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Commit | Line | Data |
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68faf689 JH |
1 | #include "cache.h" |
2 | #include "tree.h" | |
3 | #include "tree-walk.h" | |
cbd53a21 | 4 | #include "object-store.h" |
68faf689 JH |
5 | |
6 | static int score_missing(unsigned mode, const char *path) | |
7 | { | |
8 | int score; | |
9 | ||
10 | if (S_ISDIR(mode)) | |
11 | score = -1000; | |
12 | else if (S_ISLNK(mode)) | |
13 | score = -500; | |
14 | else | |
15 | score = -50; | |
16 | return score; | |
17 | } | |
18 | ||
19 | static int score_differs(unsigned mode1, unsigned mode2, const char *path) | |
20 | { | |
21 | int score; | |
22 | ||
23 | if (S_ISDIR(mode1) != S_ISDIR(mode2)) | |
24 | score = -100; | |
25 | else if (S_ISLNK(mode1) != S_ISLNK(mode2)) | |
26 | score = -50; | |
27 | else | |
28 | score = -5; | |
29 | return score; | |
30 | } | |
31 | ||
32 | static int score_matches(unsigned mode1, unsigned mode2, const char *path) | |
33 | { | |
34 | int score; | |
35 | ||
36 | /* Heh, we found SHA-1 collisions between different kind of objects */ | |
37 | if (S_ISDIR(mode1) != S_ISDIR(mode2)) | |
38 | score = -100; | |
39 | else if (S_ISLNK(mode1) != S_ISLNK(mode2)) | |
40 | score = -50; | |
41 | ||
42 | else if (S_ISDIR(mode1)) | |
43 | score = 1000; | |
44 | else if (S_ISLNK(mode1)) | |
45 | score = 500; | |
46 | else | |
47 | score = 250; | |
48 | return score; | |
49 | } | |
50 | ||
10a3fb00 | 51 | static void *fill_tree_desc_strict(struct tree_desc *desc, |
b6aec868 | 52 | const struct object_id *hash) |
10a3fb00 RS |
53 | { |
54 | void *buffer; | |
55 | enum object_type type; | |
56 | unsigned long size; | |
57 | ||
b4f5aca4 | 58 | buffer = read_object_file(hash, &type, &size); |
10a3fb00 | 59 | if (!buffer) |
b6aec868 | 60 | die("unable to read tree (%s)", oid_to_hex(hash)); |
10a3fb00 | 61 | if (type != OBJ_TREE) |
b6aec868 | 62 | die("%s is not a tree", oid_to_hex(hash)); |
10a3fb00 RS |
63 | init_tree_desc(desc, buffer, size); |
64 | return buffer; | |
65 | } | |
66 | ||
d8febde3 RS |
67 | static int base_name_entries_compare(const struct name_entry *a, |
68 | const struct name_entry *b) | |
69 | { | |
70 | return base_name_compare(a->path, tree_entry_len(a), a->mode, | |
71 | b->path, tree_entry_len(b), b->mode); | |
72 | } | |
73 | ||
68faf689 JH |
74 | /* |
75 | * Inspect two trees, and give a score that tells how similar they are. | |
76 | */ | |
b6aec868 | 77 | static int score_trees(const struct object_id *hash1, const struct object_id *hash2) |
68faf689 JH |
78 | { |
79 | struct tree_desc one; | |
80 | struct tree_desc two; | |
10a3fb00 RS |
81 | void *one_buf = fill_tree_desc_strict(&one, hash1); |
82 | void *two_buf = fill_tree_desc_strict(&two, hash2); | |
68faf689 | 83 | int score = 0; |
68faf689 | 84 | |
d8febde3 | 85 | for (;;) { |
68faf689 JH |
86 | int cmp; |
87 | ||
2ec41507 JK |
88 | if (one.size && two.size) |
89 | cmp = base_name_entries_compare(&one.entry, &two.entry); | |
90 | else if (one.size) | |
68faf689 | 91 | /* two lacks this entry */ |
d8febde3 | 92 | cmp = -1; |
