doc: add doc for git-push --recurse-submodules=only
[git] / notes-merge.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "refs.h"
4 #include "diff.h"
5 #include "diffcore.h"
6 #include "xdiff-interface.h"
7 #include "ll-merge.h"
8 #include "dir.h"
9 #include "notes.h"
10 #include "notes-merge.h"
11 #include "strbuf.h"
12 #include "notes-utils.h"
13
14 struct notes_merge_pair {
15         struct object_id obj, base, local, remote;
16 };
17
18 void init_notes_merge_options(struct notes_merge_options *o)
19 {
20         memset(o, 0, sizeof(struct notes_merge_options));
21         strbuf_init(&(o->commit_msg), 0);
22         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
23 }
24
25 static int path_to_sha1(const char *path, unsigned char *sha1)
26 {
27         char hex_sha1[40];
28         int i = 0;
29         while (*path && i < 40) {
30                 if (*path != '/')
31                         hex_sha1[i++] = *path;
32                 path++;
33         }
34         if (*path || i != 40)
35                 return -1;
36         return get_sha1_hex(hex_sha1, sha1);
37 }
38
39 static int verify_notes_filepair(struct diff_filepair *p, unsigned char *sha1)
40 {
41         switch (p->status) {
42         case DIFF_STATUS_MODIFIED:
43                 assert(p->one->mode == p->two->mode);
44                 assert(!is_null_oid(&p->one->oid));
45                 assert(!is_null_oid(&p->two->oid));
46                 break;
47         case DIFF_STATUS_ADDED:
48                 assert(is_null_oid(&p->one->oid));
49                 break;
50         case DIFF_STATUS_DELETED:
51                 assert(is_null_oid(&p->two->oid));
52                 break;
53         default:
54                 return -1;
55         }
56         assert(!strcmp(p->one->path, p->two->path));
57         return path_to_sha1(p->one->path, sha1);
58 }
59
60 static struct notes_merge_pair *find_notes_merge_pair_pos(
61                 struct notes_merge_pair *list, int len, unsigned char *obj,
62                 int insert_new, int *occupied)
63 {
64         /*
65          * Both diff_tree_remote() and diff_tree_local() tend to process
66          * merge_pairs in ascending order. Therefore, cache last returned
67          * index, and search sequentially from there until the appropriate
68          * position is found.
69          *
70          * Since inserts only happen from diff_tree_remote() (which mainly
71          * _appends_), we don't care that inserting into the middle of the
72          * list is expensive (using memmove()).
73          */
74         static int last_index;
75         int i = last_index < len ? last_index : len - 1;
76         int prev_cmp = 0, cmp = -1;
77         while (i >= 0 && i < len) {
78                 cmp = hashcmp(obj, list[i].obj.hash);
79                 if (!cmp) /* obj belongs @ i */
80                         break;
81                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
82                         i--;
83                 else if (cmp < 0) /* obj belongs between i-1 and i */
84                         break;
85                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
86                         i++;
87                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
88                         i++;
89                         break;
90                 }
91                 prev_cmp = cmp;
92         }
93         if (i < 0)
94                 i = 0;
95         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
96
97         if (!cmp)
98                 *occupied = 1;
99         else {
100                 *occupied = 0;
101                 if (insert_new && i < len) {
102                         memmove(list + i + 1, list + i,
103                                 (len - i) * sizeof(struct notes_merge_pair));
104                         memset(list + i, 0, sizeof(struct notes_merge_pair));
105                 }
106         }
107         last_index = i;
108         return list + i;
109 }
110
111 static struct object_id uninitialized = {
112         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
113         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
114 };
115
116 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
117                                                  const unsigned char *base,
118                                                  const unsigned char *remote,
119                                                  int *num_changes)
120 {
121         struct diff_options opt;
122         struct notes_merge_pair *changes;
123         int i, len = 0;
124
125         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
126                sha1_to_hex(base), sha1_to_hex(remote));
127
128         diff_setup(&opt);
129         DIFF_OPT_SET(&opt, RECURSIVE);
130         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
131         diff_setup_done(&opt);
132         diff_tree_sha1(base, remote, "", &opt);
133         diffcore_std(&opt);
134
135         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
136
137         for (i = 0; i < diff_queued_diff.nr; i++) {
138                 struct diff_filepair *p = diff_queued_diff.queue[i];
139                 struct notes_merge_pair *mp;
140                 int occupied;
141                 unsigned char obj[20];
142
143                 if (verify_notes_filepair(p, obj)) {
144                         trace_printf("\t\tCannot merge entry '%s' (%c): "
