Windows: start_command: Support non-NULL dir in struct child_process
[git/dscho.git] / tree-diff.c
blobfe9f52c4796512f40869e511b55a2d97fa84532e
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"
9 static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
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;
18 static char *malloc_fullname(const char *base, int baselen, const char *path, int pathlen)
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;
27 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
28                        const char *base, int baselen);
30 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
32         unsigned mode1, mode2;
33         const char *path1, *path2;
34         const unsigned char *sha1, *sha2;
35         int cmp, pathlen1, pathlen2;
36         char *fullname;
38         sha1 = tree_entry_extract(t1, &path1, &mode1);
39         sha2 = tree_entry_extract(t2, &path2, &mode2);
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;
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         }
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, 0, 0);
72                         newbase[baselen + pathlen1] = '/';
73                 }
74                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
75                 free(newbase);
76                 return retval;
77         }
79         fullname = malloc_fullname(base, baselen, path1, pathlen1);
80         opt->change(opt, mode1, mode2, sha1, sha2, fullname, 0, 0);
81         free(fullname);
82         return 0;
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)
96         const char *path;
97         const unsigned char *sha1;
98         unsigned mode;
99         int i;
100         int pathlen;
101         int never_interesting = -1;
103         if (!opt->nr_paths)
104                 return 1;
106         sha1 = tree_entry_extract(desc, &path, &mode);
108         pathlen = tree_entry_len(path, sha1);
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() */
115                 if (baselen >= matchlen) {
116                         /* If it doesn't match, move along... */
117                         if (strncmp(base, match, matchlen))
118                                 continue;
120                         /*
121                          * If the base is a subdirectory of a path which
122                          * was specified, all of them are interesting.
123                          */
124                         if (!matchlen ||
125                             base[matchlen] == '/' ||
126                             match[matchlen - 1] == '/')
127                                 return 2;
129                         /* Just a random prefix match */
130                         continue;
131                 }
133                 /* Does the base match? */
134                 if (strncmp(base, match, baselen))
135                         continue;
137                 match += baselen;
138                 matchlen -= baselen;
140                 if (never_interesting) {
141                         /*
142                          * We have not seen any match that sorts later
143                          * than the current path.
144                          */
146                         /*
147                          * Does match sort strictly earlier than path
148                          * with their common parts?
149                          */
150                         m = strncmp(match, path,
151                                     (matchlen < pathlen) ? matchlen : pathlen);
152                         if (m < 0)
153                                 continue;
155                         /*
156                          * If we come here even once, that means there is at
157                          * least one pathspec that would sort equal to or
158                          * later than the path we are currently looking at.
159                          * In other words, if we have never reached this point
160                          * after iterating all pathspecs, it means all
161                          * pathspecs are either outside of base, or inside the
162                          * base but sorts strictly earlier than the current
163                          * one.  In either case, they will never match the
164                          * subsequent entries.  In such a case, we initialized
165                          * the variable to -1 and that is what will be
166                          * returned, allowing the caller to terminate early.
167                          */
168                         never_interesting = 0;
169                 }
171                 if (pathlen > matchlen)
172                         continue;
174                 if (matchlen > pathlen) {
175                         if (match[pathlen] != '/')
176                                 continue;
177                         if (!S_ISDIR(mode))
178                                 continue;
179                 }
181                 if (m == -1)
182                         /*
183                          * we cheated and did not do strncmp(), so we do
184                          * that here.
185                          */
186                         m = strncmp(match, path, pathlen);
188                 /*
189                  * If common part matched earlier then it is a hit,
190                  * because we rejected the case where path is not a
191                  * leading directory and is shorter than match.
