NetBSD/usr.sbin/cron/popen.c

/*	$NetBSD: popen.c,v 1.8 2003/08/07 11:25:17 agc Exp $	*/

/*
 * Copyright (c) 1988, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software written by Ken Arnold and
 * published in UNIX Review, Vol. 6, No. 8.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 <sys/cdefs.h>
#ifndef lint
#if 0
static char rcsid[] = "Id: popen.c,v 1.5 1994/01/15 20:43:43 vixie Exp";
static char sccsid[] = "@(#)popen.c	5.7 (Berkeley) 2/14/89";
#else
__RCSID("$NetBSD: popen.c,v 1.8 2003/08/07 11:25:17 agc Exp $");
#endif
#endif /* not lint */

#include "cron.h"
#include <signal.h>

/*
 * Special version of popen which avoids call to shell.  This insures noone
 * may create a pipe to a hidden program as a side effect of a list or dir
 * command.
 */
static PID_T *pids;
static int fds;

#define MAX_ARGS 1024

FILE *
cron_popen(program, type)
	char *program, *type;
{
	char *cp;
	FILE *iop;
	int argc, pdes[2];
	PID_T pid;
	char *argv[MAX_ARGS];

#ifdef __GNUC__
	(void) &iop;	/* Avoid vfork clobbering */
#endif

	if ((*type != 'r' && *type != 'w') || type[1])
		return(NULL);

	if (!pids) {
		if ((fds = getdtablesize()) <= 0)
			return(NULL);
		if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
			return(NULL);
		bzero((char *)pids, fds * sizeof(PID_T));
	}
	if (pipe(pdes) < 0)
		return(NULL);

	/* break up string into pieces */
	for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
		if (!(argv[argc++] = strtok(cp, " \t\n")))
			break;

	iop = NULL;
	switch(pid = vfork()) {
	case -1:			/* error */
		(void)close(pdes[0]);
		(void)close(pdes[1]);
		goto pfree;
		/* NOTREACHED */
	case 0:				/* child */
		if (*type == 'r') {
			if (pdes[1] != 1) {
				dup2(pdes[1], 1);
				dup2(pdes[1], 2);	/* stderr, too! */
				(void)close(pdes[1]);
			}
			(void)close(pdes[0]);
		} else {
			if (pdes[0] != 0) {
				dup2(pdes[0], 0);
				(void)close(pdes[0]);
			}
			(void)close(pdes[1]);
		}
		execvp(argv[0], argv);
		_exit(1);
	}
	/* parent; assume fdopen can't fail...  */
	if (*type == 'r') {
		iop = fdopen(pdes[0], type);
		(void)close(pdes[1]);
	} else {
		iop = fdopen(pdes[1], type);
		(void)close(pdes[0]);
	}
	pids[fileno(iop)] = pid;

pfree:
	return(iop);
}

int
cron_pclose(iop)
	FILE *iop;
{
	int fdes;
	sigset_t oset, nset;
	WAIT_T stat_loc;
	PID_T pid;

	/*
	 * pclose returns -1 if stream is not associated with a
	 * `popened' command, or, if already `pclosed'.
	 */
	if (pids == 0 || pids[fdes = fileno(iop)] == 0)
		return(-1);
	(void)fclose(iop);
	
	sigemptyset(&nset);
	sigaddset(&nset, SIGINT);
	sigaddset(&nset, SIGQUIT);
	sigaddset(&nset, SIGHUP);
	(void)sigprocmask(SIG_BLOCK, &nset, &oset);
	while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
		;
	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
	pids[fdes] = 0;
	return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
}