set the ANDROID_SDK_DIR, NDK and TOOLCHAIN vars only if unset. And don't add to PATH if already there

Author: rhuelga

android-env.sh

@@ -10,14 +10,19 @@
 # more details.
 #
 # You should have received a copy of the GNU Lesser General Public License along with
-# this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St 
+# this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St
 # - Fifth Floor, Boston, MA 02110-1301 USA
 
 if [ ! -d $PWD/install ]; then
   echo "Please source this script from the top level directory of the clutter-android project"
   exit 1
 fi
 
+pathadd() {
+    if [ -d "$1" ] && [[ ":$PATH:" != *":$1:"* ]]; then
+        export PATH="${PATH:+"$PATH:"}$1"
+    fi
+}
 
 SOURCES="$PWD/sources"
 PREFIX="$PWD/install"
@@ -30,9 +35,9 @@ export CXX=arm-linux-androideabi-g++
 export C_INCLUDE_PATH=$PREFIX/include
 export CPLUS_INCLUDE_PATH=$PREFIX/include
 
-export ANDROID_SDK_DIR="$PWD/android-sdk-linux"
-export ANDROID_NDK_DIR=`find $PWD/* -maxdepth 0 -type d -name 'android-ndk-r*'`
-export ANDROID_NDK_TOOLCHAIN="$PWD/toolchain"
+[[ ! ${ANDROID_SDK_DIR:+isset} ]] && export ANDROID_SDK_DIR="$PWD/android-sdk-linux"
+[[ ! ${ANDROID_NDK_DIR:+isset} ]] && export ANDROID_NDK_DIR=`find $PWD/* -maxdepth 0 -type d -name 'android-ndk-r*'`
+[[ ! ${ANDROID_NDK_TOOLCHAIN:+isset} ]] && export ANDROID_NDK_TOOLCHAIN="$PWD/toolchain"
 
 export gl_cv_header_working_stdint_h=yes
 
@@ -43,8 +48,10 @@ export LINGUAS=C
 export PKG_CONFIG_LIBDIR=/foo/bar
 export PKG_CONFIG_PATH=$LIBDIR/pkgconfig
 
-export PATH="$PATH:$ANDROID_NDK_DIR:$ANDROID_NDK_TOOLCHAIN/bin"
-export PATH="$PATH:$ANDROID_SDK_DIR/tools/:$ANDROID_SDK_DIR/platform-tools"
+pathadd "$ANDROID_NDK_DIR"
+pathadd "$ANDROID_NDK_TOOLCHAIN/bin"
+pathadd "$ANDROID_SDK_DIR/tools"
+pathadd "$ANDROID_SDK_DIR/platform-tools"
 
 export NDK_MODULE_PATH=$PWD