Merge branch 'ma/t7005-bash-workaround' into maint
[git] / notes-merge.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "refs.h"
4 #include "object-store.h"
5 #include "repository.h"
6 #include "diff.h"
7 #include "diffcore.h"
8 #include "xdiff-interface.h"
9 #include "ll-merge.h"
10 #include "dir.h"
11 #include "notes.h"
12 #include "notes-merge.h"
13 #include "strbuf.h"
14 #include "notes-utils.h"
15
16 struct notes_merge_pair {
17         struct object_id obj, base, local, remote;
18 };
19
20 void init_notes_merge_options(struct notes_merge_options *o)
21 {
22         memset(o, 0, sizeof(struct notes_merge_options));
23         strbuf_init(&(o->commit_msg), 0);
24         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
25 }
26
27 static int path_to_oid(const char *path, struct object_id *oid)
28 {
29         char hex_oid[GIT_SHA1_HEXSZ];
30         int i = 0;
31         while (*path && i < GIT_SHA1_HEXSZ) {
32                 if (*path != '/')
33                         hex_oid[i++] = *path;
34                 path++;
35         }
36         if (*path || i != GIT_SHA1_HEXSZ)
37                 return -1;
38         return get_oid_hex(hex_oid, oid);
39 }
40
41 static int verify_notes_filepair(struct diff_filepair *p, struct object_id *oid)
42 {
43         switch (p->status) {
44         case DIFF_STATUS_MODIFIED:
45                 assert(p->one->mode == p->two->mode);
46                 assert(!is_null_oid(&p->one->oid));
47                 assert(!is_null_oid(&p->two->oid));
48                 break;
49         case DIFF_STATUS_ADDED:
50                 assert(is_null_oid(&p->one->oid));
51                 break;
52         case DIFF_STATUS_DELETED:
53                 assert(is_null_oid(&p->two->oid));
54                 break;
55         default:
56                 return -1;
57         }
58         assert(!strcmp(p->one->path, p->two->path));
59         return path_to_oid(p->one->path, oid);
60 }
61
62 static struct notes_merge_pair *find_notes_merge_pair_pos(
63                 struct notes_merge_pair *list, int len, struct object_id *obj,
64                 int insert_new, int *occupied)
65 {
66         /*
67          * Both diff_tree_remote() and diff_tree_local() tend to process
68          * merge_pairs in ascending order. Therefore, cache last returned
69          * index, and search sequentially from there until the appropriate
70          * position is found.
71          *
72          * Since inserts only happen from diff_tree_remote() (which mainly
73          * _appends_), we don't care that inserting into the middle of the
74          * list is expensive (using memmove()).
75          */
76         static int last_index;
77         int i = last_index < len ? last_index : len - 1;
78         int prev_cmp = 0, cmp = -1;
79         while (i >= 0 && i < len) {
80                 cmp = oidcmp(obj, &list[i].obj);
81                 if (!cmp) /* obj belongs @ i */
82                         break;
83                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
84                         i--;
85                 else if (cmp < 0) /* obj belongs between i-1 and i */
86                         break;
87                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
88                         i++;
89                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
90                         i++;
91                         break;
92                 }
93                 prev_cmp = cmp;
94         }
95         if (i < 0)
96                 i = 0;
97         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
98
99         if (!cmp)
100                 *occupied = 1;
101         else {
102                 *occupied = 0;
103                 if (insert_new && i < len) {
104                         MOVE_ARRAY(list + i + 1, list + i, len - i);
105                         memset(list + i, 0, sizeof(struct notes_merge_pair));
106                 }
107         }
108         last_index = i;
109         return list + i;
110 }
111
112 static struct object_id uninitialized = {
113         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
114         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
115 };
116
117 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
118                                                  const struct object_id *base,
119                                                  const struct object_id *remote,
120                                                  int *num_changes)
121 {
122         struct diff_options opt;
123         struct notes_merge_pair *changes;
124         int i, len = 0;
125
126         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
127                oid_to_hex(base), oid_to_hex(remote));
128
129         diff_setup(&opt);
130         opt.flags.recursive = 1;
131         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
132         diff_setup_done(&opt);
133         diff_tree_oid(base, remote, "", &opt);
134         diffcore_std(&opt);
135
136         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
137
138         for (i = 0; i < diff_queued_diff.nr; i++) {
139                 struct diff_filepair *p = diff_queued_diff.queue[i];
140                 struct notes_merge_pair *mp;
141                 int occupied;
142                 struct object_id obj;
143
144                 if (verify_notes_filepair(p, &obj)) {
145                         trace_printf("\t\tCannot merge entry '%s' (%c): "
