Documentation: tweak use case in "git stash save --keep-index"
[git] / builtin-diff.c
1 /*
2  * Builtin "git diff"
3  *
4  * Copyright (c) 2006 Junio C Hamano
5  */
6 #include "cache.h"
7 #include "color.h"
8 #include "commit.h"
9 #include "blob.h"
10 #include "tag.h"
11 #include "diff.h"
12 #include "diffcore.h"
13 #include "revision.h"
14 #include "log-tree.h"
15 #include "builtin.h"
16
17 struct blobinfo {
18         unsigned char sha1[20];
19         const char *name;
20         unsigned mode;
21 };
22
23 static const char builtin_diff_usage[] =
24 "git-diff <options> <rev>{0,2} -- <path>*";
25
26 static void stuff_change(struct diff_options *opt,
27                          unsigned old_mode, unsigned new_mode,
28                          const unsigned char *old_sha1,
29                          const unsigned char *new_sha1,
30                          const char *old_name,
31                          const char *new_name)
32 {
33         struct diff_filespec *one, *two;
34
35         if (!is_null_sha1(old_sha1) && !is_null_sha1(new_sha1) &&
36             !hashcmp(old_sha1, new_sha1) && (old_mode == new_mode))
37                 return;
38
39         if (DIFF_OPT_TST(opt, REVERSE_DIFF)) {
40                 unsigned tmp;
41                 const unsigned char *tmp_u;
42                 const char *tmp_c;
43                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
44                 tmp_u = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_u;
45                 tmp_c = old_name; old_name = new_name; new_name = tmp_c;
46         }
47
48         if (opt->prefix &&
49             (strncmp(old_name, opt->prefix, opt->prefix_length) ||
50              strncmp(new_name, opt->prefix, opt->prefix_length)))
51                 return;
52
53         one = alloc_filespec(old_name);
54         two = alloc_filespec(new_name);
55         fill_filespec(one, old_sha1, old_mode);
56         fill_filespec(two, new_sha1, new_mode);
57
58         diff_queue(&diff_queued_diff, one, two);
59 }
60
61 static int builtin_diff_b_f(struct rev_info *revs,
62                             int argc, const char **argv,
63                             struct blobinfo *blob,
64                             const char *path)
65 {
66         /* Blob vs file in the working tree*/
67         struct stat st;
68
69         if (argc > 1)
70                 usage(builtin_diff_usage);
71
72         if (lstat(path, &st))
73                 die("'%s': %s", path, strerror(errno));
74         if (!(S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)))
75                 die("'%s': not a regular file or symlink", path);
76
77         if (blob[0].mode == S_IFINVALID)
78                 blob[0].mode = canon_mode(st.st_mode);
79
80         stuff_change(&revs->diffopt,
81                      blob[0].mode, canon_mode(st.st_mode),
82                      blob[0].sha1, null_sha1,
83                      path, path);
84         diffcore_std(&revs->diffopt);
85         diff_flush(&revs->diffopt);
86         return 0;
87 }
88
89 static int builtin_diff_blobs(struct rev_info *revs,
90                               int argc, const char **argv,
91                               struct blobinfo *blob)
92 {
93         unsigned mode = canon_mode(S_IFREG | 0644);
94
95         if (argc > 1)
96                 usage(builtin_diff_usage);
97
98         if (blob[0].mode == S_IFINVALID)
99                 blob[0].mode = mode;
100
101         if (blob[1].mode == S_IFINVALID)
102                 blob[1].mode = mode;
103
104         stuff_change(&revs->diffopt,
105                      blob[0].mode, blob[1].mode,
106                      blob[0].sha1, blob[1].sha1,
107                      blob[0].name, blob[1].name);
108         diffcore_std(&revs->diffopt);
109         diff_flush(&revs->diffopt);
110         return 0;
111 }
112
113 static int builtin_diff_index(struct rev_info *revs,
114                               int argc, const char **argv)
115 {
116         int cached = 0;
117         while (1 < argc) {
118                 const char *arg = argv[1];
119                 if (!strcmp(arg, "--cached"))
120                         cached = 1;
121                 else
122                         usage(builtin_diff_usage);
123                 argv++; argc--;
124         }
125         /*
126          * Make sure there is one revision (i.e. pending object),
127          * and there is no revision filtering parameters.
128          */
129         if (revs->pending.nr != 1 ||
130             revs->max_count != -1 || revs->min_age != -1 ||
131             revs->max_age != -1)
132                 usage(builtin_diff_usage);
133         if (read_cache() < 0) {
134                 perror("read_cache");
135                 return -1;
136         }
137         return run_diff_index(revs, cached);
138 }
139
140 static int builtin_diff_tree(struct rev_info *revs,
141                              int argc, const char **argv,
142                              struct object_array_entry *ent)
143 {
144         const unsigned char *(sha1[2]);
145         int swap = 0;
146
147         if (argc > 1)
148                 usage(builtin_diff_usage);
149
150         /* We saw two trees, ent[0] and ent[1].
