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 <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
brian m. carlson committed
Apr 26, 2021 at 01:03 UTC
b8505ecbf2b1e4ef27b9597fd113cb1679792b29
1 file changed
+7
hex.c
+7
@@ -124,6 +124,13 @@ char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash,
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char *buf = buffer;
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int i;
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+ /*
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+ * Our struct object_id has been memset to 0, so default to printing
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+ * using the default hash.
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+ */
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+ if (algop == &hash_algos[0])
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+ algop = the_hash_algo;
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+
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for (i = 0; i < algop->rawsz; i++) {
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unsigned int val = *hash++;
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*buf++ = hex[val >> 4];