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object-file.c: stop dying in parse_loose_header()

Make parse_loose_header() return error codes and data instead of
invoking die() by itself.

For now we'll move the relevant die() call to loose_object_info() and
read_loose_object() to keep this change smaller. In a subsequent
commit we'll make read_loose_object() return an error code instead of
dying. We should also address the "allow_unknown" case (should be
moved to builtin/cat-file.c), but for now I'll be leaving it.

For making parse_loose_header() not die() change its prototype to
accept a "struct object_info *" instead of the "unsigned long *sizep"
it accepted before. Its callers can now check the populated populated

Because of this we don't need to pass in the "unsigned int flags"
which we used for OBJECT_INFO_ALLOW_UNKNOWN_TYPE, we can instead do
that check in loose_object_info().

This also refactors some confusing control flow around the "status"
variable. In some cases we set it to the return value of "error()",
i.e. -1, and later checked if "status < 0" was true.

Since 93cff9a978 (sha1_loose_object_info: return error for corrupted
objects, 2017-04-01) the return value of loose_object_info() (then
named sha1_loose_object_info()) had been a "status" variable that be
any negative value, as we were expecting to return the "enum

The only negative type happens to be OBJ_BAD, but the code still
assumed that more might be added. This was then used later in
e.g. c84a1f3ed4 (sha1_file: refactor read_object, 2017-06-21). Now
that parse_loose_header() will return 0 on success instead of the
type (which it'll stick into the "struct object_info") we don't need
to conflate these two cases in its callers.

Since parse_loose_header() doesn't need to return an arbitrary
"status" we only need to treat its "ret < 0" specially, but can
idiomatically overwrite it with our own error() return. This along
with having made unpack_loose_header() return an "enum
unpack_loose_header_result" in an earlier commit means that we can
move the previously nested if/else cases mostly into the "ULHR_OK"
branch of the "switch" statement.

We should be less silent if we reach that "status = -1" branch, which
happens if we've got trailing garbage in loose objects, see
f6371f9210 (sha1_file: add read_loose_object() function, 2017-01-13)
for a better way to handle it. For now let's punt on it, a subsequent
commit will address that edge case.

Signed-off-by: Ævar Arnfjörð Bjarmason <>
Signed-off-by: Junio C Hamano <>
Ævar Arnfjörð Bjarmason 11 months ago committed by Junio C Hamano
  1. 11
  2. 67
  3. 3


@ -1332,9 +1332,16 @@ enum unpack_loose_header_result unpack_loose_header(git_zstream *stream,
unsigned long bufsiz,
struct strbuf *hdrbuf);
* parse_loose_header() parses the starting "<type> <len>\0" of an
* object. If it doesn't follow that format -1 is returned. To check
* the validity of the <type> populate the "typep" in the "struct
* object_info". It will be OBJ_BAD if the object type is unknown. The
* parsed <len> can be retrieved via "oi->sizep", and from there
* passed to unpack_loose_rest().
struct object_info;
int parse_loose_header(const char *hdr, struct object_info *oi,
unsigned int flags);
int parse_loose_header(const char *hdr, struct object_info *oi);
int check_object_signature(struct repository *r, const struct object_id *oid,
void *buf, unsigned long size, const char *type);


