notes-merge: use O_EXCL to avoid overwriting existing files
[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         free_pathspec(&opt.pathspec);
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         free_pathspec(&opt.pathspec);
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_const(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_pathdup(NOTES_MERGE_WORKTREE "/%s", sha1_to_hex(obj));
299         if (safe_create_leading_directories_const(path))
300                 die_errno("unable to create directory for '%s'", path);
301
302         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
303
304         while (size > 0) {
305                 long ret = write_in_full(fd, buf, size);
306                 if (ret < 0) {
307                         /* Ignore epipe */
308                         if (errno == EPIPE)
309                                 break;
310                         die_errno("notes-merge");
311                 } else if (!ret) {
312                         die("notes-merge: disk full?");
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 unsigned char *obj,
323                                    const unsigned char *note)
324 {
325         enum object_type type;
326         unsigned long size;
327         void *buf = read_sha1_file(note, &type, &size);
328
329         if (!buf)
330                 die("cannot read note %s for object %s",
331                     sha1_to_hex(note), sha1_to_hex(obj));
332         if (type != OBJ_BLOB)
333                 die("blob expected in note %s for object %s",
334                     sha1_to_hex(note), sha1_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, sha1_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                sha1_to_hex(p->obj), sha1_to_hex(p->base),
376                sha1_to_hex(p->local), sha1_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", sha1_to_hex(p->obj));
383
384         if (o->verbosity >= 2)
385                 printf("Auto-merging notes for %s\n", sha1_to_hex(p->obj));
386         check_notes_merge_worktree(o);
387         if (is_null_sha1(p->local)) {
388                 /* D/F conflict, checkout p->remote */
389                 assert(!is_null_sha1(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                                 sha1_to_hex(p->obj), lref, rref, rref);
395                 write_note_to_worktree(p->obj, p->remote);
396         } else if (is_null_sha1(p->remote)) {
397                 /* D/F conflict, checkout p->local */
398                 assert(!is_null_sha1(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                                 sha1_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_sha1(p->base))
409                         reason = "add/add";
410                 assert(!is_null_sha1(p->local));
411                 assert(!is_null_sha1(p->remote));
412                 if (o->verbosity >= 1)
413                         printf("CONFLICT (%s): Merge conflict in notes for "
414                                 "object %s\n", reason, sha1_to_hex(p->obj));
415                 ll_merge_in_worktree(o, p);
416         }
417
418         trace_printf("\t\t\tremoving from partial merge result\n");
419         remove_note(t, p->obj);
420
421         return 1;
422 }
423
424 static int merge_one_change(struct notes_merge_options *o,
425                             struct notes_merge_pair *p, struct notes_tree *t)
426 {
427         /*
428          * Return 0 if change is successfully resolved (stored in notes_tree).
