Merge branch 'ft/doc-git-transport'
[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         unsigned char obj[20], base[20], local[20], remote[20];
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_sha1(p->one->sha1));
45                 assert(!is_null_sha1(p->two->sha1));
46                 break;
47         case DIFF_STATUS_ADDED:
48                 assert(is_null_sha1(p->one->sha1));
49                 break;
50         case DIFF_STATUS_DELETED:
51                 assert(is_null_sha1(p->two->sha1));
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);
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 unsigned char uninitialized[20] =
112         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
113         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff";
114
115 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
116                                                  const unsigned char *base,
117                                                  const unsigned char *remote,
118                                                  int *num_changes)
119 {
120         struct diff_options opt;
121         struct notes_merge_pair *changes;
122         int i, len = 0;
123
124         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
125                sha1_to_hex(base), sha1_to_hex(remote));
126
127         diff_setup(&opt);
128         DIFF_OPT_SET(&opt, RECURSIVE);
129         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
130         diff_setup_done(&opt);
131         diff_tree_sha1(base, remote, "", &opt);
132         diffcore_std(&opt);
133
134         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
135
136         for (i = 0; i < diff_queued_diff.nr; i++) {
137                 struct diff_filepair *p = diff_queued_diff.queue[i];
138                 struct notes_merge_pair *mp;
139                 int occupied;
140                 unsigned char obj[20];
141
142                 if (verify_notes_filepair(p, obj)) {
143                         trace_printf("\t\tCannot merge entry '%s' (%c): "
144                                "%.7s -> %.7s. Skipping!\n", p->one->path,
145                                p->status, sha1_to_hex(p->one->sha1),
146                                sha1_to_hex(p->two->sha1));
147                         continue;
148                 }
149                 mp = find_notes_merge_pair_pos(changes, len, obj, 1, &occupied);
150                 if (occupied) {
151                         /* We've found an addition/deletion pair */
152                         assert(!hashcmp(mp->obj, obj));
153                         if (is_null_sha1(p->one->sha1)) { /* addition */
154                                 assert(is_null_sha1(mp->remote));
155                                 hashcpy(mp->remote, p->two->sha1);
156                         } else if (is_null_sha1(p->two->sha1)) { /* deletion */
157                                 assert(is_null_sha1(mp->base));
158                                 hashcpy(mp->base, p->one->sha1);
159                         } else
160                                 assert(!"Invalid existing change recorded");
161                 } else {
162                         hashcpy(mp->obj, obj);
163                         hashcpy(mp->base, p->one->sha1);
164                         hashcpy(mp->local, uninitialized);
165                         hashcpy(mp->remote, p->two->sha1);
166                         len++;
167                 }
168                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
169                        sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
170                        sha1_to_hex(mp->remote));
171         }
172         diff_flush(&opt);
173         diff_tree_release_paths(&opt);
174
175         *num_changes = len;
176         return changes;
177 }
178
179 static void diff_tree_local(struct notes_merge_options *o,
180                             struct notes_merge_pair *changes, int len,
181                             const unsigned char *base,
182                             const unsigned char *local)
183 {
184         struct diff_options opt;
185         int i;
186
187         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
188                len, sha1_to_hex(base), sha1_to_hex(local));
189
190         diff_setup(&opt);
191         DIFF_OPT_SET(&opt, RECURSIVE);
192         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
193         diff_setup_done(&opt);
194         diff_tree_sha1(base, local, "", &opt);
195         diffcore_std(&opt);
196
197         for (i = 0; i < diff_queued_diff.nr; i++) {
198                 struct diff_filepair *p = diff_queued_diff.queue[i];
199                 struct notes_merge_pair *mp;
200                 int match;
201                 unsigned char obj[20];
202
203                 if (verify_notes_filepair(p, obj)) {
204                         trace_printf("\t\tCannot merge entry '%s' (%c): "
205                                "%.7s -> %.7s. Skipping!\n", p->one->path,
206                                p->status, sha1_to_hex(p->one->sha1),
207                                sha1_to_hex(p->two->sha1));
208                         continue;
209                 }
210                 mp = find_notes_merge_pair_pos(changes, len, obj, 0, &match);