2ec41507 | 93 | else if (two.size) |
d8febde3 RS |
94 | /* two has more entries */ |
95 | cmp = 1; | |
96 | else | |
97 | break; | |
98 | ||
2ec41507 | 99 | if (cmp < 0) { |
68faf689 | 100 | /* path1 does not appear in two */ |
2ec41507 JK |
101 | score += score_missing(one.entry.mode, one.entry.path); |
102 | update_tree_entry(&one); | |
103 | } else if (cmp > 0) { | |
68faf689 | 104 | /* path2 does not appear in one */ |
2ec41507 JK |
105 | score += score_missing(two.entry.mode, two.entry.path); |
106 | update_tree_entry(&two); | |
107 | } else { | |
108 | /* path appears in both */ | |
9001dc2a | 109 | if (!oideq(one.entry.oid, two.entry.oid)) { |
2ec41507 JK |
110 | /* they are different */ |
111 | score += score_differs(one.entry.mode, | |
112 | two.entry.mode, | |
113 | one.entry.path); | |
114 | } else { | |
115 | /* same subtree or blob */ | |
116 | score += score_matches(one.entry.mode, | |
117 | two.entry.mode, | |
118 | one.entry.path); | |
119 | } | |
120 | update_tree_entry(&one); | |
121 | update_tree_entry(&two); | |
122 | } | |
68faf689 JH |
123 | } |
124 | free(one_buf); | |
125 | free(two_buf); | |
126 | return score; | |
127 | } | |
128 | ||
129 | /* | |
130 | * Match one itself and its subtrees with two and pick the best match. | |
131 | */ | |
b6aec868 | 132 | static void match_trees(const struct object_id *hash1, |
133 | const struct object_id *hash2, | |
68faf689 JH |
134 | int *best_score, |
135 | char **best_match, | |
538dfe73 | 136 | const char *base, |
68faf689 JH |
137 | int recurse_limit) |
138 | { | |
139 | struct tree_desc one; | |
10a3fb00 | 140 | void *one_buf = fill_tree_desc_strict(&one, hash1); |
68faf689 JH |
141 | |
142 | while (one.size) { | |
143 | const char *path; | |
ce6663a9 | 144 | const struct object_id *elem; |
68faf689 JH |
145 | unsigned mode; |
146 | int score; | |
147 | ||
148 | elem = tree_entry_extract(&one, &path, &mode); | |
149 | if (!S_ISDIR(mode)) | |
150 | goto next; | |
b6aec868 | 151 | score = score_trees(elem, hash2); |
68faf689 | 152 | if (*best_score < score) { |
68faf689 | 153 | free(*best_match); |
28310186 | 154 | *best_match = xstrfmt("%s%s", base, path); |
68faf689 JH |
155 | *best_score = score; |
156 | } | |
157 | if (recurse_limit) { | |
28310186 | 158 | char *newbase = xstrfmt("%s%s/", base, path); |
b6aec868 | 159 | match_trees(elem, hash2, best_score, best_match, |
68faf689 JH |
160 | newbase, recurse_limit - 1); |
161 | free(newbase); | |
162 | } | |
163 | ||
164 | next: | |
165 | update_tree_entry(&one); | |
166 | } | |
167 | free(one_buf); | |
168 | } | |
169 | ||
170 | /* | |
3b34934d PO |
171 | * A tree "oid1" has a subdirectory at "prefix". Come up with a tree object by |
172 | * replacing it with another tree "oid2". | |
68faf689 | 173 | */ |
3b34934d PO |
174 | static int splice_tree(const struct object_id *oid1, const char *prefix, |
175 | const struct object_id *oid2, struct object_id *result) | |
68faf689 JH |
176 | { |
177 | char *subpath; | |
178 | int toplen; | |
179 | char *buf; | |
180 | unsigned long sz; | |
181 | struct tree_desc desc; | |
3b34934d PO |
182 | struct object_id *rewrite_here; |
