Merge branch 'bc/log-decoration' into maint
[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 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
13
14 struct disambiguate_state {
15         disambiguate_hint_fn fn;
16         void *cb_data;
17         unsigned char candidate[20];
18         unsigned candidate_exists:1;
19         unsigned candidate_checked:1;
20         unsigned candidate_ok:1;
21         unsigned disambiguate_fn_used:1;
22         unsigned ambiguous:1;
23         unsigned always_call_fn:1;
24 };
25
26 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
27 {
28         if (ds->always_call_fn) {
29                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
30                 return;
31         }
32         if (!ds->candidate_exists) {
33                 /* this is the first candidate */
34                 hashcpy(ds->candidate, current);
35                 ds->candidate_exists = 1;
36                 return;
37         } else if (!hashcmp(ds->candidate, current)) {
38                 /* the same as what we already have seen */
39                 return;
40         }
41
42         if (!ds->fn) {
43                 /* cannot disambiguate between ds->candidate and current */
44                 ds->ambiguous = 1;
45                 return;
46         }
47
48         if (!ds->candidate_checked) {
49                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
50                 ds->disambiguate_fn_used = 1;
51                 ds->candidate_checked = 1;
52         }
53
54         if (!ds->candidate_ok) {
55                 /* discard the candidate; we know it does not satisfy fn */
56                 hashcpy(ds->candidate, current);
57                 ds->candidate_checked = 0;
58                 return;
59         }
60
61         /* if we reach this point, we know ds->candidate satisfies fn */
62         if (ds->fn(current, ds->cb_data)) {
63                 /*
64                  * if both current and candidate satisfy fn, we cannot
65                  * disambiguate.
66                  */
67                 ds->candidate_ok = 0;
68                 ds->ambiguous = 1;
69         }
70
71         /* otherwise, current can be discarded and candidate is still good */
72 }
73
74 static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
75 {
76         struct alternate_object_database *alt;
77         char hex[40];
78         static struct alternate_object_database *fakeent;
79
80         if (!fakeent) {
81                 /*
82                  * Create a "fake" alternate object database that
83                  * points to our own object database, to make it
84                  * easier to get a temporary working space in
85                  * alt->name/alt->base while iterating over the
86                  * object databases including our own.
87                  */
88                 const char *objdir = get_object_directory();
89                 int objdir_len = strlen(objdir);
90                 int entlen = objdir_len + 43;
91                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
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         sprintf(hex, "%.2s", hex_pfx);
99         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
100                 struct dirent *de;
101                 DIR *dir;
102                 sprintf(alt->name, "%.2s/", hex_pfx);
103                 dir = opendir(alt->base);
104                 if (!dir)
105                         continue;
106
107                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
108                         unsigned char sha1[20];
109
110                         if (strlen(de->d_name) != 38)
111                                 continue;
112                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
113                                 continue;
114                         memcpy(hex + 2, de->d_name, 38);
115                         if (!get_sha1_hex(hex, sha1))
116                                 update_candidates(ds, sha1);
117                 }
118                 closedir(dir);
119         }
120 }
121
122 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
123 {
124         do {
125                 if (*a != *b)
126                         return 0;
127                 a++;
128                 b++;
129                 len -= 2;
130         } while (len > 1);
131         if (len)
132                 if ((*a ^ *b) & 0xf0)
133                         return 0;
134         return 1;
135 }
136
137 static void unique_in_pack(int len,
138                           const unsigned char *bin_pfx,
139                            struct packed_git *p,
140                            struct disambiguate_state *ds)
141 {
142         uint32_t num, last, i, first = 0;
143         const unsigned char *current = NULL;
144
145         open_pack_index(p);
146         num = p->num_objects;
147         last = num;
148         while (first < last) {
149                 uint32_t mid = (first + last) / 2;
150                 const unsigned char *current;
151                 int cmp;
152
153                 current = nth_packed_object_sha1(p, mid);
154                 cmp = hashcmp(bin_pfx, current);
155                 if (!cmp) {
156                         first = mid;
157                         break;
158                 }
159                 if (cmp > 0) {
160                         first = mid+1;
161                         continue;
162                 }
163                 last = mid;
164         }
165
166         /*
167          * At this point, "first" is the location of the lowest object
168          * with an object name that could match "bin_pfx".  See if we have
169          * 0, 1 or more objects that actually match(es).
170          */
171         for (i = first; i < num && !ds->ambiguous; i++) {
172                 current = nth_packed_object_sha1(p, i);
173                 if (!match_sha(len, bin_pfx, current))
174                         break;
175                 update_candidates(ds, current);
176         }
177 }
178
179 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
180                                      struct disambiguate_state *ds)
181 {
182         struct packed_git *p;
183
184         prepare_packed_git();
185         for (p = packed_git; p && !ds->ambiguous; p = p->next)
186                 unique_in_pack(len, bin_pfx, p, ds);
187 }
188
189 #define SHORT_NAME_NOT_FOUND (-1)
190 #define SHORT_NAME_AMBIGUOUS (-2)
191
192 static int finish_object_disambiguation(struct disambiguate_state *ds,
193                                         unsigned char *sha1)
194 {
195         if (ds->ambiguous)
196                 return SHORT_NAME_AMBIGUOUS;
197
198         if (!ds->candidate_exists)
199                 return SHORT_NAME_NOT_FOUND;
200
201         if (!ds->candidate_checked)
202                 /*
203                  * If this is the only candidate, there is no point
204                  * calling the disambiguation hint callback.
