Fix some documentation typos and grammar
[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 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
239 {
240         static const char *fmt[] = {
241                 "%.*s",
242                 "refs/%.*s",
243                 "refs/tags/%.*s",
244                 "refs/heads/%.*s",
245                 "refs/remotes/%.*s",
246                 "refs/remotes/%.*s/HEAD",
247                 NULL
248         };
249         const char **p, *r;
250         int refs_found = 0;
251
252         *ref = NULL;
253         for (p = fmt; *p; p++) {
254                 unsigned char sha1_from_ref[20];
255                 unsigned char *this_result;
256
257                 this_result = refs_found ? sha1_from_ref : sha1;
258                 r = resolve_ref(mkpath(*p, len, str), this_result, 1, NULL);
259                 if (r) {
260                         if (!refs_found++)
261                                 *ref = xstrdup(r);
262                         if (!warn_ambiguous_refs)
263                                 break;
264                 }
265         }
266         return refs_found;
267 }
268
269 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
270 {
271         static const char *warning = "warning: refname '%.*s' is ambiguous.\n";
272         char *real_ref = NULL;
273         int refs_found = 0;
274         int at, reflog_len;
275
276         if (len == 40 && !get_sha1_hex(str, sha1))
277                 return 0;
278
279         /* basic@{time or number} format to query ref-log */
280         reflog_len = at = 0;
281         if (str[len-1] == '}') {
282                 for (at = 0; at < len - 1; at++) {
283                         if (str[at] == '@' && str[at+1] == '{') {
284                                 reflog_len = (len-1) - (at+2);
285                                 len = at;
286                                 break;
287                         }
288                 }
289         }
290
291         /* Accept only unambiguous ref paths. */
292         if (len && ambiguous_path(str, len))
293                 return -1;
294
295         if (!len && reflog_len) {
296                 /* allow "@{...}" to mean the current branch reflog */
297                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
298         } else
299                 refs_found = dwim_ref(str, len, sha1, &real_ref);
300
301         if (!refs_found)
302                 return -1;
303
304         if (warn_ambiguous_refs && refs_found > 1)
305                 fprintf(stderr, warning, len, str);
306
307         if (reflog_len) {
308                 int nth, i;
309                 unsigned long at_time;
310                 unsigned long co_time;
311                 int co_tz, co_cnt;
312
313                 /*
314                  * We'll have an independent reflog for "HEAD" eventually
315                  * which won't be a synonym for the current branch reflog.
316                  * In the mean time prevent people from getting used to
317                  * such a synonym until the work is completed.
318                  */
319                 if (len && !strncmp("HEAD", str, len) &&
320                     !strncmp(real_ref, "refs/", 5)) {
321                         error("reflog for HEAD has not been implemented yet\n"
322                               "Maybe you could try %s%s instead, "
323                               "or just %s for current branch..",
324                               strchr(real_ref+5, '/')+1, str+len, str+len);
325                         exit(-1);
326                 }
327
328                 /* Is it asking for N-th entry, or approxidate? */
329                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
330                         char ch = str[at+2+i];
331                         if ('0' <= ch && ch <= '9')
332                                 nth = nth * 10 + ch - '0';
333                         else
334                                 nth = -1;
335                 }
336                 if (0 <= nth)
337                         at_time = 0;
338                 else
339                         at_time = approxidate(str + at + 2);
340                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
341                                 &co_time, &co_tz, &co_cnt)) {
342                         if (at_time)
343                                 fprintf(stderr,
344                                         "warning: Log for '%.*s' only goes "
345                                         "back to %s.\n", len, str,
346                                         show_rfc2822_date(co_time, co_tz));
347                         else
348                                 fprintf(stderr,
349                                         "warning: Log for '%.*s' only has "
350                                         "%d entries.\n", len, str, co_cnt);
351                 }
352         }
353
354         free(real_ref);
355         return 0;
356 }
357
358 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
359
360 static int get_parent(const char *name, int len,
361                       unsigned char *result, int idx)
362 {
