git

1
/*
2
 * Copyright (c) 2005, 2006 Rene Scharfe
3
 */
4
#include "builtin.h"
5
#include "commit.h"
6
#include "tar.h"
7

8
static const char builtin_get_tar_commit_id_usage[] =
9
"git get-tar-commit-id";
10

11
/* ustar header + extended global header content */
12
#define RECORDSIZE	(512)
13
#define HEADERSIZE (2 * RECORDSIZE)
14

15
int cmd_get_tar_commit_id(int argc, const char **argv UNUSED, const char *prefix)
16
{
17
	char buffer[HEADERSIZE];
18
	struct ustar_header *header = (struct ustar_header *)buffer;
19
	char *content = buffer + RECORDSIZE;
20
	const char *comment;
21
	ssize_t n;
22
	long len;
23
	char *end;
24

25
	BUG_ON_NON_EMPTY_PREFIX(prefix);
26

27
	if (argc != 1)
28
		usage(builtin_get_tar_commit_id_usage);
29

30
	n = read_in_full(0, buffer, HEADERSIZE);
31
	if (n < 0)
32
		die_errno("git get-tar-commit-id: read error");
33
	if (n != HEADERSIZE)
34
		die_errno("git get-tar-commit-id: EOF before reading tar header");
35
	if (header->typeflag[0] != TYPEFLAG_GLOBAL_HEADER)
36
		return 1;
37

38
	errno = 0;
39
	len = strtol(content, &end, 10);
40
	if (errno == ERANGE || end == content || len < 0)
41
		return 1;
42
	if (!skip_prefix(end, " comment=", &comment))
43
		return 1;
44
	len -= comment - content;
45
	if (len < 1 || !(len % 2) ||
46
	    hash_algo_by_length((len - 1) / 2) == GIT_HASH_UNKNOWN)
47
		return 1;
48

49
	if (write_in_full(1, comment, len) < 0)
50
		die_errno("git get-tar-commit-id: write error");
51

52
	return 0;
53
}
54