sha1_name.c: hide get_sha1_with_context_1() ugliness
[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
10 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
11
12 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
13 {
14         struct alternate_object_database *alt;
15         char hex[40];
16         int found = 0;
17         static struct alternate_object_database *fakeent;
18
19         if (!fakeent) {
20                 const char *objdir = get_object_directory();
21                 int objdir_len = strlen(objdir);
22                 int entlen = objdir_len + 43;
23                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
24                 memcpy(fakeent->base, objdir, objdir_len);
25                 fakeent->name = fakeent->base + objdir_len + 1;
26                 fakeent->name[-1] = '/';
27         }
28         fakeent->next = alt_odb_list;
29
30         sprintf(hex, "%.2s", name);
31         for (alt = fakeent; alt && found < 2; alt = alt->next) {
32                 struct dirent *de;
33                 DIR *dir;
34                 sprintf(alt->name, "%.2s/", name);
35                 dir = opendir(alt->base);
36                 if (!dir)
37                         continue;
38                 while ((de = readdir(dir)) != NULL) {
39                         if (strlen(de->d_name) != 38)
40                                 continue;
41                         if (memcmp(de->d_name, name + 2, len - 2))
42                                 continue;
43                         if (!found) {
44                                 memcpy(hex + 2, de->d_name, 38);
45                                 found++;
46                         }
47                         else if (memcmp(hex + 2, de->d_name, 38)) {
48                                 found = 2;
49                                 break;
50                         }
51                 }
52                 closedir(dir);
53         }
54         if (found == 1)
55                 return get_sha1_hex(hex, sha1) == 0;
56         return found;
57 }
58
59 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
60 {
61         do {
62                 if (*a != *b)
63                         return 0;
64                 a++;
65                 b++;
66                 len -= 2;
67         } while (len > 1);
68         if (len)
69                 if ((*a ^ *b) & 0xf0)
70                         return 0;
71         return 1;
72 }
73
74 static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
75 {
76         struct packed_git *p;
77         const unsigned char *found_sha1 = NULL;
78         int found = 0;
79
80         prepare_packed_git();
81         for (p = packed_git; p && found < 2; p = p->next) {
82                 uint32_t num, last;
83                 uint32_t first = 0;
84                 open_pack_index(p);
85                 num = p->num_objects;
86                 last = num;
87                 while (first < last) {
88                         uint32_t mid = (first + last) / 2;
89                         const unsigned char *now;
90                         int cmp;
91
92                         now = nth_packed_object_sha1(p, mid);
93                         cmp = hashcmp(match, now);
94                         if (!cmp) {
95                                 first = mid;
96                                 break;
97                         }
98                         if (cmp > 0) {
99                                 first = mid+1;
100                                 continue;
101                         }
102                         last = mid;
103                 }
104                 if (first < num) {
105                         const unsigned char *now, *next;
106                         now = nth_packed_object_sha1(p, first);
107                         if (match_sha(len, match, now)) {
108                                 next = nth_packed_object_sha1(p, first+1);
109                                 if (!next|| !match_sha(len, match, next)) {
110                                         /* unique within this pack */
111                                         if (!found) {
112                                                 found_sha1 = now;
113                                                 found++;
114                                         }
115                                         else if (hashcmp(found_sha1, now)) {
116                                                 found = 2;
117                                                 break;
118                                         }
119                                 }
120                                 else {
121                                         /* not even unique within this pack */
122                                         found = 2;
123                                         break;
124                                 }
125                         }
126                 }
127         }
128         if (found == 1)
129                 hashcpy(sha1, found_sha1);
130         return found;
131 }
132
133 #define SHORT_NAME_NOT_FOUND (-1)
134 #define SHORT_NAME_AMBIGUOUS (-2)
135
136 static int find_unique_short_object(int len, char *canonical,
137                                     unsigned char *res, unsigned char *sha1)
138 {
139         int has_unpacked, has_packed;
140         unsigned char unpacked_sha1[20], packed_sha1[20];
141
142         prepare_alt_odb();
143         has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
144         has_packed = find_short_packed_object(len, res, packed_sha1);
145         if (!has_unpacked && !has_packed)
146                 return SHORT_NAME_NOT_FOUND;
147         if (1 < has_unpacked || 1 < has_packed)
148                 return SHORT_NAME_AMBIGUOUS;
