Message-ID: <36E42806.E16550BF@home.com>
From: "Edward F. Sowell" <sowelled AT home DOT com>
Organization: @Home Network
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Newsgroups: comp.os.msdos.djgpp
Subject: Weird behavior with spawnl()
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Date: Mon, 08 Mar 1999 19:38:01 GMT
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NNTP-Posting-Date: Mon, 08 Mar 1999 11:38:01 PDT
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

The files below show some pretty weird  behavior with regard
to spawning processes. One problem is executables created
with DJGPP gcc cannot be launched with a spawn() (I've tried spawnl(),
spawnlp(), and a couple more) from a MS VC++
compiled executable. That is, if both buildsolxx.cpp and
tstCreateProcess.cpp  are compiled/linked with MS VC++ tools, everything
works as expected. However, if the launched program (buildsolxxx.exe)
is created with DJGPP compiler/linker (e.g., using rhide),
there is no error reported from spawnl(), but the process is not
in fact executed... i.e., the buildsol.log file is not created, etc.

Any idea what could cause such behavior?

Another piece of the puzzle: In my actual program, of which the below
is a fragment extracted to isolate the problem, buildsolver.exe needs
to spawn a "make" program. If  buildsolver is compiled with MS VC++,
it will not work, apparently because the command line (in the spawnl()
arg list) gets chopped at 126 characters. So it appears that MS and GNU
tools are somewhat incompatible with respect to the way processes
are created.  In my situation, where my software (which needs to
launch makes and compilation) is supposed to work with a range of
C++ compilers, it means that I MUST compile buildsolver with gcc (so it
can launch gmake), and on the other hand I MUST NOT compile buildsolver
with gcc (or it
cannot be lunched by my MCF Windows interface!



Comments greatly appreciated

Ed Sowell
PS: I know some may dismiss this as "another example of MS stuff not
working right," but OTOH everything works fine if only MS tools are
used---
sowelled AT home DOT com


---------
//   buildsolxx.cpp
#include <iostream.h>
#include <fstream.h>
int main(int argc, char** argv) {
       ofstream errLogFile("buildsol.log");

	if (argc != 3) {
		errLogFile << "Usage:" << endl
			 << endl
			 << "BuildSolver <problem name> <preference file>" << endl;
		return -1;
	}
       errLogFile << "Starting buildsolver with " << argv[0] << " " <<
argv[1]<< " " << argv[2] << endl;
       cout << "Starting buildsolver with " << argv[0] << " " <<
argv[1]<< " " << argv[2] << endl;
       cerr << "Starting buildsolver with " << argv[0] << " " <<
argv[1]<< " " << argv[2] << endl;
	   return 0;
}

----------------------------
// tstCreateProcess.cpp
#include <stdlib.h>
#include <afxwin.h>
#include <iostream.h>
#include <fstream.h>
#include <process.h>


int main( int argc, char *argv[])
{
	if (argc != 5) {
		cout<< " wrong # args" << endl;
		return 1;
	}
	_fileinfo =1; // pass open file info to spawn		

    ofstream logFile(argv[4]);

   if (putenv ("DJGPP=f:\\djgpp\\djgpp.env"))
  {
    perror ("Could not set DJGPP");
    exit (EXIT_FAILURE);
  }	
     if (putenv ("LFN=Y"))
  {
    perror ("Could not set LFN");
    exit (EXIT_FAILURE);
  }	 

     if (putenv
("PATH=f:\\dggpp\\bin;c:\\spark\\bin;c:\\windows\\command;k:\\sparkr~1\\builds~1\\testcr~1\\debug"))
  {
    perror ("Could not set PATH");
    exit (EXIT_FAILURE);
  }	 
	char* var;
	if(var = getenv("DJGPP"))
		cout << "set DJGPP=[" <<  var << "]" << endl;
	if(var = getenv("LFN"))
		cout << "set LFN=[" <<  var << "]" << endl;
	
	 
	 cout << flush;
		cerr << flush;

		int spawnres =  spawnl(P_WAIT, argv[1], argv[1], argv[2],argv[3],
NULL);
		if (spawnres != 0) {
		        cout << endl;
				perror("Spawn returned an error in buildsolver.");
        	}
	 
	return spawnres;
}