363         unsigned char sha1[20];
364         int ret = get_sha1_1(name, len, sha1);
365         struct commit *commit;
366         struct commit_list *p;
367
368         if (ret)
369                 return ret;
370         commit = lookup_commit_reference(sha1);
371         if (!commit)
372                 return -1;
373         if (parse_commit(commit))
374                 return -1;
375         if (!idx) {
376                 hashcpy(result, commit->object.sha1);
377                 return 0;
378         }
379         p = commit->parents;
380         while (p) {
381                 if (!--idx) {
382                         hashcpy(result, p->item->object.sha1);
383                         return 0;
384                 }
385                 p = p->next;
386         }
387         return -1;
388 }
389
390 static int get_nth_ancestor(const char *name, int len,
391                             unsigned char *result, int generation)
392 {
393         unsigned char sha1[20];
394         int ret = get_sha1_1(name, len, sha1);
395         if (ret)
396                 return ret;
397
398         while (generation--) {
399                 struct commit *commit = lookup_commit_reference(sha1);
400
401                 if (!commit || parse_commit(commit) || !commit->parents)
402                         return -1;
403                 hashcpy(sha1, commit->parents->item->object.sha1);
404         }
405         hashcpy(result, sha1);
406         return 0;
407 }
408
409 static int peel_onion(const char *name, int len, unsigned char *sha1)
410 {
411         unsigned char outer[20];
412         const char *sp;
413         unsigned int expected_type = 0;
414         struct object *o;
415
416         /*
417          * "ref^{type}" dereferences ref repeatedly until you cannot
418          * dereference anymore, or you get an object of given type,
419          * whichever comes first.  "ref^{}" means just dereference
420          * tags until you get a non-tag.  "ref^0" is a shorthand for
421          * "ref^{commit}".  "commit^{tree}" could be used to find the
422          * top-level tree of the given commit.
423          */
424         if (len < 4 || name[len-1] != '}')
425                 return -1;
426
427         for (sp = name + len - 1; name <= sp; sp--) {
428                 int ch = *sp;
429                 if (ch == '{' && name < sp && sp[-1] == '^')
430                         break;
431         }
432         if (sp <= name)
433                 return -1;
434
435         sp++; /* beginning of type name, or closing brace for empty */
436         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
437                 expected_type = OBJ_COMMIT;
438         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
439                 expected_type = OBJ_TREE;
440         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
441                 expected_type = OBJ_BLOB;
442         else if (sp[0] == '}')
443                 expected_type = OBJ_NONE;
444         else
445                 return -1;
446
447         if (get_sha1_1(name, sp - name - 2, outer))
448                 return -1;
449
450         o = parse_object(outer);
451         if (!o)
452                 return -1;
453         if (!expected_type) {
454                 o = deref_tag(o, name, sp - name - 2);
455                 if (!o || (!o->parsed && !parse_object(o->sha1)))
456                         return -1;
457                 hashcpy(sha1, o->sha1);
458         }
459         else {
460                 /* At this point, the syntax look correct, so
461                  * if we do not get the needed object, we should
462                  * barf.
463                  */
464
465                 while (1) {
466                         if (!o || (!o->parsed && !parse_object(o->sha1)))
467                                 return -1;
468                         if (o->type == expected_type) {
469                                 hashcpy(sha1, o->sha1);
470                                 return 0;
471                         }
472                         if (o->type == OBJ_TAG)
473                                 o = ((struct tag*) o)->tagged;
474                         else if (o->type == OBJ_COMMIT)
475                                 o = &(((struct commit *) o)->tree->object);
476                         else
477                                 return error("%.*s: expected %s type, but the object dereferences to %s type",
478                                              len, name, typename(expected_type),
479                                              typename(o->type));
480                         if (!o->parsed)
481                                 parse_object(o->sha1);
482                 }
483         }
484         return 0;
485 }
486
487 static int get_describe_name(const char *name, int len, unsigned char *sha1)
488 {
489         const char *cp;
490
491         for (cp = name + len - 1; name + 2 <= cp; cp--) {
492                 char ch = *cp;
493                 if (hexval(ch) & ~0377) {
494                         /* We must be looking at g in "SOMETHING-g"
495                          * for it to be describe output.