211                 if (!match) {
212                         trace_printf("\t\tIgnoring local-only change for %s: "
213                                "%.7s -> %.7s\n", sha1_to_hex(obj),
214                                sha1_to_hex(p->one->sha1),
215                                sha1_to_hex(p->two->sha1));
216                         continue;
217                 }
218
219                 assert(!hashcmp(mp->obj, obj));
220                 if (is_null_sha1(p->two->sha1)) { /* deletion */
221                         /*
222                          * Either this is a true deletion (1), or it is part
223                          * of an A/D pair (2), or D/A pair (3):
224                          *
225                          * (1) mp->local is uninitialized; set it to null_sha1
226                          * (2) mp->local is not uninitialized; don't touch it
227                          * (3) mp->local is uninitialized; set it to null_sha1
228                          *     (will be overwritten by following addition)
229                          */
230                         if (!hashcmp(mp->local, uninitialized))
231                                 hashclr(mp->local);
232                 } else if (is_null_sha1(p->one->sha1)) { /* addition */
233                         /*
234                          * Either this is a true addition (1), or it is part
235                          * of an A/D pair (2), or D/A pair (3):
236                          *
237                          * (1) mp->local is uninitialized; set to p->two->sha1
238                          * (2) mp->local is uninitialized; set to p->two->sha1
239                          * (3) mp->local is null_sha1;     set to p->two->sha1
240                          */
241                         assert(is_null_sha1(mp->local) ||
242                                !hashcmp(mp->local, uninitialized));
243                         hashcpy(mp->local, p->two->sha1);
244                 } else { /* modification */
245                         /*
246                          * This is a true modification. p->one->sha1 shall
247                          * match mp->base, and mp->local shall be uninitialized.
248                          * Set mp->local to p->two->sha1.
249                          */
250                         assert(!hashcmp(p->one->sha1, mp->base));
251                         assert(!hashcmp(mp->local, uninitialized));
252                         hashcpy(mp->local, p->two->sha1);
253                 }
254                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
255                        sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
256                        sha1_to_hex(mp->local));
257         }
258         diff_flush(&opt);
259         diff_tree_release_paths(&opt);
260 }
261
262 static void check_notes_merge_worktree(struct notes_merge_options *o)
263 {
264         if (!o->has_worktree) {
265                 /*
266                  * Must establish NOTES_MERGE_WORKTREE.
267                  * Abort if NOTES_MERGE_WORKTREE already exists
268                  */
269                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
270                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
271                         if (advice_resolve_conflict)
272                                 die("You have not concluded your previous "
273                                     "notes merge (%s exists).\nPlease, use "
274                                     "'git notes merge --commit' or 'git notes "
275                                     "merge --abort' to commit/abort the "
276                                     "previous merge before you start a new "
277                                     "notes merge.", git_path("NOTES_MERGE_*"));
278                         else
279                                 die("You have not concluded your notes merge "
280                                     "(%s exists).", git_path("NOTES_MERGE_*"));
281                 }
282
283                 if (safe_create_leading_directories(git_path(
284                                 NOTES_MERGE_WORKTREE "/.test")))
285                         die_errno("unable to create directory %s",
286                                   git_path(NOTES_MERGE_WORKTREE));
287                 o->has_worktree = 1;
288         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
289                 /* NOTES_MERGE_WORKTREE should already be established */
290                 die("missing '%s'. This should not happen",
291                     git_path(NOTES_MERGE_WORKTREE));
292 }
293
294 static void write_buf_to_worktree(const unsigned char *obj,
295                                   const char *buf, unsigned long size)
296 {
297         int fd;
298         char *path = git_path(NOTES_MERGE_WORKTREE "/%s", sha1_to_hex(obj));
299         if (safe_create_leading_directories(path))
300                 die_errno("unable to create directory for '%s'", path);
301         if (file_exists(path))
302                 die("found existing file at '%s'", path);
303
304         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0666);
305         if (fd < 0)
306                 die_errno("failed to open '%s'", path);
307
