rerere: split code to call ll_merge() further
[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"
1869bbe1 11#include "sha1-lookup.h"
5b2fd956 12
ac49f5ca
MZ
13#define RESOLVED 0
14#define PUNTED 1
15#define THREE_STAGED 2
16void *RERERE_RESOLVED = &RERERE_RESOLVED;
17
5b2fd956
SB
18/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
19static int rerere_enabled = -1;
20
21/* automatically update cleanly resolved paths to the index */
22static int rerere_autoupdate;
23
24static char *merge_rr_path;
25
1869bbe1
JH
26static int rerere_dir_nr;
27static int rerere_dir_alloc;
28
2c7929b1
JH
29#define RR_HAS_POSTIMAGE 1
30#define RR_HAS_PREIMAGE 2
1869bbe1
JH
31static struct rerere_dir {
32 unsigned char sha1[20];
a13d1370
JH
33 int status_alloc, status_nr;
34 unsigned char *status;
1869bbe1
JH
35} **rerere_dir;
36
37static void free_rerere_dirs(void)
38{
39 int i;
a13d1370
JH
40 for (i = 0; i < rerere_dir_nr; i++) {
41 free(rerere_dir[i]->status);
1869bbe1 42 free(rerere_dir[i]);
a13d1370 43 }
1869bbe1
JH
44 free(rerere_dir);
45 rerere_dir_nr = rerere_dir_alloc = 0;
46 rerere_dir = NULL;
47}
48
1d51eced 49static void free_rerere_id(struct string_list_item *item)
5b2fd956 50{
1d51eced
JH
51 free(item->util);
52}
53
54static const char *rerere_id_hex(const struct rerere_id *id)
55{
1869bbe1 56 return sha1_to_hex(id->collection->sha1);
1d51eced
JH
57}
58
a13d1370
JH
59static void fit_variant(struct rerere_dir *rr_dir, int variant)
60{
61 variant++;
62 ALLOC_GROW(rr_dir->status, variant, rr_dir->status_alloc);
63 if (rr_dir->status_nr < variant) {
64 memset(rr_dir->status + rr_dir->status_nr,
65 '\0', variant - rr_dir->status_nr);
66 rr_dir->status_nr = variant;
67 }
68}
69
70static void assign_variant(struct rerere_id *id)
71{
72 int variant;
73 struct rerere_dir *rr_dir = id->collection;
74
75 variant = id->variant;
76 if (variant < 0) {
629716d2
JH
77 for (variant = 0; variant < rr_dir->status_nr; variant++)
78 if (!rr_dir->status[variant])
79 break;
a13d1370
JH
80 }
81 fit_variant(rr_dir, variant);
82 id->variant = variant;
83}
84
1d51eced
JH
85const char *rerere_path(const struct rerere_id *id, const char *file)
86{
87 if (!file)
88 return git_path("rr-cache/%s", rerere_id_hex(id));
89
a13d1370
JH
90 if (id->variant <= 0)
91 return git_path("rr-cache/%s/%s", rerere_id_hex(id), file);
92
93 return git_path("rr-cache/%s/%s.%d",
94 rerere_id_hex(id), file, id->variant);
5b2fd956
SB
95}
96
a13d1370 97static int is_rr_file(const char *name, const char *filename, int *variant)
2c7929b1 98{
a13d1370
JH
99 const char *suffix;
100 char *ep;
101
102 if (!strcmp(name, filename)) {
103 *variant = 0;
104 return 1;
105 }
106 if (!skip_prefix(name, filename, &suffix) || *suffix != '.')
107 return 0;
108
109 errno = 0;
110 *variant = strtol(suffix + 1, &ep, 10);
111 if (errno || *ep)
112 return 0;
113 return 1;
2c7929b1
JH
114}
115
116static void scan_rerere_dir(struct rerere_dir *rr_dir)
117{
118 struct dirent *de;
119 DIR *dir = opendir(git_path("rr-cache/%s", sha1_to_hex(rr_dir->sha1)));
120
121 if (!dir)
122 return;
123 while ((de = readdir(dir)) != NULL) {
a13d1370
JH
124 int variant;
125
126 if (is_rr_file(de->d_name, "postimage", &variant)) {
127 fit_variant(rr_dir, variant);
128 rr_dir->status[variant] |= RR_HAS_POSTIMAGE;
129 } else if (is_rr_file(de->d_name, "preimage", &variant)) {
130 fit_variant(rr_dir, variant);
131 rr_dir->status[variant] |= RR_HAS_PREIMAGE;
132 }
2c7929b1
JH
133 }
134 closedir(dir);
135}
136
1869bbe1
JH
137static const unsigned char *rerere_dir_sha1(size_t i, void *table)
138{
139 struct rerere_dir **rr_dir = table;
140 return rr_dir[i]->sha1;
141}
142
143static struct rerere_dir *find_rerere_dir(const char *hex)
144{
145 unsigned char sha1[20];
146 struct rerere_dir *rr_dir;
147 int pos;
148
149 if (get_sha1_hex(hex, sha1))
150 return NULL; /* BUG */
151 pos = sha1_pos(sha1, rerere_dir, rerere_dir_nr, rerere_dir_sha1);
152 if (pos < 0) {
153 rr_dir = xmalloc(sizeof(*rr_dir));
154 hashcpy(rr_dir->sha1, sha1);
a13d1370
JH