149         if (has_unpacked != has_packed) {
150                 hashcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1));
151                 return 0;
152         }
153         /* Both have unique ones -- do they match? */
154         if (hashcmp(packed_sha1, unpacked_sha1))
155                 return SHORT_NAME_AMBIGUOUS;
156         hashcpy(sha1, packed_sha1);
157         return 0;
158 }
159
160 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
161                           int quietly)
162 {
163         int i, status;
164         char canonical[40];
165         unsigned char res[20];
166
167         if (len < MINIMUM_ABBREV || len > 40)
168                 return -1;
169         hashclr(res);
170         memset(canonical, 'x', 40);
171         for (i = 0; i < len ;i++) {
172                 unsigned char c = name[i];
173                 unsigned char val;
174                 if (c >= '0' && c <= '9')
175                         val = c - '0';
176                 else if (c >= 'a' && c <= 'f')
177                         val = c - 'a' + 10;
178                 else if (c >= 'A' && c <='F') {
179                         val = c - 'A' + 10;
180                         c -= 'A' - 'a';
181                 }
182                 else
183                         return -1;
184                 canonical[i] = c;
185                 if (!(i & 1))
186                         val <<= 4;
187                 res[i >> 1] |= val;
188         }
189
190         status = find_unique_short_object(i, canonical, res, sha1);
191         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
192                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
193         return status;
194 }
195
196 const char *find_unique_abbrev(const unsigned char *sha1, int len)
197 {
198         int status, exists;
199         static char hex[41];
200
201         exists = has_sha1_file(sha1);
202         memcpy(hex, sha1_to_hex(sha1), 40);
203         if (len == 40 || !len)
204                 return hex;
205         while (len < 40) {
206                 unsigned char sha1_ret[20];
207                 status = get_short_sha1(hex, len, sha1_ret, 1);
208                 if (exists
209                     ? !status
210                     : status == SHORT_NAME_NOT_FOUND) {
211                         hex[len] = 0;
212                         return hex;
213                 }
214                 len++;
215         }
216         return hex;
217 }
218
219 static int ambiguous_path(const char *path, int len)
220 {
221         int slash = 1;
222         int cnt;
223
224         for (cnt = 0; cnt < len; cnt++) {
225                 switch (*path++) {
226                 case '\0':
227                         break;
228                 case '/':
229                         if (slash)
230                                 break;
231                         slash = 1;
232                         continue;
233                 case '.':
234                         continue;
235                 default:
236                         slash = 0;
237                         continue;
238                 }
239                 break;
240         }
241         return slash;
242 }
243
244 static inline int upstream_mark(const char *string, int len)
245 {
246         const char *suffix[] = { "@{upstream}", "@{u}" };
247         int i;
248
249         for (i = 0; i < ARRAY_SIZE(suffix); i++) {
250                 int suffix_len = strlen(suffix[i]);
251                 if (suffix_len <= len
252                     && !memcmp(string, suffix[i], suffix_len))
253                         return suffix_len;
254         }
255         return 0;
256 }
257
258 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
259
260 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
261 {
262         static const char *warn_msg = "refname '%.*s' is ambiguous.";
263         char *real_ref = NULL;
264         int refs_found = 0;
265         int at, reflog_len;
266
267         if (len == 40 && !get_sha1_hex(str, sha1))
268                 return 0;
269
270         /* basic@{time or number or -number} format to query ref-log */
271         reflog_len = at = 0;
272         if (len && str[len-1] == '}') {
273                 for (at = len-2; at >= 0; at--) {
274                         if (str[at] == '@' && str[at+1] == '{') {
275                                 if (!upstream_mark(str + at, len - at)) {
276                                         reflog_len = (len-1) - (at+2);
277                                         len = at;
278                                 }
279                                 break;
280                         }
281                 }
282         }
283
284         /* Accept only unambiguous ref paths. */
285         if (len && ambiguous_path(str, len))
286                 return -1;
287
288         if (!len && reflog_len) {
289                 struct strbuf buf = STRBUF_INIT;
290                 int ret;
291                 /* try the @{-N} syntax for n-th checkout */
292                 ret = interpret_branch_name(str+at, &buf);
293                 if (ret > 0) {
294                         /* substitute this branch name and restart */
295                         return get_sha1_1(buf.buf, buf.len, sha1);
296                 } else if (ret == 0) {
297                         return -1;
298                 }
299                 /* allow "@{...}" to mean the current branch reflog */
300                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
301         } else if (reflog_len)
302                 refs_found = dwim_log(str, len, sha1, &real_ref);
303         else
304                 refs_found = dwim_ref(str, len, sha1, &real_ref);
