%
% (c) The GRASP/AQUA Project, Glasgow University, 1995
%
\subsection[system.lc]{system Runtime Support}

\begin{code}

#include "rtsdefs.h"
#include "stgio.h"

#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif

#ifdef HAVE_VFORK_H
#include <vfork.h>
#endif

#ifdef HAVE_VFORK
#define fork vfork
#endif

StgInt
systemCmd(cmd)
StgByteArray cmd;
{
    int pid;
    int wstat;

    switch(pid = fork()) {
    case -1:
	if (errno != EINTR) {
	    cvtErrno();
	    stdErrno();
	    return -1;
	}
    case 0:
	/* the child */
	execl("/bin/sh", "sh", "-c", cmd, NULL);
	_exit(127);
    }

    while (waitpid(pid, &wstat, 0) < 0) {
	if (errno != EINTR) {
	    cvtErrno();
	    stdErrno();
	    return -1;
	}
    }

    if (WIFEXITED(wstat))
	return WEXITSTATUS(wstat);
    else if (WIFSIGNALED(wstat)) {
	ghc_errtype = ERR_INTERRUPTED;
	ghc_errstr = "system command interrupted";
    }
    else {
	/* This should never happen */
	ghc_errtype = ERR_OTHERERROR;
	ghc_errstr = "internal error (process neither exited nor signalled)";
    }
    return -1;
}

\end{code}