155 rr_dir->status = NULL;
156 rr_dir->status_nr = 0;
157 rr_dir->status_alloc = 0;
1869bbe1
JH
158 pos = -1 - pos;
159
160 /* Make sure the array is big enough ... */
161 ALLOC_GROW(rerere_dir, rerere_dir_nr + 1, rerere_dir_alloc);
162 /* ... and add it in. */
163 rerere_dir_nr++;
164 memmove(rerere_dir + pos + 1, rerere_dir + pos,
165 (rerere_dir_nr - pos - 1) * sizeof(*rerere_dir));
166 rerere_dir[pos] = rr_dir;
2c7929b1 167 scan_rerere_dir(rr_dir);
1869bbe1
JH
168 }
169 return rerere_dir[pos];
170}
171
1d51eced 172static int has_rerere_resolution(const struct rerere_id *id)
5b2fd956 173{
05dd9f13 174 const int both = RR_HAS_POSTIMAGE|RR_HAS_PREIMAGE;
a13d1370 175 int variant = id->variant;
05dd9f13 176
a13d1370
JH
177 if (variant < 0)
178 return 0;
179 return ((id->collection->status[variant] & both) == both);
5b2fd956
SB
180}
181
1d51eced
JH
182static struct rerere_id *new_rerere_id_hex(char *hex)
183{
184 struct rerere_id *id = xmalloc(sizeof(*id));
1869bbe1 185 id->collection = find_rerere_dir(hex);
a13d1370 186 id->variant = -1; /* not known yet */
1d51eced
JH
187 return id;
188}
189
190static struct rerere_id *new_rerere_id(unsigned char *sha1)
191{
192 return new_rerere_id_hex(sha1_to_hex(sha1));
193}
194
4b68c2a0
JH
195/*
196 * $GIT_DIR/MERGE_RR file is a collection of records, each of which is
197 * "conflict ID", a HT and pathname, terminated with a NUL, and is
198 * used to keep track of the set of paths that "rerere" may need to
199 * work on (i.e. what is left by the previous invocation of "git
200 * rerere" during the current conflict resolution session).
201 */
c455c87c 202static void read_rr(struct string_list *rr)
5b2fd956 203{
f5800f6a 204 struct strbuf buf = STRBUF_INIT;
5b2fd956 205 FILE *in = fopen(merge_rr_path, "r");
f5800f6a 206
5b2fd956
SB
207 if (!in)
208 return;
f5800f6a
JH
209 while (!strbuf_getwholeline(&buf, in, '\0')) {
210 char *path;
211 unsigned char sha1[20];
1d51eced 212 struct rerere_id *id;
a13d1370 213 int variant;
f5800f6a
JH
214
215 /* There has to be the hash, tab, path and then NUL */
216 if (buf.len < 42 || get_sha1_hex(buf.buf, sha1))
5b2fd956 217 die("corrupt MERGE_RR");
f5800f6a 218
a13d1370
JH
219 if (buf.buf[40] != '.') {
220 variant = 0;
221 path = buf.buf + 40;
222 } else {
223 errno = 0;
224 variant = strtol(buf.buf + 41, &path, 10);
225 if (errno)
226 die("corrupt MERGE_RR");
227 }
228 if (*(path++) != '\t')
5b2fd956 229 die("corrupt MERGE_RR");
f5800f6a 230 buf.buf[40] = '\0';
1d51eced 231 id = new_rerere_id_hex(buf.buf);
a13d1370 232 id->variant = variant;
1d51eced 233 string_list_insert(rr, path)->util = id;
5b2fd956 234 }
f5800f6a 235 strbuf_release(&buf);
5b2fd956
SB
236 fclose(in);
237}
238
239static struct lock_file write_lock;
240
c455c87c 241static int write_rr(struct string_list *rr, int out_fd)
5b2fd956
SB
242{
243 int i;
244 for (i = 0; i < rr->nr; i++) {
e2cb6a95 245 struct strbuf buf = STRBUF_INIT;
1d51eced 246 struct rerere_id *id;
e2cb6a95
JH
247
248 assert(rr->items[i].util != RERERE_RESOLVED);
1d51eced
JH
249
250 id = rr->items[i].util;
251 if (!id)
5b2fd956 252 continue;
a13d1370
JH
253 assert(id->variant >= 0);
254 if (0 < id->variant)
255 strbuf_addf(&buf, "%s.%d\t%s%c",
256 rerere_id_hex(id), id->variant,
257 rr->items[i].string, 0);
258 else
259 strbuf_addf(&buf, "%s\t%s%c",
260 rerere_id_hex(id),
261 rr->items[i].string, 0);
262
e2cb6a95 263 if (write_in_full(out_fd, buf.buf, buf.len) != buf.len)
5b2fd956 264 die("unable to write rerere record");
e2cb6a95
JH
265
266 strbuf_release(&buf);
5b2fd956
SB
267 }
268 if (commit_lock_file(&write_lock) != 0)
269 die("unable to write rerere record");
270 return 0;
271}
272
a96847cc
JH
273/*
274 * "rerere" interacts with conflicted file contents using this I/O
275 * abstraction. It reads a conflicted contents from one place via
276 * "getline()" method, and optionally can write it out after
277 * normalizing the conflicted hunks to the "output". Subclasses of
278 * rerere_io embed this structure at the beginning of their own
279 * rerere_io object.