192                  */
193                 if (!m)
194                         return 1;
195         }
196         return never_interesting; /* No matches */
199 /* A whole sub-tree went away or appeared */
200 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
202         int all_interesting = 0;
203         while (desc->size) {
204                 int show;
206                 if (all_interesting)
207                         show = 1;
208                 else {
209                         show = tree_entry_interesting(desc, base, baselen,
210                                                       opt);
211                         if (show == 2)
212                                 all_interesting = 1;
213                 }
214                 if (show < 0)
215                         break;
216                 if (show)
217                         show_entry(opt, prefix, desc, base, baselen);
218                 update_tree_entry(desc);
219         }
222 /* A file entry went away or appeared */
223 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
224                        const char *base, int baselen)
226         unsigned mode;
227         const char *path;
228         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
229         int pathlen = tree_entry_len(path, sha1);
231         if (DIFF_OPT_TST(opt, RECURSIVE) && S_ISDIR(mode)) {
232                 enum object_type type;
233                 char *newbase = malloc_base(base, baselen, path, pathlen);
234                 struct tree_desc inner;
235                 void *tree;
236                 unsigned long size;
238                 tree = read_sha1_file(sha1, &type, &size);
239                 if (!tree || type != OBJ_TREE)
240                         die("corrupt tree sha %s", sha1_to_hex(sha1));
242                 if (DIFF_OPT_TST(opt, TREE_IN_RECURSIVE)) {
243                         newbase[baselen + pathlen] = 0;
244                         opt->add_remove(opt, *prefix, mode, sha1, newbase, 0);
245                         newbase[baselen + pathlen] = '/';
246                 }
248                 init_tree_desc(&inner, tree, size);
249                 show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
251                 free(tree);
252                 free(newbase);
253         } else {
254                 char *fullname = malloc_fullname(base, baselen, path, pathlen);
255                 opt->add_remove(opt, prefix[0], mode, sha1, fullname, 0);
256                 free(fullname);
257         }
260 static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
262         int all_interesting = 0;
263         while (t->size) {
264                 int show;
266                 if (all_interesting)
267                         show = 1;
268                 else {
269                         show = tree_entry_interesting(t, base, baselen, opt);
270                         if (show == 2)
271                                 all_interesting = 1;
272                 }
273                 if (!show) {
274                         update_tree_entry(t);
275                         continue;
276                 }
277                 /* Skip it all? */
278                 if (show < 0)
279                         t->size = 0;
280                 return;
281         }
284 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
286         int baselen = strlen(base);
288         for (;;) {
289                 if (DIFF_OPT_TST(opt, QUICK) &&
290                     DIFF_OPT_TST(opt, HAS_CHANGES))
291                         break;
292                 if (opt->nr_paths) {
293                         skip_uninteresting(t1, base, baselen, opt);
294                         skip_uninteresting(t2, base, baselen, opt);
295                 }
296                 if (!t1->size) {
297                         if (!t2->size)
298                                 break;
299                         show_entry(opt, "+", t2, base, baselen);
300                         update_tree_entry(t2);
301                         continue;
302                 }
303                 if (!t2->size) {
304                         show_entry(opt, "-", t1, base, baselen);
305                         update_tree_entry(t1);
306                         continue;
307                 }
308                 switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
309                 case -1:
310                         update_tree_entry(t1);
311                         continue;
312                 case 0:
313                         update_tree_entry(t1);
314                         /* Fallthrough */
315                 case 1:
316                         update_tree_entry(t2);
317                         continue;
318                 }
319                 die("git diff-tree: internal error");
320         }
321         return 0;
325  * Does it look like the resulting diff might be due to a rename?
