/*===========================================================================
 Copyright (c) 1998-2000, The Santa Cruz Operation 
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:

 *Redistributions of source code must retain the above copyright notice,
 this list of conditions and the following disclaimer.

 *Redistributions in binary form must reproduce the above copyright notice,
 this list of conditions and the following disclaimer in the documentation
 and/or other materials provided with the distribution.

 *Neither name of The Santa Cruz Operation nor the names of its contributors
 may be used to endorse or promote products derived from this software
 without specific prior written permission. 

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
 IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 INTERRUPTION)
 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 DAMAGE. 
 =========================================================================*/

#include <stdio.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "global.h"	/* pid_t, RETSIGTYPE, shell, and mybasename() */

#define	tst(a,b) (*mode == 'r'? (b) : (a))
#define	RDR	0
#define	WTR	1

/* HBB 20010312: make this a bit safer --- don't blindly assume it's 1 */
#ifdef FD_CLOEXEC
# define CLOSE_ON_EXEC FD_CLOEXEC
#else
# define CLOSE_ON_EXEC 1
#endif

static char const rcsid[] = "$Id: mypopen.c,v 1.3 2002/01/09 19:04:05 umeshv Exp $";

static pid_t popen_pid[20];
static RETSIGTYPE (*tstat)(int);

int
myopen(char *path, int flag, int mode)
{
	/* opens a file descriptor and then sets close-on-exec for the file */
	int fd;

	if(mode)
		fd = open(path, flag, mode);
	else
		fd = open(path, flag);

#ifdef __DJGPP__		/* FIXME: test feature, not platform */
	/* HBB 20010312: DOS GCC doesn't have FD_CLOEXEC (yet), so it 
	 * always fails this call. Have to skip that step */
	if(fd != -1)
		return(fd);
#endif
	if(fd != -1 && (fcntl(fd, F_SETFD, CLOSE_ON_EXEC) != -1))
		return(fd);

	else
	{
		/* Ensure that if the fcntl fails and fd is valid, then
		   the file is closed properly. In general this should
		   not happen. */
		if (fd != -1)
		{
			close (fd);
		}

		return(-1);
	}
}

FILE *
myfopen(char *path, char *mode)
{
	/* opens a file pointer and then sets close-on-exec for the file */
	FILE *fp;

	fp = fopen(path, mode);

#ifdef __DJGPP__ /* FIXME: test feature, not platform */
	/* HBB 20010312: DOS GCC doesn't have FD_CLOEXEC (yet), so it 
	 * always fails this call. Have to skip that step */
	if(fp)
#else
	if(fp && (fcntl(fileno(fp), F_SETFD, CLOSE_ON_EXEC) != -1))
#endif
		return(fp);

	else return(NULL);
}

FILE *
mypopen(char *cmd, char *mode)
{
#ifdef __DJGPP__
	/* HBB 20010312: Has its own implementation of popen(), which
	 * is better suited to the platform than cscope's */
	return (popen)(cmd, mode);
#else
	int	p[2];
	pid_t *poptr;
	int myside, yourside;
	pid_t pid;

	if(pipe(p) < 0)
		return(NULL);
	myside = tst(p[WTR], p[RDR]);
	yourside = tst(p[RDR], p[WTR]);
	if((pid = fork()) == 0) {
		/* myside and yourside reverse roles in child */
		int	stdio;

		/* close all pipes from other popen's */
		for (poptr = popen_pid; poptr < popen_pid+20; poptr++) {
			if(*poptr)
				(void) close(poptr - popen_pid);
		}
		stdio = tst(0, 1);
		(void) close(myside);
		(void) close(stdio);
#if V9
		(void) dup2(yourside, stdio);
#else
		(void) fcntl(yourside, F_DUPFD, stdio);
#endif
		(void) close(yourside);
		(void) execlp(shell, mybasename(shell), "-c", cmd, 0);
		_exit(1);
	} else if (pid > 0)
		tstat = signal(SIGTSTP, SIG_DFL);
	if(pid == -1)
		return(NULL);
	popen_pid[myside] = pid;
	(void) close(yourside);
	return(fdopen(myside, mode));
#endif
}

#ifndef __DJGPP__ /* Don't replace that system's pclose() with our own. */
/* FIXME: should we really override pclose(), after having left
 * popen() well alone, and calling our own version mypopen()? */
int
#if Darwin
mypclose(FILE *ptr)
#else
pclose(FILE *ptr)
#endif
{
	int f;
	pid_t r;
	int status;
	RETSIGTYPE (*hstat)(int), (*istat)(int), (*qstat)(int);

	f = fileno(ptr);
	(void) fclose(ptr);
	istat = signal(SIGINT, SIG_IGN);
	qstat = signal(SIGQUIT, SIG_IGN);
	hstat = signal(SIGHUP, SIG_IGN);
	while((r = wait(&status)) != popen_pid[f] && r != -1)
		;
	if(r == -1)
		status = -1;
	(void) signal(SIGINT, istat);
	(void) signal(SIGQUIT, qstat);
	(void) signal(SIGHUP, hstat);
	(void) signal(SIGTSTP, tstat);
	/* mark this pipe closed */
	popen_pid[f] = 0;
	return(status);
}
#endif
