Merge branch 'js/http-custom-headers'
[git] / sha1_name.c
1 #include "cache.h"
2 #include "tag.h"
3 #include "commit.h"
4 #include "tree.h"
5 #include "blob.h"
6 #include "tree-walk.h"
7 #include "refs.h"
8 #include "remote.h"
9 #include "dir.h"
10
11 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
12
13 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
14
15 struct disambiguate_state {
16         disambiguate_hint_fn fn;
17         void *cb_data;
18         unsigned char candidate[20];
19         unsigned candidate_exists:1;
20         unsigned candidate_checked:1;
21         unsigned candidate_ok:1;
22         unsigned disambiguate_fn_used:1;
23         unsigned ambiguous:1;
24         unsigned always_call_fn:1;
25 };
26
27 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
28 {
29         if (ds->always_call_fn) {
30                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
31                 return;
32         }
33         if (!ds->candidate_exists) {
34                 /* this is the first candidate */
35                 hashcpy(ds->candidate, current);
36                 ds->candidate_exists = 1;
37                 return;
38         } else if (!hashcmp(ds->candidate, current)) {
39                 /* the same as what we already have seen */
40                 return;
41         }
42
43         if (!ds->fn) {
44                 /* cannot disambiguate between ds->candidate and current */
45                 ds->ambiguous = 1;
46                 return;
47         }
48
49         if (!ds->candidate_checked) {
50                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
51                 ds->disambiguate_fn_used = 1;
52                 ds->candidate_checked = 1;
53         }
54
55         if (!ds->candidate_ok) {
56                 /* discard the candidate; we know it does not satisfy fn */
57                 hashcpy(ds->candidate, current);
58                 ds->candidate_checked = 0;
59                 return;
60         }
61
62         /* if we reach this point, we know ds->candidate satisfies fn */
63         if (ds->fn(current, ds->cb_data)) {
64                 /*
65                  * if both current and candidate satisfy fn, we cannot
66                  * disambiguate.
67                  */
68                 ds->candidate_ok = 0;
69                 ds->ambiguous = 1;
70         }
71
72         /* otherwise, current can be discarded and candidate is still good */
73 }
74
75 static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
76 {
77         struct alternate_object_database *alt;
78         char hex[40];
79         static struct alternate_object_database *fakeent;
80
81         if (!fakeent) {
82                 /*
83                  * Create a "fake" alternate object database that
84                  * points to our own object database, to make it
85                  * easier to get a temporary working space in
86                  * alt->name/alt->base while iterating over the
87                  * object databases including our own.
88                  */
89                 const char *objdir = get_object_directory();
90                 size_t objdir_len = strlen(objdir);
91                 fakeent = xmalloc(st_add3(sizeof(*fakeent), objdir_len, 43));
92                 memcpy(fakeent->base, objdir, objdir_len);
93                 fakeent->name = fakeent->base + objdir_len + 1;
94                 fakeent->name[-1] = '/';
95         }
96         fakeent->next = alt_odb_list;
97
98         xsnprintf(hex, sizeof(hex), "%.2s", hex_pfx);
99         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
100                 struct dirent *de;
101                 DIR *dir;
102                 /*
103                  * every alt_odb struct has 42 extra bytes after the base
104                  * for exactly this purpose
105                  */
106                 xsnprintf(alt->name, 42, "%.2s/", hex_pfx);
107                 dir = opendir(alt->base);
108                 if (!dir)
109                         continue;
110
111                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
112                         unsigned char sha1[20];
113
114                         if (strlen(de->d_name) != 38)
115                                 continue;
116                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
117                                 continue;
118                         memcpy(hex + 2, de->d_name, 38);
119                         if (!get_sha1_hex(hex, sha1))
120                                 update_candidates(ds, sha1);
121                 }
122                 closedir(dir);
123         }
124 }
125
126 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
127 {
128         do {
129                 if (*a != *b)
130                         return 0;
131                 a++;
132                 b++;
133                 len -= 2;
134         } while (len > 1);
135         if (len)
136                 if ((*a ^ *b) & 0xf0)
137                         return 0;
138         return 1;
139 }
140
141 static void unique_in_pack(int len,
142                           const unsigned char *bin_pfx,
143                            struct packed_git *p,
144                            struct disambiguate_state *ds)
145 {
146         uint32_t num, last, i, first = 0;
147         const unsigned char *current = NULL;
148
149         open_pack_index(p);
150         num = p->num_objects;
151         last = num;
152         while (first < last) {
153                 uint32_t mid = (first + last) / 2;
154                 const unsigned char *current;
155                 int cmp;
156
157                 current = nth_packed_object_sha1(p, mid);
158                 cmp = hashcmp(bin_pfx, current);
159                 if (!cmp) {
160                         first = mid;
161                         break;
162                 }
163                 if (cmp > 0) {
164                         first = mid+1;
165                         continue;
166                 }
167                 last = mid;
168         }
169
170         /*
171          * At this point, "first" is the location of the lowest object
172          * with an object name that could match "bin_pfx".  See if we have
173          * 0, 1 or more objects that actually match(es).
174          */
175         for (i = first; i < num && !ds->ambiguous; i++) {
176                 current = nth_packed_object_sha1(p, i);
177                 if (!match_sha(len, bin_pfx, current))
178                         break;
179                 update_candidates(ds, current);
180         }
181 }
182
183 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
184                                      struct disambiguate_state *ds)
185 {
186         struct packed_git *p;
187
188         prepare_packed_git();
189         for (p = packed_git; p && !ds->ambiguous; p = p->next)
190                 unique_in_pack(len, bin_pfx, p, ds);
191 }
192
193 #define SHORT_NAME_NOT_FOUND (-1)
194 #define SHORT_NAME_AMBIGUOUS (-2)
195
196 static int finish_object_disambiguation(struct disambiguate_state *ds,
197                                         unsigned char *sha1)
198 {
199         if (ds->ambiguous)
200                 return SHORT_NAME_AMBIGUOUS;
201
202         if (!ds->candidate_exists)
203                 return SHORT_NAME_NOT_FOUND;
204
205         if (!ds->candidate_checked)
206                 /*
207                  * If this is the only candidate, there is no point
208                  * calling the disambiguation hint callback.
