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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 RS |
85 | for (;;) { |
86 | struct name_entry e1, e2; | |
87 | int got_entry_from_one = tree_entry(&one, &e1); | |
88 | int got_entry_from_two = tree_entry(&two, &e2); | |
68faf689 JH |
89 | int cmp; |
90 | ||
d8febde3 RS |
91 | if (got_entry_from_one && got_entry_from_two) |
92 | cmp = base_name_entries_compare(&e1, &e2); | |
93 | else if (got_entry_from_one) | |
68faf689 | 94 | /* two lacks this entry */ |
d8febde3 RS |
95 | cmp = -1; |
96 | else if (got_entry_from_two) | |
97 | /* two has more entries */ | |
98 | cmp = 1; | |
99 | else | |
100 | break; | |
101 | ||
102 | if (cmp < 0) | |
68faf689 | 103 | /* path1 does not appear in two */ |
d8febde3 RS |
104 | score += score_missing(e1.mode, e1.path); |
105 | else if (cmp > 0) | |
68faf689 | 106 | /* path2 does not appear in one */ |
d8febde3 | 107 | score += score_missing(e2.mode, e2.path); |
7d924c91 | 108 | else if (oidcmp(e1.oid, e2.oid)) |
68faf689 | 109 | /* they are different */ |
d8febde3 | 110 | score += score_differs(e1.mode, e2.mode, e1.path); |
68faf689 JH |
111 | else |
112 | /* same subtree or blob */ | |
d8febde3 | 113 | score += score_matches(e1.mode, e2.mode, e1.path); |
68faf689 JH |
114 | } |
115 | free(one_buf); | |
116 | free(two_buf); | |
117 | return score; | |
118 | } | |
119 | ||
120 | /* | |
121 | * Match one itself and its subtrees with two and pick the best match. | |
122 | */ | |
b6aec868 | 123 | static void match_trees(const struct object_id *hash1, |
124 | const struct object_id *hash2, | |
68faf689 JH |
125 | int *best_score, |
126 | char **best_match, | |
538dfe73 | 127 | const char *base, |
68faf689 JH |
128 | int recurse_limit) |
129 | { | |
130 | struct tree_desc one; | |
10a3fb00 | 131 | void *one_buf = fill_tree_desc_strict(&one, hash1); |
68faf689 JH |
132 | |
133 | while (one.size) { | |
134 | const char *path; | |
ce6663a9 | 135 | const struct object_id *elem; |
68faf689 JH |
136 | unsigned mode; |
137 | int score; | |
138 | ||
139 | elem = tree_entry_extract(&one, &path, &mode); | |
140 | if (!S_ISDIR(mode)) | |
141 | goto next; | |
b6aec868 | 142 | score = score_trees(elem, hash2); |
68faf689 | 143 | if (*best_score < score) { |
68faf689 | 144 | free(*best_match); |
28310186 | 145 | *best_match = xstrfmt("%s%s", base, path); |
68faf689 JH |
146 | *best_score = score; |
147 | } | |
148 | if (recurse_limit) { | |
28310186 | 149 | char *newbase = xstrfmt("%s%s/", base, path); |
b6aec868 | 150 | match_trees(elem, hash2, best_score, best_match, |
68faf689 JH |
151 | newbase, recurse_limit - 1); |
152 | free(newbase); | |
153 | } | |
154 | ||
155 | next: | |
156 | update_tree_entry(&one); | |
157 | } | |
158 | free(one_buf); | |
159 | } | |
160 | ||
161 | /* | |
3b34934d PO |
162 | * A tree "oid1" has a subdirectory at "prefix". Come up with a tree object by |
163 | * replacing it with another tree "oid2". | |
68faf689 | 164 | */ |
3b34934d PO |
165 | static int splice_tree(const struct object_id *oid1, const char *prefix, |
166 | const struct object_id *oid2, struct object_id *result) | |
68faf689 JH |
167 | { |
168 | char *subpath; | |