146                                "%.7s -> %.7s. Skipping!\n", p->one->path,
147                                p->status, oid_to_hex(&p->one->oid),
148                                oid_to_hex(&p->two->oid));
149                         continue;
150                 }
151                 mp = find_notes_merge_pair_pos(changes, len, &obj, 1, &occupied);
152                 if (occupied) {
153                         /* We've found an addition/deletion pair */
154                         assert(!oidcmp(&mp->obj, &obj));
155                         if (is_null_oid(&p->one->oid)) { /* addition */
156                                 assert(is_null_oid(&mp->remote));
157                                 oidcpy(&mp->remote, &p->two->oid);
158                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
159                                 assert(is_null_oid(&mp->base));
160                                 oidcpy(&mp->base, &p->one->oid);
161                         } else
162                                 assert(!"Invalid existing change recorded");
163                 } else {
164                         oidcpy(&mp->obj, &obj);
165                         oidcpy(&mp->base, &p->one->oid);
166                         oidcpy(&mp->local, &uninitialized);
167                         oidcpy(&mp->remote, &p->two->oid);
168                         len++;
169                 }
170                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
171                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
172                        oid_to_hex(&mp->remote));
173         }
174         diff_flush(&opt);
175         clear_pathspec(&opt.pathspec);
176
177         *num_changes = len;
178         return changes;
179 }
180
181 static void diff_tree_local(struct notes_merge_options *o,
182                             struct notes_merge_pair *changes, int len,
183                             const struct object_id *base,
184                             const struct object_id *local)
185 {
186         struct diff_options opt;
187         int i;
188
189         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
190                len, oid_to_hex(base), oid_to_hex(local));
191
192         diff_setup(&opt);
193         opt.flags.recursive = 1;
194         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
195         diff_setup_done(&opt);
196         diff_tree_oid(base, local, "", &opt);
197         diffcore_std(&opt);
198
199         for (i = 0; i < diff_queued_diff.nr; i++) {
200                 struct diff_filepair *p = diff_queued_diff.queue[i];
201                 struct notes_merge_pair *mp;
202                 int match;
203                 struct object_id obj;
204
205                 if (verify_notes_filepair(p, &obj)) {
206                         trace_printf("\t\tCannot merge entry '%s' (%c): "
207                                "%.7s -> %.7s. Skipping!\n", p->one->path,
208                                p->status, oid_to_hex(&p->one->oid),
209                                oid_to_hex(&p->two->oid));
210                         continue;
211                 }
212                 mp = find_notes_merge_pair_pos(changes, len, &obj, 0, &match);
213                 if (!match) {
214                         trace_printf("\t\tIgnoring local-only change for %s: "
215                                "%.7s -> %.7s\n", oid_to_hex(&obj),
216                                oid_to_hex(&p->one->oid),
217                                oid_to_hex(&p->two->oid));
218                         continue;
219                 }
220
221                 assert(!oidcmp(&mp->obj, &obj));
222                 if (is_null_oid(&p->two->oid)) { /* deletion */
223                         /*
224                          * Either this is a true deletion (1), or it is part
225                          * of an A/D pair (2), or D/A pair (3):
226                          *
227                          * (1) mp->local is uninitialized; set it to null_sha1
228                          * (2) mp->local is not uninitialized; don't touch it
229                          * (3) mp->local is uninitialized; set it to null_sha1
230                          *     (will be overwritten by following addition)
231                          */
232                         if (!oidcmp(&mp->local, &uninitialized))
233                                 oidclr(&mp->local);
234                 } else if (is_null_oid(&p->one->oid)) { /* addition */
235                         /*
236                          * Either this is a true addition (1), or it is part
237                          * of an A/D pair (2), or D/A pair (3):
238                          *
239                          * (1) mp->local is uninitialized; set to p->two->sha1
240                          * (2) mp->local is uninitialized; set to p->two->sha1
241                          * (3) mp->local is null_sha1;     set to p->two->sha1
242                          */
243                         assert(is_null_oid(&mp->local) ||
244                                !oidcmp(&mp->local, &uninitialized));
245                         oidcpy(&mp->local, &p->two->oid);
246                 } else { /* modification */
247                         /*
248                          * This is a true modification. p->one->sha1 shall
249                          * match mp->base, and mp->local shall be uninitialized.
