Add custom subject prefix support to format-patch (take 3)
[git] / builtin-diff.c
1 /*
2  * Builtin "git diff"
3  *
4  * Copyright (c) 2006 Junio C Hamano
5  */
6 #include "cache.h"
7 #include "commit.h"
8 #include "blob.h"
9 #include "tag.h"
10 #include "diff.h"
11 #include "diffcore.h"
12 #include "revision.h"
13 #include "log-tree.h"
14 #include "builtin.h"
15
16 /* NEEDSWORK: struct object has place for name but we _do_
17  * know mode when we extracted the blob out of a tree, which
18  * we currently lose.
19  */
20 struct blobinfo {
21         unsigned char sha1[20];
22         const char *name;
23 };
24
25 static const char builtin_diff_usage[] =
26 "git-diff <options> <rev>{0,2} -- <path>*";
27
28 static void stuff_change(struct diff_options *opt,
29                          unsigned old_mode, unsigned new_mode,
30                          const unsigned char *old_sha1,
31                          const unsigned char *new_sha1,
32                          const char *old_name,
33                          const char *new_name)
34 {
35         struct diff_filespec *one, *two;
36
37         if (!is_null_sha1(old_sha1) && !is_null_sha1(new_sha1) &&
38             !hashcmp(old_sha1, new_sha1))
39                 return;
40
41         if (opt->reverse_diff) {
42                 unsigned tmp;
43                 const unsigned char *tmp_u;
44                 const char *tmp_c;
45                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
46                 tmp_u = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_u;
47                 tmp_c = old_name; old_name = new_name; new_name = tmp_c;
48         }
49         one = alloc_filespec(old_name);
50         two = alloc_filespec(new_name);
51         fill_filespec(one, old_sha1, old_mode);
52         fill_filespec(two, new_sha1, new_mode);
53
54         /* NEEDSWORK: shouldn't this part of diffopt??? */
55         diff_queue(&diff_queued_diff, one, two);
56 }
57
58 static int builtin_diff_b_f(struct rev_info *revs,
59                             int argc, const char **argv,
60                             struct blobinfo *blob,
61                             const char *path)
62 {
63         /* Blob vs file in the working tree*/
64         struct stat st;
65
66         if (argc > 1)
67                 usage(builtin_diff_usage);
68
69         if (lstat(path, &st))
70                 die("'%s': %s", path, strerror(errno));
71         if (!(S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)))
72                 die("'%s': not a regular file or symlink", path);
73         stuff_change(&revs->diffopt,
74                      canon_mode(st.st_mode), canon_mode(st.st_mode),
75                      blob[0].sha1, null_sha1,
76                      path, path);
77         diffcore_std(&revs->diffopt);
78         diff_flush(&revs->diffopt);
79         return 0;
80 }
81
82 static int builtin_diff_blobs(struct rev_info *revs,
83                               int argc, const char **argv,
84                               struct blobinfo *blob)
85 {
86         unsigned mode = canon_mode(S_IFREG | 0644);
87
88         if (argc > 1)
89                 usage(builtin_diff_usage);
90
91         stuff_change(&revs->diffopt,
92                      mode, mode,
93                      blob[0].sha1, blob[1].sha1,
94                      blob[0].name, blob[1].name);
95         diffcore_std(&revs->diffopt);
96         diff_flush(&revs->diffopt);
97         return 0;
98 }
99
100 static int builtin_diff_index(struct rev_info *revs,
101                               int argc, const char **argv)
102 {
103         int cached = 0;
104         while (1 < argc) {
105                 const char *arg = argv[1];
106                 if (!strcmp(arg, "--cached"))
107                         cached = 1;
108                 else
109                         usage(builtin_diff_usage);
110                 argv++; argc--;
111         }
112         /*
113          * Make sure there is one revision (i.e. pending object),
114          * and there is no revision filtering parameters.
115          */
116         if (revs->pending.nr != 1 ||
117             revs->max_count != -1 || revs->min_age != -1 ||
118             revs->max_age != -1)
119                 usage(builtin_diff_usage);
120         if (read_cache() < 0) {
121                 perror("read_cache");
122                 return -1;
123         }
124         return run_diff_index(revs, cached);
125 }
126
127 static int builtin_diff_tree(struct rev_info *revs,
128                              int argc, const char **argv,
129                              struct object_array_entry *ent)
130 {
131         const unsigned char *(sha1[2]);
132         int swap = 0;
133
134         if (argc > 1)
135                 usage(builtin_diff_usage);
136
137         /* We saw two trees, ent[0] and ent[1].
138          * if ent[1] is uninteresting, they are swapped
139          */
140         if (ent[1].item->flags & UNINTERESTING)
141                 swap = 1;
142         sha1[swap] = ent[0].item->sha1;
143         sha1[1-swap] = ent[1].item->sha1;
144         diff_tree_sha1(sha1[0], sha1[1], "", &revs->diffopt);
145         log_tree_diff_flush(revs);
146         return 0;
147 }
148
149 static int builtin_diff_combined(struct rev_info *revs,
150                                  int argc, const char **argv,
151                                  struct object_array_entry *ent,
152                                  int ents)
153 {
154         const unsigned char (*parent)[20];
155         int i;
156
157         if (argc > 1)
158                 usage(builtin_diff_usage);
159
160         if (!revs->dense_combined_merges && !revs->combine_merges)
161                 revs->dense_combined_merges = revs->combine_merges = 1;
162         parent = xmalloc(ents * sizeof(*parent));
163         /* Again, the revs are all reverse */
164         for (i = 0; i < ents; i++)
165                 hashcpy((unsigned char *)(parent + i),
166                         ent[ents - 1 - i].item->sha1);
167         diff_tree_combined(parent[0], parent + 1, ents - 1,
168                            revs->dense_combined_merges, revs);
169         return 0;
170 }
171
172 void add_head(struct rev_info *revs)
173 {
174         unsigned char sha1[20];
175         struct object *obj;
176         if (get_sha1("HEAD", sha1))
177                 return;
178         obj = parse_object(sha1);
179         if (!obj)
180                 return;
181         add_pending_object(revs, obj, "HEAD");
182 }
183
184 int cmd_diff(int argc, const char **argv, const char *prefix)
185 {
186         int i;
187         struct rev_info rev;
188         struct object_array_entry ent[100];
189         int ents = 0, blobs = 0, paths = 0;
190         const char *path = NULL;
191         struct blobinfo blob[2];
192         int nongit = 0;
193         int result = 0;
194
195         /*
196          * We could get N tree-ish in the rev.pending_objects list.
