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From: "Jan Alphenaar" <jan DOT alphenaar AT dotcolour DOT com>
To: <cygwin AT cygwin DOT com>
Subject: C / C# combination question
Date: Fri, 25 Dec 2009 22:58:34 +0100
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Hi everybody,

I have just installed the Cygwin environment with Cygwin DLL release version
1.7.1-1.

My goal is to call a Cygwin compiled C program from a C# program written in
Visual studio 2008 and read an environment variable from the Windows
environment in the C program.

Unfortunately my C program is not able to read the environment variable set
in the C# program.

For the purpose of elimination here are some facts:

1) If I replace the C program for a windows .bat file and call this .bat
file from the C# program it returns the environment variable.
2) Calling the C program directly in a dos box, results in the fact that it
can read an environment variable.
3) In previous versions of cygwin, this worked correctly, although I am not
sure with which version of the Cygwin DLL release.

Has anybody seen this rather strange behaviour before ?

Any help is greatly appreciated.

Warm regards,

Jan



This is my C program:

==== BEGIN C CODE ====
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <stdbool.h>

main()
{
   printf("%s\n", getenv("CYGWIN"));
}
==== END C CODE ====

And this is my C# code:
==== BEGIN C# CODE ====
        private void button1_Click(object sender, EventArgs e)
        {
            Process p = new Process();

            p.StartInfo.CreateNoWindow = true;
            p.StartInfo.UseShellExecute = false;
            p.StartInfo.RedirectStandardInput = true;
            p.StartInfo.RedirectStandardOutput = true;
            p.StartInfo.RedirectStandardError = true;
            p.StartInfo.FileName = @"D:\Test\bin\jan.exe";

            p.StartInfo.EnvironmentVariables["CYGWIN"] = "nodosfilewarning";

            p.OutputDataReceived += new
DataReceivedEventHandler(StdOutputHandler);
            p.ErrorDataReceived += new
DataReceivedEventHandler(StdOutputHandler);

            p.Start();

            p.StandardInput.AutoFlush = true;

            p.BeginOutputReadLine();
            p.BeginErrorReadLine();

            p.WaitForExit();

            p.Close();
        }

        private void StdOutputHandler(object sendingProcess,
DataReceivedEventArgs Entry)
        {
            MessageBox.Show(Entry.Data);
        }
==== END C# CODE ====


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