Add support for manually modified kernel headers.

This changes the scripts so that if some kernel files exists
in external/kernel-headers/modified, that they will be preferred
over the same files found in original. This is to support the case
where the kernel headers cannot be taken without some small modifications.

Included with this change, is a general cleanup of the python scripts.

This also modifies the generate uapi headers script to indicate if the
source of the modified headers has changed.

Change-Id: Id13523b244ced52a2ecd9f1399c43996dd8296fa

libc/kernel/tools/generate_uapi_headers.sh

@@ -99,6 +99,35 @@ function copy_if_exists () {
   done
 }
 
+function check_hdrs () {
+  local src_dir=$1
+  local tgt_dir=$2
+  local kernel_dir=$3
+
+  local search_dirs=()
+
+  # This only works if none of the filenames have spaces.
+  for file in $(ls -d ${src_dir}/* 2> /dev/null); do
+    if [[ -d "${file}" ]]; then
+      search_dirs+=("${file}")
+    elif [[ -f  "${file}" ]] && [[ "${file}" =~ .h$ ]]; then
+      tgt_file=${tgt_dir}/$(basename ${file})
+      if [[ -e ${tgt_file} ]] && ! diff "${file}" "${tgt_file}" > /dev/null; then
+        if [[ ${file} =~ ${kernel_dir}/*(.+) ]]; then
+          echo "New version of ${BASH_REMATCH[1]} found in kernel headers."
+        else
+          echo "New version of ${file} found in kernel headers."
+        fi
+        echo "This file needs to be updated manually."
+      fi
+    fi
+  done
+
+  for dir in "${search_dirs[@]}"; do
+    check_hdrs "${dir}" ${tgt_dir}/$(basename ${dir}) "${kernel_dir}"
+  done
+}
+
 trap cleanup EXIT
 # This automatically triggers a call to cleanup.
 trap "exit 1" HUP INT TERM TSTP
@@ -207,3 +236,8 @@ for arch in "${ARCH_LIST[@]}"; do
                  "${KERNEL_DIR}/${src_dir}/arch/${arch}/include/generated/asm" \
                  "${ANDROID_KERNEL_DIR}/uapi/asm-${arch}/asm"
 done
+
+# Verify if modified headers have changed.
+check_hdrs "${KERNEL_DIR}/${src_dir}/include/scsi" \
+           "${ANDROID_KERNEL_DIR}/scsi" \
+           "${KERNEL_DIR}/${src_dir}"