205                  *
206                  * On the other hand, if the current candidate
207                  * replaced an earlier candidate that did _not_ pass
208                  * the disambiguation hint callback, then we do have
209                  * more than one objects that match the short name
210                  * given, so we should make sure this one matches;
211                  * otherwise, if we discovered this one and the one
212                  * that we previously discarded in the reverse order,
213                  * we would end up showing different results in the
214                  * same repository!
215                  */
216                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
217                                     ds->fn(ds->candidate, ds->cb_data));
218
219         if (!ds->candidate_ok)
220                 return SHORT_NAME_AMBIGUOUS;
221
222         hashcpy(sha1, ds->candidate);
223         return 0;
224 }
225
226 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
227 {
228         int kind = sha1_object_info(sha1, NULL);
229         return kind == OBJ_COMMIT;
230 }
231
232 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
233 {
234         struct object *obj;
235         int kind;
236
237         kind = sha1_object_info(sha1, NULL);
238         if (kind == OBJ_COMMIT)
239                 return 1;
240         if (kind != OBJ_TAG)
241                 return 0;
242
243         /* We need to do this the hard way... */
244         obj = deref_tag(parse_object(sha1), NULL, 0);
245         if (obj && obj->type == OBJ_COMMIT)
246                 return 1;
247         return 0;
248 }
249
250 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
251 {
252         int kind = sha1_object_info(sha1, NULL);
253         return kind == OBJ_TREE;
254 }
255
256 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
257 {
258         struct object *obj;
259         int kind;
260
261         kind = sha1_object_info(sha1, NULL);
262         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
263                 return 1;
264         if (kind != OBJ_TAG)
265                 return 0;
266
267         /* We need to do this the hard way... */
268         obj = deref_tag(lookup_object(sha1), NULL, 0);
269         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
270                 return 1;
271         return 0;
272 }
273
274 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
275 {
276         int kind = sha1_object_info(sha1, NULL);
277         return kind == OBJ_BLOB;
278 }
279
280 static int prepare_prefixes(const char *name, int len,
281                             unsigned char *bin_pfx,
282                             char *hex_pfx)
283 {
284         int i;
285
286         hashclr(bin_pfx);
287         memset(hex_pfx, 'x', 40);
288         for (i = 0; i < len ;i++) {
289                 unsigned char c = name[i];
290                 unsigned char val;
291                 if (c >= '0' && c <= '9')
292                         val = c - '0';
293                 else if (c >= 'a' && c <= 'f')
294                         val = c - 'a' + 10;
295                 else if (c >= 'A' && c <='F') {
296                         val = c - 'A' + 10;
297                         c -= 'A' - 'a';
298                 }
299                 else
300                         return -1;
301                 hex_pfx[i] = c;
302                 if (!(i & 1))
303                         val <<= 4;
304                 bin_pfx[i >> 1] |= val;
305         }
306         return 0;
307 }
308
309 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
310                           unsigned flags)
311 {
312         int status;
313         char hex_pfx[40];
314         unsigned char bin_pfx[20];
315         struct disambiguate_state ds;
316         int quietly = !!(flags & GET_SHA1_QUIETLY);
317
318         if (len < MINIMUM_ABBREV || len > 40)
319                 return -1;
320         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
321                 return -1;
322
323         prepare_alt_odb();
324
325         memset(&ds, 0, sizeof(ds));
326         if (flags & GET_SHA1_COMMIT)
327                 ds.fn = disambiguate_commit_only;
328         else if (flags & GET_SHA1_COMMITTISH)
329                 ds.fn = disambiguate_committish_only;
330         else if (flags & GET_SHA1_TREE)
331                 ds.fn = disambiguate_tree_only;
332         else if (flags & GET_SHA1_TREEISH)
333                 ds.fn = disambiguate_treeish_only;
334         else if (flags & GET_SHA1_BLOB)
335                 ds.fn = disambiguate_blob_only;
336
337         find_short_object_filename(len, hex_pfx, &ds);
338         find_short_packed_object(len, bin_pfx, &ds);
339         status = finish_object_disambiguation(&ds, sha1);
340
341         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
342                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
343         return status;
344 }
345
346 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
347 {
348         char hex_pfx[40];
349         unsigned char bin_pfx[20];
350         struct disambiguate_state ds;
351         int len = strlen(prefix);
352
353         if (len < MINIMUM_ABBREV || len > 40)
354                 return -1;
355         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
356                 return -1;
357
358         prepare_alt_odb();
359
360         memset(&ds, 0, sizeof(ds));
361         ds.always_call_fn = 1;
362         ds.cb_data = cb_data;
363         ds.fn = fn;
364
365         find_short_object_filename(len, hex_pfx, &ds);
366         find_short_packed_object(len, bin_pfx, &ds);
367         return ds.ambiguous;
368 }
369
370 const char *find_unique_abbrev(const unsigned char *sha1, int len)
371 {
372         int status, exists;
373         static char hex[41];
374
375         exists = has_sha1_file(sha1);
376         memcpy(hex, sha1_to_hex(sha1), 40);
377         if (len == 40 || !len)
378                 return hex;
379         while (len < 40) {
380                 unsigned char sha1_ret[20];
381                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
382                 if (exists
383                     ? !status
384                     : status == SHORT_NAME_NOT_FOUND) {
385                         hex[len] = 0;
386                         return hex;
387                 }
388                 len++;
389         }
390         return hex;
391 }
392
393 static int ambiguous_path(const char *path, int len)
394 {
395         int slash = 1;
396         int cnt;
397
398         for (cnt = 0; cnt < len; cnt++) {
399                 switch (*path++) {
400                 case '\0':
401                         break;
402                 case '/':
403                         if (slash)
404                                 break;
405                         slash = 1;
406                         continue;
407                 case '.':
