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@Floppe
Created April 29, 2024 08:15
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Decompress kernels post hook
#!/bin/bash
KERNEL_VERSION="$1"
KERNEL_PATH="$2"
# extract-vmlinux is in /usr/local/bin
PATH="${PATH}:/usr/local/sbin"
# Ensure we have the extract-linux tool
if ! command -v extract-vmlinux > /dev/null; then
echo >&2 "Command 'extract-vmlinux' is not available (https://raw.githubusercontent.com/torvalds/linux/master/scripts/extract-vmlinux), Aborting"
exit 1
fi
# The KERNEL_PATH must be valid
if [ ! -f "${KERNEL_PATH}" ]; then
echo >&2 "Kernel file '${KERNEL_PATH}' not found. Aborting"
exit 1
fi
# Create a temp file
TEMP_FILE=$(mktemp /tmp/decompress-kernel-XXXXX)
trap "rm -f ${TEMP_FILE}" 0
# If the given kernel file is still a bzimage see if its needs decompression
if echo "$(file -b "${KERNEL_PATH}")" | grep -q "^Linux kernel x86 boot executable bzImage"; then
# Kernel is probably lz4 if there are lz4 headers in it
#LZ4_HEADER="$(printf '\002!L\030')"
#if ! grep -aqo "${LZ4_HEADER}" ${KERNEL_PATH}; then
# echo "No lz4 compression headers found, skipping..."
# exit 0
#fi
echo "Decompressing '${KERNEL_PATH}'..."
# Extract the kernel and replace existing if successful
if extract-vmlinux ${KERNEL_PATH} > ${TEMP_FILE}; then
# Double check the kernel is a valid ELF image
if ! readelf -h ${TEMP_FILE} > /dev/null; then
echo >&2 "Decompression of kernel file '${KERNEL_PATH}' failed!, not a valid ELF image"
exit 1
fi
echo "Decompression of kernel file '${KERNEL_PATH}' successful"
cp -v ${TEMP_FILE} ${KERNEL_PATH}
else
echo >&2 "Decompression of kernel file '${KERNEL_PATH}' failed!"
exit 1
fi
# Perhaps its already been decompressed
elif echo "$(file -b "${KERNEL_PATH}")" | grep -q "^ELF 64-bit LSB executable"; then
echo "Kernel file '${KERNEL_PATH}' appears to be decompressed already. skipping"
else
echo >&2 "Unable to determine the state of kernel file '${KERNEL_PATH}'"
exit 1
fi
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