151          * if ent[1] is uninteresting, they are swapped
152          */
153         if (ent[1].item->flags & UNINTERESTING)
154                 swap = 1;
155         sha1[swap] = ent[0].item->sha1;
156         sha1[1-swap] = ent[1].item->sha1;
157         diff_tree_sha1(sha1[0], sha1[1], "", &revs->diffopt);
158         log_tree_diff_flush(revs);
159         return 0;
160 }
161
162 static int builtin_diff_combined(struct rev_info *revs,
163                                  int argc, const char **argv,
164                                  struct object_array_entry *ent,
165                                  int ents)
166 {
167         const unsigned char (*parent)[20];
168         int i;
169
170         if (argc > 1)
171                 usage(builtin_diff_usage);
172
173         if (!revs->dense_combined_merges && !revs->combine_merges)
174                 revs->dense_combined_merges = revs->combine_merges = 1;
175         parent = xmalloc(ents * sizeof(*parent));
176         /* Again, the revs are all reverse */
177         for (i = 0; i < ents; i++)
178                 hashcpy((unsigned char *)(parent + i),
179                         ent[ents - 1 - i].item->sha1);
180         diff_tree_combined(parent[0], parent + 1, ents - 1,
181                            revs->dense_combined_merges, revs);
182         return 0;
183 }
184
185 static void refresh_index_quietly(void)
186 {
187         struct lock_file *lock_file;
188         int fd;
189
190         lock_file = xcalloc(1, sizeof(struct lock_file));
191         fd = hold_locked_index(lock_file, 0);
192         if (fd < 0)
193                 return;
194         discard_cache();
195         read_cache();
196         refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);
197
198         if (active_cache_changed &&
199             !write_cache(fd, active_cache, active_nr))
200                 commit_locked_index(lock_file);
201
202         rollback_lock_file(lock_file);
203 }
204
205 static int builtin_diff_files(struct rev_info *revs, int argc, const char **argv)
206 {
207         int result;
208         unsigned int options = 0;
209
210         while (1 < argc && argv[1][0] == '-') {
211                 if (!strcmp(argv[1], "--base"))
212                         revs->max_count = 1;
213                 else if (!strcmp(argv[1], "--ours"))
214                         revs->max_count = 2;
215                 else if (!strcmp(argv[1], "--theirs"))
216                         revs->max_count = 3;
217                 else if (!strcmp(argv[1], "-q"))
218                         options |= DIFF_SILENT_ON_REMOVED;
219                 else
220                         return error("invalid option: %s", argv[1]);
221                 argv++; argc--;
222         }
223
224         if (revs->max_count == -1 &&
225             (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
226                 revs->combine_merges = revs->dense_combined_merges = 1;
227
228         if (read_cache() < 0) {
229                 perror("read_cache");
230                 return -1;
231         }
232         result = run_diff_files(revs, options);
233         return diff_result_code(&revs->diffopt, result);
234 }
235
236 int cmd_diff(int argc, const char **argv, const char *prefix)
237 {
238         int i;
239         struct rev_info rev;
240         struct object_array_entry ent[100];
241         int ents = 0, blobs = 0, paths = 0;
242         const char *path = NULL;
243         struct blobinfo blob[2];
244         int nongit;
245         int result = 0;
246
247         /*
248          * We could get N tree-ish in the rev.pending_objects list.
249          * Also there could be M blobs there, and P pathspecs.
250          *
251          * N=0, M=0:
252          *      cache vs files (diff-files)
253          * N=0, M=2:
254          *      compare two random blobs.  P must be zero.
255          * N=0, M=1, P=1:
256          *      compare a blob with a working tree file.
257          *
258          * N=1, M=0:
259          *      tree vs cache (diff-index --cached)
260          *
261          * N=2, M=0:
262          *      tree vs tree (diff-tree)
263          *
264          * N=0, M=0, P=2:
265          *      compare two filesystem entities (aka --no-index).
266          *
267          * Other cases are errors.