145                                "%.7s -> %.7s. Skipping!\n", p->one->path,
146                                p->status, oid_to_hex(&p->one->oid),
147                                oid_to_hex(&p->two->oid));
148                         continue;
149                 }
150                 mp = find_notes_merge_pair_pos(changes, len, obj, 1, &occupied);
151                 if (occupied) {
152                         /* We've found an addition/deletion pair */
153                         assert(!hashcmp(mp->obj.hash, obj));
154                         if (is_null_oid(&p->one->oid)) { /* addition */
155                                 assert(is_null_oid(&mp->remote));
156                                 oidcpy(&mp->remote, &p->two->oid);
157                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
158                                 assert(is_null_oid(&mp->base));
159                                 oidcpy(&mp->base, &p->one->oid);
160                         } else
161                                 assert(!"Invalid existing change recorded");
162                 } else {
163                         hashcpy(mp->obj.hash, obj);
164                         oidcpy(&mp->base, &p->one->oid);
165                         oidcpy(&mp->local, &uninitialized);
166                         oidcpy(&mp->remote, &p->two->oid);
167                         len++;
168                 }
169                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
170                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
171                        oid_to_hex(&mp->remote));
172         }
173         diff_flush(&opt);
174         clear_pathspec(&opt.pathspec);
175
176         *num_changes = len;
177         return changes;
178 }
179
180 static void diff_tree_local(struct notes_merge_options *o,
181                             struct notes_merge_pair *changes, int len,
182                             const unsigned char *base,
183                             const unsigned char *local)
184 {
185         struct diff_options opt;
186         int i;
187
188         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
189                len, sha1_to_hex(base), sha1_to_hex(local));
190
191         diff_setup(&opt);
192         DIFF_OPT_SET(&opt, RECURSIVE);
193         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
194         diff_setup_done(&opt);
195         diff_tree_sha1(base, local, "", &opt);
196         diffcore_std(&opt);
197
198         for (i = 0; i < diff_queued_diff.nr; i++) {
199                 struct diff_filepair *p = diff_queued_diff.queue[i];
200                 struct notes_merge_pair *mp;
201                 int match;
202                 unsigned char obj[20];
203
204                 if (verify_notes_filepair(p, obj)) {
205                         trace_printf("\t\tCannot merge entry '%s' (%c): "
206                                "%.7s -> %.7s. Skipping!\n", p->one->path,
207                                p->status, oid_to_hex(&p->one->oid),
208                                oid_to_hex(&p->two->oid));
209                         continue;
210                 }
211                 mp = find_notes_merge_pair_pos(changes, len, obj, 0, &match);
212                 if (!match) {
213                         trace_printf("\t\tIgnoring local-only change for %s: "
214                                "%.7s -> %.7s\n", sha1_to_hex(obj),
215                                oid_to_hex(&p->one->oid),
216                                oid_to_hex(&p->two->oid));
217                         continue;
218                 }
219
220                 assert(!hashcmp(mp->obj.hash, obj));
221                 if (is_null_oid(&p->two->oid)) { /* deletion */
222                         /*
223                          * Either this is a true deletion (1), or it is part
224                          * of an A/D pair (2), or D/A pair (3):
225                          *
226                          * (1) mp->local is uninitialized; set it to null_sha1
227                          * (2) mp->local is not uninitialized; don't touch it
228                          * (3) mp->local is uninitialized; set it to null_sha1
229                          *     (will be overwritten by following addition)
230                          */
231                         if (!oidcmp(&mp->local, &uninitialized))
232                                 oidclr(&mp->local);
233                 } else if (is_null_oid(&p->one->oid)) { /* addition */
234                         /*
235                          * Either this is a true addition (1), or it is part
236                          * of an A/D pair (2), or D/A pair (3):
237                          *
238                          * (1) mp->local is uninitialized; set to p->two->sha1
239                          * (2) mp->local is uninitialized; set to p->two->sha1
240                          * (3) mp->local is null_sha1;     set to p->two->sha1
241                          */
242                         assert(is_null_oid(&mp->local) ||
243                                !oidcmp(&mp->local, &uninitialized));
244                         oidcpy(&mp->local, &p->two->oid);
245                 } else { /* modification */
246                         /*
247                          * This is a true modification. p->one->sha1 shall
248                          * match mp->base, and mp->local shall be uninitialized.
