How to start a 64-bit process from a 32-bit process

Question

I am trying to run a 64 bit executable (java.exe) from our 32-bit .NET application. I am using Process class and invoking cmd /c <command name> in order to support all possible commands (like dir, cd etc).

The problem is that on my machine I installed 64-bit version of JRE and java.exe is only available from C:\Windows\System32 folder (x64). I have tried explicily starting 64 bit version of cmd.exe by calling C:\Windows\System32\cmd.exe but it gets redirected to SysWOW64 due to calling process being 32 bit.

Is there anything else I can do to get this to work?

EDIT The whole cmd /c thing is a bit of a red herring. It is not part of the problem, being able to run 64 bit executables is.

Answer 1

You can temporarily disable filesystem redirection around the call to Process.Start, the appropriate API's to P/Invoke are Wow64DisableWow64FsRedirection and Wow64RevertWow64FsRedirection.

Another option is to use %windir%\sysnative, which is available on Windows Vista and above.

Answer 2

What you do is you use %windir%\sysnative to resolve 64-bit CMD.EXE and then you launch your other 64-bit program via "/c" command line option.

Answer 3

c:\>set proc
PROCESSOR_ARCHITECTURE=x86
PROCESSOR_ARCHITEW6432=AMD64
PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 70 Stepping 1, GenuineIntel
PROCESSOR_LEVEL=6
PROCESSOR_REVISION=4601

c:\>c:\windows\sysnative\cmd
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

c:\>set proc
PROCESSOR_ARCHITECTURE=AMD64
PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 70 Stepping 1, GenuineIntel
PROCESSOR_LEVEL=6
PROCESSOR_REVISION=4601

c:\>

Answer 4

Just in case this might help.. http://msdn.microsoft.com/en-us/library/aa384187(VS.85).aspx

Note that if the application is manifested to show the UAC prompt, then redirection will not take place. And also some folders are exempt from redirection.

Answer 5

"sysnative" seems to have some drawbacks.

Example: When you start powershell.exe via C:\Windows\sysnative\WindowsPowerShell\v1.0\powershell.exe some CmdLets like Get-AppxProvisionedPackage" and "Get-WindowsCapability don't work / throw exceptions:

Get-AppxProvisionedPackage: "Error setting current directory to "C:\Windows\SysNative\WindowsPowerShell\v1.0": Part of the path "C:\Windows\SysNative\WindowsPowerShell\v1.0" could not be found"

(translated from German "Fehler beim Festlegen des aktuellen Verzeichnisses auf "C:\Windows\SysNative\WindowsPowerShell\v1.0": Ein Teil des Pfades "C:\Windows\SysNative\WindowsPowerShell\v1.0" konnte nicht gefunden werden.")

There might be similar problems running other processes than powershell (whenever the process source directory is important?) ...