On 04/07/2016 05:57 PM, Christian Lamparter wrote:
> Implement a crude but functioning sysupgrade image check for Raspberry Pi.
> The code only checks if the master boot record boot signature (0x55aa) is
> present in the first 512-bytes at the correct location. This can prevent
> the odd, accidental bricking of a system when flashing the wrong file.
>
> The platform check supports both gzipped and raw images.
>
> Signed-off-by: Christian Lamparter <chunk...@googlemail.com>
> ---
> .../linux/brcm2708/base-files/lib/upgrade/platform.sh | 17
> ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/target/linux/brcm2708/base-files/lib/upgrade/platform.sh
> b/target/linux/brcm2708/base-files/lib/upgrade/platform.sh
> index 1d4b694..88c30cc 100644
> --- a/target/linux/brcm2708/base-files/lib/upgrade/platform.sh
> +++ b/target/linux/brcm2708/base-files/lib/upgrade/platform.sh
> @@ -1,5 +1,20 @@
> +get_magic_at() {
> + local file=$1
> + local pos=$2
> + ( gunzip -c $file 2>/dev/null || cat $file 2>/dev/null ) | dd bs=1
> count=2 skip=$pos 2>/dev/null | hexdump -v -n 2 -e '1/1 "%02x"'
Instead of calling gunzip yourself, you should just use get_image (defined
in package/base-files/files/lib/upgrade/common.sh ) as it is done on other
targets, it will transparently deal with compressed and even remote files.
Regards,
Matthias
> +}
> +
> platform_check_image() {
> - # i know no way to verify the image
> + local file=$1
> + local magic
> +
> + magic=$(get_magic_at $file 510)
> +
> + [ "$magic" != "55aa" ] && {
> + echo "Failed to verify MBR boot signature."
> + return 1
> + }
> +
> return 0;
> }
>
>
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