496                          */
497                         if (ch == 'g' && cp[-1] == '-') {
498                                 cp++;
499                                 len -= cp - name;
500                                 return get_short_sha1(cp, len, sha1, 1);
501                         }
502                 }
503         }
504         return -1;
505 }
506
507 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
508 {
509         int ret, has_suffix;
510         const char *cp;
511
512         /* "name~3" is "name^^^",
513          * "name~" and "name~0" are name -- not "name^0"!
514          * "name^" is not "name^0"; it is "name^1".
515          */
516         has_suffix = 0;
517         for (cp = name + len - 1; name <= cp; cp--) {
518                 int ch = *cp;
519                 if ('0' <= ch && ch <= '9')
520                         continue;
521                 if (ch == '~' || ch == '^')
522                         has_suffix = ch;
523                 break;
524         }
525
526         if (has_suffix) {
527                 int num = 0;
528                 int len1 = cp - name;
529                 cp++;
530                 while (cp < name + len)
531                         num = num * 10 + *cp++ - '0';
532                 if (has_suffix == '^') {
533                         if (!num && len1 == len - 1)
534                                 num = 1;
535                         return get_parent(name, len1, sha1, num);
536                 }
537                 /* else if (has_suffix == '~') -- goes without saying */
538                 return get_nth_ancestor(name, len1, sha1, num);
539         }
540
541         ret = peel_onion(name, len, sha1);
542         if (!ret)
543                 return 0;
544
545         ret = get_sha1_basic(name, len, sha1);
546         if (!ret)
547                 return 0;
548
549         /* It could be describe output that is "SOMETHING-gXXXX" */
550         ret = get_describe_name(name, len, sha1);
551         if (!ret)
552                 return 0;
553
554         return get_short_sha1(name, len, sha1, 0);
555 }
556
557 /*
558  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
559  * notably "xyz^" for "parent of xyz"
560  */
561 int get_sha1(const char *name, unsigned char *sha1)
562 {
563         int ret, bracket_depth;
564         unsigned unused;
565         int namelen = strlen(name);
566         const char *cp;
567
568         prepare_alt_odb();
569         ret = get_sha1_1(name, namelen, sha1);
570         if (!ret)
571                 return ret;
572         /* sha1:path --> object name of path in ent sha1
573          * :path -> object name of path in index
574          * :[0-3]:path -> object name of path in index at stage
575          */
576         if (name[0] == ':') {
577                 int stage = 0;
578                 struct cache_entry *ce;
579                 int pos;
580                 if (namelen < 3 ||
581                     name[2] != ':' ||
582                     name[1] < '0' || '3' < name[1])
583                         cp = name + 1;
584                 else {
585                         stage = name[1] - '0';
586                         cp = name + 3;
587                 }
588                 namelen = namelen - (cp - name);
589                 if (!active_cache)
590                         read_cache();
591                 if (active_nr < 0)
592                         return -1;
593                 pos = cache_name_pos(cp, namelen);
594                 if (pos < 0)
595                         pos = -pos - 1;
596                 while (pos < active_nr) {
597                         ce = active_cache[pos];
598                         if (ce_namelen(ce) != namelen ||
599                             memcmp(ce->name, cp, namelen))
600                                 break;
601                         if (ce_stage(ce) == stage) {
602                                 hashcpy(sha1, ce->sha1);
603                                 return 0;
604                         }
605                         pos++;
606                 }
607                 return -1;
608         }
609         for (cp = name, bracket_depth = 0; *cp; cp++) {
610                 if (*cp == '{')
611                         bracket_depth++;
612                 else if (bracket_depth && *cp == '}')
613                         bracket_depth--;
614                 else if (!bracket_depth && *cp == ':')
615                         break;
616         }
617         if (*cp == ':') {
618                 unsigned char tree_sha1[20];
619                 if (!get_sha1_1(name, cp-name, tree_sha1))
620                         return get_tree_entry(tree_sha1, cp+1, sha1,
621                                               &unused);
622         }
623         return ret;
624 }