Merge branch 'pc/submodule-helper'
[git] / sha1_name.c
1 #include "cache.h"
2 #include "config.h"
3 #include "tag.h"
4 #include "commit.h"
5 #include "tree.h"
6 #include "blob.h"
7 #include "tree-walk.h"
8 #include "refs.h"
9 #include "remote.h"
10 #include "dir.h"
11 #include "sha1-array.h"
12 #include "packfile.h"
13
14 static int get_oid_oneline(const char *, struct object_id *, struct commit_list *);
15
16 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
17
18 struct disambiguate_state {
19         int len; /* length of prefix in hex chars */
20         char hex_pfx[GIT_MAX_HEXSZ + 1];
21         struct object_id bin_pfx;
22
23         disambiguate_hint_fn fn;
24         void *cb_data;
25         struct object_id candidate;
26         unsigned candidate_exists:1;
27         unsigned candidate_checked:1;
28         unsigned candidate_ok:1;
29         unsigned disambiguate_fn_used:1;
30         unsigned ambiguous:1;
31         unsigned always_call_fn:1;
32 };
33
34 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
35 {
36         if (ds->always_call_fn) {
37                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
38                 return;
39         }
40         if (!ds->candidate_exists) {
41                 /* this is the first candidate */
42                 oidcpy(&ds->candidate, current);
43                 ds->candidate_exists = 1;
44                 return;
45         } else if (!oidcmp(&ds->candidate, current)) {
46                 /* the same as what we already have seen */
47                 return;
48         }
49
50         if (!ds->fn) {
51                 /* cannot disambiguate between ds->candidate and current */
52                 ds->ambiguous = 1;
53                 return;
54         }
55
56         if (!ds->candidate_checked) {
57                 ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
58                 ds->disambiguate_fn_used = 1;
59                 ds->candidate_checked = 1;
60         }
61
62         if (!ds->candidate_ok) {
63                 /* discard the candidate; we know it does not satisfy fn */
64                 oidcpy(&ds->candidate, current);
65                 ds->candidate_checked = 0;
66                 return;
67         }
68
69         /* if we reach this point, we know ds->candidate satisfies fn */
70         if (ds->fn(current, ds->cb_data)) {
71                 /*
72                  * if both current and candidate satisfy fn, we cannot
73                  * disambiguate.
74                  */
75                 ds->candidate_ok = 0;
76                 ds->ambiguous = 1;
77         }
78
79         /* otherwise, current can be discarded and candidate is still good */
80 }
81
82 static int append_loose_object(const struct object_id *oid, const char *path,
83                                void *data)
84 {
85         oid_array_append(data, oid);
86         return 0;
87 }
88
89 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
90
91 static void find_short_object_filename(struct disambiguate_state *ds)
92 {
93         int subdir_nr = ds->bin_pfx.hash[0];
94         struct alternate_object_database *alt;
95         static struct alternate_object_database *fakeent;
96
97         if (!fakeent) {
98                 /*
99                  * Create a "fake" alternate object database that
100                  * points to our own object database, to make it
101                  * easier to get a temporary working space in
102                  * alt->name/alt->base while iterating over the
103                  * object databases including our own.
104                  */
105                 fakeent = alloc_alt_odb(get_object_directory());
106         }
107         fakeent->next = alt_odb_list;
108
109         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
110                 int pos;
111
112                 if (!alt->loose_objects_subdir_seen[subdir_nr]) {
113                         struct strbuf *buf = alt_scratch_buf(alt);
114                         for_each_file_in_obj_subdir(subdir_nr, buf,
115                                                     append_loose_object,
116                                                     NULL, NULL,
117                                                     &alt->loose_objects_cache);
118                         alt->loose_objects_subdir_seen[subdir_nr] = 1;
119                 }
120
121                 pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
122                 if (pos < 0)
123                         pos = -1 - pos;
124                 while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
125                         const struct object_id *oid;
126                         oid = alt->loose_objects_cache.oid + pos;
127                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
128                                 break;
129                         update_candidates(ds, oid);
130                         pos++;
131                 }
132         }
133 }
134
135 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
136 {
137         do {
138                 if (*a != *b)
139                         return 0;
140                 a++;
141                 b++;
142                 len -= 2;
143         } while (len > 1);
144         if (len)
145                 if ((*a ^ *b) & 0xf0)
146                         return 0;
147         return 1;
148 }
149
150 static void unique_in_pack(struct packed_git *p,
151                            struct disambiguate_state *ds)
152 {
153         uint32_t num, last, i, first = 0;
154         const struct object_id *current = NULL;
155
156         if (open_pack_index(p) || !p->num_objects)
157                 return;
158
159         num = p->num_objects;
160         last = num;
161         while (first < last) {
162                 uint32_t mid = first + (last - first) / 2;
163                 const unsigned char *current;
164                 int cmp;
165
166                 current = nth_packed_object_sha1(p, mid);
167                 cmp = hashcmp(ds->bin_pfx.hash, current);
168                 if (!cmp) {
169                         first = mid;
170                         break;
171                 }
172                 if (cmp > 0) {
173                         first = mid+1;
174                         continue;
175                 }
176                 last = mid;
177         }
178
179         /*
180          * At this point, "first" is the location of the lowest object
181          * with an object name that could match "bin_pfx".  See if we have
182          * 0, 1 or more objects that actually match(es).
183          */
184         for (i = first; i < num && !ds->ambiguous; i++) {
185                 struct object_id oid;
186                 current = nth_packed_object_oid(&oid, p, i);
187                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
188                         break;
189                 update_candidates(ds, current);
190         }
191 }
192
193 static void find_short_packed_object(struct disambiguate_state *ds)
194 {
195         struct packed_git *p;
196
197         prepare_packed_git();
198         for (p = packed_git; p && !ds->ambiguous; p = p->next)
199                 unique_in_pack(p, ds);
200 }
201
202 #define SHORT_NAME_NOT_FOUND (-1)
203 #define SHORT_NAME_AMBIGUOUS (-2)
204
205 static int finish_object_disambiguation(struct disambiguate_state *ds,
206                                         struct object_id *oid)
207 {
208         if (ds->ambiguous)
209                 return SHORT_NAME_AMBIGUOUS;
210
211         if (!ds->candidate_exists)
212                 return SHORT_NAME_NOT_FOUND;
213
214         if (!ds->candidate_checked)
215                 /*
216                  * If this is the only candidate, there is no point
217                  * calling the disambiguation hint callback.
218                  *
219                  * On the other hand, if the current candidate
220                  * replaced an earlier candidate that did _not_ pass
221                  * the disambiguation hint callback, then we do have
222                  * more than one objects that match the short name
223                  * given, so we should make sure this one matches;
224                  * otherwise, if we discovered this one and the one
225                  * that we previously discarded in the reverse order,
226                  * we would end up showing different results in the
227                  * same repository!