429          * Return 1 is change results in a conflict (NOT stored in notes_tree,
430          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
431          */
432         switch (o->strategy) {
433         case NOTES_MERGE_RESOLVE_MANUAL:
434                 return merge_one_change_manual(o, p, t);
435         case NOTES_MERGE_RESOLVE_OURS:
436                 if (o->verbosity >= 2)
437                         printf("Using local notes for %s\n",
438                                                 sha1_to_hex(p->obj));
439                 /* nothing to do */
440                 return 0;
441         case NOTES_MERGE_RESOLVE_THEIRS:
442                 if (o->verbosity >= 2)
443                         printf("Using remote notes for %s\n",
444                                                 sha1_to_hex(p->obj));
445                 if (add_note(t, p->obj, p->remote, combine_notes_overwrite))
446                         die("BUG: combine_notes_overwrite failed");
447                 return 0;
448         case NOTES_MERGE_RESOLVE_UNION:
449                 if (o->verbosity >= 2)
450                         printf("Concatenating local and remote notes for %s\n",
451                                                         sha1_to_hex(p->obj));
452                 if (add_note(t, p->obj, p->remote, combine_notes_concatenate))
453                         die("failed to concatenate notes "
454                             "(combine_notes_concatenate)");
455                 return 0;
456         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
457                 if (o->verbosity >= 2)
458                         printf("Concatenating unique lines in local and remote "
459                                 "notes for %s\n", sha1_to_hex(p->obj));
460                 if (add_note(t, p->obj, p->remote, combine_notes_cat_sort_uniq))
461                         die("failed to concatenate notes "
462                             "(combine_notes_cat_sort_uniq)");
463                 return 0;
464         }
465         die("Unknown strategy (%i).", o->strategy);
466 }
467
468 static int merge_changes(struct notes_merge_options *o,
469                          struct notes_merge_pair *changes, int *num_changes,
470                          struct notes_tree *t)
471 {
472         int i, conflicts = 0;
473
474         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
475         for (i = 0; i < *num_changes; i++) {
476                 struct notes_merge_pair *p = changes + i;
477                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
478                        sha1_to_hex(p->obj), sha1_to_hex(p->base),
479                        sha1_to_hex(p->local), sha1_to_hex(p->remote));
480
481                 if (!hashcmp(p->base, p->remote)) {
482                         /* no remote change; nothing to do */
483                         trace_printf("\t\t\tskipping (no remote change)\n");
484                 } else if (!hashcmp(p->local, p->remote)) {
485                         /* same change in local and remote; nothing to do */
486                         trace_printf("\t\t\tskipping (local == remote)\n");
487                 } else if (!hashcmp(p->local, uninitialized) ||
488                            !hashcmp(p->local, p->base)) {
489                         /* no local change; adopt remote change */
490                         trace_printf("\t\t\tno local change, adopted remote\n");
491                         if (add_note(t, p->obj, p->remote,
492                                      combine_notes_overwrite))
493                                 die("BUG: combine_notes_overwrite failed");
494                 } else {
495                         /* need file-level merge between local and remote */
496                         trace_printf("\t\t\tneed content-level merge\n");
497                         conflicts += merge_one_change(o, p, t);
498                 }
499         }
500
501         return conflicts;
502 }
503
504 static int merge_from_diffs(struct notes_merge_options *o,
505                             const unsigned char *base,
506                             const unsigned char *local,
507                             const unsigned char *remote, struct notes_tree *t)
508 {
509         struct notes_merge_pair *changes;
510         int num_changes, conflicts;
511
512         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
513                "remote = %.7s)\n", sha1_to_hex(base), sha1_to_hex(local),
514                sha1_to_hex(remote));
515
516         changes = diff_tree_remote(o, base, remote, &num_changes);
517         diff_tree_local(o, changes, num_changes, base, local);
518
519         conflicts = merge_changes(o, changes, &num_changes, t);
520         free(changes);
521
522         if (o->verbosity >= 4)
523                 printf(t->dirty ?
524                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
525                        "Merge result: %i unmerged notes and a clean notes tree\n",
526                        conflicts);
527
528         return conflicts ? -1 : 1;
529 }
530
531 int notes_merge(struct notes_merge_options *o,
532                 struct notes_tree *local_tree,
533                 unsigned char *result_sha1)
534 {
535         unsigned char local_sha1[20], remote_sha1[20];
536         struct commit *local, *remote;
537         struct commit_list *bases = NULL;
538         const unsigned char *base_sha1, *base_tree_sha1;
539         int result = 0;
540
541         assert(o->local_ref && o->remote_ref);
542         assert(!strcmp(o->local_ref, local_tree->ref));
543         hashclr(result_sha1);
544
545         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
546                o->local_ref, o->remote_ref);
547
548         /* Dereference o->local_ref into local_sha1 */
549         if (read_ref_full(o->local_ref, 0, local_sha1, NULL))
550                 die("Failed to resolve local notes ref '%s'", o->local_ref);
551         else if (!check_refname_format(o->local_ref, 0) &&
552                 is_null_sha1(local_sha1))
553                 local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
554         else if (!(local = lookup_commit_reference(local_sha1)))
555                 die("Could not parse local commit %s (%s)",
556                     sha1_to_hex(local_sha1), o->local_ref);
557         trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
558
559         /* Dereference o->remote_ref into remote_sha1 */
560         if (get_sha1(o->remote_ref, remote_sha1)) {
561                 /*
562                  * Failed to get remote_sha1. If o->remote_ref looks like an
563                  * unborn ref, perform the merge using an empty notes tree.
