?alloc: do not return NULL when asked for zero bytes
[git.git] / diff-index.c
1 #include "cache.h"
2 #include "diff.h"
3
4 static int cached_only = 0;
5 static int match_nonexisting = 0;
6 static struct diff_options diff_options;
7
8 /* A file entry went away or appeared */
9 static void show_file(const char *prefix,
10                       struct cache_entry *ce,
11                       unsigned char *sha1, unsigned int mode)
12 {
13         diff_addremove(&diff_options, prefix[0], ntohl(mode),
14                        sha1, ce->name, NULL);
15 }
16
17 static int get_stat_data(struct cache_entry *ce,
18                          unsigned char ** sha1p, unsigned int *modep)
19 {
20         unsigned char *sha1 = ce->sha1;
21         unsigned int mode = ce->ce_mode;
22
23         if (!cached_only) {
24                 static unsigned char no_sha1[20];
25                 int changed;
26                 struct stat st;
27                 if (lstat(ce->name, &st) < 0) {
28                         if (errno == ENOENT && match_nonexisting) {
29                                 *sha1p = sha1;
30                                 *modep = mode;
31                                 return 0;
32                         }
33                         return -1;
34                 }
35                 changed = ce_match_stat(ce, &st);
36                 if (changed) {
37                         mode = create_ce_mode(st.st_mode);
38                         if (!trust_executable_bit &&
39                             S_ISREG(mode) && S_ISREG(ce->ce_mode) &&
40                             ((mode ^ ce->ce_mode) == 0111))
41                                 mode = ce->ce_mode;
42                         sha1 = no_sha1;
43                 }
44         }
45
46         *sha1p = sha1;
47         *modep = mode;
48         return 0;
49 }
50
51 static void show_new_file(struct cache_entry *new)
52 {
53         unsigned char *sha1;
54         unsigned int mode;
55
56         /* New file in the index: it might actually be different in
57          * the working copy.
58          */
59         if (get_stat_data(new, &sha1, &mode) < 0)
60                 return;
61
62         show_file("+", new, sha1, mode);
63 }
64
65 static int show_modified(struct cache_entry *old,
66                          struct cache_entry *new,
67                          int report_missing)
68 {
69         unsigned int mode, oldmode;
70         unsigned char *sha1;
71
72         if (get_stat_data(new, &sha1, &mode) < 0) {
73                 if (report_missing)
74                         show_file("-", old, old->sha1, old->ce_mode);
75                 return -1;
76         }
77
78         oldmode = old->ce_mode;
79         if (mode == oldmode && !memcmp(sha1, old->sha1, 20) &&
80             !diff_options.find_copies_harder)
81                 return 0;
82
83         mode = ntohl(mode);
84         oldmode = ntohl(oldmode);
85
86         diff_change(&diff_options, oldmode, mode,
87                     old->sha1, sha1, old->name, NULL);
88         return 0;
89 }
90
91 static int diff_cache(struct cache_entry **ac, int entries, const char **pathspec)
92 {
93         while (entries) {
94                 struct cache_entry *ce = *ac;
95                 int same = (entries > 1) && ce_same_name(ce, ac[1]);
96
97                 if (!ce_path_match(ce, pathspec))
98                         goto skip_entry;
99
100                 switch (ce_stage(ce)) {
101                 case 0:
102                         /* No stage 1 entry? That means it's a new file */
103                         if (!same) {
104                                 show_new_file(ce);
105                                 break;
106                         }
107                         /* Show difference between old and new */
108                         show_modified(ac[1], ce, 1);
109                         break;
110                 case 1:
111                         /* No stage 3 (merge) entry? That means it's been deleted */
112                         if (!same) {
113                                 show_file("-", ce, ce->sha1, ce->ce_mode);
114                                 break;
115                         }
116                         /* We come here with ce pointing at stage 1
117                          * (original tree) and ac[1] pointing at stage
118                          * 3 (unmerged).  show-modified with
119                          * report-missing set to false does not say the
120                          * file is deleted but reports true if work
121                          * tree does not have it, in which case we
122                          * fall through to report the unmerged state.
