git-svn: enable follow-parent functionality by default
[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
9 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
10 {
11         struct alternate_object_database *alt;
12         char hex[40];
13         int found = 0;
14         static struct alternate_object_database *fakeent;
15
16         if (!fakeent) {
17                 const char *objdir = get_object_directory();
18                 int objdir_len = strlen(objdir);
19                 int entlen = objdir_len + 43;
20                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
21                 memcpy(fakeent->base, objdir, objdir_len);
22                 fakeent->name = fakeent->base + objdir_len + 1;
23                 fakeent->name[-1] = '/';
24         }
25         fakeent->next = alt_odb_list;
26
27         sprintf(hex, "%.2s", name);
28         for (alt = fakeent; alt && found < 2; alt = alt->next) {
29                 struct dirent *de;
30                 DIR *dir;
31                 sprintf(alt->name, "%.2s/", name);
32                 dir = opendir(alt->base);
33                 if (!dir)
34                         continue;
35                 while ((de = readdir(dir)) != NULL) {
36                         if (strlen(de->d_name) != 38)
37                                 continue;
38                         if (memcmp(de->d_name, name + 2, len - 2))
39                                 continue;
40                         if (!found) {
41                                 memcpy(hex + 2, de->d_name, 38);
42                                 found++;
43                         }
44                         else if (memcmp(hex + 2, de->d_name, 38)) {
45                                 found = 2;
46                                 break;
47                         }
48                 }
49                 closedir(dir);
50         }
51         if (found == 1)
52                 return get_sha1_hex(hex, sha1) == 0;
53         return found;
54 }
55
56 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
57 {
58         do {
59                 if (*a != *b)
60                         return 0;
61                 a++;
62                 b++;
63                 len -= 2;
64         } while (len > 1);
65         if (len)
66                 if ((*a ^ *b) & 0xf0)
67                         return 0;
68         return 1;
69 }
70
71 static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
72 {
73         struct packed_git *p;
74         unsigned char found_sha1[20];
75         int found = 0;
76
77         prepare_packed_git();
78         for (p = packed_git; p && found < 2; p = p->next) {
79                 unsigned num = num_packed_objects(p);
80                 unsigned first = 0, last = num;
81                 while (first < last) {
82                         unsigned mid = (first + last) / 2;
83                         unsigned char now[20];
84                         int cmp;
85
86                         nth_packed_object_sha1(p, mid, now);
87                         cmp = hashcmp(match, now);
88                         if (!cmp) {
89                                 first = mid;
90                                 break;
91                         }
92                         if (cmp > 0) {
93                                 first = mid+1;
94                                 continue;
95                         }
96                         last = mid;
97                 }
98                 if (first < num) {
99                         unsigned char now[20], next[20];
100                         nth_packed_object_sha1(p, first, now);
101                         if (match_sha(len, match, now)) {
102                                 if (nth_packed_object_sha1(p, first+1, next) ||
103                                     !match_sha(len, match, next)) {
104                                         /* unique within this pack */
105                                         if (!found) {
106                                                 hashcpy(found_sha1, now);
107                                                 found++;
108                                         }
109                                         else if (hashcmp(found_sha1, now)) {
110                                                 found = 2;
111                                                 break;
112                                         }
113                                 }
114                                 else {
115                                         /* not even unique within this pack */
116                                         found = 2;
117                                         break;
118                                 }
119                         }
120                 }
121         }
122         if (found == 1)
123                 hashcpy(sha1, found_sha1);
124         return found;
125 }
126
