prepare.sh: prepare script for LEDE ENV

* use git patch framework
* simplify ifstatemends
* use script dir as reference dir

prepare.sh

 #!/bin/bash
 
+EXECDIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
 patch_target() {
-  if [ "$(find "$PWD"/gluon_patches/*.patch 2> /dev/null | wc -l)" -ge 1 ]; then
-    for patch in "$PWD"/gluon_patches/*.patch; do
-      patch --no-backup-if-mismatch -p0 -d "../" -i "$patch"
+  if [ "$(find "$EXECDIR"/gluon_patches/*.patch 2> /dev/null | wc -l)" -ge 1 ]; then
+    local base="$EXECDIR"
+    cd "$EXECDIR"/.. || exit 1
+    for patch in "$EXECDIR"/gluon_patches/*.patch; do
+      git am --ignore-space-change --ignore-whitespace "$patch"
     done
+    cd "$base" || exit 1
   fi
 }
 
 patch_gluon() {
-  if git -C ".." status | head -n1 | grep "v2016.2.x"; then
-    patch_target
-  else
-    echo "no gluon repo founden or wrong branch"
+  if ! git -C "$EXECDIR"/.. rev-parse --abbrev-ref HEAD | grep "v2017.1.x"; then
+    echo "no gluon repo found or wrong branch"
     exit 1
   fi
+  patch_target
 }
 
 update_patches() {
-  if git -C ".." status | head -n1 | grep "v2016.2.x"; then
-    make -C ".." update-patches
-    #rm -f gluon_patches/*.patch
-    local base=$PWD
-    cd ..
-    n=0
-    for patch in $(git ls-files --others --exclude-standard); do
-      let n=n+1
-      local filename="$(diff -Naur /dev/null "$patch" | grep "+Subject: " | tr " " _ )"
-      diff -Naur /dev/null "$patch" > "$base/gluon_patches/$(printf '%04u' $n)-${filename//+Subject:_/}.patch"
-      echo "creating: $(printf '%04u' $n)-${filename//+Subject:_/}.patch"
-    done
-    cd "$base" || exit 1
-  else
+  if ! git -C "$EXECDIR"/.. rev-parse --abbrev-ref HEAD | grep "v2017.1.x"; then
     echo "no gluon repo founden or wrong branch"
     exit 1
   fi
+  make -C "$EXECDIR"/.. update-patches
+  local base="$EXECDIR"
+  cd "$EXECDIR"/.. || exit 1
+  git format-patch "origin/v2017.1.x" -o "$EXECDIR/gluon_patches"
+  cd "$base" || exit 1
 }
 
 case "$1" in