git/tag.c
Junio C Hamano 2f47eae2a1 Split GPG interface into its own helper library
This mostly moves existing code from builtin/tag.c (for signing)
and builtin/verify-tag.c (for verifying) to a new gpg-interface.c
file to provide a more generic library interface.

 - sign_buffer() takes a payload strbuf, a signature strbuf, and a signing
   key, runs "gpg" to produce a detached signature for the payload, and
   appends it to the signature strbuf. The contents of a signed tag that
   concatenates the payload and the detached signature can be produced by
   giving the same strbuf as payload and signature strbuf.

 - verify_signed_buffer() takes a payload and a detached signature as
   <ptr, len> pairs, and runs "gpg --verify" to see if the payload matches
   the signature. It can optionally capture the output from GPG to allow
   the callers to pretty-print it in a way more suitable for their
   contexts.

"verify-tag" (aka "tag -v") used to save the whole tag contents as if it
is a detached signature, and fed gpg the payload part of the tag. It
relied on gpg to fail when the given tag is not signed but just is
annotated.  The updated run_gpg_verify() function detects the lack of
detached signature in the input, and errors out without bothering "gpg".

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-11-04 21:40:25 -07:00

158 lines
3.7 KiB
C

#include "cache.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
#define PGP_MESSAGE "-----BEGIN PGP MESSAGE-----"
const char *tag_type = "tag";
struct object *deref_tag(struct object *o, const char *warn, int warnlen)
{
while (o && o->type == OBJ_TAG)
if (((struct tag *)o)->tagged)
o = parse_object(((struct tag *)o)->tagged->sha1);
else
o = NULL;
if (!o && warn) {
if (!warnlen)
warnlen = strlen(warn);
error("missing object referenced by '%.*s'", warnlen, warn);
}
return o;
}
struct tag *lookup_tag(const unsigned char *sha1)
{
struct object *obj = lookup_object(sha1);
if (!obj)
return create_object(sha1, OBJ_TAG, alloc_tag_node());
if (!obj->type)
obj->type = OBJ_TAG;
if (obj->type != OBJ_TAG) {
error("Object %s is a %s, not a tag",
sha1_to_hex(sha1), typename(obj->type));
return NULL;
}
return (struct tag *) obj;
}
static unsigned long parse_tag_date(const char *buf, const char *tail)
{
const char *dateptr;
while (buf < tail && *buf++ != '>')
/* nada */;
if (buf >= tail)
return 0;
dateptr = buf;
while (buf < tail && *buf++ != '\n')
/* nada */;
if (buf >= tail)
return 0;
/* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
return strtoul(dateptr, NULL, 10);
}
int parse_tag_buffer(struct tag *item, const void *data, unsigned long size)
{
unsigned char sha1[20];
char type[20];
const char *bufptr = data;
const char *tail = bufptr + size;
const char *nl;
if (item->object.parsed)
return 0;
item->object.parsed = 1;
if (size < 64)
return -1;
if (memcmp("object ", bufptr, 7) || get_sha1_hex(bufptr + 7, sha1) || bufptr[47] != '\n')
return -1;
bufptr += 48; /* "object " + sha1 + "\n" */
if (prefixcmp(bufptr, "type "))
return -1;
bufptr += 5;
nl = memchr(bufptr, '\n', tail - bufptr);
if (!nl || sizeof(type) <= (nl - bufptr))
return -1;
strncpy(type, bufptr, nl - bufptr);
type[nl - bufptr] = '\0';
bufptr = nl + 1;
if (!strcmp(type, blob_type)) {
item->tagged = &lookup_blob(sha1)->object;
} else if (!strcmp(type, tree_type)) {
item->tagged = &lookup_tree(sha1)->object;
} else if (!strcmp(type, commit_type)) {
item->tagged = &lookup_commit(sha1)->object;
} else if (!strcmp(type, tag_type)) {
item->tagged = &lookup_tag(sha1)->object;
} else {
error("Unknown type %s", type);
item->tagged = NULL;
}
if (bufptr + 4 < tail && !prefixcmp(bufptr, "tag "))
; /* good */
else
return -1;
bufptr += 4;
nl = memchr(bufptr, '\n', tail - bufptr);
if (!nl)
return -1;
item->tag = xmemdupz(bufptr, nl - bufptr);
bufptr = nl + 1;
if (bufptr + 7 < tail && !prefixcmp(bufptr, "tagger "))
item->date = parse_tag_date(bufptr, tail);
else
item->date = 0;
return 0;
}
int parse_tag(struct tag *item)
{
enum object_type type;
void *data;
unsigned long size;
int ret;
if (item->object.parsed)
return 0;
data = read_sha1_file(item->object.sha1, &type, &size);
if (!data)
return error("Could not read %s",
sha1_to_hex(item->object.sha1));
if (type != OBJ_TAG) {
free(data);
return error("Object %s not a tag",
sha1_to_hex(item->object.sha1));
}
ret = parse_tag_buffer(item, data, size);
free(data);
return ret;
}
/*
* Look at a signed tag object, and return the offset where
* the embedded detached signature begins, or the end of the
* data when there is no such signature.
*/
size_t parse_signature(const char *buf, unsigned long size)
{
char *eol;
size_t len = 0;
while (len < size && prefixcmp(buf + len, PGP_SIGNATURE) &&
prefixcmp(buf + len, PGP_MESSAGE)) {
eol = memchr(buf + len, '\n', size - len);
len += eol ? eol - (buf + len) + 1 : size - len;
}
return len;
}