308         while (size > 0) {
309                 long ret = write_in_full(fd, buf, size);
310                 if (ret < 0) {
311                         /* Ignore epipe */
312                         if (errno == EPIPE)
313                                 break;
314                         die_errno("notes-merge");
315                 } else if (!ret) {
316                         die("notes-merge: disk full?");
317                 }
318                 size -= ret;
319                 buf += ret;
320         }
321
322         close(fd);
323 }
324
325 static void write_note_to_worktree(const unsigned char *obj,
326                                    const unsigned char *note)
327 {
328         enum object_type type;
329         unsigned long size;
330         void *buf = read_sha1_file(note, &type, &size);
331
332         if (!buf)
333                 die("cannot read note %s for object %s",
334                     sha1_to_hex(note), sha1_to_hex(obj));
335         if (type != OBJ_BLOB)
336                 die("blob expected in note %s for object %s",
337                     sha1_to_hex(note), sha1_to_hex(obj));
338         write_buf_to_worktree(obj, buf, size);
339         free(buf);
340 }
341
342 static int ll_merge_in_worktree(struct notes_merge_options *o,
343                                 struct notes_merge_pair *p)
344 {
345         mmbuffer_t result_buf;
346         mmfile_t base, local, remote;
347         int status;
348
349         read_mmblob(&base, p->base);
350         read_mmblob(&local, p->local);
351         read_mmblob(&remote, p->remote);
352
353         status = ll_merge(&result_buf, sha1_to_hex(p->obj), &base, NULL,
354                           &local, o->local_ref, &remote, o->remote_ref, NULL);
355
356         free(base.ptr);
357         free(local.ptr);
358         free(remote.ptr);
359
360         if ((status < 0) || !result_buf.ptr)
361                 die("Failed to execute internal merge");
362
363         write_buf_to_worktree(p->obj, result_buf.ptr, result_buf.size);
364         free(result_buf.ptr);
365
366         return status;
367 }
368
369 static int merge_one_change_manual(struct notes_merge_options *o,
370                                    struct notes_merge_pair *p,
371                                    struct notes_tree *t)
372 {
373         const char *lref = o->local_ref ? o->local_ref : "local version";
374         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
375
376         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
377                "local = %.7s, remote = %.7s)\n",
378                sha1_to_hex(p->obj), sha1_to_hex(p->base),
379                sha1_to_hex(p->local), sha1_to_hex(p->remote));
380
381         /* add "Conflicts:" section to commit message first time through */
382         if (!o->has_worktree)
383                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
384
385         strbuf_addf(&(o->commit_msg), "\t%s\n", sha1_to_hex(p->obj));
386
387         if (o->verbosity >= 2)
388                 printf("Auto-merging notes for %s\n", sha1_to_hex(p->obj));
389         check_notes_merge_worktree(o);
390         if (is_null_sha1(p->local)) {
391                 /* D/F conflict, checkout p->remote */
392                 assert(!is_null_sha1(p->remote));
393                 if (o->verbosity >= 1)
394                         printf("CONFLICT (delete/modify): Notes for object %s "
395                                 "deleted in %s and modified in %s. Version from %s "
396                                 "left in tree.\n",
397                                 sha1_to_hex(p->obj), lref, rref, rref);
398                 write_note_to_worktree(p->obj, p->remote);
399         } else if (is_null_sha1(p->remote)) {
400                 /* D/F conflict, checkout p->local */
401                 assert(!is_null_sha1(p->local));
402                 if (o->verbosity >= 1)
403                         printf("CONFLICT (delete/modify): Notes for object %s "
404                                 "deleted in %s and modified in %s. Version from %s "
405                                 "left in tree.\n",
406                                 sha1_to_hex(p->obj), rref, lref, lref);
407                 write_note_to_worktree(p->obj, p->local);
408         } else {
409                 /* "regular" conflict, checkout result of ll_merge() */
410                 const char *reason = "content";
411                 if (is_null_sha1(p->base))
412                         reason = "add/add";
413                 assert(!is_null_sha1(p->local));
414                 assert(!is_null_sha1(p->remote));
415                 if (o->verbosity >= 1)
416                         printf("CONFLICT (%s): Merge conflict in notes for "
417                                 "object %s\n", reason, sha1_to_hex(p->obj));
418                 ll_merge_in_worktree(o, p);
419         }
420
421         trace_printf("\t\t\tremoving from partial merge result\n");
422         remove_note(t, p->obj);
423
424         return 1;
425 }
426
427 static int merge_one_change(struct notes_merge_options *o,
428                             struct notes_merge_pair *p, struct notes_tree *t)
429 {
430         /*
431          * Return 0 if change is successfully resolved (stored in notes_tree).
