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hex: make wraparound of the index into ring-buffer explicit

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Overflow is defined for unsigned integers, but not for signed ones.

We could make the ring-buffer index in sha1_to_hex() and
get_pathname() unsigned to be on the safe side to resolve this, but
let's make it explicit that we are wrapping around at whatever the
number of elements the ring-buffer has.  The compiler is smart enough
to turn modulus into bitmask for these codepaths that use
ring-buffers of a size that is a power of 2.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
René Scharfe 2016-10-23 19:57:30 +02:00 committed by Junio C Hamano
parent 23415c26fe
commit bb84735c80
2 changed files with 4 additions and 2 deletions
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3
hex.c
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@ -78,7 +78,8 @@ char *sha1_to_hex(const unsigned char *sha1)
{
static int bufno;
static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
return sha1_to_hex_r(hexbuffer[3 & ++bufno], sha1);
bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
return sha1_to_hex_r(hexbuffer[bufno], sha1);
}
char *oid_to_hex(const struct object_id *oid)

3
path.c
View File

@ -24,7 +24,8 @@ static struct strbuf *get_pathname(void)
STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
};
static int index;
struct strbuf *sb = &pathname_array[3 & ++index];
struct strbuf *sb = &pathname_array[index];
index = (index + 1) % ARRAY_SIZE(pathname_array);
strbuf_reset(sb);
return sb;
}