mergetool: Teach about submodules
[git] / tree-diff.c
1 /*
2  * Helper functions for tree diff generation
3  */
4 #include "cache.h"
5 #include "diff.h"
6 #include "diffcore.h"
7 #include "tree.h"
8
9 static void show_entry(struct diff_options *opt, const char *prefix,
10                        struct tree_desc *desc, struct strbuf *base);
11
12 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2,
13                               struct strbuf *base, struct diff_options *opt)
14 {
15         unsigned mode1, mode2;
16         const char *path1, *path2;
17         const unsigned char *sha1, *sha2;
18         int cmp, pathlen1, pathlen2;
19         int old_baselen = base->len;
20
21         sha1 = tree_entry_extract(t1, &path1, &mode1);
22         sha2 = tree_entry_extract(t2, &path2, &mode2);
23
24         pathlen1 = tree_entry_len(path1, sha1);
25         pathlen2 = tree_entry_len(path2, sha2);
26         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
27         if (cmp < 0) {
28                 show_entry(opt, "-", t1, base);
29                 return -1;
30         }
31         if (cmp > 0) {
32                 show_entry(opt, "+", t2, base);
33                 return 1;
34         }
35         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
36                 return 0;
37
38         /*
39          * If the filemode has changed to/from a directory from/to a regular
40          * file, we need to consider it a remove and an add.
41          */
42         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
43                 show_entry(opt, "-", t1, base);
44                 show_entry(opt, "+", t2, base);
45                 return 0;
46         }
47
48         strbuf_add(base, path1, pathlen1);
49         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
50                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
51                         opt->change(opt, mode1, mode2,
52                                     sha1, sha2, base->buf, 0, 0);
53                 }
54                 strbuf_addch(base, '/');
55                 diff_tree_sha1(sha1, sha2, base->buf, opt);
56         } else {
57                 opt->change(opt, mode1, mode2, sha1, sha2, base->buf, 0, 0);
58         }
59         strbuf_setlen(base, old_baselen);
60         return 0;
61 }
62
63 /* A whole sub-tree went away or appeared */
64 static void show_tree(struct diff_options *opt, const char *prefix,
65                       struct tree_desc *desc, struct strbuf *base)
66 {
67         int all_interesting = 0;
68         while (desc->size) {
69                 int show;
70
71                 if (all_interesting)
72                         show = 1;
73                 else {
74                         show = tree_entry_interesting(&desc->entry, base, 0,
75                                                       &opt->pathspec);
76                         if (show == 2)
77                                 all_interesting = 1;
78                 }
79                 if (show < 0)
80                         break;
81                 if (show)
82                         show_entry(opt, prefix, desc, base);
83                 update_tree_entry(desc);
84         }
85 }
86
87 /* A file entry went away or appeared */
88 static void show_entry(struct diff_options *opt, const char *prefix,
89                        struct tree_desc *desc, struct strbuf *base)
90 {
91         unsigned mode;
92         const char *path;
93         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
94         int pathlen = tree_entry_len(path, sha1);
95         int old_baselen = base->len;
96
97         strbuf_add(base, path, pathlen);
98         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
99                 enum object_type type;
100                 struct tree_desc inner;
101                 void *tree;
102                 unsigned long size;
103
104                 tree = read_sha1_file(sha1, &type, &size);
105                 if (!tree || type != OBJ_TREE)
106                         die("corrupt tree sha %s", sha1_to_hex(sha1));
107
108                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE))
109                         opt->add_remove(opt, *prefix, mode, sha1, base->buf, 0);
110
111                 strbuf_addch(base, '/');
112
113                 init_tree_desc(&inner, tree, size);
114                 show_tree(opt, prefix, &inner, base);
115                 free(tree);
116         } else
117                 opt->add_remove(opt, prefix[0], mode, sha1, base->buf, 0);
118
119         strbuf_setlen(base, old_baselen);
120 }
121
122 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
123                                struct diff_options *opt, int *all_interesting)
124 {
125         while (t->size) {
126                 int show = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
127                 if (show == 2)
128                         *all_interesting = 1;
129                 if (!show) {
130                         update_tree_entry(t);
131                         continue;
132                 }
133                 /* Skip it all? */
134                 if (show < 0)
135                         t->size = 0;
136                 return;
137         }
138 }
139
140 int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
141               const char *base_str, struct diff_options *opt)
142 {
143         struct strbuf base;
144         int baselen = strlen(base_str);
145         int all_t1_interesting = 0;
146         int all_t2_interesting = 0;
147
148         /* Enable recursion indefinitely */
149         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
150         opt->pathspec.max_depth = -1;
151
152         strbuf_init(&base, PATH_MAX);
153         strbuf_add(&base, base_str, baselen);
154
155         for (;;) {
156                 if (DIFF_OPT_TST(opt, QUICK) &&
157                     DIFF_OPT_TST(opt, HAS_CHANGES))
158                         break;
159                 if (opt->pathspec.nr) {
160                         if (!all_t1_interesting)
161                                 skip_uninteresting(t1, &base, opt, &all_t1_interesting);
162                         if (!all_t2_interesting)
163                                 skip_uninteresting(t2, &base, opt, &all_t2_interesting);
164                 }
165                 if (!t1->size) {
166                         if (!t2->size)
167                                 break;
168                         show_entry(opt, "+", t2, &base);
169                         update_tree_entry(t2);
170                         continue;
171                 }
172                 if (!t2->size) {
173                         show_entry(opt, "-", t1, &base);
174                         update_tree_entry(t1);
175                         continue;
176                 }
177                 switch (compare_tree_entry(t1, t2, &base, opt)) {
178                 case -1:
179                         update_tree_entry(t1);
180                         continue;
181                 case 0:
182                         update_tree_entry(t1);
183                         /* Fallthrough */
184                 case 1:
185                         update_tree_entry(t2);
186                         continue;
187                 }
188                 die("git diff-tree: internal error");
189         }
190
191         strbuf_release(&base);
192         return 0;
193 }
194
195 /*
196  * Does it look like the resulting diff might be due to a rename?