209                  *
210                  * On the other hand, if the current candidate
211                  * replaced an earlier candidate that did _not_ pass
212                  * the disambiguation hint callback, then we do have
213                  * more than one objects that match the short name
214                  * given, so we should make sure this one matches;
215                  * otherwise, if we discovered this one and the one
216                  * that we previously discarded in the reverse order,
217                  * we would end up showing different results in the
218                  * same repository!
219                  */
220                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
221                                     ds->fn(ds->candidate, ds->cb_data));
222
223         if (!ds->candidate_ok)
224                 return SHORT_NAME_AMBIGUOUS;
225
226         hashcpy(sha1, ds->candidate);
227         return 0;
228 }
229
230 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
231 {
232         int kind = sha1_object_info(sha1, NULL);
233         return kind == OBJ_COMMIT;
234 }
235
236 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
237 {
238         struct object *obj;
239         int kind;
240
241         kind = sha1_object_info(sha1, NULL);
242         if (kind == OBJ_COMMIT)
243                 return 1;
244         if (kind != OBJ_TAG)
245                 return 0;
246
247         /* We need to do this the hard way... */
248         obj = deref_tag(parse_object(sha1), NULL, 0);
249         if (obj && obj->type == OBJ_COMMIT)
250                 return 1;
251         return 0;
252 }
253
254 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
255 {
256         int kind = sha1_object_info(sha1, NULL);
257         return kind == OBJ_TREE;
258 }
259
260 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
261 {
262         struct object *obj;
263         int kind;
264
265         kind = sha1_object_info(sha1, NULL);
266         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
267                 return 1;
268         if (kind != OBJ_TAG)
269                 return 0;
270
271         /* We need to do this the hard way... */
272         obj = deref_tag(lookup_object(sha1), NULL, 0);
273         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
274                 return 1;
275         return 0;
276 }
277
278 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
279 {
280         int kind = sha1_object_info(sha1, NULL);
281         return kind == OBJ_BLOB;
282 }
283
284 static int prepare_prefixes(const char *name, int len,
285                             unsigned char *bin_pfx,
286                             char *hex_pfx)
287 {
288         int i;
289
290         hashclr(bin_pfx);
291         memset(hex_pfx, 'x', 40);
292         for (i = 0; i < len ;i++) {
293                 unsigned char c = name[i];
294                 unsigned char val;
295                 if (c >= '0' && c <= '9')
296                         val = c - '0';
297                 else if (c >= 'a' && c <= 'f')
298                         val = c - 'a' + 10;
299                 else if (c >= 'A' && c <='F') {
300                         val = c - 'A' + 10;
301                         c -= 'A' - 'a';
302                 }
303                 else
304                         return -1;
305                 hex_pfx[i] = c;
306                 if (!(i & 1))
307                         val <<= 4;
308                 bin_pfx[i >> 1] |= val;
309         }
310         return 0;
311 }
312
313 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
314                           unsigned flags)
315 {
316         int status;
317         char hex_pfx[40];
318         unsigned char bin_pfx[20];
319         struct disambiguate_state ds;
320         int quietly = !!(flags & GET_SHA1_QUIETLY);
321
322         if (len < MINIMUM_ABBREV || len > 40)
323                 return -1;
324         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
325                 return -1;
326
327         prepare_alt_odb();
328
329         memset(&ds, 0, sizeof(ds));
330         if (flags & GET_SHA1_COMMIT)
331                 ds.fn = disambiguate_commit_only;
332         else if (flags & GET_SHA1_COMMITTISH)
333                 ds.fn = disambiguate_committish_only;
334         else if (flags & GET_SHA1_TREE)
335                 ds.fn = disambiguate_tree_only;
336         else if (flags & GET_SHA1_TREEISH)
337                 ds.fn = disambiguate_treeish_only;
338         else if (flags & GET_SHA1_BLOB)
339                 ds.fn = disambiguate_blob_only;
340
341         find_short_object_filename(len, hex_pfx, &ds);
342         find_short_packed_object(len, bin_pfx, &ds);
343         status = finish_object_disambiguation(&ds, sha1);
344
345         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
346                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
347         return status;
348 }
349
350 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
351 {
352         char hex_pfx[40];
353         unsigned char bin_pfx[20];
354         struct disambiguate_state ds;
355         int len = strlen(prefix);
356
357         if (len < MINIMUM_ABBREV || len > 40)
358                 return -1;
359         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
360                 return -1;
361
362         prepare_alt_odb();
363
364         memset(&ds, 0, sizeof(ds));
365         ds.always_call_fn = 1;
366         ds.cb_data = cb_data;
367         ds.fn = fn;
368
369         find_short_object_filename(len, hex_pfx, &ds);
370         find_short_packed_object(len, bin_pfx, &ds);
371         return ds.ambiguous;
372 }
373
374 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
375 {
376         int status, exists;
377
378         sha1_to_hex_r(hex, sha1);
379         if (len == 40 || !len)
380                 return 40;
381         exists = has_sha1_file(sha1);
382         while (len < 40) {
383                 unsigned char sha1_ret[20];
384                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
385                 if (exists
386                     ? !status
387                     : status == SHORT_NAME_NOT_FOUND) {
388                         hex[len] = 0;
389                         return len;
390                 }
391                 len++;
392         }
393         return len;
394 }
395
396 const char *find_unique_abbrev(const unsigned char *sha1, int len)
397 {
398         static char hex[GIT_SHA1_HEXSZ + 1];
399         find_unique_abbrev_r(hex, sha1, len);
400         return hex;
401 }
402
403 static int ambiguous_path(const char *path, int len)
404 {
405         int slash = 1;
406         int cnt;
407
408         for (cnt = 0; cnt < len; cnt++) {
409                 switch (*path++) {
410                 case '\0':
411                         break;
412                 case '/':
413                         if (slash)
414                                 break;
415                         slash = 1;
416                         continue;
417                 case '.':
418                         continue;
419                 default:
420                         slash = 0;
421                         continue;
422                 }
423                 break;