408                         continue;
409                 default:
410                         slash = 0;
411                         continue;
412                 }
413                 break;
414         }
415         return slash;
416 }
417
418 static inline int upstream_mark(const char *string, int len)
419 {
420         const char *suffix[] = { "@{upstream}", "@{u}" };
421         int i;
422
423         for (i = 0; i < ARRAY_SIZE(suffix); i++) {
424                 int suffix_len = strlen(suffix[i]);
425                 if (suffix_len <= len
426                     && !memcmp(string, suffix[i], suffix_len))
427                         return suffix_len;
428         }
429         return 0;
430 }
431
432 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
433 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf);
434
435 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
436 {
437         static const char *warn_msg = "refname '%.*s' is ambiguous.";
438         static const char *object_name_msg = N_(
439         "Git normally never creates a ref that ends with 40 hex characters\n"
440         "because it will be ignored when you just specify 40-hex. These refs\n"
441         "may be created by mistake. For example,\n"
442         "\n"
443         "  git checkout -b $br $(git rev-parse ...)\n"
444         "\n"
445         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
446         "examine these refs and maybe delete them. Turn this message off by\n"
447         "running \"git config advice.objectNameWarning false\"");
448         unsigned char tmp_sha1[20];
449         char *real_ref = NULL;
450         int refs_found = 0;
451         int at, reflog_len, nth_prior = 0;
452
453         if (len == 40 && !get_sha1_hex(str, sha1)) {
454                 if (warn_on_object_refname_ambiguity) {
455                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
456                         if (refs_found > 0 && warn_ambiguous_refs) {
457                                 warning(warn_msg, len, str);
458                                 if (advice_object_name_warning)
459                                         fprintf(stderr, "%s\n", _(object_name_msg));
460                         }
461                         free(real_ref);
462                 }
463                 return 0;
464         }
465
466         /* basic@{time or number or -number} format to query ref-log */
467         reflog_len = at = 0;
468         if (len && str[len-1] == '}') {
469                 for (at = len-4; at >= 0; at--) {
470                         if (str[at] == '@' && str[at+1] == '{') {
471                                 if (str[at+2] == '-') {
472                                         if (at != 0)
473                                                 /* @{-N} not at start */
474                                                 return -1;
475                                         nth_prior = 1;
476                                         continue;
477                                 }
478                                 if (!upstream_mark(str + at, len - at)) {
479                                         reflog_len = (len-1) - (at+2);
480                                         len = at;
481                                 }
482                                 break;
483                         }
484                 }
485         }
486
487         /* Accept only unambiguous ref paths. */
488         if (len && ambiguous_path(str, len))
489                 return -1;
490
491         if (nth_prior) {
492                 struct strbuf buf = STRBUF_INIT;
493                 int detached;
494
495                 if (interpret_nth_prior_checkout(str, &buf) > 0) {
496                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
497                         strbuf_release(&buf);
498                         if (detached)
499                                 return 0;
500                 }
501         }
502
503         if (!len && reflog_len)
504                 /* allow "@{...}" to mean the current branch reflog */
505                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
506         else if (reflog_len)
507                 refs_found = dwim_log(str, len, sha1, &real_ref);
508         else
509                 refs_found = dwim_ref(str, len, sha1, &real_ref);
510
511         if (!refs_found)
512                 return -1;
513
514         if (warn_ambiguous_refs &&
515             (refs_found > 1 ||
516              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
517                 warning(warn_msg, len, str);
518
519         if (reflog_len) {
520                 int nth, i;
521                 unsigned long at_time;
522                 unsigned long co_time;
523                 int co_tz, co_cnt;
524
525                 /* Is it asking for N-th entry, or approxidate? */
526                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
527                         char ch = str[at+2+i];
528                         if ('0' <= ch && ch <= '9')
529                                 nth = nth * 10 + ch - '0';
530                         else
531                                 nth = -1;
532                 }
533                 if (100000000 <= nth) {
534                         at_time = nth;
535                         nth = -1;
536                 } else if (0 <= nth)
537                         at_time = 0;
538                 else {
539                         int errors = 0;
540                         char *tmp = xstrndup(str + at + 2, reflog_len);
541                         at_time = approxidate_careful(tmp, &errors);
542                         free(tmp);
543                         if (errors)
544                                 return -1;
545                 }
546                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
547                                 &co_time, &co_tz, &co_cnt)) {
548                         if (!len) {
549                                 if (!prefixcmp(real_ref, "refs/heads/")) {
550                                         str = real_ref + 11;
551                                         len = strlen(real_ref + 11);
552                                 } else {
553                                         /* detached HEAD */
554                                         str = "HEAD";
555                                         len = 4;
556                                 }
557                         }
558                         if (at_time)
559                                 warning("Log for '%.*s' only goes "
560                                         "back to %s.", len, str,
561                                         show_date(co_time, co_tz, DATE_RFC2822));
562                         else {
563                                 die("Log for '%.*s' only has %d entries.",
564                                     len, str, co_cnt);
565                         }
566                 }
567         }
568
