contrib/git-svn: allow rebuild to work on non-linear remote heads
[git/git.git] / sha1_name.c
CommitLineData
9938af6a 1#include "cache.h"
5385f52d 2#include "tag.h"
9938af6a 3#include "commit.h"
5385f52d
JH
4#include "tree.h"
5#include "blob.h"
9938af6a
JH
6
7static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
8{
99a19b43 9 struct alternate_object_database *alt;
9938af6a 10 char hex[40];
99a19b43
JH
11 int found = 0;
12 static struct alternate_object_database *fakeent;
13
14 if (!fakeent) {
15 const char *objdir = get_object_directory();
16 int objdir_len = strlen(objdir);
17 int entlen = objdir_len + 43;
18 fakeent = xmalloc(sizeof(*fakeent) + entlen);
19 memcpy(fakeent->base, objdir, objdir_len);
20 fakeent->name = fakeent->base + objdir_len + 1;
21 fakeent->name[-1] = '/';
22 }
23 fakeent->next = alt_odb_list;
9938af6a 24
9938af6a 25 sprintf(hex, "%.2s", name);
99a19b43 26 for (alt = fakeent; alt && found < 2; alt = alt->next) {
9938af6a 27 struct dirent *de;
99a19b43
JH
28 DIR *dir;
29 sprintf(alt->name, "%.2s/", name);
30 dir = opendir(alt->base);
31 if (!dir)
32 continue;
9938af6a
JH
33 while ((de = readdir(dir)) != NULL) {
34 if (strlen(de->d_name) != 38)
35 continue;
99a19b43 36 if (memcmp(de->d_name, name + 2, len - 2))
9938af6a 37 continue;
99a19b43
JH
38 if (!found) {
39 memcpy(hex + 2, de->d_name, 38);
40 found++;
41 }
42 else if (memcmp(hex + 2, de->d_name, 38)) {
43 found = 2;
9938af6a 44 break;
99a19b43 45 }
9938af6a
JH
46 }
47 closedir(dir);
48 }
49 if (found == 1)
50 return get_sha1_hex(hex, sha1) == 0;
99a19b43 51 return found;
9938af6a
JH
52}
53
54static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
55{
56 do {
57 if (*a != *b)
58 return 0;
59 a++;
60 b++;
61 len -= 2;
62 } while (len > 1);
63 if (len)
64 if ((*a ^ *b) & 0xf0)
65 return 0;
66 return 1;
67}
68
69static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
70{
71 struct packed_git *p;
99a19b43
JH
72 unsigned char found_sha1[20];
73 int found = 0;
9938af6a
JH
74
75 prepare_packed_git();
99a19b43 76 for (p = packed_git; p && found < 2; p = p->next) {
9938af6a
JH
77 unsigned num = num_packed_objects(p);
78 unsigned first = 0, last = num;
79 while (first < last) {
80 unsigned mid = (first + last) / 2;
81 unsigned char now[20];
82 int cmp;
83
84 nth_packed_object_sha1(p, mid, now);
85 cmp = memcmp(match, now, 20);
86 if (!cmp) {
87 first = mid;
88 break;
89 }
90 if (cmp > 0) {
91 first = mid+1;
92 continue;
93 }
94 last = mid;
95 }
96 if (first < num) {
0bc45890 97 unsigned char now[20], next[20];
9938af6a
JH
98 nth_packed_object_sha1(p, first, now);
99 if (match_sha(len, match, now)) {
0bc45890
JH
100 if (nth_packed_object_sha1(p, first+1, next) ||
101 !match_sha(len, match, next)) {
102 /* unique within this pack */
103 if (!found) {
104 memcpy(found_sha1, now, 20);
105 found++;
106 }
107 else if (memcmp(found_sha1, now, 20)) {
108 found = 2;
109 break;
110 }
99a19b43 111 }
0bc45890
JH
112 else {
113 /* not even unique within this pack */
99a19b43
JH
114 found = 2;
115 break;
9938af6a
JH
116 }
117 }
118 }
119 }
99a19b43
JH
120 if (found == 1)
121 memcpy(sha1, found_sha1, 20);
122 return found;
123}
124
013f276e
JH
125#define SHORT_NAME_NOT_FOUND (-1)
126#define SHORT_NAME_AMBIGUOUS (-2)
127
99a19b43
JH
128static int find_unique_short_object(int len, char *canonical,
129 unsigned char *res, unsigned char *sha1)
130{
131 int has_unpacked, has_packed;
132 unsigned char unpacked_sha1[20], packed_sha1[20];
133
134 has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
135 has_packed = find_short_packed_object(len, res, packed_sha1);
136 if (!has_unpacked && !has_packed)
013f276e 137 return SHORT_NAME_NOT_FOUND;
99a19b43 138 if (1 < has_unpacked || 1 < has_packed)
013f276e 139 return SHORT_NAME_AMBIGUOUS;
99a19b43
JH
140 if (has_unpacked != has_packed) {
141 memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
142 return 0;
143 }
144 /* Both have unique ones -- do they match? */
145 if (memcmp(packed_sha1, unpacked_sha1, 20))
e974c9ab 146 return SHORT_NAME_AMBIGUOUS;
99a19b43 147 memcpy(sha1, packed_sha1, 20);
9938af6a
JH
148 return 0;
149}
150
013f276e
JH
151static int get_short_sha1(const char *name, int len, unsigned char *sha1,
152 int quietly)
9938af6a 153{
013f276e 154 int i, status;
9938af6a
JH
155 char canonical[40];
156 unsigned char res[20];
157
46a6c262 158 if (len < MINIMUM_ABBREV)