305
306         if (!refs_found)
307                 return -1;
308
309         if (warn_ambiguous_refs && refs_found > 1)
310                 warning(warn_msg, len, str);
311
312         if (reflog_len) {
313                 int nth, i;
314                 unsigned long at_time;
315                 unsigned long co_time;
316                 int co_tz, co_cnt;
317
318                 /* a @{-N} placed anywhere except the start is an error */
319                 if (str[at+2] == '-')
320                         return -1;
321
322                 /* Is it asking for N-th entry, or approxidate? */
323                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
324                         char ch = str[at+2+i];
325                         if ('0' <= ch && ch <= '9')
326                                 nth = nth * 10 + ch - '0';
327                         else
328                                 nth = -1;
329                 }
330                 if (100000000 <= nth) {
331                         at_time = nth;
332                         nth = -1;
333                 } else if (0 <= nth)
334                         at_time = 0;
335                 else {
336                         int errors = 0;
337                         char *tmp = xstrndup(str + at + 2, reflog_len);
338                         at_time = approxidate_careful(tmp, &errors);
339                         free(tmp);
340                         if (errors)
341                                 return -1;
342                 }
343                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
344                                 &co_time, &co_tz, &co_cnt)) {
345                         if (at_time)
346                                 warning("Log for '%.*s' only goes "
347                                         "back to %s.", len, str,
348                                         show_date(co_time, co_tz, DATE_RFC2822));
349                         else {
350                                 free(real_ref);
351                                 die("Log for '%.*s' only has %d entries.",
352                                     len, str, co_cnt);
353                         }
354                 }
355         }
356
357         free(real_ref);
358         return 0;
359 }
360
361 static int get_parent(const char *name, int len,
362                       unsigned char *result, int idx)
363 {
364         unsigned char sha1[20];
365         int ret = get_sha1_1(name, len, sha1);
366         struct commit *commit;
367         struct commit_list *p;
368
369         if (ret)
370                 return ret;
371         commit = lookup_commit_reference(sha1);
372         if (!commit)
373                 return -1;
374         if (parse_commit(commit))
375                 return -1;
376         if (!idx) {
377                 hashcpy(result, commit->object.sha1);
378                 return 0;
379         }
380         p = commit->parents;
381         while (p) {
382                 if (!--idx) {
383                         hashcpy(result, p->item->object.sha1);
384                         return 0;
385                 }
386                 p = p->next;
387         }
388         return -1;
389 }
390
391 static int get_nth_ancestor(const char *name, int len,
392                             unsigned char *result, int generation)
393 {
394         unsigned char sha1[20];
395         struct commit *commit;
396         int ret;
397
398         ret = get_sha1_1(name, len, sha1);
399         if (ret)
400                 return ret;
401         commit = lookup_commit_reference(sha1);
402         if (!commit)
403                 return -1;
404
405         while (generation--) {
406                 if (parse_commit(commit) || !commit->parents)
407                         return -1;
408                 commit = commit->parents->item;
409         }
410         hashcpy(result, commit->object.sha1);
411         return 0;
412 }
413
414 struct object *peel_to_type(const char *name, int namelen,
415                             struct object *o, enum object_type expected_type)
416 {
417         if (name && !namelen)
418                 namelen = strlen(name);
419         while (1) {
420                 if (!o || (!o->parsed && !parse_object(o->sha1)))
421                         return NULL;
422                 if (o->type == expected_type)
423                         return o;
424                 if (o->type == OBJ_TAG)
425                         o = ((struct tag*) o)->tagged;
426                 else if (o->type == OBJ_COMMIT)
427                         o = &(((struct commit *) o)->tree->object);
428                 else {
429                         if (name)
430                                 error("%.*s: expected %s type, but the object "
431                                       "dereferences to %s type",
432                                       namelen, name, typename(expected_type),
433                                       typename(o->type));
434                         return NULL;
435                 }
436         }
437 }
438
439 static int peel_onion(const char *name, int len, unsigned char *sha1)
440 {
441         unsigned char outer[20];
442         const char *sp;
443         unsigned int expected_type = 0;
444         struct object *o;
445
446         /*
447          * "ref^{type}" dereferences ref repeatedly until you cannot
448          * dereference anymore, or you get an object of given type,
449          * whichever comes first.  "ref^{}" means just dereference
450          * tags until you get a non-tag.  "ref^0" is a shorthand for
451          * "ref^{commit}".  "commit^{tree}" could be used to find the
452          * top-level tree of the given commit.
