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"'
+}
+
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;
}
--
2.8.0.rc3
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