@ -1324,8 +1324,7 @@ static void *unpack_loose_rest(git_zstream *stream,
* too permissive for what we want to check. So do an anal
* object header parse by hand.
int parse_loose_header(const char *hdr, struct object_info *oi,
unsigned int flags)
int parse_loose_header(const char *hdr, struct object_info *oi)
const char *type_buf = hdr;
unsigned long size;
@ -1347,15 +1346,6 @@ int parse_loose_header(const char *hdr, struct object_info *oi,
type = type_from_string_gently(type_buf, type_len, 1);
if (oi->type_name)
strbuf_add(oi->type_name, type_buf, type_len);
* Set type to 0 if its an unknown object and
* we're obtaining the type using '--allow-unknown-type'
* option.
if ((flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE) && (type < 0))
type = 0;
else if (type < 0)
die(_("invalid object type"));
if (oi->typep)
*oi->typep = type;
@ -1382,7 +1372,14 @@ int parse_loose_header(const char *hdr, struct object_info *oi,
* The length must be followed by a zero byte
return *hdr ? -1 : type;
if (*hdr)
return -1;
* The format is valid, but the type may still be bogus. The
* Caller needs to check its oi->typep.
return 0;
static int loose_object_info(struct repository *r,
@ -1396,6 +1393,7 @@ static int loose_object_info(struct repository *r,
char hdr[MAX_HEADER_LEN];
struct strbuf hdrbuf = STRBUF_INIT;
unsigned long size_scratch;
enum object_type type_scratch;
int allow_unknown = flags & OBJECT_INFO_ALLOW_UNKNOWN_TYPE;
if (oi->delta_base_oid)
@ -1427,6 +1425,8 @@ static int loose_object_info(struct repository *r,
if (!oi->sizep)
oi->sizep = &size_scratch;
if (!oi->typep)
oi->typep = &type_scratch;
if (oi->disk_sizep)
*oi->disk_sizep = mapsize;
@ -1434,6 +1434,18 @@ static int loose_object_info(struct repository *r,
switch (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr),
allow_unknown ? &hdrbuf : NULL)) {
case ULHR_OK:
if (parse_loose_header(hdrbuf.len ? hdrbuf.buf : hdr, oi) < 0)
status = error(_("unable to parse %s header"), oid_to_hex(oid));
else if (!allow_unknown && *oi->typep < 0)
die(_("invalid object type"));
if (!oi->contentp)
*oi->contentp = unpack_loose_rest(&stream, hdr, *oi->sizep, oid);
if (*oi->contentp)
goto cleanup;
status = -1;
case ULHR_BAD:
status = error(_("unable to unpack %s header"),
@ -1445,31 +1457,16 @@ static int loose_object_info(struct repository *r,
if (status < 0) {
/* Do nothing */
} else if (hdrbuf.len) {
if ((status = parse_loose_header(hdrbuf.buf, oi, flags)) < 0)
status = error(_("unable to parse %s header with --allow-unknown-type"),
} else if ((status = parse_loose_header(hdr, oi, flags)) < 0)
status = error(_("unable to parse %s header"), oid_to_hex(oid));
if (status >= 0 && oi->contentp) {
*oi->contentp = unpack_loose_rest(&stream, hdr,
*oi->sizep, oid);
if (!*oi->contentp) {
status = -1;
} else
munmap(map, mapsize);
if (oi->sizep == &size_scratch)
oi->sizep = NULL;
if (oi->typep == &type_scratch)
oi->typep = NULL;
oi->whence = OI_LOOSE;
return (status < 0) ? status : 0;
return status;
int obj_read_use_lock = 0;
@ -2533,6 +2530,7 @@ int read_loose_object(const char *path,
git_zstream stream;
char hdr[MAX_HEADER_LEN];
struct object_info oi = OBJECT_INFO_INIT;
oi.typep = type;
oi.sizep = size;
*contents = NULL;
@ -2549,12 +2547,13 @@ int read_loose_object(const char *path,
goto out;
*type = parse_loose_header(hdr, &oi, 0);
if (*type < 0) {
if (parse_loose_header(hdr, &oi) < 0) {
error(_("unable to parse header of %s"), path);
goto out;
if (*type < 0)
die(_("invalid object type"));
if (*type == OBJ_BLOB && *size > big_file_threshold) {
if (check_stream_oid(&stream, hdr, *size, path, expected_oid) < 0)


@ -225,6 +225,7 @@ static int open_istream_loose(struct git_istream *st, struct repository *r,
struct object_info oi = OBJECT_INFO_INIT;
oi.sizep = &st->size;
oi.typep = type;
st->u.loose.mapped = map_loose_object(r, oid, &st->u.loose.mapsize);
if (!st->u.loose.mapped)
@ -238,7 +239,7 @@ static int open_istream_loose(struct git_istream *st, struct repository *r,
goto error;
if (parse_loose_header(st->u.loose.hdr, &oi, 0) < 0)
if (parse_loose_header(st->u.loose.hdr, &oi) < 0 || *type < 0)
goto error;
st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;