249                          * Set mp->local to p->two->sha1.
250                          */
251                         assert(!oidcmp(&p->one->oid, &mp->base));
252                         assert(!oidcmp(&mp->local, &uninitialized));
253                         oidcpy(&mp->local, &p->two->oid);
254                 }
255                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
256                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
257                        oid_to_hex(&mp->local));
258         }
259         diff_flush(&opt);
260         clear_pathspec(&opt.pathspec);
261 }
262
263 static void check_notes_merge_worktree(struct notes_merge_options *o)
264 {
265         if (!o->has_worktree) {
266                 /*
267                  * Must establish NOTES_MERGE_WORKTREE.
268                  * Abort if NOTES_MERGE_WORKTREE already exists
269                  */
270                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
271                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
272                         if (advice_resolve_conflict)
273                                 die(_("You have not concluded your previous "
274                                     "notes merge (%s exists).\nPlease, use "
275                                     "'git notes merge --commit' or 'git notes "
276                                     "merge --abort' to commit/abort the "
277                                     "previous merge before you start a new "
278                                     "notes merge."), git_path("NOTES_MERGE_*"));
279                         else
280                                 die(_("You have not concluded your notes merge "
281                                     "(%s exists)."), git_path("NOTES_MERGE_*"));
282                 }
283
284                 if (safe_create_leading_directories_const(git_path(
285                                 NOTES_MERGE_WORKTREE "/.test")))
286                         die_errno("unable to create directory %s",
287                                   git_path(NOTES_MERGE_WORKTREE));
288                 o->has_worktree = 1;
289         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
290                 /* NOTES_MERGE_WORKTREE should already be established */
291                 die("missing '%s'. This should not happen",
292                     git_path(NOTES_MERGE_WORKTREE));
293 }
294
295 static void write_buf_to_worktree(const unsigned char *obj,
296                                   const char *buf, unsigned long size)
297 {
298         int fd;
299         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", sha1_to_hex(obj));
300         if (safe_create_leading_directories_const(path))
301                 die_errno("unable to create directory for '%s'", path);
302
303         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
304
305         while (size > 0) {
306                 long ret = write_in_full(fd, buf, size);
307                 if (ret < 0) {
308                         /* Ignore epipe */
309                         if (errno == EPIPE)
310                                 break;
311                         die_errno("notes-merge");
312                 } else if (!ret) {
313                         die("notes-merge: disk full?");
314                 }
315                 size -= ret;
316                 buf += ret;
317         }
318
319         close(fd);
320         free(path);
321 }
322
323 static void write_note_to_worktree(const unsigned char *obj,
324                                    const unsigned char *note)
325 {
326         enum object_type type;
327         unsigned long size;
328         void *buf = read_sha1_file(note, &type, &size);
329
330         if (!buf)
331                 die("cannot read note %s for object %s",
332                     sha1_to_hex(note), sha1_to_hex(obj));
333         if (type != OBJ_BLOB)
334                 die("blob expected in note %s for object %s",
335                     sha1_to_hex(note), sha1_to_hex(obj));
336         write_buf_to_worktree(obj, buf, size);
337         free(buf);
338 }