183 | const struct object_id *rewrite_with; | |
184 | struct object_id subtree; | |
68faf689 JH |
185 | enum object_type type; |
186 | int status; | |
187 | ||
2c5495f7 RM |
188 | subpath = strchrnul(prefix, '/'); |
189 | toplen = subpath - prefix; | |
190 | if (*subpath) | |
68faf689 | 191 | subpath++; |
68faf689 | 192 | |
b4f5aca4 | 193 | buf = read_object_file(oid1, &type, &sz); |
68faf689 | 194 | if (!buf) |
3b34934d | 195 | die("cannot read tree %s", oid_to_hex(oid1)); |
68faf689 JH |
196 | init_tree_desc(&desc, buf, sz); |
197 | ||
198 | rewrite_here = NULL; | |
199 | while (desc.size) { | |
200 | const char *name; | |
201 | unsigned mode; | |
ce6663a9 | 202 | const struct object_id *oid; |
68faf689 | 203 | |
ce6663a9 | 204 | oid = tree_entry_extract(&desc, &name, &mode); |
68faf689 JH |
205 | if (strlen(name) == toplen && |
206 | !memcmp(name, prefix, toplen)) { | |
207 | if (!S_ISDIR(mode)) | |
3b34934d PO |
208 | die("entry %s in tree %s is not a tree", name, |
209 | oid_to_hex(oid1)); | |
210 | rewrite_here = (struct object_id *)oid; | |
68faf689 JH |
211 | break; |
212 | } | |
213 | update_tree_entry(&desc); | |
214 | } | |
215 | if (!rewrite_here) | |
3b34934d PO |
216 | die("entry %.*s not found in tree %s", toplen, prefix, |
217 | oid_to_hex(oid1)); | |
2c5495f7 | 218 | if (*subpath) { |
3b34934d | 219 | status = splice_tree(rewrite_here, subpath, oid2, &subtree); |
68faf689 JH |
220 | if (status) |
221 | return status; | |
3b34934d PO |
222 | rewrite_with = &subtree; |
223 | } else { | |
224 | rewrite_with = oid2; | |
68faf689 | 225 | } |
3b34934d | 226 | oidcpy(rewrite_here, rewrite_with); |
a09c985e | 227 | status = write_object_file(buf, sz, tree_type, result); |
68faf689 JH |
228 | free(buf); |
229 | return status; | |
230 | } | |
231 | ||
232 | /* | |
233 | * We are trying to come up with a merge between one and two that | |
234 | * results in a tree shape similar to one. The tree two might | |
235 | * correspond to a subtree of one, in which case it needs to be | |
236 | * shifted down by prefixing otherwise empty directories. On the | |
237 | * other hand, it could cover tree one and we might need to pick a | |
238 | * subtree of it. | |
239 | */ | |
82db3d44 | 240 | void shift_tree(const struct object_id *hash1, |
241 | const struct object_id *hash2, | |
242 | struct object_id *shifted, | |
68faf689 JH |
243 | int depth_limit) |
244 | { | |
245 | char *add_prefix; | |
246 | char *del_prefix; | |
247 | int add_score, del_score; | |
248 | ||
85e51b78 JH |
249 | /* |
250 | * NEEDSWORK: this limits the recursion depth to hardcoded | |
251 | * value '2' to avoid excessive overhead. | |
252 | */ | |
253 | if (!depth_limit) | |
254 | depth_limit = 2; | |
255 | ||
b6aec868 | 256 | add_score = del_score = score_trees(hash1, hash2); |
68faf689 JH |
257 | add_prefix = xcalloc(1, 1); |
258 | del_prefix = xcalloc(1, 1); | |
259 | ||
260 | /* | |
261 | * See if one's subtree resembles two; if so we need to prefix | |
262 | * two with a few fake trees to match the prefix. | |
263 | */ | |
b6aec868 | 264 | match_trees(hash1, hash2, &add_score, &add_prefix, "", depth_limit); |