197          * Also there could be M blobs there, and P pathspecs.
198          *
199          * N=0, M=0:
200          *      cache vs files (diff-files)
201          * N=0, M=2:
202          *      compare two random blobs.  P must be zero.
203          * N=0, M=1, P=1:
204          *      compare a blob with a working tree file.
205          *
206          * N=1, M=0:
207          *      tree vs cache (diff-index --cached)
208          *
209          * N=2, M=0:
210          *      tree vs tree (diff-tree)
211          *
212          * Other cases are errors.
213          */
214
215         prefix = setup_git_directory_gently(&nongit);
216         git_config(git_diff_ui_config);
217         init_revisions(&rev, prefix);
218
219         if (!setup_diff_no_index(&rev, argc, argv, nongit, prefix))
220                 argc = 0;
221         else
222                 argc = setup_revisions(argc, argv, &rev, NULL);
223         if (!rev.diffopt.output_format) {
224                 rev.diffopt.output_format = DIFF_FORMAT_PATCH;
225                 if (diff_setup_done(&rev.diffopt) < 0)
226                         die("diff_setup_done failed");
227         }
228
229         /* Do we have --cached and not have a pending object, then
230          * default to HEAD by hand.  Eek.
231          */
232         if (!rev.pending.nr) {
233                 int i;
234                 for (i = 1; i < argc; i++) {
235                         const char *arg = argv[i];
236                         if (!strcmp(arg, "--"))
237                                 break;
238                         else if (!strcmp(arg, "--cached")) {
239                                 add_head(&rev);
240                                 if (!rev.pending.nr)
241                                         die("No HEAD commit to compare with (yet)");
242                                 break;
243                         }
244                 }
245         }
246
247         for (i = 0; i < rev.pending.nr; i++) {
248                 struct object_array_entry *list = rev.pending.objects+i;
249                 struct object *obj = list->item;
250                 const char *name = list->name;
251                 int flags = (obj->flags & UNINTERESTING);
252                 if (!obj->parsed)
253                         obj = parse_object(obj->sha1);
254                 obj = deref_tag(obj, NULL, 0);
255                 if (!obj)
256                         die("invalid object '%s' given.", name);
257                 if (obj->type == OBJ_COMMIT)
258                         obj = &((struct commit *)obj)->tree->object;
259                 if (obj->type == OBJ_TREE) {
260                         if (ARRAY_SIZE(ent) <= ents)
261                                 die("more than %d trees given: '%s'",
262                                     (int) ARRAY_SIZE(ent), name);
263                         obj->flags |= flags;
264                         ent[ents].item = obj;
265                         ent[ents].name = name;
266                         ents++;
267                         continue;
268                 }
269                 if (obj->type == OBJ_BLOB) {
270                         if (2 <= blobs)
271                                 die("more than two blobs given: '%s'", name);
272                         hashcpy(blob[blobs].sha1, obj->sha1);
273                         blob[blobs].name = name;
274                         blobs++;
275                         continue;
276
277                 }
278                 die("unhandled object '%s' given.", name);
279         }
280         if (rev.prune_data) {
281                 const char **pathspec = rev.prune_data;
282                 while (*pathspec) {
283                         if (!path)
284                                 path = *pathspec;
285                         paths++;
286                         pathspec++;
287                 }
288         }
289
290         /*
291          * Now, do the arguments look reasonable?
292          */
293         if (!ents) {
294                 switch (blobs) {
295                 case 0:
296                         result = run_diff_files_cmd(&rev, argc, argv);
297                         break;
298                 case 1:
299                         if (paths != 1)
300                                 usage(builtin_diff_usage);
301                         result = builtin_diff_b_f(&rev, argc, argv, blob, path);
302                         break;
303                 case 2:
304                         if (paths)
305                                 usage(builtin_diff_usage);
306                         result = builtin_diff_blobs(&rev, argc, argv, blob);
307                         break;
308                 default:
309                         usage(builtin_diff_usage);
310                 }
311         }
312         else if (blobs)
313                 usage(builtin_diff_usage);
314         else if (ents == 1)
315                 result = builtin_diff_index(&rev, argc, argv);
316         else if (ents == 2)
317                 result = builtin_diff_tree(&rev, argc, argv, ent);
318         else if ((ents == 3) && (ent[0].item->flags & UNINTERESTING)) {
319                 /* diff A...B where there is one sane merge base between
320                  * A and B.  We have ent[0] == merge-base, ent[1] == A,
321                  * and ent[2] == B.  Show diff between the base and B.
322                  */
323                 ent[1] = ent[2];
324                 result = builtin_diff_tree(&rev, argc, argv, ent);
325         }
326         else
327                 result = builtin_diff_combined(&rev, argc, argv,
328                                              ent, ents);
329         if (rev.diffopt.exit_with_status)
330                 result = rev.diffopt.has_changes;
331         return result;
332 }