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Re: [libvirt] [PATCH] storage_backend.c: avoid closing a negative file descriptor



On Tue, Feb 02, 2010 at 11:14:39AM +0100, Jim Meyering wrote:
> This close(fd) is reachable with an "fd" of -1 via
> the "goto cleanup" just before &fd is first set.
> While closing(-1) is not a big problem, it is a failing
> syscall, and would show up on an strace audit, not to mention
> the coverity and maybe-clang warnings.
> 
> >From c69369c445be53f12ec09a176fd477b9ff16bbff Mon Sep 17 00:00:00 2001
> From: Jim Meyering <meyering redhat com>
> Date: Tue, 2 Feb 2010 11:11:49 +0100
> Subject: [PATCH] storage_backend.c: avoid closing a negative file descriptor
> 
> * src/storage/storage_backend.c (virStorageBackendRunProgRegex):
> Don't close a negative (read-only) file descriptor.
> ---
>  src/storage/storage_backend.c |    8 +++++---
>  1 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> index bc656f2..84eb8aa 100644
> --- a/src/storage/storage_backend.c
> +++ b/src/storage/storage_backend.c
> @@ -1,7 +1,7 @@
>  /*
>   * storage_backend.c: internal storage driver backend contract
>   *
> - * Copyright (C) 2007-2009 Red Hat, Inc.
> + * Copyright (C) 2007-2010 Red Hat, Inc.
>   * Copyright (C) 2007-2008 Daniel P. Berrange
>   *
>   * This library is free software; you can redistribute it and/or
> @@ -1326,8 +1326,10 @@ virStorageBackendRunProgRegex(virConnectPtr conn,
> 
>      if (list)
>          fclose(list);
> -    else
> -        close(fd);
> +    else {
> +        if (0 <= fd)
> +            close(fd);
> +    }
> 
>      while ((err = waitpid(child, &exitstatus, 0) == -1) && errno == EINTR);
> 

  ACK,

tangential, though I know tests like (0 <= fd) are safer than (fd >= 0) from
a coding and maintainance perspective, I still find that harder to read
and understand.

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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