569         free(real_ref);
570         return 0;
571 }
572
573 static int get_parent(const char *name, int len,
574                       unsigned char *result, int idx)
575 {
576         unsigned char sha1[20];
577         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
578         struct commit *commit;
579         struct commit_list *p;
580
581         if (ret)
582                 return ret;
583         commit = lookup_commit_reference(sha1);
584         if (!commit)
585                 return -1;
586         if (parse_commit(commit))
587                 return -1;
588         if (!idx) {
589                 hashcpy(result, commit->object.sha1);
590                 return 0;
591         }
592         p = commit->parents;
593         while (p) {
594                 if (!--idx) {
595                         hashcpy(result, p->item->object.sha1);
596                         return 0;
597                 }
598                 p = p->next;
599         }
600         return -1;
601 }
602
603 static int get_nth_ancestor(const char *name, int len,
604                             unsigned char *result, int generation)
605 {
606         unsigned char sha1[20];
607         struct commit *commit;
608         int ret;
609
610         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
611         if (ret)
612                 return ret;
613         commit = lookup_commit_reference(sha1);
614         if (!commit)
615                 return -1;
616
617         while (generation--) {
618                 if (parse_commit(commit) || !commit->parents)
619                         return -1;
620                 commit = commit->parents->item;
621         }
622         hashcpy(result, commit->object.sha1);
623         return 0;
624 }
625
626 struct object *peel_to_type(const char *name, int namelen,
627                             struct object *o, enum object_type expected_type)
628 {
629         if (name && !namelen)
630                 namelen = strlen(name);
631         while (1) {
632                 if (!o || (!o->parsed && !parse_object(o->sha1)))
633                         return NULL;
634                 if (expected_type == OBJ_ANY || o->type == expected_type)
635                         return o;
636                 if (o->type == OBJ_TAG)
637                         o = ((struct tag*) o)->tagged;
638                 else if (o->type == OBJ_COMMIT)
639                         o = &(((struct commit *) o)->tree->object);
640                 else {
641                         if (name)
642                                 error("%.*s: expected %s type, but the object "
643                                       "dereferences to %s type",
644                                       namelen, name, typename(expected_type),
645                                       typename(o->type));
646                         return NULL;
647                 }
648         }
649 }
650
651 static int peel_onion(const char *name, int len, unsigned char *sha1)
652 {
653         unsigned char outer[20];
654         const char *sp;
655         unsigned int expected_type = 0;
656         unsigned lookup_flags = 0;
657         struct object *o;
658
659         /*
660          * "ref^{type}" dereferences ref repeatedly until you cannot
661          * dereference anymore, or you get an object of given type,
662          * whichever comes first.  "ref^{}" means just dereference
663          * tags until you get a non-tag.  "ref^0" is a shorthand for
664          * "ref^{commit}".  "commit^{tree}" could be used to find the
665          * top-level tree of the given commit.
666          */
667         if (len < 4 || name[len-1] != '}')
668                 return -1;
669
670         for (sp = name + len - 1; name <= sp; sp--) {
671                 int ch = *sp;
672                 if (ch == '{' && name < sp && sp[-1] == '^')
673                         break;
674         }
675         if (sp <= name)
676                 return -1;
677
678         sp++; /* beginning of type name, or closing brace for empty */
679         if (!prefixcmp(sp, "commit}"))
680                 expected_type = OBJ_COMMIT;
681         else if (!prefixcmp(sp, "tag}"))
682                 expected_type = OBJ_TAG;
683         else if (!prefixcmp(sp, "tree}"))
684                 expected_type = OBJ_TREE;
685         else if (!prefixcmp(sp, "blob}"))
686                 expected_type = OBJ_BLOB;
687         else if (!prefixcmp(sp, "object}"))
688                 expected_type = OBJ_ANY;
689         else if (sp[0] == '}')
690                 expected_type = OBJ_NONE;
691         else if (sp[0] == '/')
692                 expected_type = OBJ_COMMIT;
693         else
694                 return -1;
695
696         if (expected_type == OBJ_COMMIT)
697                 lookup_flags = GET_SHA1_COMMITTISH;
698         else if (expected_type == OBJ_TREE)
699                 lookup_flags = GET_SHA1_TREEISH;
700
701         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
702                 return -1;
703
704         o = parse_object(outer);
705         if (!o)
706                 return -1;
707         if (!expected_type) {
708                 o = deref_tag(o, name, sp - name - 2);
709                 if (!o || (!o->parsed && !parse_object(o->sha1)))
710                         return -1;
711                 hashcpy(sha1, o->sha1);
712                 return 0;
713         }
714
715         /*
716          * At this point, the syntax look correct, so
717          * if we do not get the needed object, we should
718          * barf.
719          */
720         o = peel_to_type(name, len, o, expected_type);
721         if (!o)
722                 return -1;
723
724         hashcpy(sha1, o->sha1);
725         if (sp[0] == '/') {
726                 /* "$commit^{/foo}" */
727                 char *prefix;
728                 int ret;
729                 struct commit_list *list = NULL;
730
731                 /*
732                  * $commit^{/}. Some regex implementation may reject.
733                  * We don't need regex anyway. '' pattern always matches.
734                  */
735                 if (sp[1] == '}')
736                         return 0;
737
738                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
739                 commit_list_insert((struct commit *)o, &list);
740                 ret = get_sha1_oneline(prefix, sha1, list);
741                 free(prefix);
742                 return ret;
743         }
744         return 0;
745 }
746
747 static int get_describe_name(const char *name, int len, unsigned char *sha1)
748 {
749         const char *cp;
750         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
751
752         for (cp = name + len - 1; name + 2 <= cp; cp--) {
753                 char ch = *cp;
754                 if (hexval(ch) & ~0377) {
755                         /* We must be looking at g in "SOMETHING-g"
756                          * for it to be describe output.