432          * Return 1 is change results in a conflict (NOT stored in notes_tree,
433          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
434          */
435         switch (o->strategy) {
436         case NOTES_MERGE_RESOLVE_MANUAL:
437                 return merge_one_change_manual(o, p, t);
438         case NOTES_MERGE_RESOLVE_OURS:
439                 if (o->verbosity >= 2)
440                         printf("Using local notes for %s\n",
441                                                 sha1_to_hex(p->obj));
442                 /* nothing to do */
443                 return 0;
444         case NOTES_MERGE_RESOLVE_THEIRS:
445                 if (o->verbosity >= 2)
446                         printf("Using remote notes for %s\n",
447                                                 sha1_to_hex(p->obj));
448                 if (add_note(t, p->obj, p->remote, combine_notes_overwrite))
449                         die("BUG: combine_notes_overwrite failed");
450                 return 0;
451         case NOTES_MERGE_RESOLVE_UNION:
452                 if (o->verbosity >= 2)
453                         printf("Concatenating local and remote notes for %s\n",
454                                                         sha1_to_hex(p->obj));
455                 if (add_note(t, p->obj, p->remote, combine_notes_concatenate))
456                         die("failed to concatenate notes "
457                             "(combine_notes_concatenate)");
458                 return 0;
459         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
460                 if (o->verbosity >= 2)
461                         printf("Concatenating unique lines in local and remote "
462                                 "notes for %s\n", sha1_to_hex(p->obj));
463                 if (add_note(t, p->obj, p->remote, combine_notes_cat_sort_uniq))
464                         die("failed to concatenate notes "
465                             "(combine_notes_cat_sort_uniq)");
466                 return 0;
467         }
468         die("Unknown strategy (%i).", o->strategy);
469 }
470
471 static int merge_changes(struct notes_merge_options *o,
472                          struct notes_merge_pair *changes, int *num_changes,
473                          struct notes_tree *t)
474 {
475         int i, conflicts = 0;
476
477         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
478         for (i = 0; i < *num_changes; i++) {
479                 struct notes_merge_pair *p = changes + i;
480                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
481                        sha1_to_hex(p->obj), sha1_to_hex(p->base),
482                        sha1_to_hex(p->local), sha1_to_hex(p->remote));
483
484                 if (!hashcmp(p->base, p->remote)) {
485                         /* no remote change; nothing to do */
486                         trace_printf("\t\t\tskipping (no remote change)\n");
487                 } else if (!hashcmp(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 (!hashcmp(p->local, uninitialized) ||
491                            !hashcmp(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, p->remote,
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, local_sha1, 0, 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, 1);
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.sha1;
605                 base_tree_sha1 = bases->item->tree->object.sha1;
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.sha1;
612                 base_tree_sha1 = bases->item->tree->object.sha1;
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", sha1_to_hex(remote->object.sha1),
621                         sha1_to_hex(local->object.sha1),
622                         sha1_to_hex(base_sha1));
623
624         if (!hashcmp(remote->object.sha1, 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.sha1);
629                 goto found_result;
630         }
631         if (!hashcmp(local->object.sha1, base_sha1)) {
632                 /* Fast-forward; result == remote commit */
633                 if (o->verbosity >= 2)
634                         printf("Fast-forward\n");
635                 hashcpy(result_sha1, remote->object.sha1);
636                 goto found_result;
637         }
638
639         result = merge_from_diffs(o, base_tree_sha1, local->tree->object.sha1,
640                                   remote->tree->object.sha1, 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, &o->commit_msg,
648                                     result_sha1);
649         }
650
651 found_result:
652         free_commit_list(bases);
653         strbuf_release(&(o->commit_msg));
654         trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
655                result, sha1_to_hex(result_sha1));
656         return result;
657 }
658
659 int notes_merge_commit(struct notes_merge_options *o,
660                        struct notes_tree *partial_tree,
661                        struct commit *partial_commit,
662                        unsigned char *result_sha1)
663 {
664         /*
665          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
666          * found notes to 'partial_tree'. Write the updated notes tree to
667          * the DB, and commit the resulting tree object while reusing the
668          * commit message and parents from 'partial_commit'.