326  *  - single entry
327  *  - not a valid previous file
328  */
329 static inline int diff_might_be_rename(void)
331         return diff_queued_diff.nr == 1 &&
332                 !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
335 static void try_to_follow_renames(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
337         struct diff_options diff_opts;
338         struct diff_queue_struct *q = &diff_queued_diff;
339         struct diff_filepair *choice;
340         const char *paths[1];
341         int i;
343         /* Remove the file creation entry from the diff queue, and remember it */
344         choice = q->queue[0];
345         q->nr = 0;
347         diff_setup(&diff_opts);
348         DIFF_OPT_SET(&diff_opts, RECURSIVE);
349         diff_opts.detect_rename = DIFF_DETECT_RENAME;
350         diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
351         diff_opts.single_follow = opt->paths[0];
352         diff_opts.break_opt = opt->break_opt;
353         paths[0] = NULL;
354         diff_tree_setup_paths(paths, &diff_opts);
355         if (diff_setup_done(&diff_opts) < 0)
356                 die("unable to set up diff options to follow renames");
357         diff_tree(t1, t2, base, &diff_opts);
358         diffcore_std(&diff_opts);
359         diff_tree_release_paths(&diff_opts);
361         /* Go through the new set of filepairing, and see if we find a more interesting one */
362         for (i = 0; i < q->nr; i++) {
363                 struct diff_filepair *p = q->queue[i];
365                 /*
366                  * Found a source? Not only do we use that for the new
367                  * diff_queued_diff, we will also use that as the path in
368                  * the future!
369                  */
370                 if ((p->status == 'R' || p->status == 'C') && !strcmp(p->two->path, opt->paths[0])) {
371                         /* Switch the file-pairs around */
372                         q->queue[i] = choice;
373                         choice = p;
375                         /* Update the path we use from now on.. */
376                         diff_tree_release_paths(opt);
377                         opt->paths[0] = xstrdup(p->one->path);
378                         diff_tree_setup_paths(opt->paths, opt);
379                         break;
380                 }
381         }
383         /*
384          * Then, discard all the non-relevant file pairs...
385          */
386         for (i = 0; i < q->nr; i++) {
387                 struct diff_filepair *p = q->queue[i];
388                 diff_free_filepair(p);
389         }
391         /*
392          * .. and re-instate the one we want (which might be either the
393          * original one, or the rename/copy we found)
394          */
395         q->queue[0] = choice;
396         q->nr = 1;
399 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
401         void *tree1, *tree2;
402         struct tree_desc t1, t2;
403         unsigned long size1, size2;
404         int retval;
406         tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
407         if (!tree1)
408                 die("unable to read source tree (%s)", sha1_to_hex(old));
409         tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
410         if (!tree2)
411                 die("unable to read destination tree (%s)", sha1_to_hex(new));
412         init_tree_desc(&t1, tree1, size1);
413         init_tree_desc(&t2, tree2, size2);
414         retval = diff_tree(&t1, &t2, base, opt);
415         if (DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename()) {
416                 init_tree_desc(&t1, tree1, size1);
417                 init_tree_desc(&t2, tree2, size2);
418                 try_to_follow_renames(&t1, &t2, base, opt);
419         }
420         free(tree1);
421         free(tree2);
422         return retval;
425 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
427         int retval;
428         void *tree;
429         unsigned long size;
430         struct tree_desc empty, real;
432         tree = read_object_with_reference(new, tree_type, &size, NULL);
433         if (!tree)
434                 die("unable to read root tree (%s)", sha1_to_hex(new));
435         init_tree_desc(&real, tree, size);
437         init_tree_desc(&empty, "", 0);
438         retval = diff_tree(&empty, &real, base, opt);
439         free(tree);
440         return retval;
443 static int count_paths(const char **paths)
445         int i = 0;
446         while (*paths++)
447                 i++;
448         return i;
451 void diff_tree_release_paths(struct diff_options *opt)
453         free(opt->pathlens);
456 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
458         opt->nr_paths = 0;
459         opt->pathlens = NULL;
460         opt->paths = NULL;
462         if (p) {
463                 int i;
465                 opt->paths = p;
466                 opt->nr_paths = count_paths(p);
467                 if (opt->nr_paths == 0) {
468                         opt->pathlens = NULL;
469                         return;
470                 }
471                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
472                 for (i=0; i < opt->nr_paths; i++)
473                         opt->pathlens[i] = strlen(p[i]);
474         }