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