757                          */
758                         if (ch == 'g' && cp[-1] == '-') {
759                                 cp++;
760                                 len -= cp - name;
761                                 return get_short_sha1(cp, len, sha1, flags);
762                         }
763                 }
764         }
765         return -1;
766 }
767
768 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
769 {
770         int ret, has_suffix;
771         const char *cp;
772
773         /*
774          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
775          */
776         has_suffix = 0;
777         for (cp = name + len - 1; name <= cp; cp--) {
778                 int ch = *cp;
779                 if ('0' <= ch && ch <= '9')
780                         continue;
781                 if (ch == '~' || ch == '^')
782                         has_suffix = ch;
783                 break;
784         }
785
786         if (has_suffix) {
787                 int num = 0;
788                 int len1 = cp - name;
789                 cp++;
790                 while (cp < name + len)
791                         num = num * 10 + *cp++ - '0';
792                 if (!num && len1 == len - 1)
793                         num = 1;
794                 if (has_suffix == '^')
795                         return get_parent(name, len1, sha1, num);
796                 /* else if (has_suffix == '~') -- goes without saying */
797                 return get_nth_ancestor(name, len1, sha1, num);
798         }
799
800         ret = peel_onion(name, len, sha1);
801         if (!ret)
802                 return 0;
803
804         ret = get_sha1_basic(name, len, sha1);
805         if (!ret)
806                 return 0;
807
808         /* It could be describe output that is "SOMETHING-gXXXX" */
809         ret = get_describe_name(name, len, sha1);
810         if (!ret)
811                 return 0;
812
813         return get_short_sha1(name, len, sha1, lookup_flags);
814 }
815
816 /*
817  * This interprets names like ':/Initial revision of "git"' by searching
818  * through history and returning the first commit whose message starts
819  * the given regular expression.
820  *
821  * For future extension, ':/!' is reserved. If you want to match a message
822  * beginning with a '!', you have to repeat the exclamation mark.
823  */
824 #define ONELINE_SEEN (1u<<20)
825
826 static int handle_one_ref(const char *path,
827                 const unsigned char *sha1, int flag, void *cb_data)
828 {
829         struct commit_list **list = cb_data;
830         struct object *object = parse_object(sha1);
831         if (!object)
832                 return 0;
833         if (object->type == OBJ_TAG) {
834                 object = deref_tag(object, path, strlen(path));
835                 if (!object)
836                         return 0;
837         }
838         if (object->type != OBJ_COMMIT)
839                 return 0;
840         commit_list_insert_by_date((struct commit *)object, list);
841         return 0;
842 }
843
844 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
845                             struct commit_list *list)
846 {
847         struct commit_list *backup = NULL, *l;
848         int found = 0;
849         regex_t regex;
850
851         if (prefix[0] == '!') {
852                 if (prefix[1] != '!')
853                         die ("Invalid search pattern: %s", prefix);
854                 prefix++;
855         }
856
857         if (regcomp(&regex, prefix, REG_EXTENDED))
858                 die("Invalid search pattern: %s", prefix);
859
860         for (l = list; l; l = l->next) {
861                 l->item->object.flags |= ONELINE_SEEN;
862                 commit_list_insert(l->item, &backup);
863         }
864         while (list) {
865                 char *p, *to_free = NULL;
866                 struct commit *commit;
867                 enum object_type type;
868                 unsigned long size;
869                 int matches;
870
871                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
872                 if (!parse_object(commit->object.sha1))
873                         continue;
874                 if (commit->buffer)
875                         p = commit->buffer;
876                 else {
877                         p = read_sha1_file(commit->object.sha1, &type, &size);
878                         if (!p)
879                                 continue;
880                         to_free = p;
881                 }
882
883                 p = strstr(p, "\n\n");
884                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
885                 free(to_free);
886
887                 if (matches) {
888                         hashcpy(sha1, commit->object.sha1);
889                         found = 1;
890                         break;
891                 }
892         }
893         regfree(&regex);
894         free_commit_list(list);
895         for (l = backup; l; l = l->next)
896                 clear_commit_marks(l->item, ONELINE_SEEN);
897         free_commit_list(backup);
898         return found ? 0 : -1;
899 }
900
901 struct grab_nth_branch_switch_cbdata {
902         int remaining;
903         struct strbuf buf;
904 };
905
906 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
907                                   const char *email, unsigned long timestamp, int tz,
908                                   const char *message, void *cb_data)
909 {
910         struct grab_nth_branch_switch_cbdata *cb = cb_data;
911         const char *match = NULL, *target = NULL;
912         size_t len;
913
914         if (!prefixcmp(message, "checkout: moving from ")) {
915                 match = message + strlen("checkout: moving from ");
916                 target = strstr(match, " to ");
917         }
918
919         if (!match || !target)
920                 return 0;
921         if (--(cb->remaining) == 0) {
922                 len = target - match;
923                 strbuf_reset(&cb->buf);
924                 strbuf_add(&cb->buf, match, len);
925                 return 1; /* we are done */
926         }
927         return 0;
928 }
929
930 /*
931  * Parse @{-N} syntax, return the number of characters parsed
932  * if successful; otherwise signal an error with negative value.