424         }
425         return slash;
426 }
427
428 static inline int at_mark(const char *string, int len,
429                           const char **suffix, int nr)
430 {
431         int i;
432
433         for (i = 0; i < nr; i++) {
434                 int suffix_len = strlen(suffix[i]);
435                 if (suffix_len <= len
436                     && !memcmp(string, suffix[i], suffix_len))
437                         return suffix_len;
438         }
439         return 0;
440 }
441
442 static inline int upstream_mark(const char *string, int len)
443 {
444         const char *suffix[] = { "@{upstream}", "@{u}" };
445         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
446 }
447
448 static inline int push_mark(const char *string, int len)
449 {
450         const char *suffix[] = { "@{push}" };
451         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
452 }
453
454 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
455 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
456
457 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
458                           unsigned int flags)
459 {
460         static const char *warn_msg = "refname '%.*s' is ambiguous.";
461         static const char *object_name_msg = N_(
462         "Git normally never creates a ref that ends with 40 hex characters\n"
463         "because it will be ignored when you just specify 40-hex. These refs\n"
464         "may be created by mistake. For example,\n"
465         "\n"
466         "  git checkout -b $br $(git rev-parse ...)\n"
467         "\n"
468         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
469         "examine these refs and maybe delete them. Turn this message off by\n"
470         "running \"git config advice.objectNameWarning false\"");
471         unsigned char tmp_sha1[20];
472         char *real_ref = NULL;
473         int refs_found = 0;
474         int at, reflog_len, nth_prior = 0;
475
476         if (len == 40 && !get_sha1_hex(str, sha1)) {
477                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
478                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
479                         if (refs_found > 0) {
480                                 warning(warn_msg, len, str);
481                                 if (advice_object_name_warning)
482                                         fprintf(stderr, "%s\n", _(object_name_msg));
483                         }
484                         free(real_ref);
485                 }
486                 return 0;
487         }
488
489         /* basic@{time or number or -number} format to query ref-log */
490         reflog_len = at = 0;
491         if (len && str[len-1] == '}') {
492                 for (at = len-4; at >= 0; at--) {
493                         if (str[at] == '@' && str[at+1] == '{') {
494                                 if (str[at+2] == '-') {
495                                         if (at != 0)
496                                                 /* @{-N} not at start */
497                                                 return -1;
498                                         nth_prior = 1;
499                                         continue;
500                                 }
501                                 if (!upstream_mark(str + at, len - at) &&
502                                     !push_mark(str + at, len - at)) {
503                                         reflog_len = (len-1) - (at+2);
504                                         len = at;
505                                 }
506                                 break;
507                         }
508                 }
509         }
510
511         /* Accept only unambiguous ref paths. */
512         if (len && ambiguous_path(str, len))
513                 return -1;
514
515         if (nth_prior) {
516                 struct strbuf buf = STRBUF_INIT;
517                 int detached;
518
519                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
520                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
521                         strbuf_release(&buf);
522                         if (detached)
523                                 return 0;
524                 }
525         }
526
527         if (!len && reflog_len)
528                 /* allow "@{...}" to mean the current branch reflog */
529                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
530         else if (reflog_len)
531                 refs_found = dwim_log(str, len, sha1, &real_ref);
532         else
533                 refs_found = dwim_ref(str, len, sha1, &real_ref);
534
535         if (!refs_found)
536                 return -1;
537
538         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
539             (refs_found > 1 ||
540              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
541                 warning(warn_msg, len, str);
542
543         if (reflog_len) {
544                 int nth, i;
545                 unsigned long at_time;
546                 unsigned long co_time;
547                 int co_tz, co_cnt;
548
549                 /* Is it asking for N-th entry, or approxidate? */
550                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
551                         char ch = str[at+2+i];
552                         if ('0' <= ch && ch <= '9')
553                                 nth = nth * 10 + ch - '0';
554                         else
555                                 nth = -1;
556                 }
557                 if (100000000 <= nth) {
558                         at_time = nth;
559                         nth = -1;
560                 } else if (0 <= nth)
561                         at_time = 0;
562                 else {
563                         int errors = 0;
564                         char *tmp = xstrndup(str + at + 2, reflog_len);
565                         at_time = approxidate_careful(tmp, &errors);
566                         free(tmp);
567                         if (errors) {
568                                 free(real_ref);
569                                 return -1;
570                         }
571                 }
572                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
573                                 &co_time, &co_tz, &co_cnt)) {
574                         if (!len) {
575                                 if (starts_with(real_ref, "refs/heads/")) {
576                                         str = real_ref + 11;
577                                         len = strlen(real_ref + 11);
578                                 } else {
579                                         /* detached HEAD */
580                                         str = "HEAD";
581                                         len = 4;
582                                 }
583                         }
584                         if (at_time) {
585                                 if (!(flags & GET_SHA1_QUIETLY)) {
586                                         warning("Log for '%.*s' only goes "
587                                                 "back to %s.", len, str,
588                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
589                                 }
590                         } else {