339
340 static int ll_merge_in_worktree(struct notes_merge_options *o,
341                                 struct notes_merge_pair *p)
342 {
343         mmbuffer_t result_buf;
344         mmfile_t base, local, remote;
345         int status;
346
347         read_mmblob(&base, &p->base);
348         read_mmblob(&local, &p->local);
349         read_mmblob(&remote, &p->remote);
350
351         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
352                           &local, o->local_ref, &remote, o->remote_ref, NULL);
353
354         free(base.ptr);
355         free(local.ptr);
356         free(remote.ptr);
357
358         if ((status < 0) || !result_buf.ptr)
359                 die("Failed to execute internal merge");
360
361         write_buf_to_worktree(p->obj.hash, result_buf.ptr, result_buf.size);
362         free(result_buf.ptr);
363
364         return status;
365 }
366
367 static int merge_one_change_manual(struct notes_merge_options *o,
368                                    struct notes_merge_pair *p,
369                                    struct notes_tree *t)
370 {
371         const char *lref = o->local_ref ? o->local_ref : "local version";
372         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
373
374         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
375                "local = %.7s, remote = %.7s)\n",
376                oid_to_hex(&p->obj), oid_to_hex(&p->base),
377                oid_to_hex(&p->local), oid_to_hex(&p->remote));
378
379         /* add "Conflicts:" section to commit message first time through */
380         if (!o->has_worktree)
381                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
382
383         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
384
385         if (o->verbosity >= 2)
386                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
387         check_notes_merge_worktree(o);
388         if (is_null_oid(&p->local)) {
389                 /* D/F conflict, checkout p->remote */
390                 assert(!is_null_oid(&p->remote));
391                 if (o->verbosity >= 1)
392                         printf("CONFLICT (delete/modify): Notes for object %s "
393                                 "deleted in %s and modified in %s. Version from %s "
394                                 "left in tree.\n",
395                                 oid_to_hex(&p->obj), lref, rref, rref);
396                 write_note_to_worktree(p->obj.hash, p->remote.hash);
397         } else if (is_null_oid(&p->remote)) {
398                 /* D/F conflict, checkout p->local */
399                 assert(!is_null_oid(&p->local));
400                 if (o->verbosity >= 1)
401                         printf("CONFLICT (delete/modify): Notes for object %s "
402                                 "deleted in %s and modified in %s. Version from %s "
403                                 "left in tree.\n",
404                                 oid_to_hex(&p->obj), rref, lref, lref);
405                 write_note_to_worktree(p->obj.hash, p->local.hash);
406         } else {
407                 /* "regular" conflict, checkout result of ll_merge() */
408                 const char *reason = "content";
409                 if (is_null_oid(&p->base))
410                         reason = "add/add";
411                 assert(!is_null_oid(&p->local));
412                 assert(!is_null_oid(&p->remote));
413                 if (o->verbosity >= 1)
414                         printf("CONFLICT (%s): Merge conflict in notes for "
415                                 "object %s\n", reason,
416                                 oid_to_hex(&p->obj));
417                 ll_merge_in_worktree(o, p);
418         }
419
420         trace_printf("\t\t\tremoving from partial merge result\n");
421         remove_note(t, p->obj.hash);
422
423         return 1;
424 }
425
426 static int merge_one_change(struct notes_merge_options *o,
427                             struct notes_merge_pair *p, struct notes_tree *t)
428 {
429         /*
430          * Return 0 if change is successfully resolved (stored in notes_tree).
