[Qemu-devel] [PATCH] pc.c: better error message on initrd sizing failure

[Qemu-devel] [PATCH] pc.c: better error message on initrd sizing failure

[Michael S. Tsirkin]

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/pc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 348b15f..e715a33 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -835,8 +835,8 @@ static void load_linux(FWCfgState *fw_cfg,
 
         initrd_size = get_image_size(initrd_filename);
         if (initrd_size < 0) {
-            fprintf(stderr, "qemu: error reading initrd %s\n",
-                    initrd_filename);
+            fprintf(stderr, "qemu: error reading initrd %s: %s\n",
+                    initrd_filename, strerror(errno));
             exit(1);
         }
 
-- 
MST

Re: [Qemu-devel] [PATCH] pc.c: better error message on initrd sizing failure

[Peter Maydell]

On 2 February 2014 20:46, Michael S. Tsirkin <mst@redhat.com> wrote:
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/i386/pc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 348b15f..e715a33 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -835,8 +835,8 @@ static void load_linux(FWCfgState *fw_cfg,
>
>          initrd_size = get_image_size(initrd_filename);
>          if (initrd_size < 0) {
> -            fprintf(stderr, "qemu: error reading initrd %s\n",
> -                    initrd_filename);
> +            fprintf(stderr, "qemu: error reading initrd %s: %s\n",
> +                    initrd_filename, strerror(errno));
>              exit(1);

get_image_size() happens to set errno on failure, but it
doesn't guarantee to -- all the doc comment says currently
is "return the size or -1 if error". If we're going to rely on
errno being set in the failure case it would be nice to at
least add an "(and errno is set)" to that. (Better still would
be to transfer the info into a properly formatted doc comment
for the prototype in include/hw/loader.h...)

thanks
-- PMM

Re: [Qemu-devel] [PATCH] pc.c: better error message on initrd sizing failure

[Michael S. Tsirkin]

On Sun, Feb 02, 2014 at 08:46:35PM +0000, Peter Maydell wrote:
> On 2 February 2014 20:46, Michael S. Tsirkin <mst@redhat.com> wrote:
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  hw/i386/pc.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 348b15f..e715a33 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -835,8 +835,8 @@ static void load_linux(FWCfgState *fw_cfg,
> >
> >          initrd_size = get_image_size(initrd_filename);
> >          if (initrd_size < 0) {
> > -            fprintf(stderr, "qemu: error reading initrd %s\n",
> > -                    initrd_filename);
> > +            fprintf(stderr, "qemu: error reading initrd %s: %s\n",
> > +                    initrd_filename, strerror(errno));
> >              exit(1);
> 
> get_image_size() happens to set errno on failure, but it
> doesn't guarantee to -- all the doc comment says currently
> is "return the size or -1 if error". If we're going to rely on
> errno being set in the failure case it would be nice to at
> least add an "(and errno is set)" to that. (Better still would
> be to transfer the info into a properly formatted doc comment
> for the prototype in include/hw/loader.h...)
> 
> thanks
> -- PMM

Good idea. This patch doesn't have to change though - I'll post
an additional one with the comment.