591                                 if (flags & GET_SHA1_QUIETLY) {
592                                         exit(128);
593                                 }
594                                 die("Log for '%.*s' only has %d entries.",
595                                     len, str, co_cnt);
596                         }
597                 }
598         }
599
600         free(real_ref);
601         return 0;
602 }
603
604 static int get_parent(const char *name, int len,
605                       unsigned char *result, int idx)
606 {
607         unsigned char sha1[20];
608         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
609         struct commit *commit;
610         struct commit_list *p;
611
612         if (ret)
613                 return ret;
614         commit = lookup_commit_reference(sha1);
615         if (parse_commit(commit))
616                 return -1;
617         if (!idx) {
618                 hashcpy(result, commit->object.oid.hash);
619                 return 0;
620         }
621         p = commit->parents;
622         while (p) {
623                 if (!--idx) {
624                         hashcpy(result, p->item->object.oid.hash);
625                         return 0;
626                 }
627                 p = p->next;
628         }
629         return -1;
630 }
631
632 static int get_nth_ancestor(const char *name, int len,
633                             unsigned char *result, int generation)
634 {
635         unsigned char sha1[20];
636         struct commit *commit;
637         int ret;
638
639         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
640         if (ret)
641                 return ret;
642         commit = lookup_commit_reference(sha1);
643         if (!commit)
644                 return -1;
645
646         while (generation--) {
647                 if (parse_commit(commit) || !commit->parents)
648                         return -1;
649                 commit = commit->parents->item;
650         }
651         hashcpy(result, commit->object.oid.hash);
652         return 0;
653 }
654
655 struct object *peel_to_type(const char *name, int namelen,
656                             struct object *o, enum object_type expected_type)
657 {
658         if (name && !namelen)
659                 namelen = strlen(name);
660         while (1) {
661                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
662                         return NULL;
663                 if (expected_type == OBJ_ANY || o->type == expected_type)
664                         return o;
665                 if (o->type == OBJ_TAG)
666                         o = ((struct tag*) o)->tagged;
667                 else if (o->type == OBJ_COMMIT)
668                         o = &(((struct commit *) o)->tree->object);
669                 else {
670                         if (name)
671                                 error("%.*s: expected %s type, but the object "
672                                       "dereferences to %s type",
673                                       namelen, name, typename(expected_type),
674                                       typename(o->type));
675                         return NULL;
676                 }
677         }
678 }
679
680 static int peel_onion(const char *name, int len, unsigned char *sha1)
681 {
682         unsigned char outer[20];
683         const char *sp;
684         unsigned int expected_type = 0;
685         unsigned lookup_flags = 0;
686         struct object *o;
687
688         /*
689          * "ref^{type}" dereferences ref repeatedly until you cannot
690          * dereference anymore, or you get an object of given type,
691          * whichever comes first.  "ref^{}" means just dereference
692          * tags until you get a non-tag.  "ref^0" is a shorthand for
693          * "ref^{commit}".  "commit^{tree}" could be used to find the
694          * top-level tree of the given commit.
695          */
696         if (len < 4 || name[len-1] != '}')
697                 return -1;
698
699         for (sp = name + len - 1; name <= sp; sp--) {
700                 int ch = *sp;
701                 if (ch == '{' && name < sp && sp[-1] == '^')
702                         break;
703         }
704         if (sp <= name)
705                 return -1;
706
707         sp++; /* beginning of type name, or closing brace for empty */
708         if (starts_with(sp, "commit}"))
709                 expected_type = OBJ_COMMIT;
710         else if (starts_with(sp, "tag}"))
711                 expected_type = OBJ_TAG;
712         else if (starts_with(sp, "tree}"))
713                 expected_type = OBJ_TREE;
714         else if (starts_with(sp, "blob}"))
715                 expected_type = OBJ_BLOB;
716         else if (starts_with(sp, "object}"))
717                 expected_type = OBJ_ANY;
718         else if (sp[0] == '}')
719                 expected_type = OBJ_NONE;
720         else if (sp[0] == '/')
721                 expected_type = OBJ_COMMIT;
722         else
723                 return -1;
724
725         if (expected_type == OBJ_COMMIT)
726                 lookup_flags = GET_SHA1_COMMITTISH;
727         else if (expected_type == OBJ_TREE)
728                 lookup_flags = GET_SHA1_TREEISH;
729
730         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
731                 return -1;
732
733         o = parse_object(outer);
734         if (!o)
735                 return -1;
736         if (!expected_type) {
737                 o = deref_tag(o, name, sp - name - 2);
738                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
739                         return -1;
740                 hashcpy(sha1, o->oid.hash);
741                 return 0;
742         }
743
744         /*
745          * At this point, the syntax look correct, so
746          * if we do not get the needed object, we should
747          * barf.
748          */
749         o = peel_to_type(name, len, o, expected_type);
750         if (!o)
751                 return -1;
752
753         hashcpy(sha1, o->oid.hash);
754         if (sp[0] == '/') {
755                 /* "$commit^{/foo}" */
756                 char *prefix;
757                 int ret;
758                 struct commit_list *list = NULL;
759
760                 /*
761                  * $commit^{/}. Some regex implementation may reject.
762                  * We don't need regex anyway. '' pattern always matches.
763                  */
764                 if (sp[1] == '}')
765                         return 0;
766
767                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
768                 commit_list_insert((struct commit *)o, &list);
769                 ret = get_sha1_oneline(prefix, sha1, list);
770                 free(prefix);
771                 return ret;
772         }
773         return 0;
774 }
775
776 static int get_describe_name(const char *name, int len, unsigned char *sha1)
777 {
778         const char *cp;
779         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
780
781         for (cp = name + len - 1; name + 2 <= cp; cp--) {
782                 char ch = *cp;
783                 if (!isxdigit(ch)) {
784                         /* We must be looking at g in "SOMETHING-g"
785                          * for it to be describe output.