280 */
281struct rerere_io {
282 int (*getline)(struct strbuf *, struct rerere_io *);
283 FILE *output;
284 int wrerror;
285 /* some more stuff */
286};
287
47d32af2
AR
288static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
289{
290 if (!count || *err)
291 return;
292 if (fwrite(p, count, 1, fp) != 1)
293 *err = errno;
294}
295
296static inline void ferr_puts(const char *s, FILE *fp, int *err)
297{
298 ferr_write(s, strlen(s), fp, err);
299}
300
27d6b085
JH
301static void rerere_io_putstr(const char *str, struct rerere_io *io)
302{
303 if (io->output)
304 ferr_puts(str, io->output, &io->wrerror);
305}
306
a96847cc
JH
307/*
308 * Write a conflict marker to io->output (if defined).
309 */
191f2417
JH
310static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
311{
312 char buf[64];
313
314 while (size) {
d3c2749d 315 if (size <= sizeof(buf) - 2) {
191f2417
JH
316 memset(buf, ch, size);
317 buf[size] = '\n';
318 buf[size + 1] = '\0';
319 size = 0;
320 } else {
321 int sz = sizeof(buf) - 1;
d3c2749d
JH
322
323 /*
324 * Make sure we will not write everything out
325 * in this round by leaving at least 1 byte
326 * for the next round, giving the next round
327 * a chance to add the terminating LF. Yuck.
328 */
191f2417
JH
329 if (size <= sz)
330 sz -= (sz - size) + 1;
331 memset(buf, ch, sz);
332 buf[sz] = '\0';
333 size -= sz;
334 }
335 rerere_io_putstr(buf, io);
336 }
337}
338
27d6b085
JH
339static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
340{
341 if (io->output)
342 ferr_write(mem, sz, io->output, &io->wrerror);
343}
344
a96847cc
JH
345/*
346 * Subclass of rerere_io that reads from an on-disk file
347 */
27d6b085
JH
348struct rerere_io_file {
349 struct rerere_io io;
350 FILE *input;
351};
352
a96847cc
JH
353/*
354 * ... and its getline() method implementation
355 */
27d6b085
JH
356static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
357{
358 struct rerere_io_file *io = (struct rerere_io_file *)io_;
359 return strbuf_getwholeline(sb, io->input, '\n');
360}
361
67711cdc
JH
362/*
363 * Require the exact number of conflict marker letters, no more, no
364 * less, followed by SP or any whitespace
365 * (including LF).
366 */
367static int is_cmarker(char *buf, int marker_char, int marker_size)
191f2417 368{
67711cdc
JH
369 int want_sp;
370
371 /*
372 * The beginning of our version and the end of their version
373 * always are labeled like "<<<<< ours" or ">>>>> theirs",
374 * hence we set want_sp for them. Note that the version from
375 * the common ancestor in diff3-style output is not always
376 * labelled (e.g. "||||| common" is often seen but "|||||"
377 * alone is also valid), so we do not set want_sp.
378 */
379 want_sp = (marker_char == '<') || (marker_char == '>');
380
191f2417
JH
381 while (marker_size--)
382 if (*buf++ != marker_char)
383 return 0;
384 if (want_sp && *buf != ' ')
385 return 0;
386 return isspace(*buf);
387}
388
cc899eca
JH
389/*
390 * Read contents a file with conflicts, normalize the conflicts
391 * by (1) discarding the common ancestor version in diff3-style,
392 * (2) reordering our side and their side so that whichever sorts
393 * alphabetically earlier comes before the other one, while
394 * computing the "conflict ID", which is just an SHA-1 hash of
395 * one side of the conflict, NUL, the other side of the conflict,
396 * and NUL concatenated together.
397 *
398 * Return the number of conflict hunks found.
399 *
400 * NEEDSWORK: the logic and theory of operation behind this conflict
401 * normalization may deserve to be documented somewhere, perhaps in
402 * Documentation/technical/rerere.txt.
403 */
191f2417 404static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
5b2fd956 405{
9126f009 406 git_SHA_CTX ctx;
cc58d7df
JH
407 int hunk_no = 0;
408 enum {
4b05548f 409 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
cc58d7df 410 } hunk = RR_CONTEXT;
f285a2d7 411 struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
d58ee6db 412 struct strbuf buf = STRBUF_INIT;
5b2fd956
SB
413
414 if (sha1)
9126f009 415 git_SHA1_Init(&ctx);
5b2fd956 416
27d6b085 417 while (!io->getline(&buf, io)) {
67711cdc 418 if (is_cmarker(buf.buf, '<', marker_size)) {
cc58d7df 419 if (hunk != RR_CONTEXT)
5b2fd956 420 goto bad;
cc58d7df 421 hunk = RR_SIDE_1;
67711cdc 422 } else if (is_cmarker(buf.buf, '|', marker_size)) {
cc58d7df 423 if (hunk != RR_SIDE_1)
5b2fd956 424 goto bad;
387c9d49 425 hunk = RR_ORIGINAL;
67711cdc 426 } else if (is_cmarker(buf.buf, '=', marker_size)) {
387c9d49 427 if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
5b2fd956 428 goto bad;
cc58d7df 429 hunk = RR_SIDE_2;
67711cdc 430 } else if (is_cmarker(buf.buf, '>', marker_size)) {
cc58d7df 431 if (hunk != RR_SIDE_2)
5b2fd956
SB
432 goto bad;
433 if (strbuf_cmp(&one, &two) > 0)
434 strbuf_swap(&one, &two);
435 hunk_no++;
cc58d7df 436 hunk = RR_CONTEXT;
191f2417 437 rerere_io_putconflict('<', marker_size, io);
27d6b085 438 rerere_io_putmem(one.buf, one.len, io);
191f2417 439 rerere_io_putconflict('=', marker_size, io);
27d6b085 440 rerere_io_putmem(two.buf, two.len, io);
191f2417 441 rerere_io_putconflict('>', marker_size, io);
5b2fd956 442 if (sha1) {
9126f009 443 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
5b2fd956 444 one.len + 1);
9126f009 445 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
5b2fd956
SB
446 two.len + 1);
447 }
448 strbuf_reset(&one);
449 strbuf_reset(&two);
cc58d7df 450 } else if (hunk == RR_SIDE_1)
e992d1eb 451 strbuf_addbuf(&one, &buf);
387c9d49
JH
452 else if (hunk == RR_ORIGINAL)
453 ; /* discard */
cc58d7df 454 else if (hunk == RR_SIDE_2)
e992d1eb 455 strbuf_addbuf(&two, &buf);
27d6b085
JH
456 else
457 rerere_io_putstr(buf.buf, io);
5b2fd956
SB
458 continue;
459 bad:
460 hunk = 99; /* force error exit */
461 break;
462 }
463 strbuf_release(&one);
464 strbuf_release(&two);
d58ee6db 465 strbuf_release(&buf);
5b2fd956 466
5b2fd956 467 if (sha1)
9126f009 468 git_SHA1_Final(sha1, &ctx);
27d6b085
JH
469 if (hunk != RR_CONTEXT)
470 return -1;
471 return hunk_no;
472}
473
cc899eca
JH
474/*
475 * Scan the path for conflicts, do the "handle_path()" thing above, and
476 * return the number of conflict hunks found.