453          */
454         if (len < 4 || name[len-1] != '}')
455                 return -1;
456
457         for (sp = name + len - 1; name <= sp; sp--) {
458                 int ch = *sp;
459                 if (ch == '{' && name < sp && sp[-1] == '^')
460                         break;
461         }
462         if (sp <= name)
463                 return -1;
464
465         sp++; /* beginning of type name, or closing brace for empty */
466         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
467                 expected_type = OBJ_COMMIT;
468         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
469                 expected_type = OBJ_TREE;
470         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
471                 expected_type = OBJ_BLOB;
472         else if (sp[0] == '}')
473                 expected_type = OBJ_NONE;
474         else if (sp[0] == '/')
475                 expected_type = OBJ_COMMIT;
476         else
477                 return -1;
478
479         if (get_sha1_1(name, sp - name - 2, outer))
480                 return -1;
481
482         o = parse_object(outer);
483         if (!o)
484                 return -1;
485         if (!expected_type) {
486                 o = deref_tag(o, name, sp - name - 2);
487                 if (!o || (!o->parsed && !parse_object(o->sha1)))
488                         return -1;
489                 hashcpy(sha1, o->sha1);
490                 return 0;
491         }
492
493         /*
494          * At this point, the syntax look correct, so
495          * if we do not get the needed object, we should
496          * barf.
497          */
498         o = peel_to_type(name, len, o, expected_type);
499         if (!o)
500                 return -1;
501
502         hashcpy(sha1, o->sha1);
503         if (sp[0] == '/') {
504                 /* "$commit^{/foo}" */
505                 char *prefix;
506                 int ret;
507                 struct commit_list *list = NULL;
508
509                 /*
510                  * $commit^{/}. Some regex implementation may reject.
511                  * We don't need regex anyway. '' pattern always matches.
512                  */
513                 if (sp[1] == '}')
514                         return 0;
515
516                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
517                 commit_list_insert((struct commit *)o, &list);
518                 ret = get_sha1_oneline(prefix, sha1, list);
519                 free(prefix);
520                 return ret;
521         }
522         return 0;
523 }
524
525 static int get_describe_name(const char *name, int len, unsigned char *sha1)
526 {
527         const char *cp;
528
529         for (cp = name + len - 1; name + 2 <= cp; cp--) {
530                 char ch = *cp;
531                 if (hexval(ch) & ~0377) {
532                         /* We must be looking at g in "SOMETHING-g"
533                          * for it to be describe output.
534                          */
535                         if (ch == 'g' && cp[-1] == '-') {
536                                 cp++;
537                                 len -= cp - name;
538                                 return get_short_sha1(cp, len, sha1, 1);
539                         }
540                 }
541         }
542         return -1;
543 }
544
545 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
546 {
547         int ret, has_suffix;
548         const char *cp;
549
550         /*
551          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
552          */
553         has_suffix = 0;
554         for (cp = name + len - 1; name <= cp; cp--) {
555                 int ch = *cp;
556                 if ('0' <= ch && ch <= '9')
557                         continue;
558                 if (ch == '~' || ch == '^')
559                         has_suffix = ch;
560                 break;
561         }
562
563         if (has_suffix) {
564                 int num = 0;
565                 int len1 = cp - name;
566                 cp++;
567                 while (cp < name + len)
568                         num = num * 10 + *cp++ - '0';
569                 if (!num && len1 == len - 1)
570                         num = 1;
571                 if (has_suffix == '^')
572                         return get_parent(name, len1, sha1, num);
573                 /* else if (has_suffix == '~') -- goes without saying */
574                 return get_nth_ancestor(name, len1, sha1, num);
575         }
576
577         ret = peel_onion(name, len, sha1);
578         if (!ret)
579                 return 0;
580
581         ret = get_sha1_basic(name, len, sha1);
582         if (!ret)
583                 return 0;
584
585         /* It could be describe output that is "SOMETHING-gXXXX" */
586         ret = get_describe_name(name, len, sha1);
587         if (!ret)
588                 return 0;
589
590         return get_short_sha1(name, len, sha1, 0);
591 }
592
593 /*
594  * This interprets names like ':/Initial revision of "git"' by searching
595  * through history and returning the first commit whose message starts
596  * the given regular expression.
597  *
598  * For future extension, ':/!' is reserved. If you want to match a message
599  * beginning with a '!', you have to repeat the exclamation mark.