786                          */
787                         if (ch == 'g' && cp[-1] == '-') {
788                                 cp++;
789                                 len -= cp - name;
790                                 return get_short_sha1(cp, len, sha1, flags);
791                         }
792                 }
793         }
794         return -1;
795 }
796
797 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
798 {
799         int ret, has_suffix;
800         const char *cp;
801
802         /*
803          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
804          */
805         has_suffix = 0;
806         for (cp = name + len - 1; name <= cp; cp--) {
807                 int ch = *cp;
808                 if ('0' <= ch && ch <= '9')
809                         continue;
810                 if (ch == '~' || ch == '^')
811                         has_suffix = ch;
812                 break;
813         }
814
815         if (has_suffix) {
816                 int num = 0;
817                 int len1 = cp - name;
818                 cp++;
819                 while (cp < name + len)
820                         num = num * 10 + *cp++ - '0';
821                 if (!num && len1 == len - 1)
822                         num = 1;
823                 if (has_suffix == '^')
824                         return get_parent(name, len1, sha1, num);
825                 /* else if (has_suffix == '~') -- goes without saying */
826                 return get_nth_ancestor(name, len1, sha1, num);
827         }
828
829         ret = peel_onion(name, len, sha1);
830         if (!ret)
831                 return 0;
832
833         ret = get_sha1_basic(name, len, sha1, lookup_flags);
834         if (!ret)
835                 return 0;
836
837         /* It could be describe output that is "SOMETHING-gXXXX" */
838         ret = get_describe_name(name, len, sha1);
839         if (!ret)
840                 return 0;
841
842         return get_short_sha1(name, len, sha1, lookup_flags);
843 }
844
845 /*
846  * This interprets names like ':/Initial revision of "git"' by searching
847  * through history and returning the first commit whose message starts
848  * the given regular expression.
849  *
850  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
851  *
852  * For a literal '!' character at the beginning of a pattern, you have to repeat
853  * that, like: ':/!!foo'
854  *
855  * For future extension, all other sequences beginning with ':/!' are reserved.
856  */
857
858 /* Remember to update object flag allocation in object.h */
859 #define ONELINE_SEEN (1u<<20)
860
861 static int handle_one_ref(const char *path, const struct object_id *oid,
862                           int flag, void *cb_data)
863 {
864         struct commit_list **list = cb_data;
865         struct object *object = parse_object(oid->hash);
866         if (!object)
867                 return 0;
868         if (object->type == OBJ_TAG) {
869                 object = deref_tag(object, path, strlen(path));
870                 if (!object)
871                         return 0;
872         }
873         if (object->type != OBJ_COMMIT)
874                 return 0;
875         commit_list_insert((struct commit *)object, list);
876         return 0;
877 }
878
879 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
880                             struct commit_list *list)
881 {
882         struct commit_list *backup = NULL, *l;
883         int found = 0;
884         int negative = 0;
885         regex_t regex;
886
887         if (prefix[0] == '!') {
888                 prefix++;
889
890                 if (prefix[0] == '-') {
891                         prefix++;
892                         negative = 1;
893                 } else if (prefix[0] != '!') {
894                         return -1;
895                 }
896         }
897
898         if (regcomp(&regex, prefix, REG_EXTENDED))
899                 return -1;
900
901         for (l = list; l; l = l->next) {
902                 l->item->object.flags |= ONELINE_SEEN;
903                 commit_list_insert(l->item, &backup);
904         }
905         while (list) {
906                 const char *p, *buf;
907                 struct commit *commit;
908                 int matches;
909
910                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
911                 if (!parse_object(commit->object.oid.hash))
912                         continue;
913                 buf = get_commit_buffer(commit, NULL);
914                 p = strstr(buf, "\n\n");
915                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
916                 unuse_commit_buffer(commit, buf);
917
918                 if (matches) {
919                         hashcpy(sha1, commit->object.oid.hash);
920                         found = 1;
921                         break;
922                 }
923         }
924         regfree(&regex);
925         free_commit_list(list);
926         for (l = backup; l; l = l->next)
927                 clear_commit_marks(l->item, ONELINE_SEEN);
928         free_commit_list(backup);
929         return found ? 0 : -1;
930 }
931
932 struct grab_nth_branch_switch_cbdata {
933         int remaining;
934         struct strbuf buf;
935 };
936
937 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
938                                   const char *email, unsigned long timestamp, int tz,
939                                   const char *message, void *cb_data)
940 {
941         struct grab_nth_branch_switch_cbdata *cb = cb_data;
942         const char *match = NULL, *target = NULL;
943         size_t len;
944
945         if (skip_prefix(message, "checkout: moving from ", &match))
946                 target = strstr(match, " to ");
947
948         if (!match || !target)
949                 return 0;
950         if (--(cb->remaining) == 0) {
951                 len = target - match;
952                 strbuf_reset(&cb->buf);
953                 strbuf_add(&cb->buf, match, len);
954                 return 1; /* we are done */
955         }
956         return 0;
957 }
958
959 /*
960  * Parse @{-N} syntax, return the number of characters parsed
961  * if successful; otherwise signal an error with negative value.