127 #define SHORT_NAME_NOT_FOUND (-1)
128 #define SHORT_NAME_AMBIGUOUS (-2)
129
130 static int find_unique_short_object(int len, char *canonical,
131                                     unsigned char *res, unsigned char *sha1)
132 {
133         int has_unpacked, has_packed;
134         unsigned char unpacked_sha1[20], packed_sha1[20];
135
136         has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
137         has_packed = find_short_packed_object(len, res, packed_sha1);
138         if (!has_unpacked && !has_packed)
139                 return SHORT_NAME_NOT_FOUND;
140         if (1 < has_unpacked || 1 < has_packed)
141                 return SHORT_NAME_AMBIGUOUS;
142         if (has_unpacked != has_packed) {
143                 hashcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1));
144                 return 0;
145         }
146         /* Both have unique ones -- do they match? */
147         if (hashcmp(packed_sha1, unpacked_sha1))
148                 return SHORT_NAME_AMBIGUOUS;
149         hashcpy(sha1, packed_sha1);
150         return 0;
151 }
152
153 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
154                           int quietly)
155 {
156         int i, status;
157         char canonical[40];
158         unsigned char res[20];
159
160         if (len < MINIMUM_ABBREV || len > 40)
161                 return -1;
162         hashclr(res);
163         memset(canonical, 'x', 40);
164         for (i = 0; i < len ;i++) {
165                 unsigned char c = name[i];
166                 unsigned char val;
167                 if (c >= '0' && c <= '9')
168                         val = c - '0';
169                 else if (c >= 'a' && c <= 'f')
170                         val = c - 'a' + 10;
171                 else if (c >= 'A' && c <='F') {
172                         val = c - 'A' + 10;
173                         c -= 'A' - 'a';
174                 }
175                 else
176                         return -1;
177                 canonical[i] = c;
178                 if (!(i & 1))
179                         val <<= 4;
180                 res[i >> 1] |= val;
181         }
182
183         status = find_unique_short_object(i, canonical, res, sha1);
184         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
185                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
186         return status;
187 }
188
189 const char *find_unique_abbrev(const unsigned char *sha1, int len)
190 {
191         int status, is_null;
192         static char hex[41];
193
194         is_null = is_null_sha1(sha1);
195         memcpy(hex, sha1_to_hex(sha1), 40);
196         if (len == 40 || !len)
197                 return hex;
198         while (len < 40) {
199                 unsigned char sha1_ret[20];
200                 status = get_short_sha1(hex, len, sha1_ret, 1);
201                 if (!status ||
202                     (is_null && status != SHORT_NAME_AMBIGUOUS)) {
203                         hex[len] = 0;
204                         return hex;
205                 }
206                 if (status != SHORT_NAME_AMBIGUOUS)
207                         return NULL;
208                 len++;
209         }
210         return NULL;
211 }
212
213 static int ambiguous_path(const char *path, int len)
214 {
215         int slash = 1;
216         int cnt;
217
218         for (cnt = 0; cnt < len; cnt++) {
219                 switch (*path++) {
220                 case '\0':
221                         break;
222                 case '/':
223                         if (slash)
224                                 break;
225                         slash = 1;
226                         continue;
227                 case '.':
228                         continue;
229                 default:
230                         slash = 0;
231                         continue;
232                 }
233                 break;
234         }
235         return slash;
236 }
237
238 static const char *ref_fmt[] = {
239         "%.*s",
240         "refs/%.*s",
241         "refs/tags/%.*s",
242         "refs/heads/%.*s",
243         "refs/remotes/%.*s",
244         "refs/remotes/%.*s/HEAD",
245         NULL
246 };
247
248 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
249 {
250         const char **p, *r;
251         int refs_found = 0;
252
253         *ref = NULL;
254         for (p = ref_fmt; *p; p++) {
255                 unsigned char sha1_from_ref[20];
256                 unsigned char *this_result;
257
258                 this_result = refs_found ? sha1_from_ref : sha1;
259                 r = resolve_ref(mkpath(*p, len, str), this_result, 1, NULL);
260                 if (r) {
261                         if (!refs_found++)
262                                 *ref = xstrdup(r);
263                         if (!warn_ambiguous_refs)
264                                 break;
265                 }
