git-svn: extra error check to ensure we open a file correctly
[git] / tree-diff.c
1 /*
2  * Helper functions for tree diff generation
3  */
4 #include "cache.h"
5 #include "diff.h"
6 #include "tree.h"
7
8 static char *malloc_base(const char *base, const char *path, int pathlen)
9 {
10         int baselen = strlen(base);
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;
16 }
17
18 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
19                        const char *base);
20
21 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
22 {
23         unsigned mode1, mode2;
24         const char *path1, *path2;
25         const unsigned char *sha1, *sha2;
26         int cmp, pathlen1, pathlen2;
27
28         sha1 = tree_entry_extract(t1, &path1, &mode1);
29         sha2 = tree_entry_extract(t2, &path2, &mode2);
30
31         pathlen1 = strlen(path1);
32         pathlen2 = strlen(path2);
33         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
34         if (cmp < 0) {
35                 show_entry(opt, "-", t1, base);
36                 return -1;
37         }
38         if (cmp > 0) {
39                 show_entry(opt, "+", t2, base);
40                 return 1;
41         }
42         if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2)
43                 return 0;
44
45         /*
46          * If the filemode has changed to/from a directory from/to a regular
47          * file, we need to consider it a remove and an add.
48          */
49         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
50                 show_entry(opt, "-", t1, base);
51                 show_entry(opt, "+", t2, base);
52                 return 0;
53         }
54
55         if (opt->recursive && S_ISDIR(mode1)) {
56                 int retval;
57                 char *newbase = malloc_base(base, path1, pathlen1);
58                 if (opt->tree_in_recursive)
59                         opt->change(opt, mode1, mode2,
60                                     sha1, sha2, base, path1);
61                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
62                 free(newbase);
63                 return retval;
64         }
65
66         opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
67         return 0;
68 }
69
70 static int interesting(struct tree_desc *desc, const char *base, struct diff_options *opt)
71 {
72         const char *path;
73         unsigned mode;
74         int i;
75         int baselen, pathlen;
76
77         if (!opt->nr_paths)
78                 return 1;
79
80         (void)tree_entry_extract(desc, &path, &mode);
81
82         pathlen = strlen(path);
83         baselen = strlen(base);
84
85         for (i=0; i < opt->nr_paths; i++) {
86                 const char *match = opt->paths[i];
87                 int matchlen = opt->pathlens[i];
88
89                 if (baselen >= matchlen) {
90                         /* If it doesn't match, move along... */
91                         if (strncmp(base, match, matchlen))
92                                 continue;
93
94                         /* The base is a subdirectory of a path which was specified. */
95                         return 1;
96                 }
97
98                 /* Does the base match? */
99                 if (strncmp(base, match, baselen))
100                         continue;
101
102                 match += baselen;
103                 matchlen -= baselen;
104
105                 if (pathlen > matchlen)
106                         continue;
107
108                 if (matchlen > pathlen) {
109                         if (match[pathlen] != '/')
110                                 continue;
111                         if (!S_ISDIR(mode))
112                                 continue;
113                 }
114
115                 if (strncmp(path, match, pathlen))
116                         continue;
117
118                 return 1;
119         }
120         return 0; /* No matches */
121 }
122
123 /* A whole sub-tree went away or appeared */
124 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base)
125 {
126         while (desc->size) {
127                 if (interesting(desc, base, opt))
128                         show_entry(opt, prefix, desc, base);
129                 update_tree_entry(desc);
130         }
131 }
132
133 /* A file entry went away or appeared */
134 static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
135                        const char *base)
136 {
137         unsigned mode;
138         const char *path;
139         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
140
141         if (opt->recursive && S_ISDIR(mode)) {
142                 char type[20];
143                 char *newbase = malloc_base(base, path, strlen(path));
144                 struct tree_desc inner;
145                 void *tree;
146
147                 tree = read_sha1_file(sha1, type, &inner.size);
148                 if (!tree || strcmp(type, tree_type))
149                         die("corrupt tree sha %s", sha1_to_hex(sha1));
150
151                 inner.buf = tree;
152                 show_tree(opt, prefix, &inner, newbase);
153
154                 free(tree);
155                 free(newbase);
156         } else {
157                 opt->add_remove(opt, prefix[0], mode, sha1, base, path);
158         }
159 }
160
161 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
162 {
163         while (t1->size | t2->size) {
164                 if (opt->nr_paths && t1->size && !interesting(t1, base, opt)) {
165                         update_tree_entry(t1);
166                         continue;
167                 }
168                 if (opt->nr_paths && t2->size && !interesting(t2, base, opt)) {
169                         update_tree_entry(t2);
170                         continue;
171                 }
172                 if (!t1->size) {
173                         show_entry(opt, "+", t2, base);
174                         update_tree_entry(t2);
175                         continue;
176                 }
177                 if (!t2->size) {
178                         show_entry(opt, "-", t1, base);
179                         update_tree_entry(t1);
180                         continue;
181                 }
182                 switch (compare_tree_entry(t1, t2, base, opt)) {
183                 case -1:
184                         update_tree_entry(t1);
185                         continue;
186                 case 0:
187                         update_tree_entry(t1);
188                         /* Fallthrough */
189                 case 1:
190                         update_tree_entry(t2);
191                         continue;
192                 }
193                 die("git-diff-tree: internal error");
194         }
195         return 0;
196 }
197
198 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
199 {
200         void *tree1, *tree2;
201         struct tree_desc t1, t2;
202         int retval;
203
204         tree1 = read_object_with_reference(old, tree_type, &t1.size, NULL);
205         if (!tree1)
206                 die("unable to read source tree (%s)", sha1_to_hex(old));
207         tree2 = read_object_with_reference(new, tree_type, &t2.size, NULL);
208         if (!tree2)
209                 die("unable to read destination tree (%s)", sha1_to_hex(new));
210         t1.buf = tree1;
211         t2.buf = tree2;
212         retval = diff_tree(&t1, &t2, base, opt);
213         free(tree1);
214         free(tree2);
215         return retval;
216 }
217
218 int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
219 {
220         int retval;
221         void *tree;
222         struct tree_desc empty, real;
223
224         tree = read_object_with_reference(new, tree_type, &real.size, NULL);
225         if (!tree)
226                 die("unable to read root tree (%s)", sha1_to_hex(new));
227         real.buf = tree;
228
229         empty.size = 0;
230         empty.buf = "";
231         retval = diff_tree(&empty, &real, base, opt);
232         free(tree);
233         return retval;
234 }
235
236 static int count_paths(const char **paths)
237 {
238         int i = 0;
239         while (*paths++)
240                 i++;
241         return i;
242 }
243
244 void diff_tree_release_paths(struct diff_options *opt)
245 {
246         free(opt->pathlens);
247 }
248
249 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
250 {
251         opt->nr_paths = 0;
252         opt->pathlens = NULL;
253         opt->paths = NULL;
254
255         if (p) {
256                 int i;
257
258                 opt->paths = p;
259                 opt->nr_paths = count_paths(p);
260                 if (opt->nr_paths == 0) {
261                         opt->pathlens = NULL;
262                         return;
263                 }
264                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
265                 for (i=0; i < opt->nr_paths; i++)
266                         opt->pathlens[i] = strlen(p[i]);
267         }
268 }