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Date: Fri, 16 Jan 2009 09:31:44 +0200
From: Gleb Natapov <gleb@redhat.com>
Subject: Re: [Qemu-devel] [6324] Return -errno on write failure (Gleb Natapov)
Message-ID: <20090116073144.GC27165@redhat.com>
References: <E1LNZ4k-0004ZW-UT@cvs.savannah.gnu.org> <2858981241-BeMail@laptop>
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To: qemu-devel@nongnu.org

On Thu, Jan 15, 2009 at 10:20:33PM +0100, Fran=C3=A7ois Revol wrote:
> > Revision: 6324
> >           http://svn.sv.gnu.org/viewvc/?view=3Drev&root=3Dqemu&revision=
=3D6324
> > > Author:   aliguori
> > Date:     2009-01-15 20:44:26 +0000 (Thu, 15 Jan 2009)
> >
> > Log Message:
> > -----------
> > Return -errno on write failure (Gleb Natapov)
>=20
> Nooooooooooo
> Please do not this bad broken Unix habit!
> errno and E* are negative in BeOS and Haiku and sometimes =3D to
> INT32_MIN which means negating it results in positive values or even
> overflows.
>=20
This is how qemu block layer passes error reason to the caller. Not only
here but in other places too.

>=20
> #if EINVAL > 0
> #define QERROR(e) (-(e)) /**< Returns a negative error code from a
> POSIX error code, to return from library functions. */
> #define QUNERROR(e) (-(e)) /**< Returns a POSIX error code from a
> library function error return value. */
> #else
> /* Some platforms have E* and errno already negated. */
> #define QERROR(e) (e)
> #define QUNERROR(e) (e)
> #endif
>=20
> and return QERROR(errno) or return QERROR(EINVAL);
>
Patch to fix qemu on BeOS are welcomed :)
=20
--
			Gleb.