gitweb: '--cc' for merges in 'commitdiff' view
[git] / tree-diff.c
1 /*
2  * Helper functions for tree diff generation
3  */
4 #include "cache.h"
5 #include "diff.h"
6 #include "tree.h"
7
8 static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
9 {
10         char *newbase = xmalloc(baselen + pathlen + 2);
11         memcpy(newbase, base, baselen);
12         memcpy(newbase + baselen, path, pathlen);
13         memcpy(newbase + baselen + pathlen, "/", 2);
14         return newbase;
15 }
16
17 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
18                        const char *base, int baselen);
19
20 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
21 {
22         unsigned mode1, mode2;
23         const char *path1, *path2;
24         const unsigned char *sha1, *sha2;
25         int cmp, pathlen1, pathlen2;
26
27         sha1 = tree_entry_extract(t1, &path1, &mode1);
28         sha2 = tree_entry_extract(t2, &path2, &mode2);
29
30         pathlen1 = tree_entry_len(path1, sha1);
31         pathlen2 = tree_entry_len(path2, sha2);
32         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
33         if (cmp < 0) {
34                 show_entry(opt, "-", t1, base, baselen);
35                 return -1;
36         }
37         if (cmp > 0) {
38                 show_entry(opt, "+", t2, base, baselen);
39                 return 1;
40         }
41         if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2)
42                 return 0;
43
44         /*
45          * If the filemode has changed to/from a directory from/to a regular
46          * file, we need to consider it a remove and an add.
47          */
48         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
49                 show_entry(opt, "-", t1, base, baselen);
50                 show_entry(opt, "+", t2, base, baselen);
51                 return 0;
52         }
53
54         if (opt->recursive && S_ISDIR(mode1)) {
55                 int retval;
56                 char *newbase = malloc_base(base, baselen, path1, pathlen1);
57                 if (opt->tree_in_recursive)
58                         opt->change(opt, mode1, mode2,
59                                     sha1, sha2, base, path1);
60                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
61                 free(newbase);
62                 return retval;
63         }
64
65         opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
66         return 0;
67 }
68
69 /*
70  * Is a tree entry interesting given the pathspec we have?
71  *
72  * Return:
73  *  - 2 for "yes, and all subsequent entries will be"
74  *  - 1 for yes
75  *  - zero for no
76  *  - negative for "no, and no subsequent entries will be either"
77  */
78 static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
79 {
80         const char *path;
81         const unsigned char *sha1;
82         unsigned mode;
83         int i;
84         int pathlen;
85         int never_interesting = -1;
86
87         if (!opt->nr_paths)
88                 return 1;
89
90         sha1 = tree_entry_extract(desc, &path, &mode);
91
92         pathlen = tree_entry_len(path, sha1);
93
94         for (i = 0; i < opt->nr_paths; i++) {
95                 const char *match = opt->paths[i];
96                 int matchlen = opt->pathlens[i];
97                 int m = -1; /* signals that we haven't called strncmp() */
98
99                 if (baselen >= matchlen) {
100                         /* If it doesn't match, move along... */
101                         if (strncmp(base, match, matchlen))
102                                 continue;
103
104                         /*
105                          * The base is a subdirectory of a path which
106                          * was specified, so all of them are interesting.
107                          */
108                         return 2;
109                 }
110
111                 /* Does the base match? */
112                 if (strncmp(base, match, baselen))
113                         continue;
114
115                 match += baselen;
116                 matchlen -= baselen;
117
118                 if (never_interesting) {
119                         /*
120                          * We have not seen any match that sorts later
121                          * than the current path.
122                          */
123
124                         /*
125                          * Does match sort strictly earlier than path
126                          * with their common parts?
127                          */
128                         m = strncmp(match, path,
129                                     (matchlen < pathlen) ? matchlen : pathlen);
130                         if (m < 0)
131                                 continue;
132
133                         /*
134                          * If we come here even once, that means there is at
135                          * least one pathspec that would sort equal to or
136                          * later than the path we are currently looking at.
137                          * In other words, if we have never reached this point
138                          * after iterating all pathspecs, it means all
139                          * pathspecs are either outside of base, or inside the
140                          * base but sorts strictly earlier than the current
141                          * one.  In either case, they will never match the
142                          * subsequent entries.  In such a case, we initialized
143                          * the variable to -1 and that is what will be
144                          * returned, allowing the caller to terminate early.
145                          */
146                         never_interesting = 0;
147                 }
148
149                 if (pathlen > matchlen)
150                         continue;
151
152                 if (matchlen > pathlen) {
153                         if (match[pathlen] != '/')
154                                 continue;
155                         if (!S_ISDIR(mode))
156                                 continue;
157                 }
158
159                 if (m == -1)
160                         /*
161                          * we cheated and did not do strncmp(), so we do
162                          * that here.
163                          */
164                         m = strncmp(match, path, pathlen);
165
166                 /*
167                  * If common part matched earlier then it is a hit,
168                  * because we rejected the case where path is not a
169                  * leading directory and is shorter than match.