669          * Finally store the new commit object SHA1 into 'result_sha1'.
670          */
671         DIR *dir;
672         struct dirent *e;
673         struct strbuf path = STRBUF_INIT;
674         char *msg = strstr(partial_commit->buffer, "\n\n");
675         struct strbuf sb_msg = STRBUF_INIT;
676         int baselen;
677
678         strbuf_addstr(&path, git_path(NOTES_MERGE_WORKTREE));
679         if (o->verbosity >= 3)
680                 printf("Committing notes in notes merge worktree at %s\n",
681                         path.buf);
682
683         if (!msg || msg[2] == '\0')
684                 die("partial notes commit has empty message");
685         msg += 2;
686
687         dir = opendir(path.buf);
688         if (!dir)
689                 die_errno("could not open %s", path.buf);
690
691         strbuf_addch(&path, '/');
692         baselen = path.len;
693         while ((e = readdir(dir)) != NULL) {
694                 struct stat st;
695                 unsigned char obj_sha1[20], blob_sha1[20];
696
697                 if (is_dot_or_dotdot(e->d_name))
698                         continue;
699
700                 if (strlen(e->d_name) != 40 || get_sha1_hex(e->d_name, obj_sha1)) {
701                         if (o->verbosity >= 3)
702                                 printf("Skipping non-SHA1 entry '%s%s'\n",
703                                         path.buf, e->d_name);
704                         continue;
705                 }
706
707                 strbuf_addstr(&path, e->d_name);
708                 /* write file as blob, and add to partial_tree */
709                 if (stat(path.buf, &st))
710                         die_errno("Failed to stat '%s'", path.buf);
711                 if (index_path(blob_sha1, path.buf, &st, HASH_WRITE_OBJECT))
712                         die("Failed to write blob object from '%s'", path.buf);
713                 if (add_note(partial_tree, obj_sha1, blob_sha1, NULL))
714                         die("Failed to add resolved note '%s' to notes tree",
715                             path.buf);
716                 if (o->verbosity >= 4)
717                         printf("Added resolved note for object %s: %s\n",
718                                 sha1_to_hex(obj_sha1), sha1_to_hex(blob_sha1));
719                 strbuf_setlen(&path, baselen);
720         }
721
722         strbuf_attach(&sb_msg, msg, strlen(msg), strlen(msg) + 1);
723         create_notes_commit(partial_tree, partial_commit->parents, &sb_msg,
724                             result_sha1);
725         if (o->verbosity >= 4)
726                 printf("Finalized notes merge commit: %s\n",
727                         sha1_to_hex(result_sha1));
728         strbuf_release(&path);
729         closedir(dir);
730         return 0;
731 }
732
733 int notes_merge_abort(struct notes_merge_options *o)
734 {
735         /*
736          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
737          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
738          * the current working directory of the user.
739          */
740         struct strbuf buf = STRBUF_INIT;
741         int ret;
742
743         strbuf_addstr(&buf, git_path(NOTES_MERGE_WORKTREE));
744         if (o->verbosity >= 3)
745                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
746         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
747         strbuf_release(&buf);
748         return ret;
749 }