(item->util);
804 item->util = hex;
dea4562b
JH
805 fprintf(stderr, "Forgot resolution for %s\n", path);
806 return 0;
807}
808
01a10b0a 809int rerere_forget(struct pathspec *pathspec)
dea4562b
JH
810{
811 int i, fd;
183113a5
TF
812 struct string_list conflict = STRING_LIST_INIT_DUP;
813 struct string_list merge_rr = STRING_LIST_INIT_DUP;
dea4562b
JH
814
815 if (read_cache() < 0)
816 return error("Could not read index");
817
6751e047 818 fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
dea4562b
JH
819
820 unmerge_cache(pathspec);
821 find_conflict(&conflict);
822 for (i = 0; i < conflict.nr; i++) {
823 struct string_list_item *it = &conflict.items[i];
854b0959 824 if (!match_pathspec(pathspec, it->string,
ae8d0824 825 strlen(it->string), 0, NULL, 0))
dea4562b
JH
826 continue;
827 rerere_forget_one_path(it->string, &merge_rr);
828 }
829 return write_rr(&merge_rr, fd);
830}
0f891e7d
JH
831
832static time_t rerere_created_at(const char *name)
833{
834 struct stat st;
835 return stat(rerere_path(name, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
836}
837
838static time_t rerere_last_used_at(const char *name)
839{
840 struct stat st;
841 return stat(rerere_path(name, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
842}
843
844static void unlink_rr_item(const char *name)
845{
846 unlink(rerere_path(name, "thisimage"));
847 unlink(rerere_path(name, "preimage"));
848 unlink(rerere_path(name, "postimage"));
849 rmdir(git_path("rr-cache/%s", name));
850}
851
0f891e7d
JH
852void rerere_gc(struct string_list *rr)
853{
854 struct string_list to_remove = STRING_LIST_INIT_DUP;
855 DIR *dir;
856 struct dirent *e;
857 int i, cutoff;
858 time_t now = time(NULL), then;
633e5ad3
TA
859 int cutoff_noresolve = 15;
860 int cutoff_resolve = 60;
0f891e7d 861
633e5ad3
TA
862 git_config_get_int("gc.rerereresolved", &cutoff_resolve);
863 git_config_get_int("gc.rerereunresolved", &cutoff_noresolve);
864 git_config(git_default_config, NULL);
0f891e7d
JH
865 dir = opendir(git_path("rr-cache"));
866 if (!dir)
867 die_errno("unable to open rr-cache directory");
868 while ((e = readdir(dir))) {
869 if (is_dot_or_dotdot(e->d_name))
870 continue;
871
872 then = rerere_last_used_at(e->d_name);
873 if (then) {
633e5ad3 874 cutoff = cutoff_resolve;
0f891e7d
JH
875 } else {
876 then = rerere_created_at(e->d_name);
877 if (!then)
878 continue;
633e5ad3 879 cutoff = cutoff_noresolve;
0f891e7d
JH
880 }
881 if (then < now - cutoff * 86400)
882 string_list_append(&to_remove, e->d_name);
883 }
a9930e35 884 closedir(dir);
0f891e7d
JH
885 for (i = 0; i < to_remove.nr; i++)
886 unlink_rr_item(to_remove.items[i].string);
887 string_list_clear(&to_remove, 0);
888}
889
890void rerere_clear(struct string_list *merge_rr)
891{
892 int i;
893
894 for (i = 0; i < merge_rr->nr; i++) {
895 const char *name = (const char *)merge_rr->items[i].util;
896 if (!has_rerere_resolution(name))
897 unlink_rr_item(name);
898 }
899 unlink_or_warn(git_path("MERGE_RR"));
900}