477 */
27d6b085
JH
478static int handle_file(const char *path, unsigned char *sha1, const char *output)
479{
480 int hunk_no = 0;
481 struct rerere_io_file io;
8588567c 482 int marker_size = ll_merge_marker_size(path);
27d6b085
JH
483
484 memset(&io, 0, sizeof(io));
485 io.io.getline = rerere_file_getline;
486 io.input = fopen(path, "r");
487 io.io.wrerror = 0;
488 if (!io.input)
489 return error("Could not open %s", path);
490
491 if (output) {
492 io.io.output = fopen(output, "w");
493 if (!io.io.output) {
494 fclose(io.input);
495 return error("Could not write %s", output);
496 }
497 }
498
191f2417 499 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
27d6b085
JH
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("Failed to flush %s: %s",
507 path, strerror(errno));
508
509 if (hunk_no < 0) {
5b2fd956 510 if (output)
691f1a28 511 unlink_or_warn(output);
5b2fd956
SB
512 return error("Could not parse conflict hunks in %s", path);
513 }
27d6b085 514 if (io.io.wrerror)
47d32af2 515 return -1;
5b2fd956
SB
516 return hunk_no;
517}
518
4b68c2a0
JH
519/*
520 * Look at a cache entry at "i" and see if it is not conflicting,
521 * conflicting and we are willing to handle, or conflicting and
522 * we are unable to handle, and return the determination in *type.
523 * Return the cache index to be looked at next, by skipping the
524 * stages we have already looked at in this invocation of this
525 * function.
526 */
ac49f5ca 527static int check_one_conflict(int i, int *type)
5b2fd956 528{
9c5e6c80 529 const struct cache_entry *e = active_cache[i];
ac49f5ca
MZ
530
531 if (!ce_stage(e)) {
532 *type = RESOLVED;
533 return i + 1;
534 }
535
536 *type = PUNTED;
5eda906b 537 while (ce_stage(active_cache[i]) == 1)
fb70a06d 538 i++;
ac49f5ca
MZ
539
540 /* Only handle regular files with both stages #2 and #3 */
541 if (i + 1 < active_nr) {
9c5e6c80
NTND
542 const struct cache_entry *e2 = active_cache[i];
543 const struct cache_entry *e3 = active_cache[i + 1];
5b2fd956
SB
544 if (ce_stage(e2) == 2 &&
545 ce_stage(e3) == 3 &&
ac49f5ca 546 ce_same_name(e, e3) &&
5b2fd956 547 S_ISREG(e2->ce_mode) &&
ac49f5ca
MZ
548 S_ISREG(e3->ce_mode))
549 *type = THREE_STAGED;
550 }
551
552 /* Skip the entries with the same name */
553 while (i < active_nr && ce_same_name(e, active_cache[i]))
554 i++;
555 return i;
556}
557
4b68c2a0
JH
558/*
559 * Scan the index and find paths that have conflicts that rerere can
560 * handle, i.e. the ones that has both stages #2 and #3.
561 *
562 * NEEDSWORK: we do not record or replay a previous "resolve by
563 * deletion" for a delete-modify conflict, as that is inherently risky
564 * without knowing what modification is being discarded. The only
565 * safe case, i.e. both side doing the deletion and modification that
566 * are identical to the previous round, might want to be handled,
567 * though.
568 */
ac49f5ca
MZ
569static int find_conflict(struct string_list *conflict)
570{
571 int i;
572 if (read_cache() < 0)
573 return error("Could not read index");
574
575 for (i = 0; i < active_nr;) {
576 int conflict_type;
9c5e6c80 577 const struct cache_entry *e = active_cache[i];
ac49f5ca
MZ
578 i = check_one_conflict(i, &conflict_type);
579 if (conflict_type == THREE_STAGED)
580 string_list_insert(conflict, (const char *)e->name);
581 }
582 return 0;
583}
584
4b68c2a0
JH
585/*
586 * The merge_rr list is meant to hold outstanding conflicted paths
587 * that rerere could handle. Abuse the list by adding other types of
588 * entries to allow the caller to show "rerere remaining".