564                  */
565                 if (!check_refname_format(o->remote_ref, 0)) {
566                         hashclr(remote_sha1);
567                         remote = NULL;
568                 } else {
569                         die("Failed to resolve remote notes ref '%s'",
570                             o->remote_ref);
571                 }
572         } else if (!(remote = lookup_commit_reference(remote_sha1))) {
573                 die("Could not parse remote commit %s (%s)",
574                     sha1_to_hex(remote_sha1), o->remote_ref);
575         }
576         trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
577
578         if (!local && !remote)
579                 die("Cannot merge empty notes ref (%s) into empty notes ref "
580                     "(%s)", o->remote_ref, o->local_ref);
581         if (!local) {
582                 /* result == remote commit */
583                 hashcpy(result_sha1, remote_sha1);
584                 goto found_result;
585         }
586         if (!remote) {
587                 /* result == local commit */
588                 hashcpy(result_sha1, local_sha1);
589                 goto found_result;
590         }
591         assert(local && remote);
592
593         /* Find merge bases */
594         bases = get_merge_bases(local, remote);
595         if (!bases) {
596                 base_sha1 = null_sha1;
597                 base_tree_sha1 = EMPTY_TREE_SHA1_BIN;
598                 if (o->verbosity >= 4)
599                         printf("No merge base found; doing history-less merge\n");
600         } else if (!bases->next) {
601                 base_sha1 = bases->item->object.oid.hash;
602                 base_tree_sha1 = bases->item->tree->object.oid.hash;
603                 if (o->verbosity >= 4)
604                         printf("One merge base found (%.7s)\n",
605                                 sha1_to_hex(base_sha1));
606         } else {
607                 /* TODO: How to handle multiple merge-bases? */
608                 base_sha1 = bases->item->object.oid.hash;
609                 base_tree_sha1 = bases->item->tree->object.oid.hash;
610                 if (o->verbosity >= 3)
611                         printf("Multiple merge bases found. Using the first "
612                                 "(%.7s)\n", sha1_to_hex(base_sha1));
613         }
614
615         if (o->verbosity >= 4)
616                 printf("Merging remote commit %.7s into local commit %.7s with "
617                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
618                         oid_to_hex(&local->object.oid),
619                         sha1_to_hex(base_sha1));
620
621         if (!hashcmp(remote->object.oid.hash, base_sha1)) {
622                 /* Already merged; result == local commit */
623                 if (o->verbosity >= 2)
624                         printf("Already up-to-date!\n");
625                 hashcpy(result_sha1, local->object.oid.hash);
626                 goto found_result;
627         }
628         if (!hashcmp(local->object.oid.hash, base_sha1)) {
629                 /* Fast-forward; result == remote commit */
630                 if (o->verbosity >= 2)
631                         printf("Fast-forward\n");
632                 hashcpy(result_sha1, remote->object.oid.hash);
633                 goto found_result;
634         }
635
636         result = merge_from_diffs(o, base_tree_sha1, local->tree->object.oid.hash,
637                                   remote->tree->object.oid.hash, local_tree);
638
639         if (result != 0) { /* non-trivial merge (with or without conflicts) */
640                 /* Commit (partial) result */
641                 struct commit_list *parents = NULL;
642                 commit_list_insert(remote, &parents); /* LIFO order */
643                 commit_list_insert(local, &parents);
644                 create_notes_commit(local_tree, parents,
645                                     o->commit_msg.buf, o->commit_msg.len,
646                                     result_sha1);
647         }
648
649 found_result:
650         free_commit_list(bases);
651         strbuf_release(&(o->commit_msg));
652         trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
653                result, sha1_to_hex(result_sha1));
654         return result;
655 }
656
657 int notes_merge_commit(struct notes_merge_options *o,
658                        struct notes_tree *partial_tree,
659                        struct commit *partial_commit,
660                        unsigned char *result_sha1)
661 {
662         /*
663          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
664          * found notes to 'partial_tree'. Write the updated notes tree to
665          * the DB, and commit the resulting tree object while reusing the
666          * commit message and parents from 'partial_commit'.