228                  */
229                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
230                                     ds->fn(&ds->candidate, ds->cb_data));
231
232         if (!ds->candidate_ok)
233                 return SHORT_NAME_AMBIGUOUS;
234
235         oidcpy(oid, &ds->candidate);
236         return 0;
237 }
238
239 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
240 {
241         int kind = sha1_object_info(oid->hash, NULL);
242         return kind == OBJ_COMMIT;
243 }
244
245 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
246 {
247         struct object *obj;
248         int kind;
249
250         kind = sha1_object_info(oid->hash, NULL);
251         if (kind == OBJ_COMMIT)
252                 return 1;
253         if (kind != OBJ_TAG)
254                 return 0;
255
256         /* We need to do this the hard way... */
257         obj = deref_tag(parse_object(oid), NULL, 0);
258         if (obj && obj->type == OBJ_COMMIT)
259                 return 1;
260         return 0;
261 }
262
263 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
264 {
265         int kind = sha1_object_info(oid->hash, NULL);
266         return kind == OBJ_TREE;
267 }
268
269 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
270 {
271         struct object *obj;
272         int kind;
273
274         kind = sha1_object_info(oid->hash, NULL);
275         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
276                 return 1;
277         if (kind != OBJ_TAG)
278                 return 0;
279
280         /* We need to do this the hard way... */
281         obj = deref_tag(parse_object(oid), NULL, 0);
282         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
283                 return 1;
284         return 0;
285 }
286
287 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
288 {
289         int kind = sha1_object_info(oid->hash, NULL);
290         return kind == OBJ_BLOB;
291 }
292
293 static disambiguate_hint_fn default_disambiguate_hint;
294
295 int set_disambiguate_hint_config(const char *var, const char *value)
296 {
297         static const struct {
298                 const char *name;
299                 disambiguate_hint_fn fn;
300         } hints[] = {
301                 { "none", NULL },
302                 { "commit", disambiguate_commit_only },
303                 { "committish", disambiguate_committish_only },
304                 { "tree", disambiguate_tree_only },
305                 { "treeish", disambiguate_treeish_only },
306                 { "blob", disambiguate_blob_only }
307         };
308         int i;
309
310         if (!value)
311                 return config_error_nonbool(var);
312
313         for (i = 0; i < ARRAY_SIZE(hints); i++) {
314                 if (!strcasecmp(value, hints[i].name)) {
315                         default_disambiguate_hint = hints[i].fn;
316                         return 0;
317                 }
318         }
319
320         return error("unknown hint type for '%s': %s", var, value);
321 }
322
323 static int init_object_disambiguation(const char *name, int len,
324                                       struct disambiguate_state *ds)
325 {
326         int i;
327
328         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
329                 return -1;
330
331         memset(ds, 0, sizeof(*ds));
332
333         for (i = 0; i < len ;i++) {
334                 unsigned char c = name[i];
335                 unsigned char val;
336                 if (c >= '0' && c <= '9')
337                         val = c - '0';
338                 else if (c >= 'a' && c <= 'f')
339                         val = c - 'a' + 10;
340                 else if (c >= 'A' && c <='F') {
341                         val = c - 'A' + 10;
342                         c -= 'A' - 'a';
343                 }
344                 else
345                         return -1;
346                 ds->hex_pfx[i] = c;
347                 if (!(i & 1))
348                         val <<= 4;
349                 ds->bin_pfx.hash[i >> 1] |= val;
350         }
351
352         ds->len = len;
353         ds->hex_pfx[len] = '\0';
354         prepare_alt_odb();
355         return 0;
356 }
357
358 static int show_ambiguous_object(const struct object_id *oid, void *data)
359 {
360         const struct disambiguate_state *ds = data;
361         struct strbuf desc = STRBUF_INIT;
362         int type;
363
364
365         if (ds->fn && !ds->fn(oid, ds->cb_data))
366                 return 0;
367
368         type = sha1_object_info(oid->hash, NULL);
369         if (type == OBJ_COMMIT) {
370                 struct commit *commit = lookup_commit(oid);
371                 if (commit) {
372                         struct pretty_print_context pp = {0};
373                         pp.date_mode.type = DATE_SHORT;
374                         format_commit_message(commit, " %ad - %s", &desc, &pp);
375                 }
376         } else if (type == OBJ_TAG) {
377                 struct tag *tag = lookup_tag(oid);
378                 if (!parse_tag(tag) && tag->tag)
379                         strbuf_addf(&desc, " %s", tag->tag);
380         }
381
382         advise("  %s %s%s",
383                find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
384                type_name(type) ? type_name(type) : "unknown type",
385                desc.buf);
386
387         strbuf_release(&desc);
388         return 0;
389 }
390
391 static int get_short_oid(const char *name, int len, struct object_id *oid,
392                           unsigned flags)
393 {
394         int status;
395         struct disambiguate_state ds;
396         int quietly = !!(flags & GET_OID_QUIETLY);
397
398         if (init_object_disambiguation(name, len, &ds) < 0)
399                 return -1;
400
401         if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
402                 die("BUG: multiple get_short_oid disambiguator flags");
403
404         if (flags & GET_OID_COMMIT)
405                 ds.fn = disambiguate_commit_only;
406         else if (flags & GET_OID_COMMITTISH)
407                 ds.fn = disambiguate_committish_only;
408         else if (flags & GET_OID_TREE)
409                 ds.fn = disambiguate_tree_only;
410         else if (flags & GET_OID_TREEISH)
411                 ds.fn = disambiguate_treeish_only;
412         else if (flags & GET_OID_BLOB)
413                 ds.fn = disambiguate_blob_only;
414         else
415                 ds.fn = default_disambiguate_hint;
416
417         find_short_object_filename(&ds);
418         find_short_packed_object(&ds);
419         status = finish_object_disambiguation(&ds, oid);
420
421         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
422                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
423
424                 /*
425                  * We may still have ambiguity if we simply saw a series of
426                  * candidates that did not satisfy our hint function. In
427                  * that case, we still want to show them, so disable the hint
428                  * function entirely.
429                  */
430                 if (!ds.ambiguous)
431                         ds.fn = NULL;
432
433                 advise(_("The candidates are:"));
434                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
435         }
436
437         return status;
438 }
439
440 static int collect_ambiguous(const struct object_id *oid, void *data)
441 {
442         oid_array_append(data, oid);
443         return 0;
444 }
445
446 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
447 {
448         struct oid_array collect = OID_ARRAY_INIT;
449         struct disambiguate_state ds;
450         int ret;
451
452         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
453                 return -1;
454
455         ds.always_call_fn = 1;
456         ds.fn = collect_ambiguous;
457         ds.cb_data = &collect;
458         find_short_object_filename(&ds);
459         find_short_packed_object(&ds);
460
461         ret = oid_array_for_each_unique(&collect, fn, cb_data);
462         oid_array_clear(&collect);
463         return ret;
464 }
465
466 /*
467  * Return the slot of the most-significant bit set in "val". There are various
468  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
469  * probably not a big deal here.
