Add "diff-tree" program to show which files have changed between two trees.
[git/git.git] / diff-tree.c
CommitLineData
9174026c
LT
1#include "cache.h"
2
3struct tree_entry;
4
5static struct tree_entry *update_tree_entry(void **bufp, unsigned long *sizep)
6{
7 void *buf = *bufp;
8 unsigned long size = *sizep;
9 int len = strlen(buf) + 1 + 20;
10
11 if (size < len)
12 usage("corrupt tree file");
13 *bufp = buf + len;
14 *sizep = size - len;
15 return buf;
16}
17
18static const unsigned char *extract(void *tree, unsigned long size, const char **pathp, unsigned int *modep)
19{
20 int len = strlen(tree)+1;
21 const unsigned char *sha1 = tree + len;
22 const char *path = strchr(tree, ' ');
23
24 if (!path || size < len + 20 || sscanf(tree, "%o", modep) != 1)
25 usage("corrupt tree file");
26 *pathp = path+1;
27 return sha1;
28}
29
30static void show_file(const char *prefix, void *tree, unsigned long size)
31{
32 unsigned mode;
33 const char *path;
34 const unsigned char *sha1 = extract(tree, size, &path, &mode);
35 printf("%s%o %s %s%c", prefix, mode, sha1_to_hex(sha1), path, 0);
36}
37
38static int compare_tree_entry(void *tree1, unsigned long size1, void *tree2, unsigned long size2)
39{
40 unsigned mode1, mode2;
41 const char *path1, *path2;
42 const unsigned char *sha1, *sha2;
43 int cmp;
44
45 sha1 = extract(tree1, size1, &path1, &mode1);
46 sha2 = extract(tree2, size2, &path2, &mode2);
47
48 cmp = cache_name_compare(path1, strlen(path1), path2, strlen(path2));
49 if (cmp < 0) {
50 show_file("-", tree1, size1);
51 return -1;
52 }
53 if (cmp > 0) {
54 show_file("+", tree2, size2);
55 return 1;
56 }
57 if (!memcmp(sha1, sha2, 20) && mode1 == mode2)
58 return 0;
59 show_file("<", tree1, size1);
60 show_file(">", tree2, size2);
61 return 0;
62}
63
64static int diff_tree(void *tree1, unsigned long size1, void *tree2, unsigned long size2)
65{
66 while (size1 | size2) {
67 if (!size1) {
68 show_file("+", tree2, size2);
69 update_tree_entry(&tree2, &size2);
70 continue;
71 }
72 if (!size2) {
73 show_file("-", tree1, size1);
74 update_tree_entry(&tree1, &size1);
75 continue;
76 }
77 switch (compare_tree_entry(tree1, size1, tree2, size2)) {
78 case -1:
79 update_tree_entry(&tree1, &size1);
80 continue;
81 case 0:
82 update_tree_entry(&tree1, &size1);
83 /* Fallthrough */
84 case 1:
85 update_tree_entry(&tree2, &size2);
86 continue;
87 }
88 usage("diff-tree: internal error");
89 }
90 return 0;
91}
92
93int main(int argc, char **argv)
94{
95 unsigned char old[20], new[20];
96 void *tree1, *tree2;
97 unsigned long size1, size2;
98 char type[20];
99
100 if (argc != 3 || get_sha1_hex(argv[1], old) || get_sha1_hex(argv[2], new))
101 usage("diff-tree <tree sha1> <tree sha1>");
102 tree1 = read_sha1_file(old, type, &size1);
103 if (!tree1 || strcmp(type, "tree"))
104 usage("unable to read source tree");
105 tree2 = read_sha1_file(new, type, &size2);
106 if (!tree2 || strcmp(type, "tree"))
107 usage("unable to read destination tree");
108 return diff_tree(tree1, size1, tree2, size2);
109}