933  */
934 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
935 {
936         long nth;
937         int retval;
938         struct grab_nth_branch_switch_cbdata cb;
939         const char *brace;
940         char *num_end;
941
942         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
943                 return -1;
944         brace = strchr(name, '}');
945         if (!brace)
946                 return -1;
947         nth = strtol(name + 3, &num_end, 10);
948         if (num_end != brace)
949                 return -1;
950         if (nth <= 0)
951                 return -1;
952         cb.remaining = nth;
953         strbuf_init(&cb.buf, 20);
954
955         retval = 0;
956         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
957                 strbuf_reset(buf);
958                 strbuf_add(buf, cb.buf.buf, cb.buf.len);
959                 retval = brace - name + 1;
960         }
961
962         strbuf_release(&cb.buf);
963         return retval;
964 }
965
966 int get_sha1_mb(const char *name, unsigned char *sha1)
967 {
968         struct commit *one, *two;
969         struct commit_list *mbs;
970         unsigned char sha1_tmp[20];
971         const char *dots;
972         int st;
973
974         dots = strstr(name, "...");
975         if (!dots)
976                 return get_sha1(name, sha1);
977         if (dots == name)
978                 st = get_sha1("HEAD", sha1_tmp);
979         else {
980                 struct strbuf sb;
981                 strbuf_init(&sb, dots - name);
982                 strbuf_add(&sb, name, dots - name);
983                 st = get_sha1_committish(sb.buf, sha1_tmp);
984                 strbuf_release(&sb);
985         }
986         if (st)
987                 return st;
988         one = lookup_commit_reference_gently(sha1_tmp, 0);
989         if (!one)
990                 return -1;
991
992         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
993                 return -1;
994         two = lookup_commit_reference_gently(sha1_tmp, 0);
995         if (!two)
996                 return -1;
997         mbs = get_merge_bases(one, two, 1);
998         if (!mbs || mbs->next)
999                 st = -1;
1000         else {
1001                 st = 0;
1002                 hashcpy(sha1, mbs->item->object.sha1);
1003         }
1004         free_commit_list(mbs);
1005         return st;
1006 }
1007
1008 /* parse @something syntax, when 'something' is not {.*} */
1009 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1010 {
1011         const char *next;
1012
1013         if (len || name[1] == '{')
1014                 return -1;
1015
1016         /* make sure it's a single @, or @@{.*}, not @foo */
1017         next = strchr(name + len + 1, '@');
1018         if (next && next[1] != '{')
1019                 return -1;
1020         if (!next)
1021                 next = name + namelen;
1022         if (next != name + 1)
1023                 return -1;
1024
1025         strbuf_reset(buf);
1026         strbuf_add(buf, "HEAD", 4);
1027         return 1;
1028 }
1029
1030 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1031 {
1032         /* we have extra data, which might need further processing */
1033         struct strbuf tmp = STRBUF_INIT;
1034         int used = buf->len;
1035         int ret;
1036
1037         strbuf_add(buf, name + len, namelen - len);
1038         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1039         /* that data was not interpreted, remove our cruft */
1040         if (ret < 0) {
1041                 strbuf_setlen(buf, used);
1042                 return len;
1043         }
1044         strbuf_reset(buf);
1045         strbuf_addbuf(buf, &tmp);
1046         strbuf_release(&tmp);
1047         /* tweak for size of {-N} versus expanded ref name */
1048         return ret - used + len;
1049 }
1050
1051 /*
1052  * This reads short-hand syntax that not only evaluates to a commit
1053  * object name, but also can act as if the end user spelled the name
1054  * of the branch from the command line.
1055  *
1056  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1057  *   places the name of the branch in the given buf and returns the
1058  *   number of characters parsed if successful.
1059  *
1060  * - "<branch>@{upstream}" finds the name of the other ref that
1061  *   <branch> is configured to merge with (missing <branch> defaults
1062  *   to the current branch), and places the name of the branch in the
1063  *   given buf and returns the number of characters parsed if
1064  *   successful.
1065  *
1066  * If the input is not of the accepted format, it returns a negative
1067  * number to signal an error.
1068  *
1069  * If the input was ok but there are not N branch switches in the
1070  * reflog, it returns 0.
1071  */
1072 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1073 {
1074         char *cp;
1075         struct branch *upstream;
1076         int len = interpret_nth_prior_checkout(name, buf);
1077         int tmp_len;
1078
1079         if (!namelen)
1080                 namelen = strlen(name);
1081
1082         if (!len) {
1083                 return len; /* syntax Ok, not enough switches */
1084         } else if (len > 0) {
1085                 if (len == namelen)
1086                         return len; /* consumed all */
1087                 else
1088                         return reinterpret(name, namelen, len, buf);
1089         }
1090
1091         cp = strchr(name, '@');
1092         if (!cp)
1093                 return -1;
1094
1095         len = interpret_empty_at(name, namelen, cp - name, buf);
1096         if (len > 0)
1097                 return reinterpret(name, namelen, len, buf);
1098
1099         tmp_len = upstream_mark(cp, namelen - (cp - name));
1100         if (!tmp_len)
1101                 return -1;
1102
1103         len = cp + tmp_len - name;
1104         cp = xstrndup(name, cp - name);
1105         upstream = branch_get(*cp ? cp : NULL);
1106         /*
1107          * Upstream can be NULL only if cp refers to HEAD and HEAD
1108          * points to something different than a branch.
