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[git] / tree-diff.c
1 /*
2  * Helper functions for tree diff generation
3  */
4 #include "cache.h"
5 #include "diff.h"
6
7 // What paths are we interested in?
8 static int nr_paths = 0;
9 static const char **paths = NULL;
10 static int *pathlens = NULL;
11
12 static void update_tree_entry(struct tree_desc *desc)
13 {
14         void *buf = desc->buf;
15         unsigned long size = desc->size;
16         int len = strlen(buf) + 1 + 20;
17
18         if (size < len)
19                 die("corrupt tree file");
20         desc->buf = buf + len;
21         desc->size = size - len;
22 }
23
24 static const unsigned char *extract(struct tree_desc *desc, const char **pathp, unsigned int *modep)
25 {
26         void *tree = desc->buf;
27         unsigned long size = desc->size;
28         int len = strlen(tree)+1;
29         const unsigned char *sha1 = tree + len;
30         const char *path = strchr(tree, ' ');
31         unsigned int mode;
32
33         if (!path || size < len + 20 || sscanf(tree, "%o", &mode) != 1)
34                 die("corrupt tree file");
35         *pathp = path+1;
36         *modep = DIFF_FILE_CANON_MODE(mode);
37         return sha1;
38 }
39
40 static char *malloc_base(const char *base, const char *path, int pathlen)
41 {
42         int baselen = strlen(base);
43         char *newbase = xmalloc(baselen + pathlen + 2);
44         memcpy(newbase, base, baselen);
45         memcpy(newbase + baselen, path, pathlen);
46         memcpy(newbase + baselen + pathlen, "/", 2);
47         return newbase;
48 }
49
50 static int show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base);
51
52 static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
53 {
54         unsigned mode1, mode2;
55         const char *path1, *path2;
56         const unsigned char *sha1, *sha2;
57         int cmp, pathlen1, pathlen2;
58
59         sha1 = extract(t1, &path1, &mode1);
60         sha2 = extract(t2, &path2, &mode2);
61
62         pathlen1 = strlen(path1);
63         pathlen2 = strlen(path2);
64         cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
65         if (cmp < 0) {
66                 show_entry(opt, "-", t1, base);
67                 return -1;
68         }
69         if (cmp > 0) {
70                 show_entry(opt, "+", t2, base);
71                 return 1;
72         }
73         if (!opt->find_copies_harder &&
74             !memcmp(sha1, sha2, 20) && mode1 == mode2)
75                 return 0;
76
77         /*
78          * If the filemode has changed to/from a directory from/to a regular
79          * file, we need to consider it a remove and an add.
80          */
81         if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
82                 show_entry(opt, "-", t1, base);
83                 show_entry(opt, "+", t2, base);
84                 return 0;
85         }
86
87         if (opt->recursive && S_ISDIR(mode1)) {
88                 int retval;
89                 char *newbase = malloc_base(base, path1, pathlen1);
90                 if (opt->tree_in_recursive)
91                         opt->change(opt, mode1, mode2,
92                                     sha1, sha2, base, path1);
93                 retval = diff_tree_sha1(sha1, sha2, newbase, opt);
94                 free(newbase);
95                 return retval;
96         }
97
98         opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
99         return 0;
100 }
101
102 static int interesting(struct tree_desc *desc, const char *base)
103 {
104         const char *path;
105         unsigned mode;
106         int i;
107         int baselen, pathlen;
108
109         if (!nr_paths)
110                 return 1;
111
112         (void)extract(desc, &path, &mode);
113
114         pathlen = strlen(path);
115         baselen = strlen(base);
116
117         for (i=0; i < nr_paths; i++) {
118                 const char *match = paths[i];
119                 int matchlen = pathlens[i];
120
121                 if (baselen >= matchlen) {
122                         /* If it doesn't match, move along... */
123                         if (strncmp(base, match, matchlen))
124                                 continue;
125
126                         /* The base is a subdirectory of a path which was specified. */
127                         return 1;
128                 }
129
130                 /* Does the base match? */
131                 if (strncmp(base, match, baselen))
132                         continue;
133
134                 match += baselen;
135                 matchlen -= baselen;
136
137                 if (pathlen > matchlen)
138                         continue;
