apply --whitespace=fix: fix handling of blank lines at the eof
[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 char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
10 {
11         char *newbase = xmalloc(baselen + pathlen + 2);
12         memcpy(newbase, base, baselen);
13         memcpy(newbase + baselen, path, pathlen);
14         memcpy(newbase + baselen + pathlen, "/", 2);
15         return newbase;
16 }
17
18 static char *malloc_fullname(const char *base, int baselen, const char *path, int pathlen)
19 {
20         char *fullname = xmalloc(baselen + pathlen + 1);
21         memcpy(fullname, base, baselen);
22         memcpy(fullname + baselen, path, pathlen);
23         fullname[baselen + pathlen] = 0;
24         return fullname;
25 }
26
27 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
28                        const char *base, int baselen);
29
30 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
31 {
32         unsigned mode1, mode2;
33         const char *path1, *path2;
34         const unsigned char *sha1, *sha2;
35         int cmp, pathlen1, pathlen2;
36         char *fullname;
37
38         sha1 = tree_entry_extract(t1, &path1, &mode1);
39         sha2 = tree_entry_extract(t2, &path2, &mode2);
40
41         pathlen1 = tree_entry_len(path1, sha1);
42         pathlen2 = tree_entry_len(path2, sha2);
43         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
44         if (cmp < 0) {
45                 show_entry(opt, "-", t1, base, baselen);
46                 return -1;
47         }
48         if (cmp > 0) {
49                 show_entry(opt, "+", t2, base, baselen);
50                 return 1;
51         }
52         if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER) && !hashcmp(sha1, sha2) && mode1 == mode2)
53                 return 0;
54
55         /*
56          * If the filemode has changed to/from a directory from/to a regular
57          * file, we need to consider it a remove and an add.
58          */
59         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
60                 show_entry(opt, "-", t1, base, baselen);
61                 show_entry(opt, "+", t2, base, baselen);
62                 return 0;
63         }
64
65         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode1)) {
66                 int retval;
67                 char *newbase = malloc_base(base, baselen, path1, pathlen1);
68                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
69                         newbase[baselen + pathlen1] = 0;
70                         opt->change(opt, mode1, mode2,
71                                     sha1, sha2, newbase);
72                         newbase[baselen + pathlen1] = '/';
73                 }
74                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
75                 free(newbase);
76                 return retval;
77         }
78
79         fullname = malloc_fullname(base, baselen, path1, pathlen1);
80         opt->change(opt, mode1, mode2, sha1, sha2, fullname);
81         free(fullname);
82         return 0;
83 }
84
85 /*
86  * Is a tree entry interesting given the pathspec we have?
87  *
88  * Return:
89  *  - 2 for "yes, and all subsequent entries will be"
90  *  - 1 for yes
91  *  - zero for no
92  *  - negative for "no, and no subsequent entries will be either"
93  */
94 static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
95 {
96         const char *path;
97         const unsigned char *sha1;
98         unsigned mode;
99         int i;
100         int pathlen;
101         int never_interesting = -1;
102
103         if (!opt->nr_paths)
104                 return 1;
105
106         sha1 = tree_entry_extract(desc, &path, &mode);
107
108         pathlen = tree_entry_len(path, sha1);
109
110         for (i = 0; i < opt->nr_paths; i++) {
111                 const char *match = opt->paths[i];
112                 int matchlen = opt->pathlens[i];
113                 int m = -1; /* signals that we haven't called strncmp() */
114
115                 if (baselen >= matchlen) {
116                         /* If it doesn't match, move along... */
117                         if (strncmp(base, match, matchlen))
118                                 continue;
119
120                         /*
121                          * The base is a subdirectory of a path which
122                          * was specified, so all of them are interesting.
123                          */
124                         return 2;
125                 }
126
127                 /* Does the base match? */
128                 if (strncmp(base, match, baselen))
129                         continue;
130
131                 match += baselen;
132                 matchlen -= baselen;
133
134                 if (never_interesting) {
135                         /*
136                          * We have not seen any match that sorts later
137                          * than the current path.
138                          */
139
140                         /*
141                          * Does match sort strictly earlier than path
142                          * with their common parts?
143                          */
144                         m = strncmp(match, path,
145                                     (matchlen < pathlen) ? matchlen : pathlen);
146                         if (m < 0)
147                                 continue;
148
149                         /*
150                          * If we come here even once, that means there is at
151                          * least one pathspec that would sort equal to or
152                          * later than the path we are currently looking at.