600  */
601 #define ONELINE_SEEN (1u<<20)
602
603 static int handle_one_ref(const char *path,
604                 const unsigned char *sha1, int flag, void *cb_data)
605 {
606         struct commit_list **list = cb_data;
607         struct object *object = parse_object(sha1);
608         if (!object)
609                 return 0;
610         if (object->type == OBJ_TAG) {
611                 object = deref_tag(object, path, strlen(path));
612                 if (!object)
613                         return 0;
614         }
615         if (object->type != OBJ_COMMIT)
616                 return 0;
617         commit_list_insert_by_date((struct commit *)object, list);
618         return 0;
619 }
620
621 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
622                             struct commit_list *list)
623 {
624         struct commit_list *backup = NULL, *l;
625         int found = 0;
626         regex_t regex;
627
628         if (prefix[0] == '!') {
629                 if (prefix[1] != '!')
630                         die ("Invalid search pattern: %s", prefix);
631                 prefix++;
632         }
633
634         if (regcomp(&regex, prefix, REG_EXTENDED))
635                 die("Invalid search pattern: %s", prefix);
636
637         for (l = list; l; l = l->next) {
638                 l->item->object.flags |= ONELINE_SEEN;
639                 commit_list_insert(l->item, &backup);
640         }
641         while (list) {
642                 char *p, *to_free = NULL;
643                 struct commit *commit;
644                 enum object_type type;
645                 unsigned long size;
646                 int matches;
647
648                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
649                 if (!parse_object(commit->object.sha1))
650                         continue;
651                 if (commit->buffer)
652                         p = commit->buffer;
653                 else {
654                         p = read_sha1_file(commit->object.sha1, &type, &size);
655                         if (!p)
656                                 continue;
657                         to_free = p;
658                 }
659
660                 p = strstr(p, "\n\n");
661                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
662                 free(to_free);
663
664                 if (matches) {
665                         hashcpy(sha1, commit->object.sha1);
666                         found = 1;
667                         break;
668                 }
669         }
670         regfree(&regex);
671         free_commit_list(list);
672         for (l = backup; l; l = l->next)
673                 clear_commit_marks(l->item, ONELINE_SEEN);
674         free_commit_list(backup);
675         return found ? 0 : -1;
676 }
677
678 struct grab_nth_branch_switch_cbdata {
679         long cnt, alloc;
680         struct strbuf *buf;
681 };
682
683 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
684                                   const char *email, unsigned long timestamp, int tz,
685                                   const char *message, void *cb_data)
686 {
687         struct grab_nth_branch_switch_cbdata *cb = cb_data;
688         const char *match = NULL, *target = NULL;
689         size_t len;
690         int nth;
691
692         if (!prefixcmp(message, "checkout: moving from ")) {
693                 match = message + strlen("checkout: moving from ");
694                 target = strstr(match, " to ");
695         }
696
697         if (!match || !target)
698                 return 0;
699
700         len = target - match;
701         nth = cb->cnt++ % cb->alloc;
702         strbuf_reset(&cb->buf[nth]);
703         strbuf_add(&cb->buf[nth], match, len);
704         return 0;
705 }
706
707 /*
708  * Parse @{-N} syntax, return the number of characters parsed
709  * if successful; otherwise signal an error with negative value.