170                  */
171                 if (!m)
172                         return 1;
173         }
174         return never_interesting; /* No matches */
175 }
176
177 /* A whole sub-tree went away or appeared */
178 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
179 {
180         int all_interesting = 0;
181         while (desc->size) {
182                 int show;
183
184                 if (all_interesting)
185                         show = 1;
186                 else {
187                         show = tree_entry_interesting(desc, base, baselen,
188                                                       opt);
189                         if (show == 2)
190                                 all_interesting = 1;
191                 }
192                 if (show < 0)
193                         break;
194                 if (show)
195                         show_entry(opt, prefix, desc, base, baselen);
196                 update_tree_entry(desc);
197         }
198 }
199
200 /* A file entry went away or appeared */
201 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
202                        const char *base, int baselen)
203 {
204         unsigned mode;
205         const char *path;
206         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
207
208         if (opt->recursive && S_ISDIR(mode)) {
209                 enum object_type type;
210                 int pathlen = tree_entry_len(path, sha1);
211                 char *newbase = malloc_base(base, baselen, path, pathlen);
212                 struct tree_desc inner;
213                 void *tree;
214                 unsigned long size;
215
216                 tree = read_sha1_file(sha1, &type, &size);
217                 if (!tree || type != OBJ_TREE)
218                         die("corrupt tree sha %s", sha1_to_hex(sha1));
219
220                 init_tree_desc(&inner, tree, size);
221                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
222
223                 free(tree);
224                 free(newbase);
225         } else {
226                 opt->add_remove(opt, prefix[0], mode, sha1, base, path);
227         }
228 }
229
230 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
231 {
232         int all_interesting = 0;
233         while (t->size) {
234                 int show;
235
236                 if (all_interesting)
237                         show = 1;
238                 else {
239                         show = tree_entry_interesting(t, base, baselen, opt);
240                         if (show == 2)
241                                 all_interesting = 1;
242                 }
243                 if (!show) {
244                         update_tree_entry(t);
245                         continue;
246                 }
247                 /* Skip it all? */
248                 if (show < 0)
249                         t->size = 0;
250                 return;
251         }
252 }
253
254 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
255 {
256         int baselen = strlen(base);
257
258         for (;;) {
259                 if (opt->quiet && opt->has_changes)
260                         break;
261                 if (opt->nr_paths) {
262                         skip_uninteresting(t1, base, baselen, opt);
263                         skip_uninteresting(t2, base, baselen, opt);
264                 }
265                 if (!t1->size) {
266                         if (!t2->size)
267                                 break;
268                         show_entry(opt, "+", t2, base, baselen);
269                         update_tree_entry(t2);
270                         continue;
271                 }
272                 if (!t2->size) {
273                         show_entry(opt, "-", t1, base, baselen);
274                         update_tree_entry(t1);
275                         continue;
276                 }
277                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
278                 case -1:
279                         update_tree_entry(t1);
280                         continue;
281                 case 0:
282                         update_tree_entry(t1);
283                         /* Fallthrough */
284                 case 1:
285                         update_tree_entry(t2);
286                         continue;
287                 }
288                 die("git-diff-tree: internal error");
289         }
290         return 0;
291 }
292
293 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
294 {
295         void *tree1, *tree2;
296         struct tree_desc t1, t2;
297         unsigned long size1, size2;
298         int retval;
299
300         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
301         if (!tree1)
302                 die("unable to read source tree (%s)", sha1_to_hex(old));
303         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
304         if (!tree2)
305                 die("unable to read destination tree (%s)", sha1_to_hex(new));
306         init_tree_desc(&t1, tree1, size1);
307         init_tree_desc(&t2, tree2, size2);
308         retval = diff_tree(&t1, &t2, base, opt);
309         free(tree1);
310         free(tree2);
311         return retval;
312 }
313
314 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
315 {
316         int retval;
317         void *tree;
318         unsigned long size;
319         struct tree_desc empty, real;
320
321         tree = read_object_with_reference(new, tree_type, &size, NULL);
322         if (!tree)
323                 die("unable to read root tree (%s)", sha1_to_hex(new));
324         init_tree_desc(&real, tree, size);
325
326         init_tree_desc(&empty, "", 0);
327         retval = diff_tree(&empty, &real, base, opt);
328         free(tree);
329         return retval;
330 }
331
332 static int count_paths(const char **paths)
333 {
334         int i = 0;
335         while (*paths++)
336                 i++;
337         return i;
338 }
339
340 void diff_tree_release_paths(struct diff_options *opt)
341 {
342         free(opt->pathlens);
343 }
344
345 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
346 {
347         opt->nr_paths = 0;
348         opt->pathlens = NULL;
349         opt->paths = NULL;
350
351         if (p) {
352                 int i;
353
354                 opt->paths = p;
355                 opt->nr_paths = count_paths(p);
356                 if (opt->nr_paths == 0) {
357                         opt->pathlens = NULL;
358                         return;
359                 }
360                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
361                 for (i=0; i < opt->nr_paths; i++)
362                         opt->pathlens[i] = strlen(p[i]);
363         }
364 }