af61c6e0 159 return -1;
9938af6a
JH
160 memset(res, 0, 20);
161 memset(canonical, 'x', 40);
af61c6e0 162 for (i = 0; i < len ;i++) {
9938af6a
JH
163 unsigned char c = name[i];
164 unsigned char val;
9938af6a
JH
165 if (c >= '0' && c <= '9')
166 val = c - '0';
167 else if (c >= 'a' && c <= 'f')
168 val = c - 'a' + 10;
169 else if (c >= 'A' && c <='F') {
170 val = c - 'A' + 10;
171 c -= 'A' - 'a';
172 }
173 else
174 return -1;
175 canonical[i] = c;
176 if (!(i & 1))
177 val <<= 4;
178 res[i >> 1] |= val;
179 }
99a19b43 180
013f276e
JH
181 status = find_unique_short_object(i, canonical, res, sha1);
182 if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
183 return error("short SHA1 %.*s is ambiguous.", len, canonical);
184 return status;
185}
186
187const char *find_unique_abbrev(const unsigned char *sha1, int len)
188{
297a1aad 189 int status, is_null;
013f276e 190 static char hex[41];
47dd0d59 191
297a1aad 192 is_null = !memcmp(sha1, null_sha1, 20);
013f276e 193 memcpy(hex, sha1_to_hex(sha1), 40);
47dd0d59
JH
194 if (len == 40)
195 return hex;
013f276e
JH
196 while (len < 40) {
197 unsigned char sha1_ret[20];
198 status = get_short_sha1(hex, len, sha1_ret, 1);
297a1aad
JH
199 if (!status ||
200 (is_null && status != SHORT_NAME_AMBIGUOUS)) {
013f276e
JH
201 hex[len] = 0;
202 return hex;
203 }
204 if (status != SHORT_NAME_AMBIGUOUS)
205 return NULL;
206 len++;
207 }
208 return NULL;
9938af6a
JH
209}
210
6677c466 211static int ambiguous_path(const char *path, int len)
af13cdf2
LT
212{
213 int slash = 1;
6677c466 214 int cnt;
af13cdf2 215
6677c466 216 for (cnt = 0; cnt < len; cnt++) {
af13cdf2
LT
217 switch (*path++) {
218 case '\0':
219 break;
220 case '/':
221 if (slash)
222 break;
223 slash = 1;
224 continue;
225 case '.':
226 continue;
227 default:
228 slash = 0;
229 continue;
230 }
c054d64e 231 break;
af13cdf2 232 }
6677c466 233 return slash;
af13cdf2
LT
234}
235
9938af6a
JH
236static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
237{
238 static const char *prefix[] = {
239 "",
240 "refs",
241 "refs/tags",
242 "refs/heads",
9938af6a
JH
243 NULL
244 };
245 const char **p;
246
3c3852e3 247 if (len == 40 && !get_sha1_hex(str, sha1))
9938af6a
JH
248 return 0;
249
af13cdf2 250 /* Accept only unambiguous ref paths. */
6677c466 251 if (ambiguous_path(str, len))
af13cdf2
LT
252 return -1;
253
9938af6a
JH
254 for (p = prefix; *p; p++) {
255 char *pathname = git_path("%s/%.*s", *p, len, str);
011fbc7f
JH
256 if (!read_ref(pathname, sha1))
257 return 0;
6677c466 258 }
011fbc7f 259 return -1;
9938af6a
JH
260}
261
262static int get_sha1_1(const char *name, int len, unsigned char *sha1);
263
264static int get_parent(const char *name, int len,
265 unsigned char *result, int idx)
266{
267 unsigned char sha1[20];
268 int ret = get_sha1_1(name, len, sha1);
269 struct commit *commit;
270 struct commit_list *p;
271
272 if (ret)
273 return ret;
274 commit = lookup_commit_reference(sha1);
275 if (!commit)
276 return -1;
277 if (parse_commit(commit))
278 return -1;
279 if (!idx) {
280 memcpy(result, commit->object.sha1, 20);
281 return 0;
282 }
283 p = commit->parents;
284 while (p) {
285 if (!--idx) {
286 memcpy(result, p->item->object.sha1, 20);
287 return 0;
288 }
289 p = p->next;
290 }
291 return -1;
292}
293
4f7599ac
JH
294static int get_nth_ancestor(const char *name, int len,
295 unsigned char *result, int generation)
296{
297 unsigned char sha1[20];
298 int ret = get_sha1_1(name, len, sha1);
299 if (ret)
300 return ret;
301
302 while (generation--) {
303 struct commit *commit = lookup_commit_reference(sha1);
304
305 if (!commit || parse_commit(commit) || !commit->parents)
306 return -1;
307 memcpy(sha1, commit->parents->item->object.sha1, 20);
308 }
309 memcpy(result, sha1, 20);
310 return 0;
311}
312
5385f52d
JH
313static int peel_onion(const char *name, int len, unsigned char *sha1)
314{
315 unsigned char outer[20];
316 const char *sp;
317 const char *type_string = NULL;
318 struct object *o;
319
320 /*
321 * "ref^{type}" dereferences ref repeatedly until you cannot
322 * dereference anymore, or you get an object of given type,
323 * whichever comes first. "ref^{}" means just dereference
324 * tags until you get a non-tag. "ref^0" is a shorthand for
325 * "ref^{commit}". "commit^{tree}" could be used to find the
326 * top-level tree of the given commit.