266         }
267         return refs_found;
268 }
269
270 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
271 {
272         const char **p;
273         int logs_found = 0;
274
275         *log = NULL;
276         for (p = ref_fmt; *p; p++) {
277                 struct stat st;
278                 unsigned char hash[20];
279                 char path[PATH_MAX];
280                 const char *ref, *it;
281
282                 strcpy(path, mkpath(*p, len, str));
283                 ref = resolve_ref(path, hash, 0, NULL);
284                 if (!ref)
285                         continue;
286                 if (!stat(git_path("logs/%s", path), &st) &&
287                     S_ISREG(st.st_mode))
288                         it = path;
289                 else if (strcmp(ref, path) &&
290                          !stat(git_path("logs/%s", ref), &st) &&
291                          S_ISREG(st.st_mode))
292                         it = ref;
293                 else
294                         continue;
295                 if (!logs_found++) {
296                         *log = xstrdup(it);
297                         hashcpy(sha1, hash);
298                 }
299                 if (!warn_ambiguous_refs)
300                         break;
301         }
302         return logs_found;
303 }
304
305 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
306 {
307         static const char *warning = "warning: refname '%.*s' is ambiguous.\n";
308         char *real_ref = NULL;
309         int refs_found = 0;
310         int at, reflog_len;
311
312         if (len == 40 && !get_sha1_hex(str, sha1))
313                 return 0;
314
315         /* basic@{time or number} format to query ref-log */
316         reflog_len = at = 0;
317         if (str[len-1] == '}') {
318                 for (at = 0; at < len - 1; at++) {
319                         if (str[at] == '@' && str[at+1] == '{') {
320                                 reflog_len = (len-1) - (at+2);
321                                 len = at;
322                                 break;
323                         }
324                 }
325         }
326
327         /* Accept only unambiguous ref paths. */
328         if (len && ambiguous_path(str, len))
329                 return -1;
330
331         if (!len && reflog_len) {
332                 /* allow "@{...}" to mean the current branch reflog */
333                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
334         } else if (reflog_len)
335                 refs_found = dwim_log(str, len, sha1, &real_ref);
336         else
337                 refs_found = dwim_ref(str, len, sha1, &real_ref);
338
339         if (!refs_found)
340                 return -1;
341
342         if (warn_ambiguous_refs && refs_found > 1)
343                 fprintf(stderr, warning, len, str);
344
345         if (reflog_len) {
346                 int nth, i;
347                 unsigned long at_time;
348                 unsigned long co_time;
349                 int co_tz, co_cnt;
350
351                 /* Is it asking for N-th entry, or approxidate? */
352                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
353                         char ch = str[at+2+i];
354                         if ('0' <= ch && ch <= '9')
355                                 nth = nth * 10 + ch - '0';
356                         else
357                                 nth = -1;
358                 }
359                 if (0 <= nth)
360                         at_time = 0;
361                 else
362                         at_time = approxidate(str + at + 2);
363                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
364                                 &co_time, &co_tz, &co_cnt)) {
365                         if (at_time)
366                                 fprintf(stderr,
367                                         "warning: Log for '%.*s' only goes "
368                                         "back to %s.\n", len, str,
369                                         show_rfc2822_date(co_time, co_tz));
370                         else
371                                 fprintf(stderr,
372                                         "warning: Log for '%.*s' only has "
373                                         "%d entries.\n", len, str, co_cnt);
374                 }
375         }
376
377         free(real_ref);
378         return 0;
379 }
380
381 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
382
383 static int get_parent(const char *name, int len,
384                       unsigned char *result, int idx)
385 {
386         unsigned char sha1[20];
387         int ret = get_sha1_1(name, len, sha1);
388         struct commit *commit;
389         struct commit_list *p;
390
391         if (ret)
392                 return ret;
393         commit = lookup_commit_reference(sha1);
394         if (!commit)