250                          * Set mp->local to p->two->sha1.
251                          */
252                         assert(!oidcmp(&p->one->oid, &mp->base));
253                         assert(!oidcmp(&mp->local, &uninitialized));
254                         oidcpy(&mp->local, &p->two->oid);
255                 }
256                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
257                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
258                        oid_to_hex(&mp->local));
259         }
260         diff_flush(&opt);
261         clear_pathspec(&opt.pathspec);
262 }
263
264 static void check_notes_merge_worktree(struct notes_merge_options *o)
265 {
266         if (!o->has_worktree) {
267                 /*
268                  * Must establish NOTES_MERGE_WORKTREE.
269                  * Abort if NOTES_MERGE_WORKTREE already exists
270                  */
271                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
272                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
273                         if (advice_resolve_conflict)
274                                 die(_("You have not concluded your previous "
275                                     "notes merge (%s exists).\nPlease, use "
276                                     "'git notes merge --commit' or 'git notes "
277                                     "merge --abort' to commit/abort the "
278                                     "previous merge before you start a new "
279                                     "notes merge."), git_path("NOTES_MERGE_*"));
280                         else
281                                 die(_("You have not concluded your notes merge "
282                                     "(%s exists)."), git_path("NOTES_MERGE_*"));
283                 }
284
285                 if (safe_create_leading_directories_const(git_path(
286                                 NOTES_MERGE_WORKTREE "/.test")))
287                         die_errno("unable to create directory %s",
288                                   git_path(NOTES_MERGE_WORKTREE));
289                 o->has_worktree = 1;
290         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
291                 /* NOTES_MERGE_WORKTREE should already be established */
292                 die("missing '%s'. This should not happen",
293                     git_path(NOTES_MERGE_WORKTREE));
294 }
295
296 static void write_buf_to_worktree(const struct object_id *obj,
297                                   const char *buf, unsigned long size)
298 {
299         int fd;
300         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", oid_to_hex(obj));
301         if (safe_create_leading_directories_const(path))
302                 die_errno("unable to create directory for '%s'", path);
303
304         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
305
306         while (size > 0) {
307                 ssize_t ret = write_in_full(fd, buf, size);
308                 if (ret < 0) {
309                         /* Ignore epipe */
310                         if (errno == EPIPE)
311                                 break;
312                         die_errno("notes-merge");
313                 }
314                 size -= ret;
315                 buf += ret;
316         }
317
318         close(fd);
319         free(path);
320 }
321
322 static void write_note_to_worktree(const struct object_id *obj,
323                                    const struct object_id *note)
324 {
325         enum object_type type;
326         unsigned long size;
327         void *buf = read_object_file(note, &type, &size);
328
329         if (!buf)
330                 die("cannot read note %s for object %s",
331                     oid_to_hex(note), oid_to_hex(obj));
332         if (type != OBJ_BLOB)
333                 die("blob expected in note %s for object %s",
334                     oid_to_hex(note), oid_to_hex(obj));
335         write_buf_to_worktree(obj, buf, size);
336         free(buf);
337 }
338
