FIX: get-sdk.bat

Requires an URL as the first arg.

README.md

@@ -5,7 +5,7 @@ Collects portable MS Visual Studio Tools.
 Currently only x64-x64 is available for host-target platforms.
 
 ```bat
-vsget [destination]
+vsget "[destination]"
 ```
 
 Downloads and unpacks (without installation) to `destination`:
@@ -23,18 +23,20 @@ Adds related `vcvars*.bat` to init the VS Tools environment.
 Windows SDK can be downloaded separately:
 
 ```bat
-get-sdk [destination]
+get-sdk "[url]" "[destination]"
 ```
 
 Downloads the ISO, extracts the MSI installers (with related CAB files) of the
 SDK components and unpacks them into `destination`.
 
+The actual `SDK_URL` can be found in `vsget.bat`.
+
 # Uncache MS Visual Studio Components
 
 Use the MS Visual Studio cache to generate `vsix-groups\*.txt` files:
 
 ```bat
-vsuncache {CachePath}
+vsuncache "{CachePath}"
 ```
 
 If the optional `CachePath` is ommited, tries to find the VS cache path in the

get-sdk.bat

@@ -16,6 +16,17 @@ call which destination >NUL 2>&1 || set "PATH=%~dp0utils;%PATH%"
 call which check-components >NUL 2>&1 || set "PATH=%~dp0sdk;%PATH%"
 
 set url=%~1
+
+if "%url%" == "" (
+  echo [ERR][%~n0] SDK URL is required!
+  exit /b 1
+)
+
+if not "%url:~0,4%" == "http" (
+  echo [ERR][%~n0] Invalid SDK URL!
+  exit /b 1
+)
+
 call destination "%~2" || exit /b 1
 
 call check-components "%destination%" && (