470  */
471 static unsigned msb(unsigned long val)
472 {
473         unsigned r = 0;
474         while (val >>= 1)
475                 r++;
476         return r;
477 }
478
479 struct min_abbrev_data {
480         unsigned int init_len;
481         unsigned int cur_len;
482         char *hex;
483         const unsigned char *hash;
484 };
485
486 static inline char get_hex_char_from_oid(const struct object_id *oid,
487                                          unsigned int pos)
488 {
489         static const char hex[] = "0123456789abcdef";
490
491         if ((pos & 1) == 0)
492                 return hex[oid->hash[pos >> 1] >> 4];
493         else
494                 return hex[oid->hash[pos >> 1] & 0xf];
495 }
496
497 static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
498 {
499         struct min_abbrev_data *mad = cb_data;
500
501         unsigned int i = mad->init_len;
502         while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
503                 i++;
504
505         if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
506                 mad->cur_len = i + 1;
507
508         return 0;
509 }
510
511 static void find_abbrev_len_for_pack(struct packed_git *p,
512                                      struct min_abbrev_data *mad)
513 {
514         int match = 0;
515         uint32_t num, last, first = 0;
516         struct object_id oid;
517
518         if (open_pack_index(p) || !p->num_objects)
519                 return;
520
521         num = p->num_objects;
522         last = num;
523         while (first < last) {
524                 uint32_t mid = first + (last - first) / 2;
525                 const unsigned char *current;
526                 int cmp;
527
528                 current = nth_packed_object_sha1(p, mid);
529                 cmp = hashcmp(mad->hash, current);
530                 if (!cmp) {
531                         match = 1;
532                         first = mid;
533                         break;
534                 }
535                 if (cmp > 0) {
536                         first = mid + 1;
537                         continue;
538                 }
539                 last = mid;
540         }
541
542         /*
543          * first is now the position in the packfile where we would insert
544          * mad->hash if it does not exist (or the position of mad->hash if
545          * it does exist). Hence, we consider a maximum of two objects
546          * nearby for the abbreviation length.
547          */
548         mad->init_len = 0;
549         if (!match) {
550                 if (nth_packed_object_oid(&oid, p, first))
551                         extend_abbrev_len(&oid, mad);
552         } else if (first < num - 1) {
553                 if (nth_packed_object_oid(&oid, p, first + 1))
554                         extend_abbrev_len(&oid, mad);
555         }
556         if (first > 0) {
557                 if (nth_packed_object_oid(&oid, p, first - 1))
558                         extend_abbrev_len(&oid, mad);
559         }
560         mad->init_len = mad->cur_len;
561 }
562
563 static void find_abbrev_len_packed(struct min_abbrev_data *mad)
564 {
565         struct packed_git *p;
566
567         prepare_packed_git();
568         for (p = packed_git; p; p = p->next)
569                 find_abbrev_len_for_pack(p, mad);
570 }
571
572 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
573 {
574         struct disambiguate_state ds;
575         struct min_abbrev_data mad;
576         struct object_id oid_ret;
577         if (len < 0) {
578                 unsigned long count = approximate_object_count();
579                 /*
580                  * Add one because the MSB only tells us the highest bit set,
581                  * not including the value of all the _other_ bits (so "15"
582                  * is only one off of 2^4, but the MSB is the 3rd bit.
583                  */
584                 len = msb(count) + 1;
585                 /*
586                  * We now know we have on the order of 2^len objects, which
587                  * expects a collision at 2^(len/2). But we also care about hex
588                  * chars, not bits, and there are 4 bits per hex. So all
589                  * together we need to divide by 2 and round up.
590                  */
591                 len = DIV_ROUND_UP(len, 2);
592                 /*
593                  * For very small repos, we stick with our regular fallback.
594                  */
595                 if (len < FALLBACK_DEFAULT_ABBREV)
596                         len = FALLBACK_DEFAULT_ABBREV;
597         }
598
599         sha1_to_hex_r(hex, sha1);
600         if (len == GIT_SHA1_HEXSZ || !len)
601                 return GIT_SHA1_HEXSZ;
602
603         mad.init_len = len;
604         mad.cur_len = len;
605         mad.hex = hex;
606         mad.hash = sha1;
607
608         find_abbrev_len_packed(&mad);
609
610         if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
611                 return -1;
612
613         ds.fn = extend_abbrev_len;
614         ds.always_call_fn = 1;
615         ds.cb_data = (void *)&mad;
616
617         find_short_object_filename(&ds);
618         (void)finish_object_disambiguation(&ds, &oid_ret);
619
620         hex[mad.cur_len] = 0;
621         return mad.cur_len;
622 }
623
624 const char *find_unique_abbrev(const unsigned char *sha1, int len)
625 {
626         static int bufno;
627         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
628         char *hex = hexbuffer[bufno];
629         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
630         find_unique_abbrev_r(hex, sha1, len);
631         return hex;
632 }
633
634 static int ambiguous_path(const char *path, int len)
635 {
636         int slash = 1;
637         int cnt;
638
639         for (cnt = 0; cnt < len; cnt++) {
640                 switch (*path++) {
641                 case '\0':
642                         break;
643                 case '/':
644                         if (slash)
645                                 break;
646                         slash = 1;
647                         continue;
648                 case '.':
649                         continue;
650                 default:
651                         slash = 0;
652                         continue;
653                 }
654                 break;
655         }
656         return slash;
657 }
658
659 static inline int at_mark(const char *string, int len,
660                           const char **suffix, int nr)
661 {
662         int i;
663
664         for (i = 0; i < nr; i++) {
665                 int suffix_len = strlen(suffix[i]);
666                 if (suffix_len <= len
667                     && !strncasecmp(string, suffix[i], suffix_len))
668                         return suffix_len;
669         }
670         return 0;
671 }
672
673 static inline int upstream_mark(const char *string, int len)
674 {
675         const char *suffix[] = { "@{upstream}", "@{u}" };
676         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
677 }
678
679 static inline int push_mark(const char *string, int len)
680 {
681         const char *suffix[] = { "@{push}" };
682         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
683 }
684
685 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
686 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
687
688 static int get_oid_basic(const char *str, int len, struct object_id *oid,
689                           unsigned int flags)
690 {
691         static const char *warn_msg = "refname '%.*s' is ambiguous.";
692         static const char *object_name_msg = N_(
693         "Git normally never creates a ref that ends with 40 hex characters\n"
694         "because it will be ignored when you just specify 40-hex. These refs\n"
695         "may be created by mistake. For example,\n"
696         "\n"
697         "  git checkout -b $br $(git rev-parse ...)\n"
698         "\n"
699         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
700         "examine these refs and maybe delete them. Turn this message off by\n"
701         "running \"git config advice.objectNameWarning false\"");
702         struct object_id tmp_oid;
703         char *real_ref = NULL;
704         int refs_found = 0;
705         int at, reflog_len, nth_prior = 0;
706
707         if (len == GIT_SHA1_HEXSZ && !get_oid_hex(str, oid)) {
708                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
709                         refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
710                         if (refs_found > 0) {
711                                 warning(warn_msg, len, str);
712                                 if (advice_object_name_warning)
713                                         fprintf(stderr, "%s\n", _(object_name_msg));