268          */
269
270         prefix = setup_git_directory_gently(&nongit);
271         git_config(git_diff_ui_config, NULL);
272
273         if (diff_use_color_default == -1)
274                 diff_use_color_default = git_use_color_default;
275
276         init_revisions(&rev, prefix);
277
278         /* If this is a no-index diff, just run it and exit there. */
279         diff_no_index(&rev, argc, argv, nongit, prefix);
280
281         /* Otherwise, we are doing the usual "git" diff */
282         rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;
283
284         if (nongit)
285                 die("Not a git repository");
286         argc = setup_revisions(argc, argv, &rev, NULL);
287         if (!rev.diffopt.output_format) {
288                 rev.diffopt.output_format = DIFF_FORMAT_PATCH;
289                 if (diff_setup_done(&rev.diffopt) < 0)
290                         die("diff_setup_done failed");
291         }
292         DIFF_OPT_SET(&rev.diffopt, ALLOW_EXTERNAL);
293         DIFF_OPT_SET(&rev.diffopt, RECURSIVE);
294
295         /*
296          * If the user asked for our exit code then don't start a
297          * pager or we would end up reporting its exit code instead.
298          */
299         if (!DIFF_OPT_TST(&rev.diffopt, EXIT_WITH_STATUS))
300                 setup_pager();
301
302         /*
303          * Do we have --cached and not have a pending object, then
304          * default to HEAD by hand.  Eek.
305          */
306         if (!rev.pending.nr) {
307                 int i;
308                 for (i = 1; i < argc; i++) {
309                         const char *arg = argv[i];
310                         if (!strcmp(arg, "--"))
311                                 break;
312                         else if (!strcmp(arg, "--cached")) {
313                                 add_head_to_pending(&rev);
314                                 if (!rev.pending.nr)
315                                         die("No HEAD commit to compare with (yet)");
316                                 break;
317                         }
318                 }
319         }
320
321         for (i = 0; i < rev.pending.nr; i++) {
322                 struct object_array_entry *list = rev.pending.objects+i;
323                 struct object *obj = list->item;
324                 const char *name = list->name;
325                 int flags = (obj->flags & UNINTERESTING);
326                 if (!obj->parsed)
327                         obj = parse_object(obj->sha1);
328                 obj = deref_tag(obj, NULL, 0);
329                 if (!obj)
330                         die("invalid object '%s' given.", name);
331                 if (obj->type == OBJ_COMMIT)
332                         obj = &((struct commit *)obj)->tree->object;
333                 if (obj->type == OBJ_TREE) {
334                         if (ARRAY_SIZE(ent) <= ents)
335                                 die("more than %d trees given: '%s'",
336                                     (int) ARRAY_SIZE(ent), name);
337                         obj->flags |= flags;
338                         ent[ents].item = obj;
339                         ent[ents].name = name;
340                         ents++;
341                         continue;
342                 }
343                 if (obj->type == OBJ_BLOB) {
344                         if (2 <= blobs)
345                                 die("more than two blobs given: '%s'", name);
346                         hashcpy(blob[blobs].sha1, obj->sha1);
347                         blob[blobs].name = name;
348                         blob[blobs].mode = list->mode;
349                         blobs++;
350                         continue;
351
352                 }
353                 die("unhandled object '%s' given.", name);
354         }
355         if (rev.prune_data) {
356                 const char **pathspec = rev.prune_data;
357                 while (*pathspec) {
358                         if (!path)
359                                 path = *pathspec;
360                         paths++;
361                         pathspec++;
362                 }
363         }
364
365         /*
366          * Now, do the arguments look reasonable?
367          */
368         if (!ents) {
369                 switch (blobs) {
370                 case 0:
371                         result = builtin_diff_files(&rev, argc, argv);
372                         break;
373                 case 1:
374                         if (paths != 1)
375                                 usage(builtin_diff_usage);
376                         result = builtin_diff_b_f(&rev, argc, argv, blob, path);
377                         break;
378                 case 2:
379                         if (paths)
380                                 usage(builtin_diff_usage);
381                         result = builtin_diff_blobs(&rev, argc, argv, blob);
382                         break;
383                 default:
384                         usage(builtin_diff_usage);
385                 }
386         }
387         else if (blobs)
388                 usage(builtin_diff_usage);
389         else if (ents == 1)
390                 result = builtin_diff_index(&rev, argc, argv);
391         else if (ents == 2)
392                 result = builtin_diff_tree(&rev, argc, argv, ent);
393         else if ((ents == 3) && (ent[0].item->flags & UNINTERESTING)) {
394                 /* diff A...B where there is one sane merge base between
395                  * A and B.  We have ent[0] == merge-base, ent[1] == A,
396                  * and ent[2] == B.  Show diff between the base and B.
397                  */
398                 ent[1] = ent[2];
399                 result = builtin_diff_tree(&rev, argc, argv, ent);
400         }
401         else
402                 result = builtin_diff_combined(&rev, argc, argv,
403                                              ent, ents);
404         result = diff_result_code(&rev.diffopt, result);
405         if (1 < rev.diffopt.skip_stat_unmatch)
406                 refresh_index_quietly();
407         return result;
408 }