Re: [Qemu-devel] [PATCH] util/error: Save errno from clobbering

["Benoît Canet" <benoit.canet@irqsave.net>]

Le Thursday 07 Nov 2013 à 20:10:29 (+0100), Max Reitz a écrit :
> There may be calls to error_setg() and especially error_setg_errno()
> which blindly (and until now wrongly) assume these functions not to
> clobber errno (e.g., they pass errno to error_setg_errno() and return
> -errno afterwards). Instead of trying to find and fix all of these
> constructs, just make sure error_setg() and error_setg_errno() indeed do
> not clobber errno.
> 
> Suggested-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  util/error.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/util/error.c b/util/error.c
> index ec0faa6..3ee362a 100644
> --- a/util/error.c
> +++ b/util/error.c
> @@ -27,6 +27,7 @@ void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
>  {
>      Error *err;
>      va_list ap;
> +    int saved_errno = errno;
>  
>      if (errp == NULL) {
>          return;
> @@ -41,6 +42,8 @@ void error_set(Error **errp, ErrorClass err_class, const char *fmt, ...)
>      err->err_class = err_class;
>  
>      *errp = err;
> +
> +    errno = saved_errno;
>  }
>  
>  void error_set_errno(Error **errp, int os_errno, ErrorClass err_class,
> @@ -49,6 +52,7 @@ void error_set_errno(Error **errp, int os_errno, ErrorClass err_class,
>      Error *err;
>      char *msg1;
>      va_list ap;
> +    int saved_errno = errno;
>  
>      if (errp == NULL) {
>          return;
> @@ -69,6 +73,8 @@ void error_set_errno(Error **errp, int os_errno, ErrorClass err_class,
>      err->err_class = err_class;
>  
>      *errp = err;
> +
> +    errno = saved_errno;
>  }
>  
>  void error_setg_file_open(Error **errp, int os_errno, const char *filename)
> -- 
> 1.8.4.2
> 
> 

Yes this look better than trying to fix all callers.

Reviewed-by: Benoit Canet <benoit@irqsave.net