710  */
711 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
712 {
713         long nth;
714         int i, retval;
715         struct grab_nth_branch_switch_cbdata cb;
716         const char *brace;
717         char *num_end;
718
719         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
720                 return -1;
721         brace = strchr(name, '}');
722         if (!brace)
723                 return -1;
724         nth = strtol(name+3, &num_end, 10);
725         if (num_end != brace)
726                 return -1;
727         if (nth <= 0)
728                 return -1;
729         cb.alloc = nth;
730         cb.buf = xmalloc(nth * sizeof(struct strbuf));
731         for (i = 0; i < nth; i++)
732                 strbuf_init(&cb.buf[i], 20);
733         cb.cnt = 0;
734         retval = 0;
735         for_each_recent_reflog_ent("HEAD", grab_nth_branch_switch, 40960, &cb);
736         if (cb.cnt < nth) {
737                 cb.cnt = 0;
738                 for_each_reflog_ent("HEAD", grab_nth_branch_switch, &cb);
739         }
740         if (cb.cnt < nth)
741                 goto release_return;
742         i = cb.cnt % nth;
743         strbuf_reset(buf);
744         strbuf_add(buf, cb.buf[i].buf, cb.buf[i].len);
745         retval = brace-name+1;
746
747 release_return:
748         for (i = 0; i < nth; i++)
749                 strbuf_release(&cb.buf[i]);
750         free(cb.buf);
751
752         return retval;
753 }
754
755 int get_sha1_mb(const char *name, unsigned char *sha1)
756 {
757         struct commit *one, *two;
758         struct commit_list *mbs;
759         unsigned char sha1_tmp[20];
760         const char *dots;
761         int st;
762
763         dots = strstr(name, "...");
764         if (!dots)
765                 return get_sha1(name, sha1);
766         if (dots == name)
767                 st = get_sha1("HEAD", sha1_tmp);
768         else {
769                 struct strbuf sb;
770                 strbuf_init(&sb, dots - name);
771                 strbuf_add(&sb, name, dots - name);
772                 st = get_sha1(sb.buf, sha1_tmp);
773                 strbuf_release(&sb);
774         }
775         if (st)
776                 return st;
777         one = lookup_commit_reference_gently(sha1_tmp, 0);
778         if (!one)
779                 return -1;
780
781         if (get_sha1(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
782                 return -1;
783         two = lookup_commit_reference_gently(sha1_tmp, 0);
784         if (!two)
785                 return -1;
786         mbs = get_merge_bases(one, two, 1);
787         if (!mbs || mbs->next)
788                 st = -1;
789         else {
790                 st = 0;
791                 hashcpy(sha1, mbs->item->object.sha1);
792         }
793         free_commit_list(mbs);
794         return st;
795 }
796
797 /*
798  * This reads short-hand syntax that not only evaluates to a commit
799  * object name, but also can act as if the end user spelled the name
800  * of the branch from the command line.
801  *
802  * - "@{-N}" finds the name of the Nth previous branch we were on, and
803  *   places the name of the branch in the given buf and returns the
804  *   number of characters parsed if successful.
805  *
806  * - "<branch>@{upstream}" finds the name of the other ref that
807  *   <branch> is configured to merge with (missing <branch> defaults
808  *   to the current branch), and places the name of the branch in the
809  *   given buf and returns the number of characters parsed if
810  *   successful.
811  *
812  * If the input is not of the accepted format, it returns a negative
813  * number to signal an error.
814  *
815  * If the input was ok but there are not N branch switches in the
816  * reflog, it returns 0.
817  */
818 int interpret_branch_name(const char *name, struct strbuf *buf)
819 {
820         char *cp;
821         struct branch *upstream;
822         int namelen = strlen(name);
823         int len = interpret_nth_prior_checkout(name, buf);
824         int tmp_len;
825
826         if (!len)
827                 return len; /* syntax Ok, not enough switches */
828         if (0 < len && len == namelen)
829                 return len; /* consumed all */
830         else if (0 < len) {
831                 /* we have extra data, which might need further processing */
832                 struct strbuf tmp = STRBUF_INIT;
833                 int used = buf->len;
834                 int ret;
835
836                 strbuf_add(buf, name + len, namelen - len);
837                 ret = interpret_branch_name(buf->buf, &tmp);
838                 /* that data was not interpreted, remove our cruft */
839                 if (ret < 0) {
840                         strbuf_setlen(buf, used);
841                         return len;
842                 }
843                 strbuf_reset(buf);
844                 strbuf_addbuf(buf, &tmp);
845                 strbuf_release(&tmp);
846                 /* tweak for size of {-N} versus expanded ref name */
847                 return ret - used + len;
848         }
849
850         cp = strchr(name, '@');
851         if (!cp)
852                 return -1;
853         tmp_len = upstream_mark(cp, namelen - (cp - name));
854         if (!tmp_len)
855                 return -1;
856         len = cp + tmp_len - name;
857         cp = xstrndup(name, cp - name);
858         upstream = branch_get(*cp ? cp : NULL);
859         if (!upstream
860             || !upstream->merge
861             || !upstream->merge[0]->dst)
862                 return error("No upstream branch found for '%s'", cp);
863         free(cp);
864         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