197  *  - single entry
198  *  - not a valid previous file
199  */
200 static inline int diff_might_be_rename(void)
201 {
202         return diff_queued_diff.nr == 1 &&
203                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
204 }
205
206 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
207 {
208         struct diff_options diff_opts;
209         struct diff_queue_struct *q = &diff_queued_diff;
210         struct diff_filepair *choice;
211         const char *paths[1];
212         int i;
213
214         /* Remove the file creation entry from the diff queue, and remember it */
215         choice = q->queue[0];
216         q->nr = 0;
217
218         diff_setup(&diff_opts);
219         DIFF_OPT_SET(&diff_opts, RECURSIVE);
220         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
221         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
222         diff_opts.single_follow = opt->pathspec.raw[0];
223         diff_opts.break_opt = opt->break_opt;
224         paths[0] = NULL;
225         diff_tree_setup_paths(paths, &diff_opts);
226         if (diff_setup_done(&diff_opts) < 0)
227                 die("unable to set up diff options to follow renames");
228         diff_tree(t1, t2, base, &diff_opts);
229         diffcore_std(&diff_opts);
230         diff_tree_release_paths(&diff_opts);
231
232         /* Go through the new set of filepairing, and see if we find a more interesting one */
233         opt->found_follow = 0;
234         for (i = 0; i < q->nr; i++) {
235                 struct diff_filepair *p = q->queue[i];
236
237                 /*
238                  * Found a source? Not only do we use that for the new
239                  * diff_queued_diff, we will also use that as the path in
240                  * the future!
241                  */
242                 if ((p->status == 'R' || p->status == 'C') &&
243                     !strcmp(p->two->path, opt->pathspec.raw[0])) {
244                         /* Switch the file-pairs around */
245                         q->queue[i] = choice;
246                         choice = p;
247
248                         /* Update the path we use from now on.. */
249                         diff_tree_release_paths(opt);
250                         opt->pathspec.raw[0] = xstrdup(p->one->path);
251                         diff_tree_setup_paths(opt->pathspec.raw, opt);
252
253                         /*
254                          * The caller expects us to return a set of vanilla
255                          * filepairs to let a later call to diffcore_std()
256                          * it makes to sort the renames out (among other
257                          * things), but we already have found renames
258                          * ourselves; signal diffcore_std() not to muck with
259                          * rename information.
260                          */
261                         opt->found_follow = 1;
262                         break;
263                 }
264         }
265
266         /*
267          * Then, discard all the non-relevant file pairs...
268          */
269         for (i = 0; i < q->nr; i++) {
270                 struct diff_filepair *p = q->queue[i];
271                 diff_free_filepair(p);
272         }
273
274         /*
275          * .. and re-instate the one we want (which might be either the
276          * original one, or the rename/copy we found)
277          */
278         q->queue[0] = choice;
279         q->nr = 1;
280 }
281
282 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
283 {
284         void *tree1, *tree2;
285         struct tree_desc t1, t2;
286         unsigned long size1, size2;
287         int retval;
288
289         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
290         if (!tree1)
291                 die("unable to read source tree (%s)", sha1_to_hex(old));
292         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
293         if (!tree2)
294                 die("unable to read destination tree (%s)", sha1_to_hex(new));
295         init_tree_desc(&t1, tree1, size1);
296         init_tree_desc(&t2, tree2, size2);
297         retval = diff_tree(&t1, &t2, base, opt);
298         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
299                 init_tree_desc(&t1, tree1, size1);
300                 init_tree_desc(&t2, tree2, size2);
301                 try_to_follow_renames(&t1, &t2, base, opt);
302         }
303         free(tree1);
304         free(tree2);
305         return retval;
306 }
307
308 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
309 {
310         int retval;
311         void *tree;
312         unsigned long size;
313         struct tree_desc empty, real;
314
315         tree = read_object_with_reference(new, tree_type, &size, NULL);
316         if (!tree)
317                 die("unable to read root tree (%s)", sha1_to_hex(new));
318         init_tree_desc(&real, tree, size);
319
320         init_tree_desc(&empty, "", 0);
321         retval = diff_tree(&empty, &real, base, opt);
322         free(tree);
323         return retval;
324 }
325
326 void diff_tree_release_paths(struct diff_options *opt)
327 {
328         free_pathspec(&opt->pathspec);
329 }
330
331 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
332 {
333         init_pathspec(&opt->pathspec, p);
334 }