962  */
963 static int interpret_nth_prior_checkout(const char *name, int namelen,
964                                         struct strbuf *buf)
965 {
966         long nth;
967         int retval;
968         struct grab_nth_branch_switch_cbdata cb;
969         const char *brace;
970         char *num_end;
971
972         if (namelen < 4)
973                 return -1;
974         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
975                 return -1;
976         brace = memchr(name, '}', namelen);
977         if (!brace)
978                 return -1;
979         nth = strtol(name + 3, &num_end, 10);
980         if (num_end != brace)
981                 return -1;
982         if (nth <= 0)
983                 return -1;
984         cb.remaining = nth;
985         strbuf_init(&cb.buf, 20);
986
987         retval = 0;
988         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
989                 strbuf_reset(buf);
990                 strbuf_addbuf(buf, &cb.buf);
991                 retval = brace - name + 1;
992         }
993
994         strbuf_release(&cb.buf);
995         return retval;
996 }
997
998 int get_sha1_mb(const char *name, unsigned char *sha1)
999 {
1000         struct commit *one, *two;
1001         struct commit_list *mbs;
1002         unsigned char sha1_tmp[20];
1003         const char *dots;
1004         int st;
1005
1006         dots = strstr(name, "...");
1007         if (!dots)
1008                 return get_sha1(name, sha1);
1009         if (dots == name)
1010                 st = get_sha1("HEAD", sha1_tmp);
1011         else {
1012                 struct strbuf sb;
1013                 strbuf_init(&sb, dots - name);
1014                 strbuf_add(&sb, name, dots - name);
1015                 st = get_sha1_committish(sb.buf, sha1_tmp);
1016                 strbuf_release(&sb);
1017         }
1018         if (st)
1019                 return st;
1020         one = lookup_commit_reference_gently(sha1_tmp, 0);
1021         if (!one)
1022                 return -1;
1023
1024         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
1025                 return -1;
1026         two = lookup_commit_reference_gently(sha1_tmp, 0);
1027         if (!two)
1028                 return -1;
1029         mbs = get_merge_bases(one, two);
1030         if (!mbs || mbs->next)
1031                 st = -1;
1032         else {
1033                 st = 0;
1034                 hashcpy(sha1, mbs->item->object.oid.hash);
1035         }
1036         free_commit_list(mbs);
1037         return st;
1038 }
1039
1040 /* parse @something syntax, when 'something' is not {.*} */
1041 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1042 {
1043         const char *next;
1044
1045         if (len || name[1] == '{')
1046                 return -1;
1047
1048         /* make sure it's a single @, or @@{.*}, not @foo */
1049         next = memchr(name + len + 1, '@', namelen - len - 1);
1050         if (next && next[1] != '{')
1051                 return -1;
1052         if (!next)
1053                 next = name + namelen;
1054         if (next != name + 1)
1055                 return -1;
1056
1057         strbuf_reset(buf);
1058         strbuf_add(buf, "HEAD", 4);
1059         return 1;
1060 }
1061
1062 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1063 {
1064         /* we have extra data, which might need further processing */
1065         struct strbuf tmp = STRBUF_INIT;
1066         int used = buf->len;
1067         int ret;
1068
1069         strbuf_add(buf, name + len, namelen - len);
1070         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1071         /* that data was not interpreted, remove our cruft */
1072         if (ret < 0) {
1073                 strbuf_setlen(buf, used);
1074                 return len;
1075         }
1076         strbuf_reset(buf);
1077         strbuf_addbuf(buf, &tmp);
1078         strbuf_release(&tmp);
1079         /* tweak for size of {-N} versus expanded ref name */
1080         return ret - used + len;
1081 }
1082
1083 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1084 {
1085         char *s = shorten_unambiguous_ref(ref, 0);
1086         strbuf_reset(buf);
1087         strbuf_addstr(buf, s);
1088         free(s);
1089 }
1090
1091 static int interpret_branch_mark(const char *name, int namelen,
1092                                  int at, struct strbuf *buf,
1093                                  int (*get_mark)(const char *, int),
1094                                  const char *(*get_data)(struct branch *,
1095                                                          struct strbuf *))
1096 {
1097         int len;
1098         struct branch *branch;
1099         struct strbuf err = STRBUF_INIT;
1100         const char *value;
1101
1102         len = get_mark(name + at, namelen - at);
1103         if (!len)
1104                 return -1;
1105
1106         if (memchr(name, ':', at))
1107                 return -1;
1108
1109         if (at) {
1110                 char *name_str = xmemdupz(name, at);
1111                 branch = branch_get(name_str);
1112                 free(name_str);
1113         } else
1114                 branch = branch_get(NULL);
1115
1116         value = get_data(branch, &err);
1117         if (!value)
1118                 die("%s", err.buf);
1119
1120         set_shortened_ref(buf, value);
1121         return len + at;
1122 }
1123
1124 /*
1125  * This reads short-hand syntax that not only evaluates to a commit
1126  * object name, but also can act as if the end user spelled the name
1127  * of the branch from the command line.
1128  *
1129  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1130  *   places the name of the branch in the given buf and returns the
1131  *   number of characters parsed if successful.
1132  *
1133  * - "<branch>@{upstream}" finds the name of the other ref that
1134  *   <branch> is configured to merge with (missing <branch> defaults
1135  *   to the current branch), and places the name of the branch in the
1136  *   given buf and returns the number of characters parsed if
1137  *   successful.
1138  *
1139  * If the input is not of the accepted format, it returns a negative
1140  * number to signal an error.
1141  *
1142  * If the input was ok but there are not N branch switches in the
1143  * reflog, it returns 0.
