git-svnimport: Improved detection of merges.
[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 int show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base);
19
20 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
21 {
22         unsigned mode1, mode2;
23         const char *path1, *path2;
24         const unsigned char *sha1, *sha2;
25         int cmp, pathlen1, pathlen2;
26
27         sha1 = tree_entry_extract(t1, &path1, &mode1);
28         sha2 = tree_entry_extract(t2, &path2, &mode2);
29
30         pathlen1 = strlen(path1);
31         pathlen2 = strlen(path2);
32         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
33         if (cmp < 0) {
34                 show_entry(opt, "-", t1, base);
35                 return -1;
36         }
37         if (cmp > 0) {
38                 show_entry(opt, "+", t2, base);
39                 return 1;
40         }
41         if (!opt->find_copies_harder &&
42             !memcmp(sha1, sha2, 20) && 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 int show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base)
135 {
136         unsigned mode;
137         const char *path;
138         const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
139
140         if (opt->recursive && S_ISDIR(mode)) {
141                 char type[20];
142                 char *newbase = malloc_base(base, path, strlen(path));
143                 struct tree_desc inner;
144                 void *tree;
145
146                 tree = read_sha1_file(sha1, type, &inner.size);
147                 if (!tree || strcmp(type, tree_type))
148                         die("corrupt tree sha %s", sha1_to_hex(sha1));
149
150                 inner.buf = tree;
151                 show_tree(opt, prefix, &inner, newbase);
152
153                 free(tree);
154                 free(newbase);
155                 return 0;
156         }
157
158         opt->add_remove(opt, prefix[0], mode, sha1, base, path);
159         return 0;
160 }
161
162 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
163 {
164         while (t1->size | t2->size) {
165                 if (opt->nr_paths && t1->size && !interesting(t1, base, opt)) {
166                         update_tree_entry(t1);
167                         continue;
168                 }
169                 if (opt->nr_paths && t2->size && !interesting(t2, base, opt)) {
170                         update_tree_entry(t2);
171                         continue;
172                 }
173                 if (!t1->size) {
174                         show_entry(opt, "+", t2, base);
175                         update_tree_entry(t2);
176                         continue;
177                 }
178                 if (!t2->size) {
179                         show_entry(opt, "-", t1, base);
180                         update_tree_entry(t1);
181                         continue;
182                 }
183                 switch (compare_tree_entry(t1, t2, base, opt)) {
184                 case -1:
185                         update_tree_entry(t1);
186                         continue;
187                 case 0:
188                         update_tree_entry(t1);
189                         /* Fallthrough */
190                 case 1:
191                         update_tree_entry(t2);
192                         continue;
193                 }
194                 die("git-diff-tree: internal error");
195         }
196         return 0;
197 }
198
199 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
200 {
201         void *tree1, *tree2;
202         struct tree_desc t1, t2;
203         int retval;
204
205         tree1 = read_object_with_reference(old, tree_type, &t1.size, NULL);
206         if (!tree1)
207                 die("unable to read source tree (%s)", sha1_to_hex(old));
208         tree2 = read_object_with_reference(new, tree_type, &t2.size, NULL);
209         if (!tree2)
210                 die("unable to read destination tree (%s)", sha1_to_hex(new));
211         t1.buf = tree1;
212         t2.buf = tree2;
213         retval = diff_tree(&t1, &t2, base, opt);
214         free(tree1);
215         free(tree2);
216         return retval;
217 }
218
219 static int count_paths(const char **paths)
220 {
221         int i = 0;
222         while (*paths++)
223                 i++;
224         return i;
225 }
226
227 void diff_tree_release_paths(struct diff_options *opt)
228 {
229         free(opt->pathlens);
230 }
231
232 void diff_tree_setup_paths(const char **p, struct diff_options *opt)
233 {
234         opt->nr_paths = 0;
235         opt->pathlens = NULL;
236         opt->paths = NULL;
237
238         if (p) {
239                 int i;
240
241                 opt->paths = p;
242                 opt->nr_paths = count_paths(p);
243                 if (opt->nr_paths == 0) {
244                         opt->pathlens = NULL;
245                         return;
246                 }
247                 opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
248                 for (i=0; i < opt->nr_paths; i++)
249                         opt->pathlens[i] = strlen(p[i]);
250         }
251 }