Git 1.7.6-rc2
[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 match = 0;
68         for (; desc->size; update_tree_entry(desc)) {
69                 if (match != 2) {
70                         match = tree_entry_interesting(&desc->entry, base, 0,
71                                                        &opt->pathspec);
72                         if (match < 0)
73                                 break;
74                         if (match == 0)
75                                 continue;
76                 }
77                 show_entry(opt, prefix, desc, base);
78         }
79 }
80
81 /* A file entry went away or appeared */
82 static void show_entry(struct diff_options *opt, const char *prefix,
83                        struct tree_desc *desc, struct strbuf *base)
84 {
85         unsigned mode;
86         const char *path;
87         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
88         int pathlen = tree_entry_len(path, sha1);
89         int old_baselen = base->len;
90
91         strbuf_add(base, path, pathlen);
92         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
93                 enum object_type type;
94                 struct tree_desc inner;
95                 void *tree;
96                 unsigned long size;
97
98                 tree = read_sha1_file(sha1, &type, &size);
99                 if (!tree || type != OBJ_TREE)
100                         die("corrupt tree sha %s", sha1_to_hex(sha1));
101
102                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE))
103                         opt->add_remove(opt, *prefix, mode, sha1, base->buf, 0);
104
105                 strbuf_addch(base, '/');
106
107                 init_tree_desc(&inner, tree, size);
108                 show_tree(opt, prefix, &inner, base);
109                 free(tree);
110         } else
111                 opt->add_remove(opt, prefix[0], mode, sha1, base->buf, 0);
112
113         strbuf_setlen(base, old_baselen);
114 }
115
116 static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
117                                struct diff_options *opt, int *match)
118 {
119         while (t->size) {
120                 *match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
121                 if (*match) {
122                         if (*match < 0)
123                                 t->size = 0;
124                         break;
125                 }
126                 update_tree_entry(t);
127         }
128 }
129
130 int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
131               const char *base_str, struct diff_options *opt)
132 {
133         struct strbuf base;
134         int baselen = strlen(base_str);
135         int t1_match = 0, t2_match = 0;
136
137         /* Enable recursion indefinitely */
138         opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);
139         opt->pathspec.max_depth = -1;
140
141         strbuf_init(&base, PATH_MAX);
142         strbuf_add(&base, base_str, baselen);
143
144         for (;;) {
145                 if (diff_can_quit_early(opt))
146                         break;
147                 if (opt->pathspec.nr) {
148                         skip_uninteresting(t1, &base, opt, &t1_match);
149                         skip_uninteresting(t2, &base, opt, &t2_match);
150                 }
151                 if (!t1->size) {
152                         if (!t2->size)
153                                 break;
154                         show_entry(opt, "+", t2, &base);
155                         update_tree_entry(t2);
156                         continue;
157                 }
158                 if (!t2->size) {
159                         show_entry(opt, "-", t1, &base);
160                         update_tree_entry(t1);
161                         continue;
162                 }
163                 switch (compare_tree_entry(t1, t2, &base, opt)) {
164                 case -1:
165                         update_tree_entry(t1);
166                         continue;
167                 case 0:
168                         update_tree_entry(t1);
169                         /* Fallthrough */
170                 case 1:
171                         update_tree_entry(t2);
172                         continue;
173                 }
174                 die("git diff-tree: internal error");
175         }
176
177         strbuf_release(&base);
178         return 0;
179 }
180
181 /*
182  * Does it look like the resulting diff might be due to a rename?
