[PATCH v7 15/17] object-file.c: stop dying in parse_loose_header()
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Sep 20, 2021, 19:04 UTC
- Message-ID
- <patch-v7-15.17-1ca875395c1-20210920T190305Z-avarab@gmail.com>
- In-Reply-To
- <cover-v7-00.17-00000000000-20210920T190304Z-avarab@gmail.com>
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 "oi->typep".
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 93cff9a978e (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 object_type".
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. c84a1f3ed4d (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 f6371f92104 (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 <avarab@gmail.com> --- cache.h | 11 +++++++-- object-file.c | 67 +++++++++++++++++++++++++-------------------------- streaming.c | 3 ++- 3 files changed, 44 insertions(+), 37 deletions(-)
diff --git a/cache.h b/cache.h index 49b18f2755c..23f0534b70e 100644 --- a/cache.h +++ b/cache.h @@ -1343,9 +1343,16 @@ 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); diff --git a/object-file.c b/object-file.c index ca4abe172ce..1af914c19c6 100644 --- a/object-file.c +++ b/object-file.c @@ -1347,8 +1347,7 @@ 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; @@ -1370,15 +1369,6 @@ 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; @@ -1405,7 +1395,14 @@ 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, @@ -1419,6 +1416,7 @@ 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) @@ -1450,6 +1448,8 @@ 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; @@ -1457,6 +1457,18 @@ 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) + break; + *oi->contentp = unpack_loose_rest(&stream, hdr, *oi->sizep, oid); + if (*oi->contentp) + goto cleanup; + + status = -1; break; case ULHR_BAD: status = error(_("unable to unpack %s header"), @@ -1468,31 +1480,16 @@ static int loose_object_info(struct repository *r, break; } - 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"), - oid_to_hex(oid)); - } 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) { - git_inflate_end(&stream); - status = -1; - } - } else - git_inflate_end(&stream); - + git_inflate_end(&stream); +cleanup: munmap(map, mapsize); if (oi->sizep == &size_scratch) oi->sizep = NULL; strbuf_release(&hdrbuf); + 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; @@ -2559,6 +2556,7 @@ 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; @@ -2575,12 +2573,13 @@ 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); git_inflate_end(&stream); 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) diff --git a/streaming.c b/streaming.c index bd89c50e7b3..fe54665d86e 100644 --- a/streaming.c +++ b/streaming.c @@ -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, case ULHR_TOO_LONG: 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;
-- 2.33.0.1098.g29a6526ae47