667          * Finally store the new commit object SHA1 into 'result_sha1'.
668          */
669         DIR *dir;
670         struct dirent *e;
671         struct strbuf path = STRBUF_INIT;
672         const char *buffer = get_commit_buffer(partial_commit, NULL);
673         const char *msg = strstr(buffer, "\n\n");
674         int baselen;
675
676         strbuf_addstr(&path, git_path(NOTES_MERGE_WORKTREE));
677         if (o->verbosity >= 3)
678                 printf("Committing notes in notes merge worktree at %s\n",
679                         path.buf);
680
681         if (!msg || msg[2] == '\0')
682                 die("partial notes commit has empty message");
683         msg += 2;
684
685         dir = opendir(path.buf);
686         if (!dir)
687                 die_errno("could not open %s", path.buf);
688
689         strbuf_addch(&path, '/');
690         baselen = path.len;
691         while ((e = readdir(dir)) != NULL) {
692                 struct stat st;
693                 unsigned char obj_sha1[20], blob_sha1[20];
694
695                 if (is_dot_or_dotdot(e->d_name))
696                         continue;
697
698                 if (strlen(e->d_name) != 40 || get_sha1_hex(e->d_name, obj_sha1)) {
699                         if (o->verbosity >= 3)
700                                 printf("Skipping non-SHA1 entry '%s%s'\n",
701                                         path.buf, e->d_name);
702                         continue;
703                 }
704
705                 strbuf_addstr(&path, e->d_name);
706                 /* write file as blob, and add to partial_tree */
707                 if (stat(path.buf, &st))
708                         die_errno("Failed to stat '%s'", path.buf);
709                 if (index_path(blob_sha1, path.buf, &st, HASH_WRITE_OBJECT))
710                         die("Failed to write blob object from '%s'", path.buf);
711                 if (add_note(partial_tree, obj_sha1, blob_sha1, NULL))
712                         die("Failed to add resolved note '%s' to notes tree",
713                             path.buf);
714                 if (o->verbosity >= 4)
715                         printf("Added resolved note for object %s: %s\n",
716                                 sha1_to_hex(obj_sha1), sha1_to_hex(blob_sha1));
717                 strbuf_setlen(&path, baselen);
718         }
719
720         create_notes_commit(partial_tree, partial_commit->parents,
721                             msg, strlen(msg), result_sha1);
722         unuse_commit_buffer(partial_commit, buffer);
723         if (o->verbosity >= 4)
724                 printf("Finalized notes merge commit: %s\n",
725                         sha1_to_hex(result_sha1));
726         strbuf_release(&path);
727         closedir(dir);
728         return 0;
729 }
730
731 int notes_merge_abort(struct notes_merge_options *o)
732 {
733         /*
734          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
735          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
736          * the current working directory of the user.
737          */
738         struct strbuf buf = STRBUF_INIT;
739         int ret;
740
741         strbuf_addstr(&buf, git_path(NOTES_MERGE_WORKTREE));
742         if (o->verbosity >= 3)
743                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
744         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
745         strbuf_release(&buf);
746         return ret;
747 }