1109          */
1110         if (!upstream)
1111                 die(_("HEAD does not point to a branch"));
1112         if (!upstream->merge || !upstream->merge[0]->dst) {
1113                 if (!ref_exists(upstream->refname))
1114                         die(_("No such branch: '%s'"), cp);
1115                 if (!upstream->merge) {
1116                         die(_("No upstream configured for branch '%s'"),
1117                                 upstream->name);
1118                 }
1119                 die(
1120                         _("Upstream branch '%s' not stored as a remote-tracking branch"),
1121                         upstream->merge[0]->src);
1122         }
1123         free(cp);
1124         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
1125         strbuf_reset(buf);
1126         strbuf_addstr(buf, cp);
1127         free(cp);
1128         return len;
1129 }
1130
1131 int strbuf_branchname(struct strbuf *sb, const char *name)
1132 {
1133         int len = strlen(name);
1134         int used = interpret_branch_name(name, len, sb);
1135
1136         if (used == len)
1137                 return 0;
1138         if (used < 0)
1139                 used = 0;
1140         strbuf_add(sb, name + used, len - used);
1141         return len;
1142 }
1143
1144 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1145 {
1146         strbuf_branchname(sb, name);
1147         if (name[0] == '-')
1148                 return -1;
1149         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1150         return check_refname_format(sb->buf, 0);
1151 }
1152
1153 /*
1154  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1155  * notably "xyz^" for "parent of xyz"
1156  */
1157 int get_sha1(const char *name, unsigned char *sha1)
1158 {
1159         struct object_context unused;
1160         return get_sha1_with_context(name, 0, sha1, &unused);
1161 }
1162
1163 /*
1164  * Many callers know that the user meant to name a commit-ish by
1165  * syntactical positions where the object name appears.  Calling this
1166  * function allows the machinery to disambiguate shorter-than-unique
1167  * abbreviated object names between commit-ish and others.
1168  *
1169  * Note that this does NOT error out when the named object is not a
1170  * commit-ish. It is merely to give a hint to the disambiguation
1171  * machinery.
1172  */
1173 int get_sha1_committish(const char *name, unsigned char *sha1)
1174 {
1175         struct object_context unused;
1176         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1177                                      sha1, &unused);
1178 }
1179
1180 int get_sha1_treeish(const char *name, unsigned char *sha1)
1181 {
1182         struct object_context unused;
1183         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1184                                      sha1, &unused);
1185 }
1186
1187 int get_sha1_commit(const char *name, unsigned char *sha1)
1188 {
1189         struct object_context unused;
1190         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1191                                      sha1, &unused);
1192 }
1193
1194 int get_sha1_tree(const char *name, unsigned char *sha1)
1195 {
1196         struct object_context unused;
1197         return get_sha1_with_context(name, GET_SHA1_TREE,
1198                                      sha1, &unused);
1199 }
1200
1201 int get_sha1_blob(const char *name, unsigned char *sha1)
1202 {
1203         struct object_context unused;
1204         return get_sha1_with_context(name, GET_SHA1_BLOB,
1205                                      sha1, &unused);
1206 }
1207
1208 /* Must be called only when object_name:filename doesn't exist. */
1209 static void diagnose_invalid_sha1_path(const char *prefix,
1210                                        const char *filename,
1211                                        const unsigned char *tree_sha1,
1212                                        const char *object_name,
1213                                        int object_name_len)
1214 {
1215         struct stat st;
1216         unsigned char sha1[20];
1217         unsigned mode;
1218
1219         if (!prefix)
1220                 prefix = "";
1221
1222         if (!lstat(filename, &st))
1223                 die("Path '%s' exists on disk, but not in '%.*s'.",
1224                     filename, object_name_len, object_name);
1225         if (errno == ENOENT || errno == ENOTDIR) {
1226                 char *fullname = xmalloc(strlen(filename)
1227                                              + strlen(prefix) + 1);
1228                 strcpy(fullname, prefix);
1229                 strcat(fullname, filename);
1230
1231                 if (!get_tree_entry(tree_sha1, fullname,
1232                                     sha1, &mode)) {
1233                         die("Path '%s' exists, but not '%s'.\n"
1234                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1235                             fullname,
1236                             filename,
1237                             object_name_len, object_name,
1238                             fullname,
1239                             object_name_len, object_name,
1240                             filename);
1241                 }
1242                 die("Path '%s' does not exist in '%.*s'",
1243                     filename, object_name_len, object_name);
1244         }
1245 }
1246
1247 /* Must be called only when :stage:filename doesn't exist. */
1248 static void diagnose_invalid_index_path(int stage,
1249                                         const char *prefix,
1250                                         const char *filename)
1251 {
1252         struct stat st;
1253         const struct cache_entry *ce;
1254         int pos;
1255         unsigned namelen = strlen(filename);
1256         unsigned fullnamelen;
1257         char *fullname;
1258
1259         if (!prefix)
1260                 prefix = "";
1261
1262         /* Wrong stage number? */
1263         pos = cache_name_pos(filename, namelen);
1264         if (pos < 0)
1265                 pos = -pos - 1;
1266         if (pos < active_nr) {
1267                 ce = active_cache[pos];
1268                 if (ce_namelen(ce) == namelen &&
1269                     !memcmp(ce->name, filename, namelen))
1270                         die("Path '%s' is in the index, but not at stage %d.\n"
1271                             "Did you mean ':%d:%s'?",
1272                             filename, stage,
1273                             ce_stage(ce), filename);
1274         }
1275
1276         /* Confusion between relative and absolute filenames? */
1277         fullnamelen = namelen + strlen(prefix);
1278         fullname = xmalloc(fullnamelen + 1);
1279         strcpy(fullname, prefix);
1280         strcat(fullname, filename);
1281         pos = cache_name_pos(fullname, fullnamelen);
1282         if (pos < 0)
1283                 pos = -pos - 1;
1284         if (pos < active_nr) {
1285                 ce = active_cache[pos];
1286                 if (ce_namelen(ce) == fullnamelen &&
1287                     !memcmp(ce->name, fullname, fullnamelen))
1288                         die("Path '%s' is in the index, but not '%s'.\n"