589 *
590 * - Conflicted paths that rerere does not handle are added
591 * - Conflicted paths that have been resolved are marked as such
592 * by storing RERERE_RESOLVED to .util field (where conflict ID
593 * is expected to be stored).
594 *
595 * Do *not* write MERGE_RR file out after calling this function.
596 *
597 * NEEDSWORK: we may want to fix the caller that implements "rerere
598 * remaining" to do this without abusing merge_rr.
599 */
ac49f5ca
MZ
600int rerere_remaining(struct string_list *merge_rr)
601{
602 int i;
603 if (read_cache() < 0)
604 return error("Could not read index");
605
606 for (i = 0; i < active_nr;) {
607 int conflict_type;
9c5e6c80 608 const struct cache_entry *e = active_cache[i];
ac49f5ca
MZ
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) {
1d51eced 616 free_rerere_id(it);
ac49f5ca
MZ
617 it->util = RERERE_RESOLVED;
618 }
5b2fd956
SB
619 }
620 }
621 return 0;
622}
623
0ce02b36
JH
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 */
629static 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
cc899eca 651/*
18bb9934 652 * Find the conflict identified by "id"; the change between its
cc899eca
JH
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 */
1d51eced 661static int merge(const struct rerere_id *id, const char *path)
5b2fd956 662{
15ed07d5 663 FILE *f;
5b2fd956 664 int ret;
0ce02b36 665 mmfile_t cur = {NULL, 0};
5b2fd956 666 mmbuffer_t result = {NULL, 0};
5b2fd956 667
cc899eca
JH
668 /*
669 * Normalize the conflicts in path and write it out to
670 * "thisimage" temporary file.
671 */
0ce02b36
JH
672 if ((handle_file(path, NULL, rerere_path(id, "thisimage")) < 0) ||
673 read_mmfile(&cur, rerere_path(id, "thisimage"))) {
689b8c29
BW
674 ret = 1;
675 goto out;
676 }
cc899eca 677
0ce02b36 678 ret = try_merge(id, path, &cur, &result);
15ed07d5
JH
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("failed utime() on %s: %s",
688 rerere_path(id, "postimage"),
689 strerror(errno));
690
691 /* Update "path" with the resolution */
692 f = fopen(path, "w");
693 if (!f)
694 return error("Could not open %s: %s", path,
695 strerror(errno));
696 if (fwrite(result.ptr, result.size, 1, f) != 1)
697 error("Could not write %s: %s", path, strerror(errno));
698 if (fclose(f))
699 return error("Writing %s failed: %s", path,
700 strerror(errno));
5b2fd956 701
689b8c29 702out:
5b2fd956 703 free(cur.ptr);
5b2fd956
SB
704 free(result.ptr);
705
706 return ret;
707}
708
709static struct lock_file index_lock;
710
89ea9035 711static void update_paths(struct string_list *update)
5b2fd956
SB
712{
713 int i;
5b2fd956 714
89ea9035 715 hold_locked_index(&index_lock, 1);
5b2fd956
SB
716
717 for (i = 0; i < update->nr; i++) {
c455c87c 718 struct string_list_item *item = &update->items[i];
89ea9035
JN
719 if (add_file_to_cache(item->string, 0))
720 exit(128);
a14c7ab8
JH
721 fprintf(stderr, "Staged '%s' using previous resolution.\n",
722 item->string);
5b2fd956
SB
723 }
724
89ea9035 725 if (active_cache_changed) {
03b86647 726 if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
5b2fd956 727 die("Unable to write new index file");
89ea9035 728 } else
5b2fd956 729 rollback_lock_file(&index_lock);
5b2fd956
SB
730}
731
629716d2
JH
732static void remove_variant(struct rerere_id *id)
733{
734 unlink_or_warn(rerere_path(id, "postimage"));
735 unlink_or_warn(rerere_path(id, "preimage"));
736 id->collection->status[id->variant] = 0;
737}
738
8e7768b2
JH
739/*
740 * The path indicated by rr_item may still have conflict for which we
741 * have a recorded resolution, in which case replay it and optionally
742 * update it. Or it may have been resolved by the user and we may
743 * only have the preimage for that conflict, in which case the result
744 * needs to be recorded as a resolution in a postimage file.
745 */
746static void do_rerere_one_path(struct string_list_item *rr_item,
747 struct string_list *update)
748{
749 const char *path = rr_item->string;
a13d1370 750 struct rerere_id *id = rr_item->util;
629716d2 751 struct rerere_dir *rr_dir = id->collection;
a13d1370
JH
752 int variant;
753
a13d1370 754 variant = id->variant;
8e7768b2 755
629716d2
JH
756 /* Has the user resolved it already? */
757 if (variant >= 0) {
758 if (!handle_file(path, NULL, NULL)) {
759 copy_file(rerere_path(id, "postimage"), path, 0666);
760 id->collection->status[variant] |= RR_HAS_POSTIMAGE;
761 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
762 free_rerere_id(rr_item);
763 rr_item->util = NULL;
764 return;
765 }
c0a5423b 766 /*
629716d2
JH
767 * There may be other variants that can cleanly
768 * replay. Try them and update the variant number for
769 * this one.
c0a5423b 770 */
629716d2
JH
771 }
772
773 /* Does any existing resolution apply cleanly? */
774 for (variant = 0; variant < rr_dir->status_nr; variant++) {
775 const int both = RR_HAS_PREIMAGE | RR_HAS_POSTIMAGE;
776 struct rerere_id vid = *id;
777
778 if ((rr_dir->status[variant] & both) != both)
779 continue;
780
781 vid.variant = variant;
782 if (merge(&vid, path))
783 continue; /* failed to replay */
784
785 /*
786 * If there already is a different variant that applies
787 * cleanly, there is no point maintaining our own variant.