714                         }
715                         free(real_ref);
716                 }
717                 return 0;
718         }
719
720         /* basic@{time or number or -number} format to query ref-log */
721         reflog_len = at = 0;
722         if (len && str[len-1] == '}') {
723                 for (at = len-4; at >= 0; at--) {
724                         if (str[at] == '@' && str[at+1] == '{') {
725                                 if (str[at+2] == '-') {
726                                         if (at != 0)
727                                                 /* @{-N} not at start */
728                                                 return -1;
729                                         nth_prior = 1;
730                                         continue;
731                                 }
732                                 if (!upstream_mark(str + at, len - at) &&
733                                     !push_mark(str + at, len - at)) {
734                                         reflog_len = (len-1) - (at+2);
735                                         len = at;
736                                 }
737                                 break;
738                         }
739                 }
740         }
741
742         /* Accept only unambiguous ref paths. */
743         if (len && ambiguous_path(str, len))
744                 return -1;
745
746         if (nth_prior) {
747                 struct strbuf buf = STRBUF_INIT;
748                 int detached;
749
750                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
751                         detached = (buf.len == GIT_SHA1_HEXSZ && !get_oid_hex(buf.buf, oid));
752                         strbuf_release(&buf);
753                         if (detached)
754                                 return 0;
755                 }
756         }
757
758         if (!len && reflog_len)
759                 /* allow "@{...}" to mean the current branch reflog */
760                 refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
761         else if (reflog_len)
762                 refs_found = dwim_log(str, len, oid, &real_ref);
763         else
764                 refs_found = dwim_ref(str, len, oid, &real_ref);
765
766         if (!refs_found)
767                 return -1;
768
769         if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
770             (refs_found > 1 ||
771              !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
772                 warning(warn_msg, len, str);
773
774         if (reflog_len) {
775                 int nth, i;
776                 timestamp_t at_time;
777                 timestamp_t co_time;
778                 int co_tz, co_cnt;
779
780                 /* Is it asking for N-th entry, or approxidate? */
781                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
782                         char ch = str[at+2+i];
783                         if ('0' <= ch && ch <= '9')
784                                 nth = nth * 10 + ch - '0';
785                         else
786                                 nth = -1;
787                 }
788                 if (100000000 <= nth) {
789                         at_time = nth;
790                         nth = -1;
791                 } else if (0 <= nth)
792                         at_time = 0;
793                 else {
794                         int errors = 0;
795                         char *tmp = xstrndup(str + at + 2, reflog_len);
796                         at_time = approxidate_careful(tmp, &errors);
797                         free(tmp);
798                         if (errors) {
799                                 free(real_ref);
800                                 return -1;
801                         }
802                 }
803                 if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
804                                 &co_time, &co_tz, &co_cnt)) {
805                         if (!len) {
806                                 if (starts_with(real_ref, "refs/heads/")) {
807                                         str = real_ref + 11;
808                                         len = strlen(real_ref + 11);
809                                 } else {
810                                         /* detached HEAD */
811                                         str = "HEAD";
812                                         len = 4;
813                                 }
814                         }
815                         if (at_time) {
816                                 if (!(flags & GET_OID_QUIETLY)) {
817                                         warning("Log for '%.*s' only goes "
818                                                 "back to %s.", len, str,
819                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
820                                 }
821                         } else {
822                                 if (flags & GET_OID_QUIETLY) {
823                                         exit(128);
824                                 }
825                                 die("Log for '%.*s' only has %d entries.",
826                                     len, str, co_cnt);
827                         }
828                 }
829         }
830
831         free(real_ref);
832         return 0;
833 }
834
835 static int get_parent(const char *name, int len,
836                       struct object_id *result, int idx)
837 {
838         struct object_id oid;
839         int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
840         struct commit *commit;
841         struct commit_list *p;
842
843         if (ret)
844                 return ret;
845         commit = lookup_commit_reference(&oid);
846         if (parse_commit(commit))
847                 return -1;
848         if (!idx) {
849                 oidcpy(result, &commit->object.oid);
850                 return 0;
851         }
852         p = commit->parents;
853         while (p) {
854                 if (!--idx) {
855                         oidcpy(result, &p->item->object.oid);
856                         return 0;
857                 }
858                 p = p->next;
859         }
860         return -1;
861 }
862
863 static int get_nth_ancestor(const char *name, int len,
864                             struct object_id *result, int generation)
865 {
866         struct object_id oid;
867         struct commit *commit;
868         int ret;
869
870         ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
871         if (ret)
872                 return ret;
873         commit = lookup_commit_reference(&oid);
874         if (!commit)
875                 return -1;
876
877         while (generation--) {
878                 if (parse_commit(commit) || !commit->parents)
879                         return -1;
880                 commit = commit->parents->item;
881         }
882         oidcpy(result, &commit->object.oid);
883         return 0;
884 }
885
886 struct object *peel_to_type(const char *name, int namelen,
887                             struct object *o, enum object_type expected_type)
888 {
889         if (name && !namelen)
890                 namelen = strlen(name);
891         while (1) {
892                 if (!o || (!o->parsed && !parse_object(&o->oid)))
893                         return NULL;
894                 if (expected_type == OBJ_ANY || o->type == expected_type)
895                         return o;
896                 if (o->type == OBJ_TAG)
897                         o = ((struct tag*) o)->tagged;
898                 else if (o->type == OBJ_COMMIT)
899                         o = &(((struct commit *) o)->tree->object);
900                 else {
901                         if (name)
902                                 error("%.*s: expected %s type, but the object "
903                                       "dereferences to %s type",
904                                       namelen, name, type_name(expected_type),
905                                       type_name(o->type));
906                         return NULL;
907                 }
908         }
909 }
910
911 static int peel_onion(const char *name, int len, struct object_id *oid,
912                       unsigned lookup_flags)
913 {
914         struct object_id outer;
915         const char *sp;
916         unsigned int expected_type = 0;
917         struct object *o;
918
919         /*
920          * "ref^{type}" dereferences ref repeatedly until you cannot
921          * dereference anymore, or you get an object of given type,
922          * whichever comes first.  "ref^{}" means just dereference
923          * tags until you get a non-tag.  "ref^0" is a shorthand for
924          * "ref^{commit}".  "commit^{tree}" could be used to find the
925          * top-level tree of the given commit.