339 static int ll_merge_in_worktree(struct notes_merge_options *o,
340                                 struct notes_merge_pair *p)
341 {
342         mmbuffer_t result_buf;
343         mmfile_t base, local, remote;
344         int status;
345
346         read_mmblob(&base, &p->base);
347         read_mmblob(&local, &p->local);
348         read_mmblob(&remote, &p->remote);
349
350         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
351                           &local, o->local_ref, &remote, o->remote_ref, NULL);
352
353         free(base.ptr);
354         free(local.ptr);
355         free(remote.ptr);
356
357         if ((status < 0) || !result_buf.ptr)
358                 die("Failed to execute internal merge");
359
360         write_buf_to_worktree(&p->obj, result_buf.ptr, result_buf.size);
361         free(result_buf.ptr);
362
363         return status;
364 }
365
366 static int merge_one_change_manual(struct notes_merge_options *o,
367                                    struct notes_merge_pair *p,
368                                    struct notes_tree *t)
369 {
370         const char *lref = o->local_ref ? o->local_ref : "local version";
371         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
372
373         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
374                "local = %.7s, remote = %.7s)\n",
375                oid_to_hex(&p->obj), oid_to_hex(&p->base),
376                oid_to_hex(&p->local), oid_to_hex(&p->remote));
377
378         /* add "Conflicts:" section to commit message first time through */
379         if (!o->has_worktree)
380                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
381
382         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
383
384         if (o->verbosity >= 2)
385                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
386         check_notes_merge_worktree(o);
387         if (is_null_oid(&p->local)) {
388                 /* D/F conflict, checkout p->remote */
389                 assert(!is_null_oid(&p->remote));
390                 if (o->verbosity >= 1)
391                         printf("CONFLICT (delete/modify): Notes for object %s "
392                                 "deleted in %s and modified in %s. Version from %s "
393                                 "left in tree.\n",
394                                 oid_to_hex(&p->obj), lref, rref, rref);
395                 write_note_to_worktree(&p->obj, &p->remote);
396         } else if (is_null_oid(&p->remote)) {
397                 /* D/F conflict, checkout p->local */
398                 assert(!is_null_oid(&p->local));
399                 if (o->verbosity >= 1)
400                         printf("CONFLICT (delete/modify): Notes for object %s "
401                                 "deleted in %s and modified in %s. Version from %s "
402                                 "left in tree.\n",
403                                 oid_to_hex(&p->obj), rref, lref, lref);
404                 write_note_to_worktree(&p->obj, &p->local);
405         } else {
406                 /* "regular" conflict, checkout result of ll_merge() */
407                 const char *reason = "content";
408                 if (is_null_oid(&p->base))
409                         reason = "add/add";
410                 assert(!is_null_oid(&p->local));
411                 assert(!is_null_oid(&p->remote));
412                 if (o->verbosity >= 1)
413                         printf("CONFLICT (%s): Merge conflict in notes for "
414                                 "object %s\n", reason,
415                                 oid_to_hex(&p->obj));
416                 ll_merge_in_worktree(o, p);
417         }
418
419         trace_printf("\t\t\tremoving from partial merge result\n");
420         remove_note(t, p->obj.hash);
421
422         return 1;
423 }
424
425 static int merge_one_change(struct notes_merge_options *o,
426                             struct notes_merge_pair *p, struct notes_tree *t)
427 {
428         /*
429          * Return 0 if change is successfully resolved (stored in notes_tree).