395                 return -1;
396         if (parse_commit(commit))
397                 return -1;
398         if (!idx) {
399                 hashcpy(result, commit->object.sha1);
400                 return 0;
401         }
402         p = commit->parents;
403         while (p) {
404                 if (!--idx) {
405                         hashcpy(result, p->item->object.sha1);
406                         return 0;
407                 }
408                 p = p->next;
409         }
410         return -1;
411 }
412
413 static int get_nth_ancestor(const char *name, int len,
414                             unsigned char *result, int generation)
415 {
416         unsigned char sha1[20];
417         int ret = get_sha1_1(name, len, sha1);
418         if (ret)
419                 return ret;
420
421         while (generation--) {
422                 struct commit *commit = lookup_commit_reference(sha1);
423
424                 if (!commit || parse_commit(commit) || !commit->parents)
425                         return -1;
426                 hashcpy(sha1, commit->parents->item->object.sha1);
427         }
428         hashcpy(result, sha1);
429         return 0;
430 }
431
432 static int peel_onion(const char *name, int len, unsigned char *sha1)
433 {
434         unsigned char outer[20];
435         const char *sp;
436         unsigned int expected_type = 0;
437         struct object *o;
438
439         /*
440          * "ref^{type}" dereferences ref repeatedly until you cannot
441          * dereference anymore, or you get an object of given type,
442          * whichever comes first.  "ref^{}" means just dereference
443          * tags until you get a non-tag.  "ref^0" is a shorthand for
444          * "ref^{commit}".  "commit^{tree}" could be used to find the
445          * top-level tree of the given commit.
446          */
447         if (len < 4 || name[len-1] != '}')
448                 return -1;
449
450         for (sp = name + len - 1; name <= sp; sp--) {
451                 int ch = *sp;
452                 if (ch == '{' && name < sp && sp[-1] == '^')
453                         break;
454         }
455         if (sp <= name)
456                 return -1;
457
458         sp++; /* beginning of type name, or closing brace for empty */
459         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
460                 expected_type = OBJ_COMMIT;
461         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
462                 expected_type = OBJ_TREE;
463         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
464                 expected_type = OBJ_BLOB;
465         else if (sp[0] == '}')
466                 expected_type = OBJ_NONE;
467         else
468                 return -1;
469
470         if (get_sha1_1(name, sp - name - 2, outer))
471                 return -1;
472
473         o = parse_object(outer);
474         if (!o)
475                 return -1;
476         if (!expected_type) {
477                 o = deref_tag(o, name, sp - name - 2);
478                 if (!o || (!o->parsed && !parse_object(o->sha1)))
479                         return -1;
480                 hashcpy(sha1, o->sha1);
481         }
482         else {
483                 /* At this point, the syntax look correct, so
484                  * if we do not get the needed object, we should
485                  * barf.
486                  */
487
488                 while (1) {
489                         if (!o || (!o->parsed && !parse_object(o->sha1)))
490                                 return -1;
491                         if (o->type == expected_type) {
492                                 hashcpy(sha1, o->sha1);
493                                 return 0;
494                         }
495                         if (o->type == OBJ_TAG)
496                                 o = ((struct tag*) o)->tagged;
497                         else if (o->type == OBJ_COMMIT)
498                                 o = &(((struct commit *) o)->tree->object);
499                         else
500                                 return error("%.*s: expected %s type, but the object dereferences to %s type",
501                                              len, name, typename(expected_type),
502                                              typename(o->type));
503                         if (!o->parsed)
504                                 parse_object(o->sha1);
505                 }
506         }
507         return 0;
508 }
509
510 static int get_describe_name(const char *name, int len, unsigned char *sha1)
511 {
512         const char *cp;
513
514         for (cp = name + len - 1; name + 2 <= cp; cp--) {
515                 char ch = *cp;
516                 if (hexval(ch) & ~0377) {
517                         /* We must be looking at g in "SOMETHING-g"
518                          * for it to be describe output.