926          */
927         if (len < 4 || name[len-1] != '}')
928                 return -1;
929
930         for (sp = name + len - 1; name <= sp; sp--) {
931                 int ch = *sp;
932                 if (ch == '{' && name < sp && sp[-1] == '^')
933                         break;
934         }
935         if (sp <= name)
936                 return -1;
937
938         sp++; /* beginning of type name, or closing brace for empty */
939         if (starts_with(sp, "commit}"))
940                 expected_type = OBJ_COMMIT;
941         else if (starts_with(sp, "tag}"))
942                 expected_type = OBJ_TAG;
943         else if (starts_with(sp, "tree}"))
944                 expected_type = OBJ_TREE;
945         else if (starts_with(sp, "blob}"))
946                 expected_type = OBJ_BLOB;
947         else if (starts_with(sp, "object}"))
948                 expected_type = OBJ_ANY;
949         else if (sp[0] == '}')
950                 expected_type = OBJ_NONE;
951         else if (sp[0] == '/')
952                 expected_type = OBJ_COMMIT;
953         else
954                 return -1;
955
956         lookup_flags &= ~GET_OID_DISAMBIGUATORS;
957         if (expected_type == OBJ_COMMIT)
958                 lookup_flags |= GET_OID_COMMITTISH;
959         else if (expected_type == OBJ_TREE)
960                 lookup_flags |= GET_OID_TREEISH;
961
962         if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
963                 return -1;
964
965         o = parse_object(&outer);
966         if (!o)
967                 return -1;
968         if (!expected_type) {
969                 o = deref_tag(o, name, sp - name - 2);
970                 if (!o || (!o->parsed && !parse_object(&o->oid)))
971                         return -1;
972                 oidcpy(oid, &o->oid);
973                 return 0;
974         }
975
976         /*
977          * At this point, the syntax look correct, so
978          * if we do not get the needed object, we should
979          * barf.
980          */
981         o = peel_to_type(name, len, o, expected_type);
982         if (!o)
983                 return -1;
984
985         oidcpy(oid, &o->oid);
986         if (sp[0] == '/') {
987                 /* "$commit^{/foo}" */
988                 char *prefix;
989                 int ret;
990                 struct commit_list *list = NULL;
991
992                 /*
993                  * $commit^{/}. Some regex implementation may reject.
994                  * We don't need regex anyway. '' pattern always matches.
995                  */
996                 if (sp[1] == '}')
997                         return 0;
998
999                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1000                 commit_list_insert((struct commit *)o, &list);
1001                 ret = get_oid_oneline(prefix, oid, list);
1002                 free(prefix);
1003                 return ret;
1004         }
1005         return 0;
1006 }
1007
1008 static int get_describe_name(const char *name, int len, struct object_id *oid)
1009 {
1010         const char *cp;
1011         unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1012
1013         for (cp = name + len - 1; name + 2 <= cp; cp--) {
1014                 char ch = *cp;
1015                 if (!isxdigit(ch)) {
1016                         /* We must be looking at g in "SOMETHING-g"
1017                          * for it to be describe output.
1018                          */
1019                         if (ch == 'g' && cp[-1] == '-') {
1020                                 cp++;
1021                                 len -= cp - name;
1022                                 return get_short_oid(cp, len, oid, flags);
1023                         }
1024                 }
1025         }
1026         return -1;
1027 }
1028
1029 static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
1030 {
1031         int ret, has_suffix;
1032         const char *cp;
1033
1034         /*
1035          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1036          */
1037         has_suffix = 0;
1038         for (cp = name + len - 1; name <= cp; cp--) {
1039                 int ch = *cp;
1040                 if ('0' <= ch && ch <= '9')
1041                         continue;
1042                 if (ch == '~' || ch == '^')
1043                         has_suffix = ch;
1044                 break;
1045         }
1046
1047         if (has_suffix) {
1048                 int num = 0;
1049                 int len1 = cp - name;
1050                 cp++;
1051                 while (cp < name + len)
1052                         num = num * 10 + *cp++ - '0';
1053                 if (!num && len1 == len - 1)
1054                         num = 1;
1055                 if (has_suffix == '^')
1056                         return get_parent(name, len1, oid, num);
1057                 /* else if (has_suffix == '~') -- goes without saying */
1058                 return get_nth_ancestor(name, len1, oid, num);
1059         }
1060
1061         ret = peel_onion(name, len, oid, lookup_flags);
1062         if (!ret)
1063                 return 0;
1064
1065         ret = get_oid_basic(name, len, oid, lookup_flags);
1066         if (!ret)
1067                 return 0;
1068
1069         /* It could be describe output that is "SOMETHING-gXXXX" */
1070         ret = get_describe_name(name, len, oid);
1071         if (!ret)
1072                 return 0;
1073
1074         return get_short_oid(name, len, oid, lookup_flags);
1075 }
1076
1077 /*
1078  * This interprets names like ':/Initial revision of "git"' by searching
1079  * through history and returning the first commit whose message starts
1080  * the given regular expression.
1081  *
1082  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1083  *
1084  * For a literal '!' character at the beginning of a pattern, you have to repeat
1085  * that, like: ':/!!foo'
1086  *
1087  * For future extension, all other sequences beginning with ':/!' are reserved.