327 */
328 if (len < 4 || name[len-1] != '}')
329 return -1;
330
331 for (sp = name + len - 1; name <= sp; sp--) {
332 int ch = *sp;
333 if (ch == '{' && name < sp && sp[-1] == '^')
334 break;
335 }
336 if (sp <= name)
337 return -1;
338
339 sp++; /* beginning of type name, or closing brace for empty */
340 if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
341 type_string = commit_type;
342 else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
343 type_string = tree_type;
344 else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
345 type_string = blob_type;
346 else if (sp[0] == '}')
347 type_string = NULL;
348 else
349 return -1;
350
351 if (get_sha1_1(name, sp - name - 2, outer))
352 return -1;
353
354 o = parse_object(outer);
355 if (!o)
356 return -1;
357 if (!type_string) {
9534f40b 358 o = deref_tag(o, name, sp - name - 2);
6e1c6c10
JH
359 if (!o || (!o->parsed && !parse_object(o->sha1)))
360 return -1;
5385f52d
JH
361 memcpy(sha1, o->sha1, 20);
362 }
363 else {
364 /* At this point, the syntax look correct, so
365 * if we do not get the needed object, we should
366 * barf.
367 */
368
369 while (1) {
6e1c6c10 370 if (!o || (!o->parsed && !parse_object(o->sha1)))
5385f52d
JH
371 return -1;
372 if (o->type == type_string) {
373 memcpy(sha1, o->sha1, 20);
374 return 0;
375 }
376 if (o->type == tag_type)
377 o = ((struct tag*) o)->tagged;
378 else if (o->type == commit_type)
379 o = &(((struct commit *) o)->tree->object);
380 else
381 return error("%.*s: expected %s type, but the object dereferences to %s type",
382 len, name, type_string,
383 o->type);
384 if (!o->parsed)
385 parse_object(o->sha1);
386 }
387 }
388 return 0;
389}
390
9938af6a
JH
391static int get_sha1_1(const char *name, int len, unsigned char *sha1)
392{
0601dbe1 393 int ret, has_suffix;
4f7599ac 394 const char *cp;
9938af6a 395
4f7599ac 396 /* "name~3" is "name^^^",
4f7599ac 397 * "name~" and "name~0" are name -- not "name^0"!
0601dbe1 398 * "name^" is not "name^0"; it is "name^1".
4f7599ac 399 */
0601dbe1 400 has_suffix = 0;
4f7599ac
JH
401 for (cp = name + len - 1; name <= cp; cp--) {
402 int ch = *cp;
403 if ('0' <= ch && ch <= '9')
404 continue;
0601dbe1
JH
405 if (ch == '~' || ch == '^')
406 has_suffix = ch;
4f7599ac
JH
407 break;
408 }
0601dbe1
JH
409
410 if (has_suffix) {
411 int num = 0;
4f7599ac
JH
412 int len1 = cp - name;
413 cp++;
414 while (cp < name + len)
0601dbe1
JH
415 num = num * 10 + *cp++ - '0';
416 if (has_suffix == '^') {
417 if (!num && len1 == len - 1)
418 num = 1;
419 return get_parent(name, len1, sha1, num);
420 }
421 /* else if (has_suffix == '~') -- goes without saying */
422 return get_nth_ancestor(name, len1, sha1, num);
4f7599ac
JH
423 }
424
5385f52d
JH
425 ret = peel_onion(name, len, sha1);
426 if (!ret)
427 return 0;
428
9938af6a
JH
429 ret = get_sha1_basic(name, len, sha1);
430 if (!ret)
431 return 0;
013f276e 432 return get_short_sha1(name, len, sha1, 0);
9938af6a
JH
433}
434
435/*
436 * This is like "get_sha1_basic()", except it allows "sha1 expressions",
437 * notably "xyz^" for "parent of xyz"
438 */
439int get_sha1(const char *name, unsigned char *sha1)
440{
99a19b43 441 prepare_alt_odb();
9938af6a
JH
442 return get_sha1_1(name, strlen(name), sha1);
443}