1289                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1290                             fullname, filename,
1291                             ce_stage(ce), fullname,
1292                             ce_stage(ce), filename);
1293         }
1294
1295         if (!lstat(filename, &st))
1296                 die("Path '%s' exists on disk, but not in the index.", filename);
1297         if (errno == ENOENT || errno == ENOTDIR)
1298                 die("Path '%s' does not exist (neither on disk nor in the index).",
1299                     filename);
1300
1301         free(fullname);
1302 }
1303
1304
1305 static char *resolve_relative_path(const char *rel)
1306 {
1307         if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
1308                 return NULL;
1309
1310         if (!startup_info)
1311                 die("BUG: startup_info struct is not initialized.");
1312
1313         if (!is_inside_work_tree())
1314                 die("relative path syntax can't be used outside working tree.");
1315
1316         /* die() inside prefix_path() if resolved path is outside worktree */
1317         return prefix_path(startup_info->prefix,
1318                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1319                            rel);
1320 }
1321
1322 static int get_sha1_with_context_1(const char *name,
1323                                    unsigned flags,
1324                                    const char *prefix,
1325                                    unsigned char *sha1,
1326                                    struct object_context *oc)
1327 {
1328         int ret, bracket_depth;
1329         int namelen = strlen(name);
1330         const char *cp;
1331         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1332
1333         memset(oc, 0, sizeof(*oc));
1334         oc->mode = S_IFINVALID;
1335         ret = get_sha1_1(name, namelen, sha1, flags);
1336         if (!ret)
1337                 return ret;
1338         /*
1339          * sha1:path --> object name of path in ent sha1
1340          * :path -> object name of absolute path in index
1341          * :./path -> object name of path relative to cwd in index
1342          * :[0-3]:path -> object name of path in index at stage
1343          * :/foo -> recent commit matching foo
1344          */
1345         if (name[0] == ':') {
1346                 int stage = 0;
1347                 const struct cache_entry *ce;
1348                 char *new_path = NULL;
1349                 int pos;
1350                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1351                         struct commit_list *list = NULL;
1352                         for_each_ref(handle_one_ref, &list);
1353                         return get_sha1_oneline(name + 2, sha1, list);
1354                 }
1355                 if (namelen < 3 ||
1356                     name[2] != ':' ||
1357                     name[1] < '0' || '3' < name[1])
1358                         cp = name + 1;
1359                 else {
1360                         stage = name[1] - '0';
1361                         cp = name + 3;
1362                 }
1363                 new_path = resolve_relative_path(cp);
1364                 if (!new_path) {
1365                         namelen = namelen - (cp - name);
1366                 } else {
1367                         cp = new_path;
1368                         namelen = strlen(cp);
1369                 }
1370
1371                 strncpy(oc->path, cp,
1372                         sizeof(oc->path));
1373                 oc->path[sizeof(oc->path)-1] = '\0';
1374
1375                 if (!active_cache)
1376                         read_cache();
1377                 pos = cache_name_pos(cp, namelen);
1378                 if (pos < 0)
1379                         pos = -pos - 1;
1380                 while (pos < active_nr) {
1381                         ce = active_cache[pos];
1382                         if (ce_namelen(ce) != namelen ||
1383                             memcmp(ce->name, cp, namelen))
1384                                 break;
1385                         if (ce_stage(ce) == stage) {
1386                                 hashcpy(sha1, ce->sha1);
1387                                 oc->mode = ce->ce_mode;
1388                                 free(new_path);
1389                                 return 0;
1390                         }
1391                         pos++;
1392                 }
1393                 if (only_to_die && name[1] && name[1] != '/')
1394                         diagnose_invalid_index_path(stage, prefix, cp);
1395                 free(new_path);
1396                 return -1;
1397         }
1398         for (cp = name, bracket_depth = 0; *cp; cp++) {
1399                 if (*cp == '{')
1400                         bracket_depth++;
1401                 else if (bracket_depth && *cp == '}')
1402                         bracket_depth--;
1403                 else if (!bracket_depth && *cp == ':')
1404                         break;
1405         }
1406         if (*cp == ':') {
1407                 unsigned char tree_sha1[20];
1408                 int len = cp - name;
1409                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1410                         const char *filename = cp+1;
1411                         char *new_filename = NULL;
1412
1413                         new_filename = resolve_relative_path(filename);
1414                         if (new_filename)
1415                                 filename = new_filename;
1416                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1417                         if (ret && only_to_die) {
1418                                 diagnose_invalid_sha1_path(prefix, filename,
1419                                                            tree_sha1,
1420                                                            name, len);
1421                         }
1422                         hashcpy(oc->tree, tree_sha1);
1423                         strncpy(oc->path, filename,
1424                                 sizeof(oc->path));
1425                         oc->path[sizeof(oc->path)-1] = '\0';
1426
1427                         free(new_filename);
1428                         return ret;
1429                 } else {
1430                         if (only_to_die)
1431                                 die("Invalid object name '%.*s'.", len, name);
1432                 }
1433         }
1434         return ret;
1435 }
1436
1437 /*
1438  * Call this function when you know "name" given by the end user must
1439  * name an object but it doesn't; the function _may_ die with a better
1440  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1441  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1442  * you have a chance to diagnose the error further.
1443  */
1444 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1445 {
1446         struct object_context oc;
1447         unsigned char sha1[20];
1448         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1449 }
1450
1451 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1452 {
1453         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1454 }