1088  */
1089
1090 /* Remember to update object flag allocation in object.h */
1091 #define ONELINE_SEEN (1u<<20)
1092
1093 static int handle_one_ref(const char *path, const struct object_id *oid,
1094                           int flag, void *cb_data)
1095 {
1096         struct commit_list **list = cb_data;
1097         struct object *object = parse_object(oid);
1098         if (!object)
1099                 return 0;
1100         if (object->type == OBJ_TAG) {
1101                 object = deref_tag(object, path, strlen(path));
1102                 if (!object)
1103                         return 0;
1104         }
1105         if (object->type != OBJ_COMMIT)
1106                 return 0;
1107         commit_list_insert((struct commit *)object, list);
1108         return 0;
1109 }
1110
1111 static int get_oid_oneline(const char *prefix, struct object_id *oid,
1112                             struct commit_list *list)
1113 {
1114         struct commit_list *backup = NULL, *l;
1115         int found = 0;
1116         int negative = 0;
1117         regex_t regex;
1118
1119         if (prefix[0] == '!') {
1120                 prefix++;
1121
1122                 if (prefix[0] == '-') {
1123                         prefix++;
1124                         negative = 1;
1125                 } else if (prefix[0] != '!') {
1126                         return -1;
1127                 }
1128         }
1129
1130         if (regcomp(&regex, prefix, REG_EXTENDED))
1131                 return -1;
1132
1133         for (l = list; l; l = l->next) {
1134                 l->item->object.flags |= ONELINE_SEEN;
1135                 commit_list_insert(l->item, &backup);
1136         }
1137         while (list) {
1138                 const char *p, *buf;
1139                 struct commit *commit;
1140                 int matches;
1141
1142                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1143                 if (!parse_object(&commit->object.oid))
1144                         continue;
1145                 buf = get_commit_buffer(commit, NULL);
1146                 p = strstr(buf, "\n\n");
1147                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1148                 unuse_commit_buffer(commit, buf);
1149
1150                 if (matches) {
1151                         oidcpy(oid, &commit->object.oid);
1152                         found = 1;
1153                         break;
1154                 }
1155         }
1156         regfree(&regex);
1157         free_commit_list(list);
1158         for (l = backup; l; l = l->next)
1159                 clear_commit_marks(l->item, ONELINE_SEEN);
1160         free_commit_list(backup);
1161         return found ? 0 : -1;
1162 }
1163
1164 struct grab_nth_branch_switch_cbdata {
1165         int remaining;
1166         struct strbuf buf;
1167 };
1168
1169 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1170                                   const char *email, timestamp_t timestamp, int tz,
1171                                   const char *message, void *cb_data)
1172 {
1173         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1174         const char *match = NULL, *target = NULL;
1175         size_t len;
1176
1177         if (skip_prefix(message, "checkout: moving from ", &match))
1178                 target = strstr(match, " to ");
1179
1180         if (!match || !target)
1181                 return 0;
1182         if (--(cb->remaining) == 0) {
1183                 len = target - match;
1184                 strbuf_reset(&cb->buf);
1185                 strbuf_add(&cb->buf, match, len);
1186                 return 1; /* we are done */
1187         }
1188         return 0;
1189 }
1190
1191 /*
1192  * Parse @{-N} syntax, return the number of characters parsed
1193  * if successful; otherwise signal an error with negative value.
1194  */
1195 static int interpret_nth_prior_checkout(const char *name, int namelen,
1196                                         struct strbuf *buf)
1197 {
1198         long nth;
1199         int retval;
1200         struct grab_nth_branch_switch_cbdata cb;
1201         const char *brace;
1202         char *num_end;
1203
1204         if (namelen < 4)
1205                 return -1;
1206         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1207                 return -1;
1208         brace = memchr(name, '}', namelen);
1209         if (!brace)
1210                 return -1;
1211         nth = strtol(name + 3, &num_end, 10);
1212         if (num_end != brace)
1213                 return -1;
1214         if (nth <= 0)
1215                 return -1;
1216         cb.remaining = nth;
1217         strbuf_init(&cb.buf, 20);
1218
1219         retval = 0;
1220         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1221                 strbuf_reset(buf);
1222                 strbuf_addbuf(buf, &cb.buf);
1223                 retval = brace - name + 1;
1224         }
1225
1226         strbuf_release(&cb.buf);
1227         return retval;
1228 }
1229
1230 int get_oid_mb(const char *name, struct object_id *oid)
1231 {
1232         struct commit *one, *two;
1233         struct commit_list *mbs;
1234         struct object_id oid_tmp;
1235         const char *dots;
1236         int st;
1237
1238         dots = strstr(name, "...");
1239         if (!dots)
1240                 return get_oid(name, oid);
1241         if (dots == name)
1242                 st = get_oid("HEAD", &oid_tmp);
1243         else {
1244                 struct strbuf sb;
1245                 strbuf_init(&sb, dots - name);
1246                 strbuf_add(&sb, name, dots - name);
1247                 st = get_oid_committish(sb.buf, &oid_tmp);
1248                 strbuf_release(&sb);
1249         }
1250         if (st)
1251                 return st;
1252         one = lookup_commit_reference_gently(&oid_tmp, 0);
1253         if (!one)
1254                 return -1;
1255
1256         if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1257                 return -1;
1258         two = lookup_commit_reference_gently(&oid_tmp, 0);
1259         if (!two)
1260                 return -1;
1261         mbs = get_merge_bases(one, two);
1262         if (!mbs || mbs->next)
1263                 st = -1;
1264         else {
1265                 st = 0;
1266                 oidcpy(oid, &mbs->item->object.oid);
1267         }
1268         free_commit_list(mbs);
1269         return st;
1270 }
1271
1272 /* parse @something syntax, when 'something' is not {.*} */
1273 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1274 {
1275         const char *next;
1276
1277         if (len || name[1] == '{')
1278                 return -1;
1279
1280         /* make sure it's a single @, or @@{.*}, not @foo */
1281         next = memchr(name + len + 1, '@', namelen - len - 1);
1282         if (next && next[1] != '{')
1283                 return -1;
1284         if (!next)
1285                 next = name + namelen;
1286         if (next != name + 1)
1287                 return -1;
1288
1289         strbuf_reset(buf);
1290         strbuf_add(buf, "HEAD", 4);
1291         return 1;
1292 }
1293
1294 static int reinterpret(const char *name, int namelen, int len,
1295                        struct strbuf *buf, unsigned allowed)
1296 {
1297         /* we have extra data, which might need further processing */
1298         struct strbuf tmp = STRBUF_INIT;
1299         int used = buf->len;
1300         int ret;
1301
1302         strbuf_add(buf, name + len, namelen - len);
1303         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1304         /* that data was not interpreted, remove our cruft */
1305         if (ret < 0) {
1306                 strbuf_setlen(buf, used);
1307                 return len;
1308         }
1309         strbuf_reset(buf);
1310         strbuf_addbuf(buf, &tmp);
1311         strbuf_release(&tmp);
1312         /* tweak for size of {-N} versus expanded ref name */
1313         return ret - used + len;
1314 }
1315
1316 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1317 {
1318         char *s = shorten_unambiguous_ref(ref, 0);
1319         strbuf_reset(buf);
1320         strbuf_addstr(buf, s);
1321         free(s);
1322 }
1323
1324 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1325 {
1326         if (!allowed)
1327                 return 1;
1328
1329         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1330             starts_with(refname, "refs/heads/"))
1331                 return 1;
1332         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1333             starts_with(refname, "refs/remotes/"))
1334                 return 1;
1335
1336         return 0;
1337 }
1338
1339 static int interpret_branch_mark(const char *name, int namelen,
1340                                  int at, struct strbuf *buf,