183  *  - single entry
184  *  - not a valid previous file
185  */
186 static inline int diff_might_be_rename(void)
187 {
188         return diff_queued_diff.nr == 1 &&
189                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
190 }
191
192 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
193 {
194         struct diff_options diff_opts;
195         struct diff_queue_struct *q = &diff_queued_diff;
196         struct diff_filepair *choice;
197         const char *paths[1];
198         int i;
199
200         /* Remove the file creation entry from the diff queue, and remember it */
201         choice = q->queue[0];
202         q->nr = 0;
203
204         diff_setup(&diff_opts);
205         DIFF_OPT_SET(&diff_opts, RECURSIVE);
206         DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
207         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
208         diff_opts.single_follow = opt->pathspec.raw[0];
209         diff_opts.break_opt = opt->break_opt;
210         paths[0] = NULL;
211         diff_tree_setup_paths(paths, &diff_opts);
212         if (diff_setup_done(&diff_opts) < 0)
213                 die("unable to set up diff options to follow renames");
214         diff_tree(t1, t2, base, &diff_opts);
215         diffcore_std(&diff_opts);
216         diff_tree_release_paths(&diff_opts);
217
218         /* Go through the new set of filepairing, and see if we find a more interesting one */
219         opt->found_follow = 0;
220         for (i = 0; i < q->nr; i++) {
221                 struct diff_filepair *p = q->queue[i];
222
223                 /*
224                  * Found a source? Not only do we use that for the new
225                  * diff_queued_diff, we will also use that as the path in
226                  * the future!
227                  */
228                 if ((p->status == 'R' || p->status == 'C') &&
229                     !strcmp(p->two->path, opt->pathspec.raw[0])) {
230                         /* Switch the file-pairs around */
231                         q->queue[i] = choice;
232                         choice = p;
233
234                         /* Update the path we use from now on.. */
235                         diff_tree_release_paths(opt);
236                         opt->pathspec.raw[0] = xstrdup(p->one->path);
237                         diff_tree_setup_paths(opt->pathspec.raw, opt);
238
239                         /*
240                          * The caller expects us to return a set of vanilla
241                          * filepairs to let a later call to diffcore_std()
242                          * it makes to sort the renames out (among other
243                          * things), but we already have found renames
244                          * ourselves; signal diffcore_std() not to muck with
245                          * rename information.
246                          */
247                         opt->found_follow = 1;
248                         break;
249                 }
250         }
251
252         /*
253          * Then, discard all the non-relevant file pairs...
254          */
255         for (i = 0; i < q->nr; i++) {
256                 struct diff_filepair *p = q->queue[i];
257                 diff_free_filepair(p);
258         }
259
260         /*
261          * .. and re-instate the one we want (which might be either the
262          * original one, or the rename/copy we found)
263          */
264         q->queue[0] = choice;
265         q->nr = 1;
266 }
267
268 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
269 {
270         void *tree1, *tree2;
271         struct tree_desc t1, t2;
272         unsigned long size1, size2;
273         int retval;
274
275         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
276         if (!tree1)
277                 die("unable to read source tree (%s)", sha1_to_hex(old));
278         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
279         if (!tree2)
280                 die("unable to read destination tree (%s)", sha1_to_hex(new));
281         init_tree_desc(&t1, tree1, size1);
282         init_tree_desc(&t2, tree2, size2);
283         retval = diff_tree(&t1, &t2, base, opt);
284         if (!*base && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
285                 init_tree_desc(&t1, tree1, size1);
286                 init_tree_desc(&t2, tree2, size2);
287                 try_to_follow_renames(&t1, &t2, base, opt);
288         }
289         free(tree1);
290         free(tree2);
291         return retval;
292 }
293
294 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
295 {
296         int retval;
297         void *tree;
298         unsigned long size;
299         struct tree_desc empty, real;
300
301         tree = read_object_with_reference(new, tree_type, &size, NULL);
302         if (!tree)
303                 die("unable to read root tree (%s)", sha1_to_hex(new));
304         init_tree_desc(&real, tree, size);
305
306         init_tree_desc(&empty, "", 0);
307         retval = diff_tree(&empty, &real, base, opt);
308         free(tree);
309         return retval;
310 }
311
312 void diff_tree_release_paths(struct diff_options *opt)
313 {
314         free_pathspec(&opt->pathspec);
315 }
316
317 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
318 {
319         init_pathspec(&opt->pathspec, p);
320 }