430          * Return 1 is change results in a conflict (NOT stored in notes_tree,
431          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
432          */
433         switch (o->strategy) {
434         case NOTES_MERGE_RESOLVE_MANUAL:
435                 return merge_one_change_manual(o, p, t);
436         case NOTES_MERGE_RESOLVE_OURS:
437                 if (o->verbosity >= 2)
438                         printf("Using local notes for %s\n",
439                                                 oid_to_hex(&p->obj));
440                 /* nothing to do */
441                 return 0;
442         case NOTES_MERGE_RESOLVE_THEIRS:
443                 if (o->verbosity >= 2)
444                         printf("Using remote notes for %s\n",
445                                                 oid_to_hex(&p->obj));
446                 if (add_note(t, &p->obj, &p->remote, combine_notes_overwrite))
447                         BUG("combine_notes_overwrite failed");
448                 return 0;
449         case NOTES_MERGE_RESOLVE_UNION:
450                 if (o->verbosity >= 2)
451                         printf("Concatenating local and remote notes for %s\n",
452                                                         oid_to_hex(&p->obj));
453                 if (add_note(t, &p->obj, &p->remote, combine_notes_concatenate))
454                         die("failed to concatenate notes "
455                             "(combine_notes_concatenate)");
456                 return 0;
457         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
458                 if (o->verbosity >= 2)
459                         printf("Concatenating unique lines in local and remote "
460                                 "notes for %s\n", oid_to_hex(&p->obj));
461                 if (add_note(t, &p->obj, &p->remote, combine_notes_cat_sort_uniq))
462                         die("failed to concatenate notes "
463                             "(combine_notes_cat_sort_uniq)");
464                 return 0;
465         }
466         die("Unknown strategy (%i).", o->strategy);
467 }
468
469 static int merge_changes(struct notes_merge_options *o,
470                          struct notes_merge_pair *changes, int *num_changes,
471                          struct notes_tree *t)
472 {
473         int i, conflicts = 0;
474
475         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
476         for (i = 0; i < *num_changes; i++) {
477                 struct notes_merge_pair *p = changes + i;
478                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
479                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
480                        oid_to_hex(&p->local),
481                        oid_to_hex(&p->remote));
482
483                 if (!oidcmp(&p->base, &p->remote)) {
484                         /* no remote change; nothing to do */
485                         trace_printf("\t\t\tskipping (no remote change)\n");
486                 } else if (!oidcmp(&p->local, &p->remote)) {
487                         /* same change in local and remote; nothing to do */
488                         trace_printf("\t\t\tskipping (local == remote)\n");
489                 } else if (!oidcmp(&p->local, &uninitialized) ||
490                            !oidcmp(&p->local, &p->base)) {
491                         /* no local change; adopt remote change */
492                         trace_printf("\t\t\tno local change, adopted remote\n");
493                         if (add_note(t, &p->obj, &p->remote,
494                                      combine_notes_overwrite))
495                                 BUG("combine_notes_overwrite failed");
496                 } else {
497                         /* need file-level merge between local and remote */
498                         trace_printf("\t\t\tneed content-level merge\n");
499                         conflicts += merge_one_change(o, p, t);
500                 }
501         }
502
503         return conflicts;
504 }
505
506 static int merge_from_diffs(struct notes_merge_options *o,
507                             const struct object_id *base,
508                             const struct object_id *local,
509                             const struct object_id *remote,
510                             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", oid_to_hex(base), oid_to_hex(local),
517                oid_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                 struct object_id *result_oid)
537 {
538         struct object_id local_oid, remote_oid;
539         struct commit *local, *remote;
540         struct commit_list *bases = NULL;
541         const struct object_id *base_oid, *base_tree_oid;
542         int result = 0;
543
544         assert(o->local_ref && o->remote_ref);
545         assert(!strcmp(o->local_ref, local_tree->ref));
546         oidclr(result_oid);
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_oid, 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_oid(&local_oid))
556                 local = NULL; /* local_oid == null_oid indicates unborn ref */
557         else if (!(local = lookup_commit_reference(the_repository, &local_oid)))