153                          * In other words, if we have never reached this point
154                          * after iterating all pathspecs, it means all
155                          * pathspecs are either outside of base, or inside the
156                          * base but sorts strictly earlier than the current
157                          * one.  In either case, they will never match the
158                          * subsequent entries.  In such a case, we initialized
159                          * the variable to -1 and that is what will be
160                          * returned, allowing the caller to terminate early.
161                          */
162                         never_interesting = 0;
163                 }
164
165                 if (pathlen > matchlen)
166                         continue;
167
168                 if (matchlen > pathlen) {
169                         if (match[pathlen] != '/')
170                                 continue;
171                         if (!S_ISDIR(mode))
172                                 continue;
173                 }
174
175                 if (m == -1)
176                         /*
177                          * we cheated and did not do strncmp(), so we do
178                          * that here.
179                          */
180                         m = strncmp(match, path, pathlen);
181
182                 /*
183                  * If common part matched earlier then it is a hit,
184                  * because we rejected the case where path is not a
185                  * leading directory and is shorter than match.
186                  */
187                 if (!m)
188                         return 1;
189         }
190         return never_interesting; /* No matches */
191 }
192
193 /* A whole sub-tree went away or appeared */
194 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
195 {
196         int all_interesting = 0;
197         while (desc->size) {
198                 int show;
199
200                 if (all_interesting)
201                         show = 1;
202                 else {
203                         show = tree_entry_interesting(desc, base, baselen,
204                                                       opt);
205                         if (show == 2)
206                                 all_interesting = 1;
207                 }
208                 if (show < 0)
209                         break;
210                 if (show)
211                         show_entry(opt, prefix, desc, base, baselen);
212                 update_tree_entry(desc);
213         }
214 }
215
216 /* A file entry went away or appeared */
217 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
218                        const char *base, int baselen)
219 {
220         unsigned mode;
221         const char *path;
222         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
223         int pathlen = tree_entry_len(path, sha1);
224
225         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
226                 enum object_type type;
227                 char *newbase = malloc_base(base, baselen, path, pathlen);
228                 struct tree_desc inner;
229                 void *tree;
230                 unsigned long size;
231
232                 tree = read_sha1_file(sha1, &type, &size);
233                 if (!tree || type != OBJ_TREE)
234                         die("corrupt tree sha %s", sha1_to_hex(sha1));
235
236                 init_tree_desc(&inner, tree, size);
237                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
238
239                 free(tree);
240                 free(newbase);
241         } else {
242                 char *fullname = malloc_fullname(base, baselen, path, pathlen);
243                 opt->add_remove(opt, prefix[0], mode, sha1, fullname);
244                 free(fullname);
245         }
246 }
247
248 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
249 {
250         int all_interesting = 0;
251         while (t->size) {
252                 int show;
253
254                 if (all_interesting)
255                         show = 1;
256                 else {
257                         show = tree_entry_interesting(t, base, baselen, opt);
258                         if (show == 2)
259                                 all_interesting = 1;
260                 }
261                 if (!show) {
262                         update_tree_entry(t);
263                         continue;
264                 }
265                 /* Skip it all? */
266                 if (show < 0)
267                         t->size = 0;
268                 return;
269         }
270 }
271
272 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
273 {
274         int baselen = strlen(base);
275
276         for (;;) {
277                 if (DIFF_OPT_TST(opt, QUIET) && DIFF_OPT_TST(opt, HAS_CHANGES))
278                         break;
279                 if (opt->nr_paths) {
280                         skip_uninteresting(t1, base, baselen, opt);
281                         skip_uninteresting(t2, base, baselen, opt);
282                 }
283                 if (!t1->size) {
284                         if (!t2->size)
285                                 break;
286                         show_entry(opt, "+", t2, base, baselen);
287                         update_tree_entry(t2);
288                         continue;
289                 }
290                 if (!t2->size) {
291                         show_entry(opt, "-", t1, base, baselen);
292                         update_tree_entry(t1);
293                         continue;
294                 }
295                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
296                 case -1:
297                         update_tree_entry(t1);
298                         continue;
299                 case 0:
300                         update_tree_entry(t1);
301                         /* Fallthrough */
302                 case 1:
303                         update_tree_entry(t2);
304                         continue;
305                 }
306                 die("git diff-tree: internal error");
307         }
308         return 0;
309 }
310
311 /*
312  * Does it look like the resulting diff might be due to a rename?
