wrong datatype in stdlib/merge.c

Christian Siebert christian.siebert at cs.tu-chemnitz.de
Wed May 19 15:22:31 UTC 2010


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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