431          * Return 1 is change results in a conflict (NOT stored in notes_tree,
432          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
433          */
434         switch (o->strategy) {
435         case NOTES_MERGE_RESOLVE_MANUAL:
436                 return merge_one_change_manual(o, p, t);
437         case NOTES_MERGE_RESOLVE_OURS:
438                 if (o->verbosity >= 2)
439                         printf("Using local notes for %s\n",
440                                                 oid_to_hex(&p->obj));
441                 /* nothing to do */
442                 return 0;
443         case NOTES_MERGE_RESOLVE_THEIRS:
444                 if (o->verbosity >= 2)
445                         printf("Using remote notes for %s\n",
446                                                 oid_to_hex(&p->obj));
447                 if (add_note(t, p->obj.hash, p->remote.hash, combine_notes_overwrite))
448                         die("BUG: combine_notes_overwrite failed");
449                 return 0;
450         case NOTES_MERGE_RESOLVE_UNION:
451                 if (o->verbosity >= 2)
452                         printf("Concatenating local and remote notes for %s\n",
453                                                         oid_to_hex(&p->obj));
454                 if (add_note(t, p->obj.hash, p->remote.hash, combine_notes_concatenate))
455                         die("failed to concatenate notes "
456                             "(combine_notes_concatenate)");
457                 return 0;
458         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
459                 if (o->verbosity >= 2)
460                         printf("Concatenating unique lines in local and remote "
461                                 "notes for %s\n", oid_to_hex(&p->obj));
462                 if (add_note(t, p->obj.hash, p->remote.hash, combine_notes_cat_sort_uniq))
463                         die("failed to concatenate notes "
464                             "(combine_notes_cat_sort_uniq)");
465                 return 0;
466         }
467         die("Unknown strategy (%i).", o->strategy);
468 }
469
470 static int merge_changes(struct notes_merge_options *o,
471                          struct notes_merge_pair *changes, int *num_changes,
472                          struct notes_tree *t)
473 {
474         int i, conflicts = 0;
475
476         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
477         for (i = 0; i < *num_changes; i++) {
478                 struct notes_merge_pair *p = changes + i;
479                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
480                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
481                        oid_to_hex(&p->local),
482                        oid_to_hex(&p->remote));
483
484                 if (!oidcmp(&p->base, &p->remote)) {
485                         /* no remote change; nothing to do */
486                         trace_printf("\t\t\tskipping (no remote change)\n");
487                 } else if (!oidcmp(&p->local, &p->remote)) {
488                         /* same change in local and remote; nothing to do */
489                         trace_printf("\t\t\tskipping (local == remote)\n");
490                 } else if (!oidcmp(&p->local, &uninitialized) ||
491                            !oidcmp(&p->local, &p->base)) {
492                         /* no local change; adopt remote change */
493                         trace_printf("\t\t\tno local change, adopted remote\n");
494                         if (add_note(t, p->obj.hash, p->remote.hash,
495                                      combine_notes_overwrite))
496                                 die("BUG: combine_notes_overwrite failed");
497                 } else {
498                         /* need file-level merge between local and remote */
499                         trace_printf("\t\t\tneed content-level merge\n");
500                         conflicts += merge_one_change(o, p, t);
501                 }
502         }
503
504         return conflicts;
505 }
506
507 static int merge_from_diffs(struct notes_merge_options *o,
508                             const unsigned char *base,
509                             const unsigned char *local,
510                             const unsigned char *remote, struct notes_tree *t)
511 {
512         struct notes_merge_pair *changes;
513         int num_changes, conflicts;
514
515         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
516                "remote = %.7s)\n", sha1_to_hex(base), sha1_to_hex(local),
517                sha1_to_hex(remote));
518
519         changes = diff_tree_remote(o, base, remote, &num_changes);
520         diff_tree_local(o, changes, num_changes, base, local);
521
522         conflicts = merge_changes(o, changes, &num_changes, t);
523         free(changes);
524
525         if (o->verbosity >= 4)
526                 printf(t->dirty ?