558                 die("Could not parse local commit %s (%s)",
559                     oid_to_hex(&local_oid), o->local_ref);
560         trace_printf("\tlocal commit: %.7s\n", oid_to_hex(&local_oid));
561
562         /* Dereference o->remote_ref into remote_oid */
563         if (get_oid(o->remote_ref, &remote_oid)) {
564                 /*
565                  * Failed to get remote_oid. 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                         oidclr(&remote_oid);
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(the_repository, &remote_oid))) {
576                 die("Could not parse remote commit %s (%s)",
577                     oid_to_hex(&remote_oid), o->remote_ref);
578         }
579         trace_printf("\tremote commit: %.7s\n", oid_to_hex(&remote_oid));
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                 oidcpy(result_oid, &remote_oid);
587                 goto found_result;
588         }
589         if (!remote) {
590                 /* result == local commit */
591                 oidcpy(result_oid, &local_oid);
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_oid = &null_oid;
600                 base_tree_oid = the_hash_algo->empty_tree;
601                 if (o->verbosity >= 4)
602                         printf("No merge base found; doing history-less merge\n");
603         } else if (!bases->next) {
604                 base_oid = &bases->item->object.oid;
605                 base_tree_oid = get_commit_tree_oid(bases->item);
606                 if (o->verbosity >= 4)
607                         printf("One merge base found (%.7s)\n",
608                                oid_to_hex(base_oid));
609         } else {
610                 /* TODO: How to handle multiple merge-bases? */
611                 base_oid = &bases->item->object.oid;
612                 base_tree_oid = get_commit_tree_oid(bases->item);
613                 if (o->verbosity >= 3)
614                         printf("Multiple merge bases found. Using the first "
615                                 "(%.7s)\n", oid_to_hex(base_oid));
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                         oid_to_hex(base_oid));
623
624         if (!oidcmp(&remote->object.oid, base_oid)) {
625                 /* Already merged; result == local commit */
626                 if (o->verbosity >= 2)
627                         printf("Already up to date!\n");
628                 oidcpy(result_oid, &local->object.oid);
629                 goto found_result;
630         }
631         if (!oidcmp(&local->object.oid, base_oid)) {
632                 /* Fast-forward; result == remote commit */
633                 if (o->verbosity >= 2)
634                         printf("Fast-forward\n");
635                 oidcpy(result_oid, &remote->object.oid);
636                 goto found_result;
637         }
638
639         result = merge_from_diffs(o, base_tree_oid,
640                                   get_commit_tree_oid(local),
641                                   get_commit_tree_oid(remote), local_tree);
642
643         if (result != 0) { /* non-trivial merge (with or without conflicts) */
644                 /* Commit (partial) result */
645                 struct commit_list *parents = NULL;
646                 commit_list_insert(remote, &parents); /* LIFO order */
647                 commit_list_insert(local, &parents);
648                 create_notes_commit(local_tree, parents, o->commit_msg.buf,
649                                     o->commit_msg.len, result_oid);
650         }
651
652 found_result:
653         free_commit_list(bases);
654         strbuf_release(&(o->commit_msg));
655         trace_printf("notes_merge(): result = %i, result_oid = %.7s\n",
656                result, oid_to_hex(result_oid));
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                        struct object_id *result_oid)
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 OID into 'result_oid'.
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         git_path_buf(&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                 struct object_id obj_oid, blob_oid;
697
698                 if (is_dot_or_dotdot(e->d_name))
699                         continue;
700
701                 if (get_oid_hex(e->d_name, &obj_oid)) {
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_oid, path.buf, &st, HASH_WRITE_OBJECT))
713                         die("Failed to write blob object from '%s'", path.buf);
714                 if (add_note(partial_tree, &obj_oid, &blob_oid, 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                                 oid_to_hex(&obj_oid), oid_to_hex(&blob_oid));
720                 strbuf_setlen(&path, baselen);
721         }
722
723         create_notes_commit(partial_tree, partial_commit->parents, msg,
724                             strlen(msg), result_oid);
725         unuse_commit_buffer(partial_commit, buffer);
726         if (o->verbosity >= 4)
727                 printf("Finalized notes merge commit: %s\n",
728                         oid_to_hex(result_oid));
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         git_path_buf(&buf, 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 }