865         strbuf_reset(buf);
866         strbuf_addstr(buf, cp);
867         free(cp);
868         return len;
869 }
870
871 int strbuf_branchname(struct strbuf *sb, const char *name)
872 {
873         int len = strlen(name);
874         if (interpret_branch_name(name, sb) == len)
875                 return 0;
876         strbuf_add(sb, name, len);
877         return len;
878 }
879
880 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
881 {
882         strbuf_branchname(sb, name);
883         if (name[0] == '-')
884                 return -1;
885         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
886         return check_refname_format(sb->buf, 0);
887 }
888
889 /*
890  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
891  * notably "xyz^" for "parent of xyz"
892  */
893 int get_sha1(const char *name, unsigned char *sha1)
894 {
895         struct object_context unused;
896         return get_sha1_with_context(name, sha1, &unused);
897 }
898
899 /* Must be called only when object_name:filename doesn't exist. */
900 static void diagnose_invalid_sha1_path(const char *prefix,
901                                        const char *filename,
902                                        const unsigned char *tree_sha1,
903                                        const char *object_name)
904 {
905         struct stat st;
906         unsigned char sha1[20];
907         unsigned mode;
908
909         if (!prefix)
910                 prefix = "";
911
912         if (!lstat(filename, &st))
913                 die("Path '%s' exists on disk, but not in '%s'.",
914                     filename, object_name);
915         if (errno == ENOENT || errno == ENOTDIR) {
916                 char *fullname = xmalloc(strlen(filename)
917                                              + strlen(prefix) + 1);
918                 strcpy(fullname, prefix);
919                 strcat(fullname, filename);
920
921                 if (!get_tree_entry(tree_sha1, fullname,
922                                     sha1, &mode)) {
923                         die("Path '%s' exists, but not '%s'.\n"
924                             "Did you mean '%s:%s' aka '%s:./%s'?",
925                             fullname,
926                             filename,
927                             object_name,
928                             fullname,
929                             object_name,
930                             filename);
931                 }
932                 die("Path '%s' does not exist in '%s'",
933                     filename, object_name);
934         }
935 }
936
937 /* Must be called only when :stage:filename doesn't exist. */
938 static void diagnose_invalid_index_path(int stage,
939                                         const char *prefix,
940                                         const char *filename)
941 {
942         struct stat st;
943         struct cache_entry *ce;
944         int pos;
945         unsigned namelen = strlen(filename);
946         unsigned fullnamelen;
947         char *fullname;
948
949         if (!prefix)
950                 prefix = "";
951
952         /* Wrong stage number? */
953         pos = cache_name_pos(filename, namelen);
954         if (pos < 0)
955                 pos = -pos - 1;
956         if (pos < active_nr) {
957                 ce = active_cache[pos];
958                 if (ce_namelen(ce) == namelen &&
959                     !memcmp(ce->name, filename, namelen))
960                         die("Path '%s' is in the index, but not at stage %d.\n"
961                             "Did you mean ':%d:%s'?",
962                             filename, stage,
963                             ce_stage(ce), filename);
964         }
965
966         /* Confusion between relative and absolute filenames? */
967         fullnamelen = namelen + strlen(prefix);
968         fullname = xmalloc(fullnamelen + 1);
969         strcpy(fullname, prefix);
970         strcat(fullname, filename);
971         pos = cache_name_pos(fullname, fullnamelen);
972         if (pos < 0)
973                 pos = -pos - 1;
974         if (pos < active_nr) {
975                 ce = active_cache[pos];
976                 if (ce_namelen(ce) == fullnamelen &&
977                     !memcmp(ce->name, fullname, fullnamelen))
978                         die("Path '%s' is in the index, but not '%s'.\n"
979                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
980                             fullname, filename,
981                             ce_stage(ce), fullname,
982                             ce_stage(ce), filename);
983         }
984
985         if (!lstat(filename, &st))
986                 die("Path '%s' exists on disk, but not in the index.", filename);
987         if (errno == ENOENT || errno == ENOTDIR)
988                 die("Path '%s' does not exist (neither on disk nor in the index).",
989                     filename);
990
991         free(fullname);
992 }
993
994
995 static char *resolve_relative_path(const char *rel)
996 {
997         if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
998                 return NULL;
999
1000         if (!startup_info)
1001                 die("BUG: startup_info struct is not initialized.");
1002
1003         if (!is_inside_work_tree())
1004                 die("relative path syntax can't be used outside working tree.");
1005
1006         /* die() inside prefix_path() if resolved path is outside worktree */
1007         return prefix_path(startup_info->prefix,
1008                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1009                            rel);
1010 }
1011
1012 static int get_sha1_with_context_1(const char *name, unsigned char *sha1,
