From: Junio C Hamano <gitster@pobox•com>
To: Patryk Obara <patryk.obara@gmail•com>
Cc: git@vger•kernel.org, "brian m . carlson" <sandals@crustytoothpaste•net>
Subject: Re: [PATCH 2/5] sha1_file: fix hardcoded size in null_sha1
Date: Tue, 15 Aug 2017 11:23:01 -0700 [thread overview]
Message-ID: <xmqq1socsnay.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <a21088f049390828cdee957f88503e8466e1d34e.1502796628.git.patryk.obara@gmail.com> (Patryk Obara's message of "Tue, 15 Aug 2017 13:49:03 +0200")
Patryk Obara <patryk.obara@gmail•com> writes:
> This prevents compilation error if GIT_MAX_RAWSZ is different than 20.
>
> Signed-off-by: Patryk Obara <patryk.obara@gmail•com>
> ---
> sha1_file.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
I think this is OK for "null" thing, but in general I feel
ambivalent when I see the use of "MAX" thing.
Use of "MAX" here implies that we wish to support multiple hashes at
the same time in a single binary, so that longer or shorter hashes
fit there. But in such a case, the callers would want a union of
some sort so that they can say "I am using SHA2, give me the null
thing"?
I said this is OK for "null" because we assume we will use ^\0{len}$
for any hash function we choose as the "impossible" value, and for
that particular use pattern, we do not need such a union. Just
letting the caller peek at an appropriate number of bytes at the
beginning of that NUL buffer for hash the caller wants to use is
sufficient.
Thanks.
>
> diff --git a/sha1_file.c b/sha1_file.c
> index b60ae15..f5b5bec 100644
> --- a/sha1_file.c
> +++ b/sha1_file.c
> @@ -32,7 +32,7 @@
> #define SZ_FMT PRIuMAX
> static inline uintmax_t sz_fmt(size_t s) { return s; }
>
> -const unsigned char null_sha1[20];
> +const unsigned char null_sha1[GIT_MAX_RAWSZ];
> const struct object_id null_oid;
> const struct object_id empty_tree_oid = {
> EMPTY_TREE_SHA1_BIN_LITERAL
next prev parent reply other threads:[~2017-08-15 18:23 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-15 11:49 [PATCH 0/5] Modernize read_graft_line implementation Patryk Obara
2017-08-15 11:49 ` [PATCH 1/5] cache: extend object_id size to sha3-256 Patryk Obara
2017-08-15 11:49 ` [PATCH 2/5] sha1_file: fix hardcoded size in null_sha1 Patryk Obara
2017-08-15 18:23 ` Junio C Hamano [this message]
2017-08-15 18:29 ` Stefan Beller
2017-08-15 19:02 ` Junio C Hamano
2017-08-16 12:11 ` Patryk Obara
2017-08-16 19:32 ` Junio C Hamano
2017-08-15 11:49 ` [PATCH 3/5] commit: replace the raw buffer with strbuf in read_graft_line Patryk Obara
2017-08-15 17:02 ` Stefan Beller
2017-08-16 12:24 ` Patryk Obara
2017-08-16 22:59 ` brian m. carlson
2017-08-17 5:55 ` Jeff King
2017-08-17 21:17 ` Junio C Hamano
2017-08-17 21:38 ` Patryk Obara
2017-08-15 18:25 ` Junio C Hamano
2017-08-15 11:49 ` [PATCH 4/5] commit: implement free_commit_graft Patryk Obara
2017-08-15 17:04 ` Stefan Beller
2017-08-15 18:26 ` Junio C Hamano
2017-08-16 12:28 ` Patryk Obara
2017-08-15 11:49 ` [PATCH 5/5] commit: rewrite read_graft_line Patryk Obara
2017-08-15 17:11 ` Stefan Beller
2017-08-15 18:30 ` Junio C Hamano
2017-08-16 13:07 ` Patryk Obara
2017-08-16 19:39 ` Junio C Hamano
2017-08-15 17:19 ` [PATCH 0/5] Modernize read_graft_line implementation Stefan Beller
2017-08-16 17:58 ` [PATCH v2 0/4] " Patryk Obara
2017-08-16 17:58 ` [PATCH v2 1/4] sha1_file: fix hardcoded size in null_sha1 Patryk Obara
2017-08-16 19:46 ` Junio C Hamano
2017-08-16 17:58 ` [PATCH v2 2/4] commit: replace the raw buffer with strbuf in read_graft_line Patryk Obara
2017-08-16 17:58 ` [PATCH v2 3/4] commit: implement free_commit_graft Patryk Obara
2017-08-16 17:58 ` [PATCH v2 4/4] commit: rewrite read_graft_line Patryk Obara
2017-08-17 21:20 ` Junio C Hamano
2017-08-17 21:42 ` Patryk Obara
2017-08-18 1:59 ` [PATCH v3 0/4] Modernize read_graft_line implementation Patryk Obara
2017-08-18 1:59 ` [PATCH v3 1/4] sha1_file: fix definition of null_sha1 Patryk Obara
2017-08-18 1:59 ` [PATCH v3 2/4] commit: replace the raw buffer with strbuf in read_graft_line Patryk Obara
2017-08-18 6:29 ` Jeff King
2017-08-18 10:12 ` Patryk Obara
2017-08-18 11:50 ` Jeff King
2017-08-18 1:59 ` [PATCH v3 3/4] commit: allocate array using object_id size Patryk Obara
2017-08-18 1:59 ` [PATCH v3 4/4] commit: rewrite read_graft_line Patryk Obara
2017-08-18 6:43 ` Jeff King
2017-08-18 7:44 ` Junio C Hamano
2017-08-18 11:30 ` Patryk Obara
2017-08-18 11:45 ` Jeff King
2017-08-18 16:44 ` Junio C Hamano
2017-08-18 17:05 ` Patryk Obara
2017-08-18 18:29 ` Junio C Hamano
2017-08-18 2:20 ` [PATCH v3 0/4] Modernize read_graft_line implementation Junio C Hamano
2017-08-18 18:33 ` [PATCH v4 " Patryk Obara
2017-08-18 18:33 ` [PATCH v4 1/4] sha1_file: fix definition of null_sha1 Patryk Obara
2017-08-18 18:33 ` [PATCH v4 2/4] commit: replace the raw buffer with strbuf in read_graft_line Patryk Obara
2017-08-18 18:33 ` [PATCH v4 3/4] commit: allocate array using object_id size Patryk Obara
2017-08-18 18:33 ` [PATCH v4 4/4] commit: rewrite read_graft_line Patryk Obara
2017-08-18 18:38 ` Patryk Obara
2017-08-18 19:12 ` Junio C Hamano
2017-08-18 19:33 ` Patryk Obara
2017-08-18 19:47 ` Junio C Hamano
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