139
140                 if (matchlen > pathlen) {
141                         if (match[pathlen] != '/')
142                                 continue;
143                         if (!S_ISDIR(mode))
144                                 continue;
145                 }
146
147                 if (strncmp(path, match, pathlen))
148                         continue;
149
150                 return 1;
151         }
152         return 0; /* No matches */
153 }
154
155 /* A whole sub-tree went away or appeared */
156 static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base)
157 {
158         while (desc->size) {
159                 if (interesting(desc, base))
160                         show_entry(opt, prefix, desc, base);
161                 update_tree_entry(desc);
162         }
163 }
164
165 /* A file entry went away or appeared */
166 static int show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base)
167 {
168         unsigned mode;
169         const char *path;
170         const unsigned char *sha1 = extract(desc, &path, &mode);
171
172         if (opt->recursive && S_ISDIR(mode)) {
173                 char type[20];
174                 char *newbase = malloc_base(base, path, strlen(path));
175                 struct tree_desc inner;
176                 void *tree;
177
178                 tree = read_sha1_file(sha1, type, &inner.size);
179                 if (!tree || strcmp(type, "tree"))
180                         die("corrupt tree sha %s", sha1_to_hex(sha1));
181
182                 inner.buf = tree;
183                 show_tree(opt, prefix, &inner, newbase);
184
185                 free(tree);
186                 free(newbase);
187                 return 0;
188         }
189
190         opt->add_remove(opt, prefix[0], mode, sha1, base, path);
191         return 0;
192 }
193
194 int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
195 {
196         while (t1->size | t2->size) {
197                 if (nr_paths && t1->size && !interesting(t1, base)) {
198                         update_tree_entry(t1);
199                         continue;
200                 }
201                 if (nr_paths && t2->size && !interesting(t2, base)) {
202                         update_tree_entry(t2);
203                         continue;
204                 }
205                 if (!t1->size) {
206                         show_entry(opt, "+", t2, base);
207                         update_tree_entry(t2);
208                         continue;
209                 }
210                 if (!t2->size) {
211                         show_entry(opt, "-", t1, base);
212                         update_tree_entry(t1);
213                         continue;
214                 }
215                 switch (compare_tree_entry(t1, t2, base, opt)) {
216                 case -1:
217                         update_tree_entry(t1);
218                         continue;
219                 case 0:
220                         update_tree_entry(t1);
221                         /* Fallthrough */
222                 case 1:
223                         update_tree_entry(t2);
224                         continue;
225                 }
226                 die("git-diff-tree: internal error");
227         }
228         return 0;
229 }
230
231 int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
232 {
233         void *tree1, *tree2;
234         struct tree_desc t1, t2;
235         int retval;
236
237         tree1 = read_object_with_reference(old, "tree", &t1.size, NULL);
238         if (!tree1)
239                 die("unable to read source tree (%s)", sha1_to_hex(old));
240         tree2 = read_object_with_reference(new, "tree", &t2.size, NULL);
241         if (!tree2)
242                 die("unable to read destination tree (%s)", sha1_to_hex(new));
243         t1.buf = tree1;
244         t2.buf = tree2;
245         retval = diff_tree(&t1, &t2, base, opt);
246         free(tree1);
247         free(tree2);
248         return retval;
249 }
250
251 static int count_paths(const char **paths)
252 {
253         int i = 0;
254         while (*paths++)
255                 i++;
256         return i;
257 }
258
259 void diff_tree_setup_paths(const char **p)
260 {
261         if (p) {
262                 int i;
263
264                 paths = p;
265                 nr_paths = count_paths(paths);
266                 if (nr_paths == 0) {
267                         pathlens = NULL;
268                         return;
269                 }
270                 pathlens = xmalloc(nr_paths * sizeof(int));
271                 for (i=0; i<nr_paths; i++)
272                         pathlens[i] = strlen(paths[i]);
273         }
274 }