git-merge: fail correctly when we cannot fast forward.
[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 int builtin_diff_files(struct rev_info *revs,
29                               int argc, const char **argv)
30 {
31         int silent = 0;
32         while (1 < argc) {
33                 const char *arg = argv[1];
34                 if (!strcmp(arg, "--base"))
35                         revs->max_count = 1;
36                 else if (!strcmp(arg, "--ours"))
37                         revs->max_count = 2;
38                 else if (!strcmp(arg, "--theirs"))
39                         revs->max_count = 3;
40                 else if (!strcmp(arg, "-q"))
41                         silent = 1;
42                 else
43                         usage(builtin_diff_usage);
44                 argv++; argc--;
45         }
46         /*
47          * Make sure there are NO revision (i.e. pending object) parameter,
48          * specified rev.max_count is reasonable (0 <= n <= 3), and
49          * there is no other revision filtering parameter.
50          */
51         if (revs->pending.nr ||
52             revs->min_age != -1 ||
53             revs->max_age != -1 ||
54             3 < revs->max_count)
55                 usage(builtin_diff_usage);
56         if (revs->max_count < 0 &&
57             (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
58                 revs->combine_merges = revs->dense_combined_merges = 1;
59         return run_diff_files(revs, silent);
60 }
61
62 static void stuff_change(struct diff_options *opt,
63                          unsigned old_mode, unsigned new_mode,
64                          const unsigned char *old_sha1,
65                          const unsigned char *new_sha1,
66                          const char *old_name,
67                          const char *new_name)
68 {
69         struct diff_filespec *one, *two;
70
71         if (!is_null_sha1(old_sha1) && !is_null_sha1(new_sha1) &&
72             !hashcmp(old_sha1, new_sha1))
73                 return;
74
75         if (opt->reverse_diff) {
76                 unsigned tmp;
77                 const unsigned char *tmp_u;
78                 const char *tmp_c;
79                 tmp = old_mode; old_mode = new_mode; new_mode = tmp;
80                 tmp_u = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_u;
81                 tmp_c = old_name; old_name = new_name; new_name = tmp_c;
82         }
83         one = alloc_filespec(old_name);
84         two = alloc_filespec(new_name);
85         fill_filespec(one, old_sha1, old_mode);
86         fill_filespec(two, new_sha1, new_mode);
87
88         /* NEEDSWORK: shouldn't this part of diffopt??? */
89         diff_queue(&diff_queued_diff, one, two);
90 }
91
92 static int builtin_diff_b_f(struct rev_info *revs,
93                             int argc, const char **argv,
94                             struct blobinfo *blob,
95                             const char *path)
96 {
97         /* Blob vs file in the working tree*/
98         struct stat st;
99
100         if (argc > 1)
101                 usage(builtin_diff_usage);
102
103         if (lstat(path, &st))
104                 die("'%s': %s", path, strerror(errno));
105         if (!(S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)))
106                 die("'%s': not a regular file or symlink", path);
107         stuff_change(&revs->diffopt,
108                      canon_mode(st.st_mode), canon_mode(st.st_mode),
109                      blob[0].sha1, null_sha1,
110                      path, path);
111         diffcore_std(&revs->diffopt);
112         diff_flush(&revs->diffopt);
113         return 0;
114 }
115
116 static int builtin_diff_blobs(struct rev_info *revs,
117                               int argc, const char **argv,
118                               struct blobinfo *blob)
119 {
120         unsigned mode = canon_mode(S_IFREG | 0644);
121
122         if (argc > 1)
123                 usage(builtin_diff_usage);
124
125         stuff_change(&revs->diffopt,
126                      mode, mode,
127                      blob[0].sha1, blob[1].sha1,
128                      blob[0].name, blob[1].name);
129         diffcore_std(&revs->diffopt);
130         diff_flush(&revs->diffopt);
131         return 0;
132 }
133
134 static int builtin_diff_index(struct rev_info *revs,
135                               int argc, const char **argv)
136 {
137         int cached = 0;
138         while (1 < argc) {
139                 const char *arg = argv[1];
140                 if (!strcmp(arg, "--cached"))
141                         cached = 1;
142                 else
143                         usage(builtin_diff_usage);
144                 argv++; argc--;
145         }
146         /*
147          * Make sure there is one revision (i.e. pending object),
148          * and there is no revision filtering parameters.
149          */
150         if (revs->pending.nr != 1 ||
151             revs->max_count != -1 || revs->min_age != -1 ||
152             revs->max_age != -1)
153                 usage(builtin_diff_usage);
154         return run_diff_index(revs, cached);
155 }
156
157 static int builtin_diff_tree(struct rev_info *revs,
158                              int argc, const char **argv,
159                              struct object_array_entry *ent)
160 {
161         const unsigned char *(sha1[2]);
162         int swap = 0;
163
164         if (argc > 1)
165                 usage(builtin_diff_usage);
166
167         /* We saw two trees, ent[0] and ent[1].