788 */
789 if (0 <= id->variant && id->variant != variant)
790 remove_variant(id);
8e7768b2
JH
791
792 if (rerere_autoupdate)
793 string_list_insert(update, path);
794 else
795 fprintf(stderr,
796 "Resolved '%s' using previous resolution.\n",
797 path);
629716d2
JH
798 free_rerere_id(rr_item);
799 rr_item->util = NULL;
925d73c4 800 return;
8e7768b2 801 }
629716d2
JH
802
803 /* None of the existing one applies; we need a new variant */
804 assign_variant(id);
805
806 variant = id->variant;
807 handle_file(path, NULL, rerere_path(id, "preimage"));
808 if (id->collection->status[variant] & RR_HAS_POSTIMAGE) {
809 const char *path = rerere_path(id, "postimage");
810 if (unlink(path))
811 die_errno("cannot unlink stray '%s'", path);
812 id->collection->status[variant] &= ~RR_HAS_POSTIMAGE;
813 }
814 id->collection->status[variant] |= RR_HAS_PREIMAGE;
815 fprintf(stderr, "Recorded preimage for '%s'\n", path);
8e7768b2
JH
816}
817
c455c87c 818static int do_plain_rerere(struct string_list *rr, int fd)
5b2fd956 819{
183113a5
TF
820 struct string_list conflict = STRING_LIST_INIT_DUP;
821 struct string_list update = STRING_LIST_INIT_DUP;
5b2fd956
SB
822 int i;
823
824 find_conflict(&conflict);
825
826 /*
cc899eca
JH
827 * MERGE_RR records paths with conflicts immediately after
828 * merge failed. Some of the conflicted paths might have been
829 * hand resolved in the working tree since then, but the
830 * initial run would catch all and register their preimages.
5b2fd956 831 */
5b2fd956 832 for (i = 0; i < conflict.nr; i++) {
1d51eced 833 struct rerere_id *id;
c7a25d37 834 unsigned char sha1[20];
c455c87c 835 const char *path = conflict.items[i].string;
1d51eced 836 int ret;
cc899eca 837
c7a25d37
JH
838 if (string_list_has_string(rr, path))
839 continue;
cc899eca 840
c7a25d37
JH
841 /*
842 * Ask handle_file() to scan and assign a
843 * conflict ID. No need to write anything out
844 * yet.
845 */
846 ret = handle_file(path, sha1, NULL);
847 if (ret < 1)
848 continue;
1d51eced
JH
849
850 id = new_rerere_id(sha1);
18bb9934 851 string_list_insert(rr, path)->util = id;
cc899eca 852
c0a5423b
JH
853 /* Ensure that the directory exists. */
854 mkdir_in_gitdir(rerere_path(id, NULL));
5b2fd956
SB
855 }
856
8e7768b2
JH
857 for (i = 0; i < rr->nr; i++)
858 do_rerere_one_path(&rr->items[i], &update);
5b2fd956
SB
859
860 if (update.nr)
861 update_paths(&update);
862
863 return write_rr(rr, fd);
864}
865
633e5ad3 866static void git_rerere_config(void)
5b2fd956 867{
633e5ad3
TA
868 git_config_get_bool("rerere.enabled", &rerere_enabled);
869 git_config_get_bool("rerere.autoupdate", &rerere_autoupdate);
870 git_config(git_default_config, NULL);
5b2fd956
SB
871}
872
873static int is_rerere_enabled(void)
874{
5b2fd956
SB
875 const char *rr_cache;
876 int rr_cache_exists;
877
878 if (!rerere_enabled)
879 return 0;
880
881 rr_cache = git_path("rr-cache");
90b4a71c 882 rr_cache_exists = is_directory(rr_cache);
5b2fd956
SB
883 if (rerere_enabled < 0)
884 return rr_cache_exists;
885
90a6464b 886 if (!rr_cache_exists && mkdir_in_gitdir(rr_cache))
5b2fd956
SB
887 die("Could not create directory %s", rr_cache);
888 return 1;
889}
890
cb6020bb 891int setup_rerere(struct string_list *merge_rr, int flags)
5b2fd956
SB
892{
893 int fd;
894
633e5ad3 895 git_rerere_config();
5b2fd956
SB
896 if (!is_rerere_enabled())
897 return -1;
898
cb6020bb
JH
899 if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
900 rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
a4f34cbb 901 merge_rr_path = git_pathdup("MERGE_RR");
acd3b9ec
JH
902 fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
903 LOCK_DIE_ON_ERROR);
5b2fd956
SB
904 read_rr(merge_rr);
905 return fd;
906}
907
cc899eca
JH
908/*
909 * The main entry point that is called internally from codepaths that
910 * perform mergy operations, possibly leaving conflicted index entries
911 * and working tree files.