527                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
528                        "Merge result: %i unmerged notes and a clean notes tree\n",
529                        conflicts);
530
531         return conflicts ? -1 : 1;
532 }
533
534 int notes_merge(struct notes_merge_options *o,
535                 struct notes_tree *local_tree,
536                 unsigned char *result_sha1)
537 {
538         unsigned char local_sha1[20], remote_sha1[20];
539         struct commit *local, *remote;
540         struct commit_list *bases = NULL;
541         const unsigned char *base_sha1, *base_tree_sha1;
542         int result = 0;
543
544         assert(o->local_ref && o->remote_ref);
545         assert(!strcmp(o->local_ref, local_tree->ref));
546         hashclr(result_sha1);
547
548         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
549                o->local_ref, o->remote_ref);
550
551         /* Dereference o->local_ref into local_sha1 */
552         if (read_ref_full(o->local_ref, 0, local_sha1, NULL))
553                 die("Failed to resolve local notes ref '%s'", o->local_ref);
554         else if (!check_refname_format(o->local_ref, 0) &&
555                 is_null_sha1(local_sha1))
556                 local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
557         else if (!(local = lookup_commit_reference(local_sha1)))
558                 die("Could not parse local commit %s (%s)",
559                     sha1_to_hex(local_sha1), o->local_ref);
560         trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
561
562         /* Dereference o->remote_ref into remote_sha1 */
563         if (get_sha1(o->remote_ref, remote_sha1)) {
564                 /*
565                  * Failed to get remote_sha1. If o->remote_ref looks like an
566                  * unborn ref, perform the merge using an empty notes tree.
567                  */
568                 if (!check_refname_format(o->remote_ref, 0)) {
569                         hashclr(remote_sha1);
570                         remote = NULL;
571                 } else {
572                         die("Failed to resolve remote notes ref '%s'",
573                             o->remote_ref);
574                 }
575         } else if (!(remote = lookup_commit_reference(remote_sha1))) {
576                 die("Could not parse remote commit %s (%s)",
577                     sha1_to_hex(remote_sha1), o->remote_ref);
578         }
579         trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
580
581         if (!local && !remote)
582                 die("Cannot merge empty notes ref (%s) into empty notes ref "
583                     "(%s)", o->remote_ref, o->local_ref);
584         if (!local) {
585                 /* result == remote commit */
586                 hashcpy(result_sha1, remote_sha1);
587                 goto found_result;
588         }
589         if (!remote) {
590                 /* result == local commit */
591                 hashcpy(result_sha1, local_sha1);
592                 goto found_result;
593         }
594         assert(local && remote);
595
596         /* Find merge bases */
597         bases = get_merge_bases(local, remote);
598         if (!bases) {
599                 base_sha1 = null_sha1;
600                 base_tree_sha1 = EMPTY_TREE_SHA1_BIN;
601                 if (o->verbosity >= 4)
602                         printf("No merge base found; doing history-less merge\n");
603         } else if (!bases->next) {
604                 base_sha1 = bases->item->object.oid.hash;
605                 base_tree_sha1 = bases->item->tree->object.oid.hash;
606                 if (o->verbosity >= 4)
607                         printf("One merge base found (%.7s)\n",
608                                 sha1_to_hex(base_sha1));
609         } else {
610                 /* TODO: How to handle multiple merge-bases? */
611                 base_sha1 = bases->item->object.oid.hash;
612                 base_tree_sha1 = bases->item->tree->object.oid.hash;
613                 if (o->verbosity >= 3)
614                         printf("Multiple merge bases found. Using the first "
615                                 "(%.7s)\n", sha1_to_hex(base_sha1));
616         }
617
618         if (o->verbosity >= 4)
619                 printf("Merging remote commit %.7s into local commit %.7s with "
620                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
621                         oid_to_hex(&local->object.oid),
622                         sha1_to_hex(base_sha1));
623
624         if (!hashcmp(remote->object.oid.hash, base_sha1)) {
625                 /* Already merged; result == local commit */
626                 if (o->verbosity >= 2)
627                         printf("Already up-to-date!\n");
628                 hashcpy(result_sha1, local->object.oid.hash);
629                 goto found_result;
630         }
631         if (!hashcmp(local->object.oid.hash, base_sha1)) {
632                 /* Fast-forward; result == remote commit */
633                 if (o->verbosity >= 2)
634                         printf("Fast-forward\n");
635                 hashcpy(result_sha1, remote->object.oid.hash);
636                 goto found_result;
637         }
638
639         result = merge_from_diffs(o, base_tree_sha1, local->tree->object.oid.hash,
640                                   remote->tree->object.oid.hash, local_tree);
641
642         if (result != 0) { /* non-trivial merge (with or without conflicts) */
643                 /* Commit (partial) result */
644                 struct commit_list *parents = NULL;
645                 commit_list_insert(remote, &parents); /* LIFO order */
646                 commit_list_insert(local, &parents);
647                 create_notes_commit(local_tree, parents,
648                                     o->commit_msg.buf, o->commit_msg.len,
649                                     result_sha1);
650         }
651
652 found_result:
653         free_commit_list(bases);
654         strbuf_release(&(o->commit_msg));
655         trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
656                result, sha1_to_hex(result_sha1));
657         return result;
658 }
659
660 int notes_merge_commit(struct notes_merge_options *o,
661                        struct notes_tree *partial_tree,
662                        struct commit *partial_commit,
663                        unsigned char *result_sha1)
664 {
665         /*
666          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
667          * found notes to 'partial_tree'. Write the updated notes tree to
668          * the DB, and commit the resulting tree object while reusing the
669          * commit message and parents from 'partial_commit'.