519                          */
520                         if (ch == 'g' && cp[-1] == '-') {
521                                 cp++;
522                                 len -= cp - name;
523                                 return get_short_sha1(cp, len, sha1, 1);
524                         }
525                 }
526         }
527         return -1;
528 }
529
530 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
531 {
532         int ret, has_suffix;
533         const char *cp;
534
535         /* "name~3" is "name^^^",
536          * "name~" and "name~0" are name -- not "name^0"!
537          * "name^" is not "name^0"; it is "name^1".
538          */
539         has_suffix = 0;
540         for (cp = name + len - 1; name <= cp; cp--) {
541                 int ch = *cp;
542                 if ('0' <= ch && ch <= '9')
543                         continue;
544                 if (ch == '~' || ch == '^')
545                         has_suffix = ch;
546                 break;
547         }
548
549         if (has_suffix) {
550                 int num = 0;
551                 int len1 = cp - name;
552                 cp++;
553                 while (cp < name + len)
554                         num = num * 10 + *cp++ - '0';
555                 if (has_suffix == '^') {
556                         if (!num && len1 == len - 1)
557                                 num = 1;
558                         return get_parent(name, len1, sha1, num);
559                 }
560                 /* else if (has_suffix == '~') -- goes without saying */
561                 return get_nth_ancestor(name, len1, sha1, num);
562         }
563
564         ret = peel_onion(name, len, sha1);
565         if (!ret)
566                 return 0;
567
568         ret = get_sha1_basic(name, len, sha1);
569         if (!ret)
570                 return 0;
571
572         /* It could be describe output that is "SOMETHING-gXXXX" */
573         ret = get_describe_name(name, len, sha1);
574         if (!ret)
575                 return 0;
576
577         return get_short_sha1(name, len, sha1, 0);
578 }
579
580 /*
581  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
582  * notably "xyz^" for "parent of xyz"
583  */
584 int get_sha1(const char *name, unsigned char *sha1)
585 {
586         int ret, bracket_depth;
587         unsigned unused;
588         int namelen = strlen(name);
589         const char *cp;
590
591         prepare_alt_odb();
592         ret = get_sha1_1(name, namelen, sha1);
593         if (!ret)
594                 return ret;
595         /* sha1:path --> object name of path in ent sha1
596          * :path -> object name of path in index
597          * :[0-3]:path -> object name of path in index at stage
598          */
599         if (name[0] == ':') {
600                 int stage = 0;
601                 struct cache_entry *ce;
602                 int pos;
603                 if (namelen < 3 ||
604                     name[2] != ':' ||
605                     name[1] < '0' || '3' < name[1])
606                         cp = name + 1;
607                 else {
608                         stage = name[1] - '0';
609                         cp = name + 3;
610                 }
611                 namelen = namelen - (cp - name);
612                 if (!active_cache)
613                         read_cache();
614                 if (active_nr < 0)
615                         return -1;
616                 pos = cache_name_pos(cp, namelen);
617                 if (pos < 0)
618                         pos = -pos - 1;
619                 while (pos < active_nr) {
620                         ce = active_cache[pos];
621                         if (ce_namelen(ce) != namelen ||
622                             memcmp(ce->name, cp, namelen))
623                                 break;
624                         if (ce_stage(ce) == stage) {
625                                 hashcpy(sha1, ce->sha1);
626                                 return 0;
627                         }
628                         pos++;
629                 }
630                 return -1;
631         }
632         for (cp = name, bracket_depth = 0; *cp; cp++) {
633                 if (*cp == '{')
634                         bracket_depth++;
635                 else if (bracket_depth && *cp == '}')
636                         bracket_depth--;
637                 else if (!bracket_depth && *cp == ':')
638                         break;
639         }
640         if (*cp == ':') {
641                 unsigned char tree_sha1[20];
642                 if (!get_sha1_1(name, cp-name, tree_sha1))
643                         return get_tree_entry(tree_sha1, cp+1, sha1,
644                                               &unused);
645         }
646         return ret;
647 }