Docs: Added SSymlinker bash script usage case

- Updated QT_build_instructions.md
- Fixed bugs in SSymlinker bash script.
- Added `sudo` privilege to `ln` commands in SSymlinker.
- Changed line endings to UNIX.

Author: abhiTronix

QT_build_instructions.md

@@ -233,17 +233,26 @@ sudo mkdir /usr/local/qt5.15
 sudo chown -R pi:pi /usr/local/qt5.15
 ```
 
-Also don't forget to setup Important Symlinks as follows: **(Important)**
-  
- ```sh
- sudo ln -sf -r /usr/include/arm-linux-gnueabihf/asm /usr/include
- sudo ln -sf -r /usr/include/arm-linux-gnueabihf/gnu /usr/include
- sudo ln -sf -r /usr/include/arm-linux-gnueabihf/bits /usr/include
- sudo ln -sf -r /usr/include/arm-linux-gnueabihf/sys /usr/include
- sudo ln -sf -r /usr/include/arm-linux-gnueabihf/openssl /usr/include
- sudo ln -sf /usr/lib/arm-linux-gnueabihf/crtn.o /usr/lib/crtn.o
- sudo ln -sf /usr/lib/arm-linux-gnueabihf/crt1.o /usr/lib/crt1.o
- sudo ln -sf /usr/lib/arm-linux-gnueabihf/crti.o /usr/lib/crti.o
+### 11. Setup Important Symlinks as follows: *(Important)*
+
+Our toolchains requires few additional symbolic links to work properly. Therefore, to create all required symbolic link reliably, we need to download `SSymlinker` bash script as follows:
+
+```sh
+wget https://raw.githubusercontent.com/abhiTronix/raspberry-pi-cross-compilers/master/utils/SSymlinker
+```
+
+Once it is downloaded, you just need to make it executable, and then run it for each path manually using the following commands:
+
+```sh
+sudo chmod +x SSymlinker
+./SSymlinker -s /usr/include/arm-linux-gnueabihf/asm -d /usr/include
+./SSymlinker -s /usr/include/arm-linux-gnueabihf/gnu -d /usr/include
+./SSymlinker -s /usr/include/arm-linux-gnueabihf/bits -d /usr/include
+./SSymlinker -s /usr/include/arm-linux-gnueabihf/sys -d /usr/include
+./SSymlinker -s /usr/include/arm-linux-gnueabihf/openssl -d /usr/include
+./SSymlinker -s /usr/lib/arm-linux-gnueabihf/crtn.o -d /usr/lib/crtn.o
+./SSymlinker -s /usr/lib/arm-linux-gnueabihf/crt1.o -d /usr/lib/crt1.o
+./SSymlinker -s /usr/lib/arm-linux-gnueabihf/crti.o -d /usr/lib/crti.o
 ```
 
 That's it for Raspberry Pi setup.

utils/SSymlinker

@@ -29,7 +29,7 @@ set -eo pipefail # abort on errors
 helpFunction() {
 	echo ""
 	echo ""
-	figlet -t -k -f /usr/share/figlet/standard.flf "SSymlinker: easy and safe"
+	figlet -t -k -f /usr/share/figlet/standard.flf "SSymlinker: Safe Symlinker"
 	echo ""
 	echo "Usage: $0 -s SOURCE -d DESTINATION"
 	echo -e "\t-s Source directory/file."
@@ -46,21 +46,27 @@ while getopts "s:d:" opt; do
 	esac
 done
 
-#print helpFunction in case parameters are empty
+# print helpFunction in case parameters are empty
 if [ -z "$SOURCE" ] || [ -z "$DESTINATION" ]; then
 	echo "Parameters are not valid. Aborting!"
 	helpFunction
 fi
 
+# throw error if source doesn't exists
+if [[ ! -d "$SOURCE" && ! -f "$SOURCE" ]]; then
+	echo "Source $SOURCE doesn't exist. Aborting!"
+	exit 1
+fi
+
 # get valid destination
-if [[ -d $DESTINATION && -L $DESTINATION ]]; then
+if [[ -f $DESTINATION ]]; then
 	# get parent directory
-	DESTINATION=$(cd -- "$DESTINATION" && pwd)
+	DESTINATION=$(dirname $(readlink -f $DESTINATION))
 else
 	DESTINATION=$(readlink -f "$DESTINATION")
 fi
-if [[ ! -d $DESTINATION && ! -w $DESTINATION ]]; then
-	echo "$DESTINATION is not valid destination directory. Aborting!"
+if [[ ! -d $DESTINATION ]]; then
+	echo "$DESTINATION is not valid destination. Aborting!"
 	exit 1
 fi
 
@@ -74,8 +80,8 @@ fi
 
 # check if symlink already present or
 # SOURCE path and DESTINATION path are same
-if [[ $DESTINATION == $SOURCE ]]; then
-	if [[ -f $DESTINATION ]]; then
+if [[ $DESTINATION == $SOURCE || $DESTINATION == $(dirname $SOURCE) ]]; then
+	if [[ $DESTINATION == $(dirname $SOURCE) ]]; then
 		echo "Symlink already present, Aborting!"
 		exit 0
 	else
@@ -87,7 +93,7 @@ fi
 # handle symlink creation
 if [[ ! -L "$DESTINATION/$(basename $SOURCE)" && -d "$DESTINATION/$(basename $SOURCE)" ]]; then
 	# a similar named non-empty folder already present at destination
-	ln -s -f -v "$SOURCE/*" "$DESTINATION/$(basename $SOURCE)/*"
+	sudo ln -s -f -v "$SOURCE/*" "$DESTINATION/$(basename $SOURCE)/*"
 	exit 0
 elif [[ -f $DESTINATION ]]; then
 	# a similar named file already present a destination
@@ -98,4 +104,4 @@ else
 	answer=y
 fi
 # create symlink
-[[ "$answer" = @(y|Y) ]] && ln -s -n -f -v -- "$SOURCE" "$DESTINATION"
+[[ "$answer" = @(y|Y) ]] && sudo ln -s -n -f -v -- "$SOURCE" "$DESTINATION"