169 | int toplen; | |
170 | char *buf; | |
171 | unsigned long sz; | |
172 | struct tree_desc desc; | |
3b34934d PO |
173 | struct object_id *rewrite_here; |
174 | const struct object_id *rewrite_with; | |
175 | struct object_id subtree; | |
68faf689 JH |
176 | enum object_type type; |
177 | int status; | |
178 | ||
2c5495f7 RM |
179 | subpath = strchrnul(prefix, '/'); |
180 | toplen = subpath - prefix; | |
181 | if (*subpath) | |
68faf689 | 182 | subpath++; |
68faf689 | 183 | |
b4f5aca4 | 184 | buf = read_object_file(oid1, &type, &sz); |
68faf689 | 185 | if (!buf) |
3b34934d | 186 | die("cannot read tree %s", oid_to_hex(oid1)); |
68faf689 JH |
187 | init_tree_desc(&desc, buf, sz); |
188 | ||
189 | rewrite_here = NULL; | |
190 | while (desc.size) { | |
191 | const char *name; | |
192 | unsigned mode; | |
ce6663a9 | 193 | const struct object_id *oid; |
68faf689 | 194 | |
ce6663a9 | 195 | oid = tree_entry_extract(&desc, &name, &mode); |
68faf689 JH |
196 | if (strlen(name) == toplen && |
197 | !memcmp(name, prefix, toplen)) { | |
198 | if (!S_ISDIR(mode)) | |
3b34934d PO |
199 | die("entry %s in tree %s is not a tree", name, |
200 | oid_to_hex(oid1)); | |
201 | rewrite_here = (struct object_id *)oid; | |
68faf689 JH |
202 | break; |
203 | } | |
204 | update_tree_entry(&desc); | |
205 | } | |
206 | if (!rewrite_here) | |
3b34934d PO |
207 | die("entry %.*s not found in tree %s", toplen, prefix, |
208 | oid_to_hex(oid1)); | |
2c5495f7 | 209 | if (*subpath) { |
3b34934d | 210 | status = splice_tree(rewrite_here, subpath, oid2, &subtree); |
68faf689 JH |
211 | if (status) |
212 | return status; | |
3b34934d PO |
213 | rewrite_with = &subtree; |
214 | } else { | |
215 | rewrite_with = oid2; | |
68faf689 | 216 | } |
3b34934d | 217 | oidcpy(rewrite_here, rewrite_with); |
a09c985e | 218 | status = write_object_file(buf, sz, tree_type, result); |
68faf689 JH |
219 | free(buf); |
220 | return status; | |
221 | } | |
222 | ||
223 | /* | |
224 | * We are trying to come up with a merge between one and two that | |
225 | * results in a tree shape similar to one. The tree two might | |
226 | * correspond to a subtree of one, in which case it needs to be | |
227 | * shifted down by prefixing otherwise empty directories. On the | |
228 | * other hand, it could cover tree one and we might need to pick a | |
229 | * subtree of it. | |
230 | */ | |
82db3d44 | 231 | void shift_tree(const struct object_id *hash1, |
232 | const struct object_id *hash2, | |
233 | struct object_id *shifted, | |
68faf689 JH |
234 | int depth_limit) |
235 | { | |
236 | char *add_prefix; | |
237 | char *del_prefix; | |
238 | int add_score, del_score; | |
239 | ||
85e51b78 JH |
240 | /* |
241 | * NEEDSWORK: this limits the recursion depth to hardcoded | |
242 | * value '2' to avoid excessive overhead. | |
243 | */ | |
244 | if (!depth_limit) | |
245 | depth_limit = 2; | |
246 | ||
b6aec868 | 247 | add_score = del_score = score_trees(hash1, hash2); |
68faf689 JH |
248 | add_prefix = xcalloc(1, 1); |
249 | del_prefix = xcalloc(1, 1); | |
250 | ||
251 | /* | |
252 | * See if one's subtree resembles two; if so we need to prefix | |
253 | * two with a few fake trees to match the prefix. | |
254 | */ | |