912 */
cb6020bb 913int rerere(int flags)
5b2fd956 914{
183113a5 915 struct string_list merge_rr = STRING_LIST_INIT_DUP;
1869bbe1 916 int fd, status;
5b2fd956 917
cb6020bb 918 fd = setup_rerere(&merge_rr, flags);
5b2fd956
SB
919 if (fd < 0)
920 return 0;
1869bbe1
JH
921 status = do_plain_rerere(&merge_rr, fd);
922 free_rerere_dirs();
923 return status;
5b2fd956 924}
dea4562b 925
3d730ed9
JH
926/*
927 * Subclass of rerere_io that reads from an in-core buffer that is a
928 * strbuf
929 */
930struct rerere_io_mem {
931 struct rerere_io io;
932 struct strbuf input;
933};
934
935/*
936 * ... and its getline() method implementation
937 */
938static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
939{
940 struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
941 char *ep;
942 size_t len;
943
944 strbuf_release(sb);
945 if (!io->input.len)
946 return -1;
947 ep = memchr(io->input.buf, '\n', io->input.len);
948 if (!ep)
949 ep = io->input.buf + io->input.len;
950 else if (*ep == '\n')
951 ep++;
952 len = ep - io->input.buf;
953 strbuf_add(sb, io->input.buf, len);
954 strbuf_remove(&io->input, 0, len);
955 return 0;
956}
957
958static int handle_cache(const char *path, unsigned char *sha1, const char *output)
959{
960 mmfile_t mmfile[3] = {{NULL}};
961 mmbuffer_t result = {NULL, 0};
962 const struct cache_entry *ce;
963 int pos, len, i, hunk_no;
964 struct rerere_io_mem io;
965 int marker_size = ll_merge_marker_size(path);
966
967 /*
968 * Reproduce the conflicted merge in-core
969 */
970 len = strlen(path);
971 pos = cache_name_pos(path, len);
972 if (0 <= pos)
973 return -1;
974 pos = -pos - 1;
975
976 while (pos < active_nr) {
977 enum object_type type;
978 unsigned long size;
979
980 ce = active_cache[pos++];
981 if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
982 break;
983 i = ce_stage(ce) - 1;
984 if (!mmfile[i].ptr) {
985 mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
986 mmfile[i].size = size;
987 }
988 }
989 for (i = 0; i < 3; i++)
990 if (!mmfile[i].ptr && !mmfile[i].size)
991 mmfile[i].ptr = xstrdup("");
992
993 /*
994 * NEEDSWORK: handle conflicts from merges with
995 * merge.renormalize set, too?
996 */
997 ll_merge(&result, path, &mmfile[0], NULL,
998 &mmfile[1], "ours",
999 &mmfile[2], "theirs", NULL);
1000 for (i = 0; i < 3; i++)
1001 free(mmfile[i].ptr);
1002
1003 memset(&io, 0, sizeof(io));
1004 io.io.getline = rerere_mem_getline;
1005 if (output)
1006 io.io.output = fopen(output, "w");
1007 else
1008 io.io.output = NULL;
1009 strbuf_init(&io.input, 0);
1010 strbuf_attach(&io.input, result.ptr, result.size, result.size);
1011
1012 /*
1013 * Grab the conflict ID and optionally write the original
1014 * contents with conflict markers out.
1015 */
1016 hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
1017 strbuf_release(&io.input);
1018 if (io.io.output)
1019 fclose(io.io.output);
1020 return hunk_no;
1021}
1022
dea4562b
JH
1023static int rerere_forget_one_path(const char *path, struct string_list *rr)
1024{
1025 const char *filename;
1d51eced 1026 struct rerere_id *id;
dea4562b
JH
1027 unsigned char sha1[20];
1028 int ret;
8d9b5a4a 1029 struct string_list_item *item;
dea4562b 1030
963ec003
JH
1031 /*
1032 * Recreate the original conflict from the stages in the
1033 * index and compute the conflict ID
1034 */
dea4562b
JH
1035 ret = handle_cache(path, sha1, NULL);
1036 if (ret < 1)
1037 return error("Could not parse conflict hunks in '%s'", path);
963ec003
JH
1038
1039 /* Nuke the recorded resolution for the conflict */
1d51eced 1040 id = new_rerere_id(sha1);
a13d1370 1041 id->variant = 0; /* for now */
18bb9934 1042 filename = rerere_path(id, "postimage");
dea4562b
JH
1043 if (unlink(filename))
1044 return (errno == ENOENT
1045 ? error("no remembered resolution for %s", path)
1046 : error("cannot unlink %s: %s", filename, strerror(errno)));
1047
963ec003
JH
1048 /*
1049 * Update the preimage so that the user can resolve the
1050 * conflict in the working tree, run us again to record
1051 * the postimage.
1052 */
18bb9934 1053 handle_cache(path, sha1, rerere_path(id, "preimage"));
dea4562b
JH
1054 fprintf(stderr, "Updated preimage for '%s'\n", path);
1055
963ec003
JH
1056 /*
1057 * And remember that we can record resolution for this
1058 * conflict when the user is done.
1059 */
8d9b5a4a 1060 item = string_list_insert(rr, path);
1d51eced 1061 free_rerere_id(item);
18bb9934 1062 item->util = id;
dea4562b
JH
1063 fprintf(stderr, "Forgot resolution for %s\n", path);
1064 return 0;
1065}
1066
01a10b0a 1067int rerere_forget(struct pathspec *pathspec)
dea4562b
JH
1068{
1069 int i, fd;
183113a5
TF
1070 struct string_list conflict = STRING_LIST_INIT_DUP;
1071 struct string_list merge_rr = STRING_LIST_INIT_DUP;
dea4562b
JH
1072
1073 if (read_cache() < 0)
1074 return error("Could not read index");
1075
6751e047 1076 fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
dea4562b 1077
963ec003
JH
1078 /*
1079 * The paths may have been resolved (incorrectly);
1080 * recover the original conflicted state and then
1081 * find the conflicted paths.