313  *  - single entry
314  *  - not a valid previous file
315  */
316 static inline int diff_might_be_rename(void)
317 {
318         return diff_queued_diff.nr == 1 &&
319                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
320 }
321
322 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
323 {
324         struct diff_options diff_opts;
325         struct diff_queue_struct *q = &diff_queued_diff;
326         struct diff_filepair *choice;
327         const char *paths[1];
328         int i;
329
330         /* Remove the file creation entry from the diff queue, and remember it */
331         choice = q->queue[0];
332         q->nr = 0;
333
334         diff_setup(&diff_opts);
335         DIFF_OPT_SET(&diff_opts, RECURSIVE);
336         diff_opts.detect_rename = DIFF_DETECT_RENAME;
337         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
338         diff_opts.single_follow = opt->paths[0];
339         diff_opts.break_opt = opt->break_opt;
340         paths[0] = NULL;
341         diff_tree_setup_paths(paths, &diff_opts);
342         if (diff_setup_done(&diff_opts) < 0)
343                 die("unable to set up diff options to follow renames");
344         diff_tree(t1, t2, base, &diff_opts);
345         diffcore_std(&diff_opts);
346         diff_tree_release_paths(&diff_opts);
347
348         /* Go through the new set of filepairing, and see if we find a more interesting one */
349         for (i = 0; i < q->nr; i++) {
350                 struct diff_filepair *p = q->queue[i];
351
352                 /*
353                  * Found a source? Not only do we use that for the new
354                  * diff_queued_diff, we will also use that as the path in
355                  * the future!
356                  */
357                 if ((p->status == 'R' || p->status == 'C') && !strcmp(p->two->path, opt->paths[0])) {
358                         /* Switch the file-pairs around */
359                         q->queue[i] = choice;
360                         choice = p;
361
362                         /* Update the path we use from now on.. */
363                         diff_tree_release_paths(opt);
364                         opt->paths[0] = xstrdup(p->one->path);
365                         diff_tree_setup_paths(opt->paths, opt);
366                         break;
367                 }
368         }
369
370         /*
371          * Then, discard all the non-relevane file pairs...
372          */
373         for (i = 0; i < q->nr; i++) {
374                 struct diff_filepair *p = q->queue[i];
375                 diff_free_filepair(p);
376         }
377
378         /*
379          * .. and re-instate the one we want (which might be either the
380          * original one, or the rename/copy we found)
381          */
382         q->queue[0] = choice;
383         q->nr = 1;
384 }
385
386 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
387 {
388         void *tree1, *tree2;
389         struct tree_desc t1, t2;
390         unsigned long size1, size2;
391         int retval;
392
393         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
394         if (!tree1)
395                 die("unable to read source tree (%s)", sha1_to_hex(old));
396         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
397         if (!tree2)
398                 die("unable to read destination tree (%s)", sha1_to_hex(new));
399         init_tree_desc(&t1, tree1, size1);
400         init_tree_desc(&t2, tree2, size2);
401         retval = diff_tree(&t1, &t2, base, opt);
402         if (DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
403                 init_tree_desc(&t1, tree1, size1);
404                 init_tree_desc(&t2, tree2, size2);
405                 try_to_follow_renames(&t1, &t2, base, opt);
406         }
407         free(tree1);
408         free(tree2);
409         return retval;
410 }
411
412 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
413 {
414         int retval;
415         void *tree;
416         unsigned long size;
417         struct tree_desc empty, real;
418
419         tree = read_object_with_reference(new, tree_type, &size, NULL);
420         if (!tree)
421                 die("unable to read root tree (%s)", sha1_to_hex(new));
422         init_tree_desc(&real, tree, size);
423
424         init_tree_desc(&empty, "", 0);
425         retval = diff_tree(&empty, &real, base, opt);
426         free(tree);
427         return retval;
428 }
429
430 static int count_paths(const char **paths)
431 {
432         int i = 0;
433         while (*paths++)
434                 i++;
435         return i;
436 }
437
438 void diff_tree_release_paths(struct diff_options *opt)
439 {
440         free(opt->pathlens);
441 }
442
443 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
444 {
445         opt->nr_paths = 0;
446         opt->pathlens = NULL;
447         opt->paths = NULL;
448
449         if (p) {
450                 int i;
451
452                 opt->paths = p;
453                 opt->nr_paths = count_paths(p);
454                 if (opt->nr_paths == 0) {
455                         opt->pathlens = NULL;
456                         return;
457                 }
458                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
459                 for (i=0; i < opt->nr_paths; i++)
460                         opt->pathlens[i] = strlen(p[i]);
461         }
462 }