Automatic searching for vcvars32.bat and report if missing.

chrome-update.bat

Index: chrome-update.bat
===================================================================
--- chrome-update.bat	(revision 17850)
+++ chrome-update.bat	(working copy)
@@ -2,9 +2,33 @@
 
 :: This batch file assumes that the correct version of python can be found in
 :: the current directory, and that you have Visual Studio 8 installed in the
-:: default location.
+:: default location. It will try to find Visual Studio in the default
+:: installation paths for x86 and x64 versions of windows as well as through
+:: the PATH environment variable.
 
 setlocal
-call vcvars32.bat
+IF EXIST "%ProgramFiles(x86)%\Microsoft Visual Studio 8\VC\bin\vcvars32.bat" (
+  CALL "%ProgramFiles(x86)%\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"
+) ELSE IF EXIST "%ProgramFiles%\Microsoft Visual Studio 8\VC\bin\vcvars32.bat" (
+  CALL "%ProgramFiles%\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"
+) ELSE (
+  :: See "HELP CALL" for information on how to use %~$PATH:1 to find a file in
+  :: the PATH.
+  CALL :FIND_IN_PATH "vcvars32.bat"
+)
 
+:: If vcvasr32.bat cannot be found or there was a problem, stop execution.
+IF %ERRORLEVEL%==1 GOTO :EOF
 python "%~dp0chrome-update.py" %*
+GOTO :EOF
+
+:FIND_IN_PATH
+  :: %~$PATH:1 works like "which" on linux; use it to see if the file exists and
+  :: call it if found. If it cannot be found print an error and set errorlevel
+  IF EXIST "%~$PATH:1" (
+    CALL "%~$PATH:1"
+  ) ELSE (
+    ECHO Cannot find vcvars32.bat! (Do you have Visual Studio in your PATH?)
+    SET ERRORLEVEL=1
+  )
+  GOTO :EOF