1144  */
1145 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1146 {
1147         char *at;
1148         const char *start;
1149         int len = interpret_nth_prior_checkout(name, namelen, buf);
1150
1151         if (!namelen)
1152                 namelen = strlen(name);
1153
1154         if (!len) {
1155                 return len; /* syntax Ok, not enough switches */
1156         } else if (len > 0) {
1157                 if (len == namelen)
1158                         return len; /* consumed all */
1159                 else
1160                         return reinterpret(name, namelen, len, buf);
1161         }
1162
1163         for (start = name;
1164              (at = memchr(start, '@', namelen - (start - name)));
1165              start = at + 1) {
1166
1167                 len = interpret_empty_at(name, namelen, at - name, buf);
1168                 if (len > 0)
1169                         return reinterpret(name, namelen, len, buf);
1170
1171                 len = interpret_branch_mark(name, namelen, at - name, buf,
1172                                             upstream_mark, branch_get_upstream);
1173                 if (len > 0)
1174                         return len;
1175
1176                 len = interpret_branch_mark(name, namelen, at - name, buf,
1177                                             push_mark, branch_get_push);
1178                 if (len > 0)
1179                         return len;
1180         }
1181
1182         return -1;
1183 }
1184
1185 int strbuf_branchname(struct strbuf *sb, const char *name)
1186 {
1187         int len = strlen(name);
1188         int used = interpret_branch_name(name, len, sb);
1189
1190         if (used == len)
1191                 return 0;
1192         if (used < 0)
1193                 used = 0;
1194         strbuf_add(sb, name + used, len - used);
1195         return len;
1196 }
1197
1198 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1199 {
1200         strbuf_branchname(sb, name);
1201         if (name[0] == '-')
1202                 return -1;
1203         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1204         return check_refname_format(sb->buf, 0);
1205 }
1206
1207 /*
1208  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1209  * notably "xyz^" for "parent of xyz"
1210  */
1211 int get_sha1(const char *name, unsigned char *sha1)
1212 {
1213         struct object_context unused;
1214         return get_sha1_with_context(name, 0, sha1, &unused);
1215 }
1216
1217 /*
1218  * Many callers know that the user meant to name a commit-ish by
1219  * syntactical positions where the object name appears.  Calling this
1220  * function allows the machinery to disambiguate shorter-than-unique
1221  * abbreviated object names between commit-ish and others.
1222  *
1223  * Note that this does NOT error out when the named object is not a
1224  * commit-ish. It is merely to give a hint to the disambiguation
1225  * machinery.
1226  */
1227 int get_sha1_committish(const char *name, unsigned char *sha1)
1228 {
1229         struct object_context unused;
1230         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1231                                      sha1, &unused);
1232 }
1233
1234 int get_sha1_treeish(const char *name, unsigned char *sha1)
1235 {
1236         struct object_context unused;
1237         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1238                                      sha1, &unused);
1239 }
1240
1241 int get_sha1_commit(const char *name, unsigned char *sha1)
1242 {
1243         struct object_context unused;
1244         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1245                                      sha1, &unused);
1246 }
1247
1248 int get_sha1_tree(const char *name, unsigned char *sha1)
1249 {
1250         struct object_context unused;
1251         return get_sha1_with_context(name, GET_SHA1_TREE,
1252                                      sha1, &unused);
1253 }
1254
1255 int get_sha1_blob(const char *name, unsigned char *sha1)
1256 {
1257         struct object_context unused;
1258         return get_sha1_with_context(name, GET_SHA1_BLOB,
1259                                      sha1, &unused);
1260 }
1261
1262 /* Must be called only when object_name:filename doesn't exist. */
1263 static void diagnose_invalid_sha1_path(const char *prefix,
1264                                        const char *filename,
1265                                        const unsigned char *tree_sha1,
1266                                        const char *object_name,
1267                                        int object_name_len)
1268 {
1269         unsigned char sha1[20];
1270         unsigned mode;
1271
1272         if (!prefix)
1273                 prefix = "";
1274
1275         if (file_exists(filename))
1276                 die("Path '%s' exists on disk, but not in '%.*s'.",
1277                     filename, object_name_len, object_name);
1278         if (errno == ENOENT || errno == ENOTDIR) {
1279                 char *fullname = xstrfmt("%s%s", prefix, filename);
1280
1281                 if (!get_tree_entry(tree_sha1, fullname,
1282                                     sha1, &mode)) {
1283                         die("Path '%s' exists, but not '%s'.\n"
1284                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1285                             fullname,
1286                             filename,
1287                             object_name_len, object_name,
1288                             fullname,
1289                             object_name_len, object_name,
1290                             filename);
1291                 }
1292                 die("Path '%s' does not exist in '%.*s'",
1293                     filename, object_name_len, object_name);
1294         }
1295 }
1296
1297 /* Must be called only when :stage:filename doesn't exist. */
1298 static void diagnose_invalid_index_path(int stage,
1299                                         const char *prefix,
1300                                         const char *filename)
1301 {
1302         const struct cache_entry *ce;
1303         int pos;
1304         unsigned namelen = strlen(filename);
1305         struct strbuf fullname = STRBUF_INIT;
1306
1307         if (!prefix)
1308                 prefix = "";
1309
1310         /* Wrong stage number? */
1311         pos = cache_name_pos(filename, namelen);
1312         if (pos < 0)
1313                 pos = -pos - 1;
1314         if (pos < active_nr) {
1315                 ce = active_cache[pos];
1316                 if (ce_namelen(ce) == namelen &&
1317                     !memcmp(ce->name, filename, namelen))
1318                         die("Path '%s' is in the index, but not at stage %d.\n"
1319                             "Did you mean ':%d:%s'?",
1320                             filename, stage,
1321                             ce_stage(ce), filename);
1322         }
1323
1324         /* Confusion between relative and absolute filenames? */
1325         strbuf_addstr(&fullname, prefix);
1326         strbuf_addstr(&fullname, filename);
1327         pos = cache_name_pos(fullname.buf, fullname.len);
1328         if (pos < 0)
1329                 pos = -pos - 1;
1330         if (pos < active_nr) {
1331                 ce = active_cache[pos];
1332                 if (ce_namelen(ce) == fullname.len &&
1333                     !memcmp(ce->name, fullname.buf, fullname.len))
1334                         die("Path '%s' is in the index, but not '%s'.\n"
1335                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1336                             fullname.buf, filename,