670          * Finally store the new commit object SHA1 into 'result_sha1'.
671          */
672         DIR *dir;
673         struct dirent *e;
674         struct strbuf path = STRBUF_INIT;
675         const char *buffer = get_commit_buffer(partial_commit, NULL);
676         const char *msg = strstr(buffer, "\n\n");
677         int baselen;
678
679         strbuf_addstr(&path, git_path(NOTES_MERGE_WORKTREE));
680         if (o->verbosity >= 3)
681                 printf("Committing notes in notes merge worktree at %s\n",
682                         path.buf);
683
684         if (!msg || msg[2] == '\0')
685                 die("partial notes commit has empty message");
686         msg += 2;
687
688         dir = opendir(path.buf);
689         if (!dir)
690                 die_errno("could not open %s", path.buf);
691
692         strbuf_addch(&path, '/');
693         baselen = path.len;
694         while ((e = readdir(dir)) != NULL) {
695                 struct stat st;
696                 unsigned char obj_sha1[20], blob_sha1[20];
697
698                 if (is_dot_or_dotdot(e->d_name))
699                         continue;
700
701                 if (strlen(e->d_name) != 40 || get_sha1_hex(e->d_name, obj_sha1)) {
702                         if (o->verbosity >= 3)
703                                 printf("Skipping non-SHA1 entry '%s%s'\n",
704                                         path.buf, e->d_name);
705                         continue;
706                 }
707
708                 strbuf_addstr(&path, e->d_name);
709                 /* write file as blob, and add to partial_tree */
710                 if (stat(path.buf, &st))
711                         die_errno("Failed to stat '%s'", path.buf);
712                 if (index_path(blob_sha1, path.buf, &st, HASH_WRITE_OBJECT))
713                         die("Failed to write blob object from '%s'", path.buf);
714                 if (add_note(partial_tree, obj_sha1, blob_sha1, NULL))
715                         die("Failed to add resolved note '%s' to notes tree",
716                             path.buf);
717                 if (o->verbosity >= 4)
718                         printf("Added resolved note for object %s: %s\n",
719                                 sha1_to_hex(obj_sha1), sha1_to_hex(blob_sha1));
720                 strbuf_setlen(&path, baselen);
721         }
722
723         create_notes_commit(partial_tree, partial_commit->parents,
724                             msg, strlen(msg), result_sha1);
725         unuse_commit_buffer(partial_commit, buffer);
726         if (o->verbosity >= 4)
727                 printf("Finalized notes merge commit: %s\n",
728                         sha1_to_hex(result_sha1));
729         strbuf_release(&path);
730         closedir(dir);
731         return 0;
732 }
733
734 int notes_merge_abort(struct notes_merge_options *o)
735 {
736         /*
737          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
738          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
739          * the current working directory of the user.
740          */
741         struct strbuf buf = STRBUF_INIT;
742         int ret;
743
744         strbuf_addstr(&buf, git_path(NOTES_MERGE_WORKTREE));
745         if (o->verbosity >= 3)
746                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
747         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
748         strbuf_release(&buf);
749         return ret;
750 }