First cut at git-unpack-objects
[git/git.git] / unpack-objects.c
1 #include "cache.h"
2
3 static int nr_entries;
4 static const char *base_name;
5 static const char unpack_usage[] = "git-unpack-objects basename";
6
7 struct pack_entry {
8 unsigned int offset;
9 unsigned char sha1[20];
10 };
11
12 static struct pack_entry **pack_list;
13
14 static void *map_file(const char *suffix, unsigned long *sizep)
15 {
16 static char pathname[PATH_MAX];
17 unsigned long len;
18 int fd;
19 struct stat st;
20 void *map;
21
22 len = snprintf(pathname, PATH_MAX, "%s.%s", base_name, suffix);
23 if (len >= PATH_MAX)
24 die("bad pack base-name");
25 fd = open(pathname, O_RDONLY);
26 if (fd < 0 || fstat(fd, &st))
27 die("unable to open '%s'", pathname);
28 len = st.st_size;
29 if (!len)
30 die("bad pack file '%s'", pathname);
31 map = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
32 if (-1 == (int)(long)map)
33 die("unable to mmap '%s'", pathname);
34 close(fd);
35 *sizep = len;
36 return map;
37 }
38
39 static int sort_by_offset(const void *_a, const void *_b)
40 {
41 struct pack_entry *a = *(struct pack_entry **)_a;
42 struct pack_entry *b = *(struct pack_entry **)_b;
43 unsigned int o1, o2;
44
45 o1 = ntohl(a->offset);
46 o2 = ntohl(b->offset);
47 return o1 < o2 ? -1 : 1;
48 }
49
50 static int check_index(void *index, unsigned long idx_size)
51 {
52 unsigned int *array = index;
53 unsigned int nr;
54 int i;
55
56 if (idx_size < 4*256)
57 return error("index file too small");
58 nr = 0;
59 for (i = 0; i < 256; i++) {
60 unsigned int n = ntohl(array[i]);
61 if (n < nr)
62 return error("non-monotonic index");
63 nr = n;
64 }
65 if (idx_size != 4*256 + nr * 24) {
66 printf("idx_size=%d, expected %d (%d)\n", idx_size, 4*256 + nr * 24, nr);
67 return error("wrong index file size");
68 }
69
70 nr_entries = nr;
71 pack_list = xmalloc(nr * sizeof(struct pack_entry *));
72 for (i = 0; i < nr; i++)
73 pack_list[i] = index + 4*256 + i*24;
74
75 qsort(pack_list, nr, sizeof(*pack_list), sort_by_offset);
76
77 printf("%d entries\n", nr);
78 return 0;
79 }
80
81 int main(int argc, char **argv)
82 {
83 int i;
84 unsigned long idx_size, pack_size;
85 void *index, *pack;
86
87 for (i = 1 ; i < argc; i++) {
88 const char *arg = argv[i];
89
90 if (*arg == '-') {
91 /* Maybe we'll have some flags here some day.. */
92 usage(unpack_usage);
93 }
94 if (base_name)
95 usage(unpack_usage);
96 base_name = arg;
97 }
98 if (!base_name)
99 usage(unpack_usage);
100 index = map_file("idx", &idx_size);
101 pack = map_file("pack", &pack_size);
102 if (check_index(index, idx_size) < 0)
103 die("bad index file");
104 return 0;
105 }