1082 */
dea4562b
JH
1083 unmerge_cache(pathspec);
1084 find_conflict(&conflict);
1085 for (i = 0; i < conflict.nr; i++) {
1086 struct string_list_item *it = &conflict.items[i];
854b0959 1087 if (!match_pathspec(pathspec, it->string,
ae8d0824 1088 strlen(it->string), 0, NULL, 0))
dea4562b
JH
1089 continue;
1090 rerere_forget_one_path(it->string, &merge_rr);
1091 }
1092 return write_rr(&merge_rr, fd);
1093}
0f891e7d 1094
e828de82
JH
1095/*
1096 * Garbage collection support
1097 */
1d51eced 1098
1be1e851 1099static time_t rerere_created_at(struct rerere_id *id)
0f891e7d
JH
1100{
1101 struct stat st;
1d51eced 1102
18bb9934 1103 return stat(rerere_path(id, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
0f891e7d
JH
1104}
1105
1be1e851 1106static time_t rerere_last_used_at(struct rerere_id *id)
0f891e7d
JH
1107{
1108 struct stat st;
1d51eced 1109
18bb9934 1110 return stat(rerere_path(id, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
0f891e7d
JH
1111}
1112
e828de82
JH
1113/*
1114 * Remove the recorded resolution for a given conflict ID
1115 */
1d51eced 1116static void unlink_rr_item(struct rerere_id *id)
0f891e7d 1117{
1be1e851
JH
1118 unlink_or_warn(rerere_path(id, "thisimage"));
1119 remove_variant(id);
1120 id->collection->status[id->variant] = 0;
1121}
1122
1123static void prune_one(struct rerere_id *id, time_t now,
1124 int cutoff_resolve, int cutoff_noresolve)
1125{
1126 time_t then;
1127 int cutoff;
1128
1129 then = rerere_last_used_at(id);
1130 if (then)
1131 cutoff = cutoff_resolve;
1132 else {
1133 then = rerere_created_at(id);
1134 if (!then)
1135 return;
1136 cutoff = cutoff_noresolve;
1137 }
1138 if (then < now - cutoff * 86400)
1139 unlink_rr_item(id);
0f891e7d
JH
1140}
1141
0f891e7d
JH
1142void rerere_gc(struct string_list *rr)
1143{
1144 struct string_list to_remove = STRING_LIST_INIT_DUP;
1145 DIR *dir;
1146 struct dirent *e;
1be1e851
JH
1147 int i;
1148 time_t now = time(NULL);
633e5ad3
TA
1149 int cutoff_noresolve = 15;
1150 int cutoff_resolve = 60;
0f891e7d 1151
633e5ad3
TA
1152 git_config_get_int("gc.rerereresolved", &cutoff_resolve);
1153 git_config_get_int("gc.rerereunresolved", &cutoff_noresolve);
1154 git_config(git_default_config, NULL);
0f891e7d
JH
1155 dir = opendir(git_path("rr-cache"));
1156 if (!dir)
1157 die_errno("unable to open rr-cache directory");
e828de82 1158 /* Collect stale conflict IDs ... */
0f891e7d 1159 while ((e = readdir(dir))) {
1be1e851
JH
1160 struct rerere_dir *rr_dir;
1161 struct rerere_id id;
1162 int now_empty;
1163
0f891e7d
JH
1164 if (is_dot_or_dotdot(e->d_name))
1165 continue;
1be1e851
JH
1166 rr_dir = find_rerere_dir(e->d_name);
1167 if (!rr_dir)
1168 continue; /* or should we remove e->d_name? */
1169
1170 now_empty = 1;
1171 for (id.variant = 0, id.collection = rr_dir;
1172 id.variant < id.collection->status_nr;
1173 id.variant++) {
1174 prune_one(&id, now, cutoff_resolve, cutoff_noresolve);
1175 if (id.collection->status[id.variant])
1176 now_empty = 0;
0f891e7d 1177 }
1be1e851 1178 if (now_empty)
0f891e7d
JH
1179 string_list_append(&to_remove, e->d_name);
1180 }
a9930e35 1181 closedir(dir);
1be1e851
JH
1182
1183 /* ... and then remove the empty directories */
0f891e7d 1184 for (i = 0; i < to_remove.nr; i++)
1be1e851 1185 rmdir(git_path("rr-cache/%s", to_remove.items[i].string));
0f891e7d
JH
1186 string_list_clear(&to_remove, 0);
1187}
1188
e828de82
JH
1189/*
1190 * During a conflict resolution, after "rerere" recorded the
1191 * preimages, abandon them if the user did not resolve them or
1192 * record their resolutions. And drop $GIT_DIR/MERGE_RR.
1193 *
1194 * NEEDSWORK: shouldn't we be calling this from "reset --hard"?
1195 */
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1196void rerere_clear(struct string_list *merge_rr)
1197{
1198 int i;
1199
1200 for (i = 0; i < merge_rr->nr; i++) {
1d51eced 1201 struct rerere_id *id = merge_rr->items[i].util;
1be1e851 1202 if (!has_rerere_resolution(id)) {
18bb9934 1203 unlink_rr_item(id);
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1204 rmdir(rerere_path(id, NULL));
1205 }
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1206 }
1207 unlink_or_warn(git_path("MERGE_RR"));
1208}