Date: Tue, 28 Apr 2009 10:25:43 -0700 From: Chuck Swiger <cswiger@mac.com> To: Channa <channa.kad@gmail.com> Cc: freebsd-arm@FreeBSD.org, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: strncmp issue Message-ID: <FBA2BA91-D13F-41B2-95B6-21DE8E020B6F@mac.com> In-Reply-To: <515c64960904280252sc9fe2afy24e8db8ab13b13e4@mail.gmail.com> References: <515c64960904280252sc9fe2afy24e8db8ab13b13e4@mail.gmail.com>
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Hi, Channa--
On Apr 28, 2009, at 2:52 AM, Channa wrote:
> I am using the freebsd implementation of strncmp for ARM which is an
> assembly implementation.
> I have a small doubt, when i tested the strncmp by passing the third
> argument:
> 'n' as -1 the return values is '0' instead it should '-1'.
> When the third argument to strncmp is as below:
>
> ret = strncmp("a","b",-1)
Thanks for the thought, but strncmp() is defined to take a size_t as
the third argument, which is unsigned (ie, uint32_t or uint64_t).
Presumably when you tell it to compare with length of -1, that will be
converted to UINT_MAX or ULONG_MAX, and strncmp() will run until it
finds a null somewhere in one the strings and then return the
comparison result. (Or get a segfault, perhaps, if you run off the
end into unallocated address space.)
Regards,
--
-Chuck
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