The program I am invoking - slave.exe - simply displays its arguments on stdout.

import std.process;
import std.c.stdio;

int main(string[] args)
{
   // This compiles and runs.  It creates out.txt but the file is
   // empty.
   string[] pargs = [ "?", "A", "B" ];
   freopen("out.txt", "w", stdout);
   int rv = execvp("slave.exe", pargs);
   return rv;

// If I build the following VC6 program it behaves as expected
// I see the echoed arguments in out.txt
/*
   char *pargs[4];
	pargs[0] = "?";
	pargs[1] = "A";
	pargs[2] = "B";
	pargs[3] = NULL;
	freopen("out.txt", "w", stdout);
	execvp("slave.exe", pargs);
	return 0;
*/
}

Without the freopen, slave.exe displays the arguments to the console and then hangs - the C program behaves the same way in that case.

I tried constructing an array of char* arguments explicitly with a terminating null, and then calling std.c.process.execvp, but the behavior is the same.

Steve Teale Wrote:

> The program I am invoking - slave.exe - simply displays its arguments on stdout.
> 
> import std.process;
> import std.c.stdio;
> 
> int main(string[] args)
> {
>    // This compiles and runs.  It creates out.txt but the file is
>    // empty.
>    string[] pargs = [ "?", "A", "B" ];
>    freopen("out.txt", "w", stdout);
>    int rv = execvp("slave.exe", pargs);
>    return rv;
> 
> // If I build the following VC6 program it behaves as expected
> // I see the echoed arguments in out.txt
> /*
>    char *pargs[4];
> 	pargs[0] = "?";
> 	pargs[1] = "A";
> 	pargs[2] = "B";
> 	pargs[3] = NULL;
> 	freopen("out.txt", "w", stdout);
> 	execvp("slave.exe", pargs);
> 	return 0;
> */
> }
> 
> Without the freopen, slave.exe displays the arguments to the console and then hangs - the C program behaves the same way in that case.
> 
> I tried constructing an array of char* arguments explicitly with a terminating null, and then calling std.c.process.execvp, but the behavior is the same.
> 

Sory about the double posting.

I eventually got what I wanted working with CreateFile and CreateProcess.  I think the problem may be that the C library freopen function is not creating a Windows file handle that has its security descriptor set to inheritable.  Before I did that in my implementation it was behaving the same way.