From b8505ecbf2b1e4ef27b9597fd113cb1679792b29 Mon Sep 17 00:00:00 2001 From: "brian m. carlson" Date: Mon, 26 Apr 2021 01:03:00 +0000 Subject: [PATCH] hex: default to the_hash_algo on zero algorithm value There are numerous places in the codebase where we assume we can initialize data by zeroing all its bytes. However, when we do that with a struct object_id, it leaves the structure with a zero value for the algorithm, which is invalid. We could forbid this pattern and require that all struct object_id instances be initialized using oidclr, but this seems burdensome and it's unnatural to most C programmers. Instead, if the algorithm is zero, assume we wanted to use the default hash algorithm instead. Signed-off-by: brian m. carlson Signed-off-by: Junio C Hamano --- hex.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/hex.c b/hex.c index e7af18fe55..74d256f239 100644 --- a/hex.c +++ b/hex.c @@ -124,6 +124,13 @@ char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash, char *buf = buffer; int i; + /* + * Our struct object_id has been memset to 0, so default to printing + * using the default hash. + */ + if (algop == &hash_algos[0]) + algop = the_hash_algo; + for (i = 0; i < algop->rawsz; i++) { unsigned int val = *hash++; *buf++ = hex[val >> 4];