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