1341                                  int (*get_mark)(const char *, int),
1342                                  const char *(*get_data)(struct branch *,
1343                                                          struct strbuf *),
1344                                  unsigned allowed)
1345 {
1346         int len;
1347         struct branch *branch;
1348         struct strbuf err = STRBUF_INIT;
1349         const char *value;
1350
1351         len = get_mark(name + at, namelen - at);
1352         if (!len)
1353                 return -1;
1354
1355         if (memchr(name, ':', at))
1356                 return -1;
1357
1358         if (at) {
1359                 char *name_str = xmemdupz(name, at);
1360                 branch = branch_get(name_str);
1361                 free(name_str);
1362         } else
1363                 branch = branch_get(NULL);
1364
1365         value = get_data(branch, &err);
1366         if (!value)
1367                 die("%s", err.buf);
1368
1369         if (!branch_interpret_allowed(value, allowed))
1370                 return -1;
1371
1372         set_shortened_ref(buf, value);
1373         return len + at;
1374 }
1375
1376 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1377                           unsigned allowed)
1378 {
1379         char *at;
1380         const char *start;
1381         int len;
1382
1383         if (!namelen)
1384                 namelen = strlen(name);
1385
1386         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1387                 len = interpret_nth_prior_checkout(name, namelen, buf);
1388                 if (!len) {
1389                         return len; /* syntax Ok, not enough switches */
1390                 } else if (len > 0) {
1391                         if (len == namelen)
1392                                 return len; /* consumed all */
1393                         else
1394                                 return reinterpret(name, namelen, len, buf, allowed);
1395                 }
1396         }
1397
1398         for (start = name;
1399              (at = memchr(start, '@', namelen - (start - name)));
1400              start = at + 1) {
1401
1402                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1403                         len = interpret_empty_at(name, namelen, at - name, buf);
1404                         if (len > 0)
1405                                 return reinterpret(name, namelen, len, buf,
1406                                                    allowed);
1407                 }
1408
1409                 len = interpret_branch_mark(name, namelen, at - name, buf,
1410                                             upstream_mark, branch_get_upstream,
1411                                             allowed);
1412                 if (len > 0)
1413                         return len;
1414
1415                 len = interpret_branch_mark(name, namelen, at - name, buf,
1416                                             push_mark, branch_get_push,
1417                                             allowed);
1418                 if (len > 0)
1419                         return len;
1420         }
1421
1422         return -1;
1423 }
1424
1425 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1426 {
1427         int len = strlen(name);
1428         int used = interpret_branch_name(name, len, sb, allowed);
1429
1430         if (used < 0)
1431                 used = 0;
1432         strbuf_add(sb, name + used, len - used);
1433 }
1434
1435 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1436 {
1437         if (startup_info->have_repository)
1438                 strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1439         else
1440                 strbuf_addstr(sb, name);
1441
1442         /*
1443          * This splice must be done even if we end up rejecting the
1444          * name; builtin/branch.c::copy_or_rename_branch() still wants
1445          * to see what the name expanded to so that "branch -m" can be
1446          * used as a tool to correct earlier mistakes.
1447          */
1448         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1449
1450         if (*name == '-' ||
1451             !strcmp(sb->buf, "refs/heads/HEAD"))
1452                 return -1;
1453
1454         return check_refname_format(sb->buf, 0);
1455 }
1456
1457 /*
1458  * This is like "get_oid_basic()", except it allows "object ID expressions",
1459  * notably "xyz^" for "parent of xyz"
1460  */
1461 int get_oid(const char *name, struct object_id *oid)
1462 {
1463         struct object_context unused;
1464         return get_oid_with_context(name, 0, oid, &unused);
1465 }
1466
1467
1468 /*
1469  * Many callers know that the user meant to name a commit-ish by
1470  * syntactical positions where the object name appears.  Calling this
1471  * function allows the machinery to disambiguate shorter-than-unique
1472  * abbreviated object names between commit-ish and others.
1473  *
1474  * Note that this does NOT error out when the named object is not a
1475  * commit-ish. It is merely to give a hint to the disambiguation
1476  * machinery.
1477  */
1478 int get_oid_committish(const char *name, struct object_id *oid)
1479 {
1480         struct object_context unused;
1481         return get_oid_with_context(name, GET_OID_COMMITTISH,
1482                                     oid, &unused);
1483 }
1484
1485 int get_oid_treeish(const char *name, struct object_id *oid)
1486 {
1487         struct object_context unused;
1488         return get_oid_with_context(name, GET_OID_TREEISH,
1489                                     oid, &unused);
1490 }
1491
1492 int get_oid_commit(const char *name, struct object_id *oid)
1493 {
1494         struct object_context unused;
1495         return get_oid_with_context(name, GET_OID_COMMIT,
1496                                     oid, &unused);
1497 }
1498
1499 int get_oid_tree(const char *name, struct object_id *oid)
1500 {
1501         struct object_context unused;
1502         return get_oid_with_context(name, GET_OID_TREE,
1503                                     oid, &unused);
1504 }
1505
1506 int get_oid_blob(const char *name, struct object_id *oid)
1507 {
1508         struct object_context unused;
1509         return get_oid_with_context(name, GET_OID_BLOB,
1510                                     oid, &unused);
1511 }
1512
1513 /* Must be called only when object_name:filename doesn't exist. */
1514 static void diagnose_invalid_oid_path(const char *prefix,
1515                                       const char *filename,
1516                                       const struct object_id *tree_oid,
1517                                       const char *object_name,
1518                                       int object_name_len)
1519 {
1520         struct object_id oid;
1521         unsigned mode;
1522
1523         if (!prefix)
1524                 prefix = "";
1525
1526         if (file_exists(filename))
1527                 die("Path '%s' exists on disk, but not in '%.*s'.",
1528                     filename, object_name_len, object_name);
1529         if (is_missing_file_error(errno)) {
1530                 char *fullname = xstrfmt("%s%s", prefix, filename);
1531
1532                 if (!get_tree_entry(tree_oid->hash, fullname,
1533                                     oid.hash, &mode)) {
1534                         die("Path '%s' exists, but not '%s'.\n"
1535                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1536                             fullname,
1537                             filename,
1538                             object_name_len, object_name,
1539                             fullname,
1540                             object_name_len, object_name,
1541                             filename);
1542                 }
1543                 die("Path '%s' does not exist in '%.*s'",
1544                     filename, object_name_len, object_name);
1545         }
1546 }
1547
1548 /* Must be called only when :stage:filename doesn't exist. */
1549 static void diagnose_invalid_index_path(int stage,
1550                                         const char *prefix,
1551                                         const char *filename)
1552 {
1553         const struct cache_entry *ce;
1554         int pos;
1555         unsigned namelen = strlen(filename);
1556         struct strbuf fullname = STRBUF_INIT;
1557
1558         if (!prefix)
1559                 prefix = "";
1560
1561         /* Wrong stage number? */
1562         pos = cache_name_pos(filename, namelen);
1563         if (pos < 0)
1564                 pos = -pos - 1;
1565         if (pos < active_nr) {
1566                 ce = active_cache[pos];
1567                 if (ce_namelen(ce) == namelen &&
1568                     !memcmp(ce->name, filename, namelen))
1569                         die("Path '%s' is in the index, but not at stage %d.\n"