123                          * Otherwise, we show the differences between
124                          * the original tree and the work tree.
125                          */
126                         if (!cached_only && !show_modified(ce, ac[1], 0))
127                                 break;
128                         /* fallthru */
129                 case 3:
130                         diff_unmerge(&diff_options, ce->name);
131                         break;
132
133                 default:
134                         die("impossible cache entry stage");
135                 }
136
137 skip_entry:
138                 /*
139                  * Ignore all the different stages for this file,
140                  * we've handled the relevant cases now.
141                  */
142                 do {
143                         ac++;
144                         entries--;
145                 } while (entries && ce_same_name(ce, ac[0]));
146         }
147         return 0;
148 }
149
150 /*
151  * This turns all merge entries into "stage 3". That guarantees that
152  * when we read in the new tree (into "stage 1"), we won't lose sight
153  * of the fact that we had unmerged entries.
154  */
155 static void mark_merge_entries(void)
156 {
157         int i;
158         for (i = 0; i < active_nr; i++) {
159                 struct cache_entry *ce = active_cache[i];
160                 if (!ce_stage(ce))
161                         continue;
162                 ce->ce_flags |= htons(CE_STAGEMASK);
163         }
164 }
165
166 static const char diff_cache_usage[] =
167 "git-diff-index [-m] [--cached] "
168 "[<common diff options>] <tree-ish> [<path>...]"
169 COMMON_DIFF_OPTIONS_HELP;
170
171 int main(int argc, const char **argv)
172 {
173         const char *tree_name = NULL;
174         unsigned char sha1[20];
175         const char *prefix = setup_git_directory();
176         const char **pathspec = NULL;
177         void *tree;
178         unsigned long size;
179         int ret;
180         int allow_options = 1;
181         int i;
182
183         git_config(git_diff_config);
184         diff_setup(&diff_options);
185         for (i = 1; i < argc; i++) {
186                 const char *arg = argv[i];
187                 int diff_opt_cnt;
188
189                 if (!allow_options || *arg != '-') {
190                         if (tree_name)
191                                 break;
192                         tree_name = arg;
193                         continue;
194                 }
195                         
196                 if (!strcmp(arg, "--")) {
197                         allow_options = 0;
198                         continue;
199                 }
200                 if (!strcmp(arg, "-r")) {
201                         /* We accept the -r flag just to look like git-diff-tree */
202                         continue;
203                 }
204                 diff_opt_cnt = diff_opt_parse(&diff_options, argv + i,
205                                               argc - i);
206                 if (diff_opt_cnt < 0)
207                         usage(diff_cache_usage);
208                 else if (diff_opt_cnt) {
209                         i += diff_opt_cnt - 1;
210                         continue;
211                 }
212
213                 if (!strcmp(arg, "-m")) {
214                         match_nonexisting = 1;
215                         continue;
216                 }
217                 if (!strcmp(arg, "--cached")) {
218                         cached_only = 1;
219                         continue;
220                 }
221                 usage(diff_cache_usage);
222         }
223
224         pathspec = get_pathspec(prefix, argv + i);
225
226         if (diff_setup_done(&diff_options) < 0)
227                 usage(diff_cache_usage);
228
229         if (!tree_name || get_sha1(tree_name, sha1))
230                 usage(diff_cache_usage);
231
232         read_cache();
233
234         mark_merge_entries();
235
236         tree = read_object_with_reference(sha1, "tree", &size, NULL);
237         if (!tree)
238                 die("bad tree object %s", tree_name);
239         if (read_tree(tree, size, 1, pathspec))
240                 die("unable to read tree object %s", tree_name);
241
242         ret = diff_cache(active_cache, active_nr, pathspec);
243
244         diffcore_std(&diff_options);
245         diff_flush(&diff_options);
246         return ret;
247 }