b6aec868 | 255 | match_trees(hash1, hash2, &add_score, &add_prefix, "", depth_limit); |
68faf689 JH |
256 | |
257 | /* | |
258 | * See if two's subtree resembles one; if so we need to | |
259 | * pick only subtree of two. | |
260 | */ | |
b6aec868 | 261 | match_trees(hash2, hash1, &del_score, &del_prefix, "", depth_limit); |
68faf689 JH |
262 | |
263 | /* Assume we do not have to do any shifting */ | |
82db3d44 | 264 | oidcpy(shifted, hash2); |
68faf689 JH |
265 | |
266 | if (add_score < del_score) { | |
267 | /* We need to pick a subtree of two */ | |
268 | unsigned mode; | |
269 | ||
270 | if (!*del_prefix) | |
271 | return; | |
272 | ||
916bc35b | 273 | if (get_tree_entry(hash2, del_prefix, shifted, &mode)) |
68faf689 | 274 | die("cannot find path %s in tree %s", |
82db3d44 | 275 | del_prefix, oid_to_hex(hash2)); |
68faf689 JH |
276 | return; |
277 | } | |
278 | ||
279 | if (!*add_prefix) | |
280 | return; | |
281 | ||
3b34934d | 282 | splice_tree(hash1, add_prefix, hash2, shifted); |
68faf689 | 283 | } |
85e51b78 JH |
284 | |
285 | /* | |
286 | * The user says the trees will be shifted by this much. | |
287 | * Unfortunately we cannot fundamentally tell which one to | |
288 | * be prefixed, as recursive merge can work in either direction. | |
289 | */ | |
82db3d44 | 290 | void shift_tree_by(const struct object_id *hash1, |
291 | const struct object_id *hash2, | |
292 | struct object_id *shifted, | |
85e51b78 JH |
293 | const char *shift_prefix) |
294 | { | |
82db3d44 | 295 | struct object_id sub1, sub2; |
85e51b78 JH |
296 | unsigned mode1, mode2; |
297 | unsigned candidate = 0; | |
298 | ||
299 | /* Can hash2 be a tree at shift_prefix in tree hash1? */ | |
916bc35b | 300 | if (!get_tree_entry(hash1, shift_prefix, &sub1, &mode1) && |
85e51b78 JH |
301 | S_ISDIR(mode1)) |
302 | candidate |= 1; | |
303 | ||
304 | /* Can hash1 be a tree at shift_prefix in tree hash2? */ | |
916bc35b | 305 | if (!get_tree_entry(hash2, shift_prefix, &sub2, &mode2) && |
85e51b78 JH |
306 | S_ISDIR(mode2)) |
307 | candidate |= 2; | |
308 | ||
309 | if (candidate == 3) { | |
310 | /* Both are plausible -- we need to evaluate the score */ | |
b6aec868 | 311 | int best_score = score_trees(hash1, hash2); |
85e51b78 JH |
312 | int score; |
313 | ||
314 | candidate = 0; | |
b6aec868 | 315 | score = score_trees(&sub1, hash2); |
85e51b78 JH |
316 | if (score > best_score) { |
317 | candidate = 1; | |
318 | best_score = score; | |
319 | } | |
b6aec868 | 320 | score = score_trees(&sub2, hash1); |
85e51b78 JH |
321 | if (score > best_score) |
322 | candidate = 2; | |
323 | } | |
324 | ||
325 | if (!candidate) { | |
326 | /* Neither is plausible -- do not shift */ | |
82db3d44 | 327 | oidcpy(shifted, hash2); |
85e51b78 JH |
328 | return; |
329 | } | |
330 | ||
331 | if (candidate == 1) | |
332 | /* | |
333 | * shift tree2 down by adding shift_prefix above it | |
334 | * to match tree1. | |
335 | */ | |
3b34934d | 336 | splice_tree(hash1, shift_prefix, hash2, shifted); |
85e51b78 JH |
337 | else |
338 | /* | |
339 | * shift tree2 up by removing shift_prefix from it | |
340 | * to match tree1. | |
341 | */ | |
82db3d44 | 342 | oidcpy(shifted, &sub2); |
85e51b78 | 343 | } |