1570                             "Did you mean ':%d:%s'?",
1571                             filename, stage,
1572                             ce_stage(ce), filename);
1573         }
1574
1575         /* Confusion between relative and absolute filenames? */
1576         strbuf_addstr(&fullname, prefix);
1577         strbuf_addstr(&fullname, filename);
1578         pos = cache_name_pos(fullname.buf, fullname.len);
1579         if (pos < 0)
1580                 pos = -pos - 1;
1581         if (pos < active_nr) {
1582                 ce = active_cache[pos];
1583                 if (ce_namelen(ce) == fullname.len &&
1584                     !memcmp(ce->name, fullname.buf, fullname.len))
1585                         die("Path '%s' is in the index, but not '%s'.\n"
1586                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1587                             fullname.buf, filename,
1588                             ce_stage(ce), fullname.buf,
1589                             ce_stage(ce), filename);
1590         }
1591
1592         if (file_exists(filename))
1593                 die("Path '%s' exists on disk, but not in the index.", filename);
1594         if (is_missing_file_error(errno))
1595                 die("Path '%s' does not exist (neither on disk nor in the index).",
1596                     filename);
1597
1598         strbuf_release(&fullname);
1599 }
1600
1601
1602 static char *resolve_relative_path(const char *rel)
1603 {
1604         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1605                 return NULL;
1606
1607         if (!is_inside_work_tree())
1608                 die("relative path syntax can't be used outside working tree.");
1609
1610         /* die() inside prefix_path() if resolved path is outside worktree */
1611         return prefix_path(startup_info->prefix,
1612                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1613                            rel);
1614 }
1615
1616 static int get_oid_with_context_1(const char *name,
1617                                   unsigned flags,
1618                                   const char *prefix,
1619                                   struct object_id *oid,
1620                                   struct object_context *oc)
1621 {
1622         int ret, bracket_depth;
1623         int namelen = strlen(name);
1624         const char *cp;
1625         int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1626
1627         if (only_to_die)
1628                 flags |= GET_OID_QUIETLY;
1629
1630         memset(oc, 0, sizeof(*oc));
1631         oc->mode = S_IFINVALID;
1632         strbuf_init(&oc->symlink_path, 0);
1633         ret = get_oid_1(name, namelen, oid, flags);
1634         if (!ret)
1635                 return ret;
1636         /*
1637          * sha1:path --> object name of path in ent sha1
1638          * :path -> object name of absolute path in index
1639          * :./path -> object name of path relative to cwd in index
1640          * :[0-3]:path -> object name of path in index at stage
1641          * :/foo -> recent commit matching foo
1642          */
1643         if (name[0] == ':') {
1644                 int stage = 0;
1645                 const struct cache_entry *ce;
1646                 char *new_path = NULL;
1647                 int pos;
1648                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1649                         struct commit_list *list = NULL;
1650
1651                         for_each_ref(handle_one_ref, &list);
1652                         commit_list_sort_by_date(&list);
1653                         return get_oid_oneline(name + 2, oid, list);
1654                 }
1655                 if (namelen < 3 ||
1656                     name[2] != ':' ||
1657                     name[1] < '0' || '3' < name[1])
1658                         cp = name + 1;
1659                 else {
1660                         stage = name[1] - '0';
1661                         cp = name + 3;
1662                 }
1663                 new_path = resolve_relative_path(cp);
1664                 if (!new_path) {
1665                         namelen = namelen - (cp - name);
1666                 } else {
1667                         cp = new_path;
1668                         namelen = strlen(cp);
1669                 }
1670
1671                 if (flags & GET_OID_RECORD_PATH)
1672                         oc->path = xstrdup(cp);
1673
1674                 if (!active_cache)
1675                         read_cache();
1676                 pos = cache_name_pos(cp, namelen);
1677                 if (pos < 0)
1678                         pos = -pos - 1;
1679                 while (pos < active_nr) {
1680                         ce = active_cache[pos];
1681                         if (ce_namelen(ce) != namelen ||
1682                             memcmp(ce->name, cp, namelen))
1683                                 break;
1684                         if (ce_stage(ce) == stage) {
1685                                 oidcpy(oid, &ce->oid);
1686                                 oc->mode = ce->ce_mode;
1687                                 free(new_path);
1688                                 return 0;
1689                         }
1690                         pos++;
1691                 }
1692                 if (only_to_die && name[1] && name[1] != '/')
1693                         diagnose_invalid_index_path(stage, prefix, cp);
1694                 free(new_path);
1695                 return -1;
1696         }
1697         for (cp = name, bracket_depth = 0; *cp; cp++) {
1698                 if (*cp == '{')
1699                         bracket_depth++;
1700                 else if (bracket_depth && *cp == '}')
1701                         bracket_depth--;
1702                 else if (!bracket_depth && *cp == ':')
1703                         break;
1704         }
1705         if (*cp == ':') {
1706                 struct object_id tree_oid;
1707                 int len = cp - name;
1708                 unsigned sub_flags = flags;
1709
1710                 sub_flags &= ~GET_OID_DISAMBIGUATORS;
1711                 sub_flags |= GET_OID_TREEISH;
1712
1713                 if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1714                         const char *filename = cp+1;
1715                         char *new_filename = NULL;
1716
1717                         new_filename = resolve_relative_path(filename);
1718                         if (new_filename)
1719                                 filename = new_filename;
1720                         if (flags & GET_OID_FOLLOW_SYMLINKS) {
1721                                 ret = get_tree_entry_follow_symlinks(tree_oid.hash,
1722                                         filename, oid->hash, &oc->symlink_path,
1723                                         &oc->mode);
1724                         } else {
1725                                 ret = get_tree_entry(tree_oid.hash, filename,
1726                                                      oid->hash, &oc->mode);
1727                                 if (ret && only_to_die) {
1728                                         diagnose_invalid_oid_path(prefix,
1729                                                                    filename,
1730                                                                    &tree_oid,
1731                                                                    name, len);
1732                                 }
1733                         }
1734                         hashcpy(oc->tree, tree_oid.hash);
1735                         if (flags & GET_OID_RECORD_PATH)
1736                                 oc->path = xstrdup(filename);
1737
1738                         free(new_filename);
1739                         return ret;
1740                 } else {
1741                         if (only_to_die)
1742                                 die("Invalid object name '%.*s'.", len, name);
1743                 }
1744         }
1745         return ret;
1746 }
1747
1748 /*
1749  * Call this function when you know "name" given by the end user must
1750  * name an object but it doesn't; the function _may_ die with a better
1751  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1752  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1753  * you have a chance to diagnose the error further.
1754  */
1755 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1756 {
1757         struct object_context oc;
1758         struct object_id oid;
1759         get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1760 }
1761
1762 int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1763 {
1764         if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1765                 die("BUG: incompatible flags for get_sha1_with_context");
1766         return get_oid_with_context_1(str, flags, NULL, oid, oc);
1767 }