git/tag.c
Jeff King 228c78fbd4 commit, tag: don't set parsed bit for parse failures
If we can't parse a commit, then parse_commit() will return an error
code. But it _also_ sets the "parsed" flag, which tells us not to bother
trying to re-parse the object. That means that subsequent parses have no
idea that the information in the struct may be bogus.  I.e., doing this:

  parse_commit(commit);
  ...
  if (parse_commit(commit) < 0)
          die("commit is broken");

will never trigger the die(). The second parse_commit() will see the
"parsed" flag and quietly return success.

There are two obvious ways to fix this:

  1. Stop setting "parsed" until we've successfully parsed.

  2. Keep a second "corrupt" flag to indicate that we saw an error (and
     when the parsed flag is set, return 0/-1 depending on the corrupt
     flag).

This patch does option 1. The obvious downside versus option 2 is that
we might continually re-parse a broken object. But in practice,
corruption like this is rare, and we typically die() or return an error
in the caller. So it's OK not to worry about optimizing for corruption.
And it's much simpler: we don't need to use an extra bit in the object
struct, and callers which check the "parsed" flag don't need to learn
about the corrupt bit, too.

There's no new test here, because this case is already covered in t5318.
Note that we do need to update the expected message there, because we
now detect the problem in the return from "parse_commit()", and not with
a separate check for a NULL tree. In fact, we can now ditch that
explicit tree check entirely, as we're covered robustly by this change
(and the previous recent change to treat a NULL tree as a parse error).

We'll also give tags the same treatment. I don't know offhand of any
cases where the problem can be triggered (it implies somebody ignoring a
parse error earlier in the process), but consistently returning an error
should cause the least surprise.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-28 14:04:49 +09:00

237 lines
5.5 KiB
C

#include "cache.h"
#include "tag.h"
#include "object-store.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "alloc.h"
#include "gpg-interface.h"
#include "packfile.h"
const char *tag_type = "tag";
static int run_gpg_verify(const char *buf, unsigned long size, unsigned flags)
{
struct signature_check sigc;
size_t payload_size;
int ret;
memset(&sigc, 0, sizeof(sigc));
payload_size = parse_signature(buf, size);
if (size == payload_size) {
if (flags & GPG_VERIFY_VERBOSE)
write_in_full(1, buf, payload_size);
return error("no signature found");
}
ret = check_signature(buf, payload_size, buf + payload_size,
size - payload_size, &sigc);
if (!(flags & GPG_VERIFY_OMIT_STATUS))
print_signature_buffer(&sigc, flags);
signature_check_clear(&sigc);
return ret;
}
int gpg_verify_tag(const struct object_id *oid, const char *name_to_report,
unsigned flags)
{
enum object_type type;
char *buf;
unsigned long size;
int ret;
type = oid_object_info(the_repository, oid, NULL);
if (type != OBJ_TAG)
return error("%s: cannot verify a non-tag object of type %s.",
name_to_report ?
name_to_report :
find_unique_abbrev(oid, DEFAULT_ABBREV),
type_name(type));
buf = read_object_file(oid, &type, &size);
if (!buf)
return error("%s: unable to read file.",
name_to_report ?
name_to_report :
find_unique_abbrev(oid, DEFAULT_ABBREV));
ret = run_gpg_verify(buf, size, flags);
free(buf);
return ret;
}
struct object *deref_tag(struct repository *r, struct object *o, const char *warn, int warnlen)
{
struct object_id *last_oid = NULL;
while (o && o->type == OBJ_TAG)
if (((struct tag *)o)->tagged) {
last_oid = &((struct tag *)o)->tagged->oid;
o = parse_object(r, last_oid);
} else {
last_oid = NULL;
o = NULL;
}
if (!o && warn) {
if (last_oid && is_promisor_object(last_oid))
return NULL;
if (!warnlen)
warnlen = strlen(warn);
error("missing object referenced by '%.*s'", warnlen, warn);
}
return o;
}
struct object *deref_tag_noverify(struct object *o)
{
while (o && o->type == OBJ_TAG) {
o = parse_object(the_repository, &o->oid);
if (o && o->type == OBJ_TAG && ((struct tag *)o)->tagged)
o = ((struct tag *)o)->tagged;
else
o = NULL;
}
return o;
}
struct tag *lookup_tag(struct repository *r, const struct object_id *oid)
{
struct object *obj = lookup_object(r, oid);
if (!obj)
return create_object(r, oid, alloc_tag_node(r));
return object_as_type(r, obj, OBJ_TAG, 0);
}
static timestamp_t 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 parsing will stop at buf-1 */
return parse_timestamp(dateptr, NULL, 10);
}
void release_tag_memory(struct tag *t)
{
free(t->tag);
t->tagged = NULL;
t->object.parsed = 0;
t->date = 0;
}
int parse_tag_buffer(struct repository *r, struct tag *item, const void *data, unsigned long size)
{
struct object_id oid;
char type[20];
const char *bufptr = data;
const char *tail = bufptr + size;
const char *nl;
if (item->object.parsed)
return 0;
if (item->tag) {
/*
* Presumably left over from a previous failed parse;
* clear it out in preparation for re-parsing (we'll probably
* hit the same error, which lets us tell our current caller
* about the problem).
*/
FREE_AND_NULL(item->tag);
}
if (size < the_hash_algo->hexsz + 24)
return -1;
if (memcmp("object ", bufptr, 7) || parse_oid_hex(bufptr + 7, &oid, &bufptr) || *bufptr++ != '\n')
return -1;
if (!starts_with(bufptr, "type "))
return -1;
bufptr += 5;
nl = memchr(bufptr, '\n', tail - bufptr);
if (!nl || sizeof(type) <= (nl - bufptr))
return -1;
memcpy(type, bufptr, nl - bufptr);
type[nl - bufptr] = '\0';
bufptr = nl + 1;
if (!strcmp(type, blob_type)) {
item->tagged = (struct object *)lookup_blob(r, &oid);
} else if (!strcmp(type, tree_type)) {
item->tagged = (struct object *)lookup_tree(r, &oid);
} else if (!strcmp(type, commit_type)) {
item->tagged = (struct object *)lookup_commit(r, &oid);
} else if (!strcmp(type, tag_type)) {
item->tagged = (struct object *)lookup_tag(r, &oid);
} else {
return error("unknown tag type '%s' in %s",
type, oid_to_hex(&item->object.oid));
}
if (!item->tagged)
return error("bad tag pointer to %s in %s",
oid_to_hex(&oid),
oid_to_hex(&item->object.oid));
if (bufptr + 4 < tail && starts_with(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 && starts_with(bufptr, "tagger "))
item->date = parse_tag_date(bufptr, tail);
else
item->date = 0;
item->object.parsed = 1;
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_object_file(&item->object.oid, &type, &size);
if (!data)
return error("Could not read %s",
oid_to_hex(&item->object.oid));
if (type != OBJ_TAG) {
free(data);
return error("Object %s not a tag",
oid_to_hex(&item->object.oid));
}
ret = parse_tag_buffer(the_repository, item, data, size);
free(data);
return ret;
}
struct object_id *get_tagged_oid(struct tag *tag)
{
if (!tag->tagged)
die("bad tag");
return &tag->tagged->oid;
}