1013                                    struct object_context *oc,
1014                                    int only_to_die, const char *prefix)
1015 {
1016         int ret, bracket_depth;
1017         int namelen = strlen(name);
1018         const char *cp;
1019
1020         memset(oc, 0, sizeof(*oc));
1021         oc->mode = S_IFINVALID;
1022         ret = get_sha1_1(name, namelen, sha1);
1023         if (!ret)
1024                 return ret;
1025         /* sha1:path --> object name of path in ent sha1
1026          * :path -> object name of absolute path in index
1027          * :./path -> object name of path relative to cwd in index
1028          * :[0-3]:path -> object name of path in index at stage
1029          * :/foo -> recent commit matching foo
1030          */
1031         if (name[0] == ':') {
1032                 int stage = 0;
1033                 struct cache_entry *ce;
1034                 char *new_path = NULL;
1035                 int pos;
1036                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1037                         struct commit_list *list = NULL;
1038                         for_each_ref(handle_one_ref, &list);
1039                         return get_sha1_oneline(name + 2, sha1, list);
1040                 }
1041                 if (namelen < 3 ||
1042                     name[2] != ':' ||
1043                     name[1] < '0' || '3' < name[1])
1044                         cp = name + 1;
1045                 else {
1046                         stage = name[1] - '0';
1047                         cp = name + 3;
1048                 }
1049                 new_path = resolve_relative_path(cp);
1050                 if (!new_path) {
1051                         namelen = namelen - (cp - name);
1052                 } else {
1053                         cp = new_path;
1054                         namelen = strlen(cp);
1055                 }
1056
1057                 strncpy(oc->path, cp,
1058                         sizeof(oc->path));
1059                 oc->path[sizeof(oc->path)-1] = '\0';
1060
1061                 if (!active_cache)
1062                         read_cache();
1063                 pos = cache_name_pos(cp, namelen);
1064                 if (pos < 0)
1065                         pos = -pos - 1;
1066                 while (pos < active_nr) {
1067                         ce = active_cache[pos];
1068                         if (ce_namelen(ce) != namelen ||
1069                             memcmp(ce->name, cp, namelen))
1070                                 break;
1071                         if (ce_stage(ce) == stage) {
1072                                 hashcpy(sha1, ce->sha1);
1073                                 oc->mode = ce->ce_mode;
1074                                 free(new_path);
1075                                 return 0;
1076                         }
1077                         pos++;
1078                 }
1079                 if (only_to_die && name[1] && name[1] != '/')
1080                         diagnose_invalid_index_path(stage, prefix, cp);
1081                 free(new_path);
1082                 return -1;
1083         }
1084         for (cp = name, bracket_depth = 0; *cp; cp++) {
1085                 if (*cp == '{')
1086                         bracket_depth++;
1087                 else if (bracket_depth && *cp == '}')
1088                         bracket_depth--;
1089                 else if (!bracket_depth && *cp == ':')
1090                         break;
1091         }
1092         if (*cp == ':') {
1093                 unsigned char tree_sha1[20];
1094                 char *object_name = NULL;
1095                 if (only_to_die) {
1096                         object_name = xmalloc(cp-name+1);
1097                         strncpy(object_name, name, cp-name);
1098                         object_name[cp-name] = '\0';
1099                 }
1100                 if (!get_sha1_1(name, cp-name, tree_sha1)) {
1101                         const char *filename = cp+1;
1102                         char *new_filename = NULL;
1103
1104                         new_filename = resolve_relative_path(filename);
1105                         if (new_filename)
1106                                 filename = new_filename;
1107                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1108                         if (only_to_die) {
1109                                 diagnose_invalid_sha1_path(prefix, filename,
1110                                                            tree_sha1, object_name);
1111                                 free(object_name);
1112                         }
1113                         hashcpy(oc->tree, tree_sha1);
1114                         strncpy(oc->path, filename,
1115                                 sizeof(oc->path));
1116                         oc->path[sizeof(oc->path)-1] = '\0';
1117
1118                         free(new_filename);
1119                         return ret;
1120                 } else {
1121                         if (only_to_die)
1122                                 die("Invalid object name '%s'.", object_name);
1123                 }
1124         }
1125         return ret;
1126 }
1127
1128 int get_sha1_with_mode_1(const char *name, unsigned char *sha1, unsigned *mode,
1129                          int only_to_die, const char *prefix)
1130 {
1131         struct object_context oc;
1132         int ret;
1133         ret = get_sha1_with_context_1(name, sha1, &oc, only_to_die, prefix);
1134         *mode = oc.mode;
1135         return ret;
1136 }
1137
1138 int get_sha1_with_context(const char *str, unsigned char *sha1, struct object_context *orc)
1139 {
1140         return get_sha1_with_context_1(str, sha1, orc, 0, NULL);
1141 }