1337                             ce_stage(ce), fullname.buf,
1338                             ce_stage(ce), filename);
1339         }
1340
1341         if (file_exists(filename))
1342                 die("Path '%s' exists on disk, but not in the index.", filename);
1343         if (errno == ENOENT || errno == ENOTDIR)
1344                 die("Path '%s' does not exist (neither on disk nor in the index).",
1345                     filename);
1346
1347         strbuf_release(&fullname);
1348 }
1349
1350
1351 static char *resolve_relative_path(const char *rel)
1352 {
1353         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1354                 return NULL;
1355
1356         if (!is_inside_work_tree())
1357                 die("relative path syntax can't be used outside working tree.");
1358
1359         /* die() inside prefix_path() if resolved path is outside worktree */
1360         return prefix_path(startup_info->prefix,
1361                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1362                            rel);
1363 }
1364
1365 static int get_sha1_with_context_1(const char *name,
1366                                    unsigned flags,
1367                                    const char *prefix,
1368                                    unsigned char *sha1,
1369                                    struct object_context *oc)
1370 {
1371         int ret, bracket_depth;
1372         int namelen = strlen(name);
1373         const char *cp;
1374         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1375
1376         memset(oc, 0, sizeof(*oc));
1377         oc->mode = S_IFINVALID;
1378         ret = get_sha1_1(name, namelen, sha1, flags);
1379         if (!ret)
1380                 return ret;
1381         /*
1382          * sha1:path --> object name of path in ent sha1
1383          * :path -> object name of absolute path in index
1384          * :./path -> object name of path relative to cwd in index
1385          * :[0-3]:path -> object name of path in index at stage
1386          * :/foo -> recent commit matching foo
1387          */
1388         if (name[0] == ':') {
1389                 int stage = 0;
1390                 const struct cache_entry *ce;
1391                 char *new_path = NULL;
1392                 int pos;
1393                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1394                         struct commit_list *list = NULL;
1395
1396                         for_each_ref(handle_one_ref, &list);
1397                         commit_list_sort_by_date(&list);
1398                         return get_sha1_oneline(name + 2, sha1, list);
1399                 }
1400                 if (namelen < 3 ||
1401                     name[2] != ':' ||
1402                     name[1] < '0' || '3' < name[1])
1403                         cp = name + 1;
1404                 else {
1405                         stage = name[1] - '0';
1406                         cp = name + 3;
1407                 }
1408                 new_path = resolve_relative_path(cp);
1409                 if (!new_path) {
1410                         namelen = namelen - (cp - name);
1411                 } else {
1412                         cp = new_path;
1413                         namelen = strlen(cp);
1414                 }
1415
1416                 strlcpy(oc->path, cp, sizeof(oc->path));
1417
1418                 if (!active_cache)
1419                         read_cache();
1420                 pos = cache_name_pos(cp, namelen);
1421                 if (pos < 0)
1422                         pos = -pos - 1;
1423                 while (pos < active_nr) {
1424                         ce = active_cache[pos];
1425                         if (ce_namelen(ce) != namelen ||
1426                             memcmp(ce->name, cp, namelen))
1427                                 break;
1428                         if (ce_stage(ce) == stage) {
1429                                 hashcpy(sha1, ce->sha1);
1430                                 oc->mode = ce->ce_mode;
1431                                 free(new_path);
1432                                 return 0;
1433                         }
1434                         pos++;
1435                 }
1436                 if (only_to_die && name[1] && name[1] != '/')
1437                         diagnose_invalid_index_path(stage, prefix, cp);
1438                 free(new_path);
1439                 return -1;
1440         }
1441         for (cp = name, bracket_depth = 0; *cp; cp++) {
1442                 if (*cp == '{')
1443                         bracket_depth++;
1444                 else if (bracket_depth && *cp == '}')
1445                         bracket_depth--;
1446                 else if (!bracket_depth && *cp == ':')
1447                         break;
1448         }
1449         if (*cp == ':') {
1450                 unsigned char tree_sha1[20];
1451                 int len = cp - name;
1452                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1453                         const char *filename = cp+1;
1454                         char *new_filename = NULL;
1455
1456                         new_filename = resolve_relative_path(filename);
1457                         if (new_filename)
1458                                 filename = new_filename;
1459                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1460                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1461                                         filename, sha1, &oc->symlink_path,
1462                                         &oc->mode);
1463                         } else {
1464                                 ret = get_tree_entry(tree_sha1, filename,
1465                                                      sha1, &oc->mode);
1466                                 if (ret && only_to_die) {
1467                                         diagnose_invalid_sha1_path(prefix,
1468                                                                    filename,
1469                                                                    tree_sha1,
1470                                                                    name, len);
1471                                 }
1472                         }
1473                         hashcpy(oc->tree, tree_sha1);
1474                         strlcpy(oc->path, filename, sizeof(oc->path));
1475
1476                         free(new_filename);
1477                         return ret;
1478                 } else {
1479                         if (only_to_die)
1480                                 die("Invalid object name '%.*s'.", len, name);
1481                 }
1482         }
1483         return ret;
1484 }
1485
1486 /*
1487  * Call this function when you know "name" given by the end user must
1488  * name an object but it doesn't; the function _may_ die with a better
1489  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1490  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1491  * you have a chance to diagnose the error further.
1492  */
1493 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1494 {
1495         struct object_context oc;
1496         unsigned char sha1[20];
1497         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1498 }
1499
1500 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1501 {
1502         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1503                 die("BUG: incompatible flags for get_sha1_with_context");
1504         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1505 }