git/builtin/get-tar-commit-id.c

54 lines
1.3 KiB
C

/*
* Copyright (c) 2005, 2006 Rene Scharfe
*/
#include "builtin.h"
#include "commit.h"
#include "tar.h"
static const char builtin_get_tar_commit_id_usage[] =
"git get-tar-commit-id";
/* ustar header + extended global header content */
#define RECORDSIZE (512)
#define HEADERSIZE (2 * RECORDSIZE)
int cmd_get_tar_commit_id(int argc, const char **argv UNUSED, const char *prefix)
{
char buffer[HEADERSIZE];
struct ustar_header *header = (struct ustar_header *)buffer;
char *content = buffer + RECORDSIZE;
const char *comment;
ssize_t n;
long len;
char *end;
BUG_ON_NON_EMPTY_PREFIX(prefix);
if (argc != 1)
usage(builtin_get_tar_commit_id_usage);
n = read_in_full(0, buffer, HEADERSIZE);
if (n < 0)
die_errno("git get-tar-commit-id: read error");
if (n != HEADERSIZE)
die_errno("git get-tar-commit-id: EOF before reading tar header");
if (header->typeflag[0] != TYPEFLAG_GLOBAL_HEADER)
return 1;
errno = 0;
len = strtol(content, &end, 10);
if (errno == ERANGE || end == content || len < 0)
return 1;
if (!skip_prefix(end, " comment=", &comment))
return 1;
len -= comment - content;
if (len < 1 || !(len % 2) ||
hash_algo_by_length((len - 1) / 2) == GIT_HASH_UNKNOWN)
return 1;
if (write_in_full(1, comment, len) < 0)
die_errno("git get-tar-commit-id: write error");
return 0;
}