Date: Wed, 19 May 2010 16:52:37 +0200 From: Christian Siebert <christian.siebert@cs.tu-chemnitz.de> To: freebsd-bugs@FreeBSD.org, bugs@openbsd.org Subject: wrong datatype in stdlib/merge.c Message-ID: <20100519165237.80222q5mxazqxtth@mail.tu-chemnitz.de>
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Hi all,
this file hasn't been touch for quite a while, so I'm wondering why
nobody discovered this bug before.
Location: in src/lib/libc/stdlib/merge.c in function setup()
What is wrong: variable 'tmp' is an 'int' type
Correction: this variable 'tmp' should be an 'u_char' type
While this variable 'tmp' is used correctly in the other function
insertionsort(), it is here (in setup) used incorrectly. At best, the
compiler detects this problem (icc for example issues a remark) and
corrects it automatically. More likely (gcc?) it just turns into
unnecessary type conversions, leading to some performance loss. In the
worst case (I think/hope not), this might even be problematic, because
the result is written back to memory within the macros swap() and
reverse().
Since the bug should be easy to fix, I'm looking forward to the
appropriate commit.
Best regards,
Christian
PS: I don't know who is responsible for this function, but it seems to
be no standard ANSI/ISO C, but rather a BSD extension (according to
the man pages at least). So I just checked the OpenBSD and FreeBSD web
cvs and both showed this bug.
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