Re: [Qemu-devel] [PATCH 05/10] hw/i386/pc.c: Don't use load_image()

[Eric Blake <eblake@redhat.com>]

On 11/30/18 9:17 AM, Peter Maydell wrote:
> The load_image() function is deprecated, as it does not let the
> caller specify how large the buffer to read the file into is.
> Use the glib g_file_get_contents() function instead, which does
> the whole "allocate memory for the file and read it in" operation.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   hw/i386/pc.c | 22 ++++++++++++----------
>   1 file changed, 12 insertions(+), 10 deletions(-)
> 

> +++ b/hw/i386/pc.c
> @@ -839,10 +839,9 @@ static void load_linux(PCMachineState *pcms,
>   {
>       uint16_t protocol;
>       int setup_size, kernel_size, cmdline_size;
> -    int64_t initrd_size = 0;
>       int dtb_size, setup_data_offset;
>       uint32_t initrd_max;
> -    uint8_t header[8192], *setup, *kernel, *initrd_data;
> +    uint8_t header[8192], *setup, *kernel;

Unrelated - but 'header' at 8k is larger than I like for an auto 
variable.  Some OSs put guard pages at only 4k granularity, so this much 
stack allocation can miss stack overflow.


> -        initrd_size = get_image_size(initrd_filename);
> -        if (initrd_size < 0) {
> +        if (!g_file_get_contents(initrd_filename, &initrd_data,
> +                                 &initrd_size, &gerr)) {
>               fprintf(stderr, "qemu: error reading initrd %s: %s\n",
> -                    initrd_filename, strerror(errno));
> +                    initrd_filename, gerr->message);
>               exit(1);
> -        } else if (initrd_size >= initrd_max) {
> +        }
> +        if (initrd_size >= initrd_max) {
>               fprintf(stderr, "qemu: initrd is too large, cannot support."
> -                    "(max: %"PRIu32", need %"PRId64")\n", initrd_max, initrd_size);
> +                    "(max: %"PRIu32", need %"PRId64")\n",
> +                    initrd_max, initrd_size);
>               exit(1);

You're exiting anyway, so it doesn't matter, but free'ing initrd_data 
might satisfy a lint-checker.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org