Re: System call v.s. errno

["Richard B. Johnson" <linux-os@analogic.com>]

On Wed, 4 May 2005, Jakub Jelinek wrote:

> On Wed, May 04, 2005 at 09:22:09AM -0400, Richard B. Johnson wrote:
> > Does anybody know for sure if global 'errno' is supposed to
> > be altered after a successful system call? I'm trying to
> > track down a problem where system calls return with EINTR
> > even though all signal handlers are set with SA_RESTART in
> > the flags. It appears as though there may be a race somewhere
> > because if I directly set errno to 0x1234, within a few
> > hundred system calls, it gets set to EINTR even though all
> > system calls seemed to return 'good'. This makes it
> > hard to trace down the real problem.
>
> http://www.opengroup.org/onlinepubs/009695399/functions/errno.html
> is very clear on this.  Unless indicated that errno is valid after a call
> (for many syscalls it is valid when the syscall returns -1), errno has
> unspecified value.
>
> 	Jakub
> -

Okay, thanks. That means that it's okay for it to get trashed
NotGood(tm) for debugging.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.11 on an i686 machine (5537.79 BogoMips).
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