68faf689 JH |
265 | |
266 | /* | |
267 | * See if two's subtree resembles one; if so we need to | |
268 | * pick only subtree of two. | |
269 | */ | |
b6aec868 | 270 | match_trees(hash2, hash1, &del_score, &del_prefix, "", depth_limit); |
68faf689 JH |
271 | |
272 | /* Assume we do not have to do any shifting */ | |
82db3d44 | 273 | oidcpy(shifted, hash2); |
68faf689 JH |
274 | |
275 | if (add_score < del_score) { | |
276 | /* We need to pick a subtree of two */ | |
277 | unsigned mode; | |
278 | ||
279 | if (!*del_prefix) | |
280 | return; | |
281 | ||
916bc35b | 282 | if (get_tree_entry(hash2, del_prefix, shifted, &mode)) |
68faf689 | 283 | die("cannot find path %s in tree %s", |
82db3d44 | 284 | del_prefix, oid_to_hex(hash2)); |
68faf689 JH |
285 | return; |
286 | } | |
287 | ||
288 | if (!*add_prefix) | |
289 | return; | |
290 | ||
3b34934d | 291 | splice_tree(hash1, add_prefix, hash2, shifted); |
68faf689 | 292 | } |
85e51b78 JH |
293 | |
294 | /* | |
295 | * The user says the trees will be shifted by this much. | |
296 | * Unfortunately we cannot fundamentally tell which one to | |
297 | * be prefixed, as recursive merge can work in either direction. | |
298 | */ | |
82db3d44 | 299 | void shift_tree_by(const struct object_id *hash1, |
300 | const struct object_id *hash2, | |
301 | struct object_id *shifted, | |
85e51b78 JH |
302 | const char *shift_prefix) |
303 | { | |
82db3d44 | 304 | struct object_id sub1, sub2; |
85e51b78 JH |
305 | unsigned mode1, mode2; |
306 | unsigned candidate = 0; | |
307 | ||
308 | /* Can hash2 be a tree at shift_prefix in tree hash1? */ | |
916bc35b | 309 | if (!get_tree_entry(hash1, shift_prefix, &sub1, &mode1) && |
85e51b78 JH |
310 | S_ISDIR(mode1)) |
311 | candidate |= 1; | |
312 | ||
313 | /* Can hash1 be a tree at shift_prefix in tree hash2? */ | |
916bc35b | 314 | if (!get_tree_entry(hash2, shift_prefix, &sub2, &mode2) && |
85e51b78 JH |
315 | S_ISDIR(mode2)) |
316 | candidate |= 2; | |
317 | ||
318 | if (candidate == 3) { | |
319 | /* Both are plausible -- we need to evaluate the score */ | |
b6aec868 | 320 | int best_score = score_trees(hash1, hash2); |
85e51b78 JH |
321 | int score; |
322 | ||
323 | candidate = 0; | |
b6aec868 | 324 | score = score_trees(&sub1, hash2); |
85e51b78 JH |
325 | if (score > best_score) { |
326 | candidate = 1; | |
327 | best_score = score; | |
328 | } | |
b6aec868 | 329 | score = score_trees(&sub2, hash1); |
85e51b78 JH |
330 | if (score > best_score) |
331 | candidate = 2; | |
332 | } | |
333 | ||
334 | if (!candidate) { | |
335 | /* Neither is plausible -- do not shift */ | |
82db3d44 | 336 | oidcpy(shifted, hash2); |
85e51b78 JH |
337 | return; |
338 | } | |
339 | ||
340 | if (candidate == 1) | |
341 | /* | |
342 | * shift tree2 down by adding shift_prefix above it | |
343 | * to match tree1. | |
344 | */ | |
3b34934d | 345 | splice_tree(hash1, shift_prefix, hash2, shifted); |
85e51b78 JH |
346 | else |
347 | /* | |
348 | * shift tree2 up by removing shift_prefix from it | |
349 | * to match tree1. | |
350 | */ | |
82db3d44 | 351 | oidcpy(shifted, &sub2); |
85e51b78 | 352 | } |