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From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: Garrett Cooper <yanefbsd@gmail.com>
References: <7d6fde3d0901160041n55466290l55f737d274a40895@mail.gmail.com>
Date: Sat, 17 Jan 2009 14:23:49 +0100
In-Reply-To: <7d6fde3d0901160041n55466290l55f737d274a40895@mail.gmail.com>
	(Garrett Cooper's message of "Fri, 16 Jan 2009 00:41:37 -0800")
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Cc: "amd64@freebsd.org" <amd64@freebsd.org>,
	Hackers freeBSD <freebsd-hackers@freebsd.org>
Subject: Re: Confused by segfault with legitimate call to strerror(3) on
	amd64 / sysctl(3) setting `odd' errno's
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Garrett Cooper <yanefbsd@gmail.com> writes:
> #include <err.h>
> #include <errno.h>
> #include <stdio.h>
> #include <sys/types.h>
> #include <sys/sysctl.h>

You should always put your sys includes before your non-sys includes,
and in any case, <sys/types.h> should always come first.

>                 printf("Errno: %d\n", errno);
>                 errx(errno, "Error: %s", strerror(errno));

In addition to what everybody else said, errno is not an appropriate
value for errx's first argument.  Use 1 or EXIT_FAILURE (or one of the
macros defined in <sysexits.h>, but I wouldn't recommend it).  Also, you
probably want to use err(), not errx(), and *always* compile with -Wall
-Wextra, and unless you're going to run gdb on your program, -O2 (which
enables additional code analysis)

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no