168          * if ent[1] is uninteresting, they are swapped
169          */
170         if (ent[1].item->flags & UNINTERESTING)
171                 swap = 1;
172         sha1[swap] = ent[0].item->sha1;
173         sha1[1-swap] = ent[1].item->sha1;
174         diff_tree_sha1(sha1[0], sha1[1], "", &revs->diffopt);
175         log_tree_diff_flush(revs);
176         return 0;
177 }
178
179 static int builtin_diff_combined(struct rev_info *revs,
180                                  int argc, const char **argv,
181                                  struct object_array_entry *ent,
182                                  int ents)
183 {
184         const unsigned char (*parent)[20];
185         int i;
186
187         if (argc > 1)
188                 usage(builtin_diff_usage);
189
190         if (!revs->dense_combined_merges && !revs->combine_merges)
191                 revs->dense_combined_merges = revs->combine_merges = 1;
192         parent = xmalloc(ents * sizeof(*parent));
193         /* Again, the revs are all reverse */
194         for (i = 0; i < ents; i++)
195                 hashcpy((unsigned char *)(parent + i),
196                         ent[ents - 1 - i].item->sha1);
197         diff_tree_combined(parent[0], parent + 1, ents - 1,
198                            revs->dense_combined_merges, revs);
199         return 0;
200 }
201
202 void add_head(struct rev_info *revs)
203 {
204         unsigned char sha1[20];
205         struct object *obj;
206         if (get_sha1("HEAD", sha1))
207                 return;
208         obj = parse_object(sha1);
209         if (!obj)
210                 return;
211         add_pending_object(revs, obj, "HEAD");
212 }
213
214 int cmd_diff(int argc, const char **argv, const char *prefix)
215 {
216         int i;
217         struct rev_info rev;
218         struct object_array_entry ent[100];
219         int ents = 0, blobs = 0, paths = 0;
220         const char *path = NULL;
221         struct blobinfo blob[2];
222
223         /*
224          * We could get N tree-ish in the rev.pending_objects list.
225          * Also there could be M blobs there, and P pathspecs.
226          *
227          * N=0, M=0:
228          *      cache vs files (diff-files)
229          * N=0, M=2:
230          *      compare two random blobs.  P must be zero.
231          * N=0, M=1, P=1:
232          *      compare a blob with a working tree file.
233          *
234          * N=1, M=0:
235          *      tree vs cache (diff-index --cached)
236          *
237          * N=2, M=0:
238          *      tree vs tree (diff-tree)
239          *
240          * Other cases are errors.
241          */
242
243         git_config(git_diff_ui_config);
244         init_revisions(&rev, prefix);
245
246         argc = setup_revisions(argc, argv, &rev, NULL);
247         if (!rev.diffopt.output_format) {
248                 rev.diffopt.output_format = DIFF_FORMAT_PATCH;
249                 if (diff_setup_done(&rev.diffopt) < 0)
250                         die("diff_setup_done failed");
251         }
252
253         /* Do we have --cached and not have a pending object, then
254          * default to HEAD by hand.  Eek.
255          */
256         if (!rev.pending.nr) {
257                 int i;
258                 for (i = 1; i < argc; i++) {
259                         const char *arg = argv[i];
260                         if (!strcmp(arg, "--"))
261                                 break;
262                         else if (!strcmp(arg, "--cached")) {
263                                 add_head(&rev);
264                                 break;
265                         }
266                 }
267         }
268
269         for (i = 0; i < rev.pending.nr; i++) {
270                 struct object_array_entry *list = rev.pending.objects+i;
271                 struct object *obj = list->item;
272                 const char *name = list->name;
273                 int flags = (obj->flags & UNINTERESTING);
274                 if (!obj->parsed)
275                         obj = parse_object(obj->sha1);
276                 obj = deref_tag(obj, NULL, 0);
277                 if (!obj)
278                         die("invalid object '%s' given.", name);
279                 if (obj->type == OBJ_COMMIT)
280                         obj = &((struct commit *)obj)->tree->object;
281                 if (obj->type == OBJ_TREE) {
282                         if (ARRAY_SIZE(ent) <= ents)
283                                 die("more than %d trees given: '%s'",
284                                     (int) ARRAY_SIZE(ent), name);
285                         obj->flags |= flags;
286                         ent[ents].item = obj;
287                         ent[ents].name = name;
288                         ents++;
289                         continue;
290                 }
291                 if (obj->type == OBJ_BLOB) {
292                         if (2 <= blobs)
293                                 die("more than two blobs given: '%s'", name);
294                         hashcpy(blob[blobs].sha1, obj->sha1);
295                         blob[blobs].name = name;
296                         blobs++;
297                         continue;
298
299                 }
300                 die("unhandled object '%s' given.", name);
301         }
302         if (rev.prune_data) {
303                 const char **pathspec = rev.prune_data;
304                 while (*pathspec) {
305                         if (!path)
306                                 path = *pathspec;
307                         paths++;
308                         pathspec++;
309                 }
310         }
311
312         /*
313          * Now, do the arguments look reasonable?
314          */
315         if (!ents) {
316                 switch (blobs) {
317                 case 0:
318                         return builtin_diff_files(&rev, argc, argv);
319                         break;
320                 case 1:
321                         if (paths != 1)
322                                 usage(builtin_diff_usage);
323                         return builtin_diff_b_f(&rev, argc, argv, blob, path);
324                         break;
325                 case 2:
326                         if (paths)
327                                 usage(builtin_diff_usage);
328                         return builtin_diff_blobs(&rev, argc, argv, blob);
329                         break;
330                 default:
331                         usage(builtin_diff_usage);
332                 }
333         }
334         else if (blobs)
335                 usage(builtin_diff_usage);
336         else if (ents == 1)
337                 return builtin_diff_index(&rev, argc, argv);
338         else if (ents == 2)
339                 return builtin_diff_tree(&rev, argc, argv, ent);
340         else if ((ents == 3) && (ent[0].item->flags & UNINTERESTING)) {
341                 /* diff A...B where there is one sane merge base between
342                  * A and B.  We have ent[0] == merge-base, ent[1] == A,
343                  * and ent[2] == B.  Show diff between the base and B.
344                  */
345                 ent[1] = ent[2];
346                 return builtin_diff_tree(&rev, argc, argv, ent);
347         }
348         else
349                 return builtin_diff_combined(&rev, argc, argv,
350                                              ent, ents);
351         usage(builtin_diff_usage);
352 }