feat: Add script for extracting the boot.img from an OTA update

src/android/extract-bootimg.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+# I keep forgetting how to extract the boot.img from an Android OTA update
+# for patching by Magisk.
+set -e
+
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    --payload-dumper)
+      # Specify the path to the payload_dumper binary
+      PAYLOAD_DUMPER=$2
+      shift
+      shift
+      ;;
+    --diff)
+      PAYLOAD_DUMPER_EXTRA_ARGS="${PAYLOAD_DUMPER_EXTRA_ARGS} --diff"
+      shift
+      ;;
+    *)
+      # The last argument is the file
+      UPDATE_FILE=$1
+      shift
+      ;;
+  esac
+done
+
+if [[ ! -f "$UPDATE_FILE" ]]; then
+  echo "Android update file $UPDATE_FILE does not exist"
+  exit 1
+fi
+
+out_dir=./payload-dumper-output
+if [[ -d "$out_dir" ]]; then
+  echo "Output path $out_dir already exists. Refusing to work!"
+  exit 1
+fi
+mkdir "$out_dir"
+
+# Print some basic info
+PAYLOAD_DUMPER=${PAYLOAD_DUMPER:-payload_dumper}
+echo "INFO: payload_dumper: $PAYLOAD_DUMPER"
+echo
+
+# Extract only the payload.bin file
+echo "Extracting payload..."
+unzip -q -C "$UPDATE_FILE" -d "$out_dir" payload.bin
+
+# Use payload_dumper to get to the boot.img
+echo "Dumping data from payload..."
+${PAYLOAD_DUMPER} ${PAYLOAD_DUMPER_EXTRA_ARGS} --out "$out_dir" "${out_dir}/payload.bin"