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warnx?/errx? paranoia (use "%s" not a bare string unless it is a
constant).  These are not security holes but it is worth fixing
them anyway both for robustness and so folks looking for examples
in the tree are not misled into doing something potentially dangerous.
Furthermore, it is a bad idea to assume that pathnames will not
include '%' in them and that error routines don't return strings
with '%' in them (especially in light of the possibility of locales).

/*	$OpenBSD: popen.c,v 1.24 2000/06/30 16:00:18 millert Exp $	*/
/*	$NetBSD: popen.c,v 1.6 1997/05/13 06:48:42 mikel Exp $	*/

/*
 * Copyright (c) 1980, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University 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 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.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)popen.c	8.1 (Berkeley) 6/6/93";
#else
static char rcsid[] = "$OpenBSD: popen.c,v 1.24 2000/06/30 16:00:18 millert Exp $";
#endif
#endif /* not lint */

#include "rcv.h"
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include "extern.h"

#define READ 0
#define WRITE 1

struct fp {
	FILE *fp;
	int pipe;
	int pid;
	struct fp *link;
};
static struct fp *fp_head;

struct child {
	int pid;
	char done;
	char free;
	int status;
	struct child *link;
};
static struct child *child, *child_freelist = NULL;
static struct child *findchild __P((int, int));
static void delchild __P((struct child *));
static int file_pid __P((FILE *));
static int handle_spool_locks __P((int));

FILE *
Fopen(file, mode)
	char *file, *mode;
{
	FILE *fp;

	if ((fp = fopen(file, mode)) != NULL) {
		register_file(fp, 0, 0);
		(void)fcntl(fileno(fp), F_SETFD, 1);
	}
	return(fp);
}

FILE *
Fdopen(fd, mode)
	int fd;
	char *mode;
{
	FILE *fp;

	if ((fp = fdopen(fd, mode)) != NULL) {
		register_file(fp, 0, 0);
		(void)fcntl(fileno(fp), F_SETFD, 1);
	}
	return(fp);
}

int
Fclose(fp)
	FILE *fp;
{
	unregister_file(fp);
	return(fclose(fp));
}

FILE *
Popen(cmd, mode)
	char *cmd;
	char *mode;
{
	int p[2];
	int myside, hisside, fd0, fd1;
	int pid;
	sigset_t nset;
	FILE *fp;

	if (pipe(p) < 0)
		return(NULL);
	(void)fcntl(p[READ], F_SETFD, 1);
	(void)fcntl(p[WRITE], F_SETFD, 1);
	if (*mode == 'r') {
		myside = p[READ];
		fd0 = -1;
		hisside = fd1 = p[WRITE];
	} else {
		myside = p[WRITE];
		hisside = fd0 = p[READ];
		fd1 = -1;
	}
	sigemptyset(&nset);
	if ((pid = start_command(cmd, &nset, fd0, fd1, NULL, NULL, NULL)) < 0) {
		(void)close(p[READ]);
		(void)close(p[WRITE]);
		return(NULL);
	}
	(void)close(hisside);
	if ((fp = fdopen(myside, mode)) != NULL)
		register_file(fp, 1, pid);
	return(fp);
}

int
Pclose(ptr)
	FILE *ptr;
{
	int i;
	sigset_t nset, oset;

	i = file_pid(ptr);
	unregister_file(ptr);
	(void)fclose(ptr);
	sigemptyset(&nset);
	sigaddset(&nset, SIGINT);
	sigaddset(&nset, SIGHUP);
	sigprocmask(SIG_BLOCK, &nset, &oset);
	i = wait_child(i);
	sigprocmask(SIG_SETMASK, &oset, NULL);
	return(i);
}

void
close_all_files()
{

	while (fp_head)
		if (fp_head->pipe)
			(void)Pclose(fp_head->fp);
		else
			(void)Fclose(fp_head->fp);
}

void
register_file(fp, pipe, pid)
	FILE *fp;
	int pipe, pid;
{
	struct fp *fpp;

	if ((fpp = (struct fp *)malloc(sizeof(*fpp))) == NULL)
		errx(1, "Out of memory");
	fpp->fp = fp;
	fpp->pipe = pipe;
	fpp->pid = pid;
	fpp->link = fp_head;
	fp_head = fpp;
}

void
unregister_file(fp)
	FILE *fp;
{
	struct fp **pp, *p;

	for (pp = &fp_head; (p = *pp) != NULL; pp = &p->link)
		if (p->fp == fp) {
			*pp = p->link;
			(void)free(p);
			return;
		}
	errx(1, "Invalid file pointer");
}

static int
file_pid(fp)
	FILE *fp;
{
	struct fp *p;

	for (p = fp_head; p; p = p->link)
		if (p->fp == fp)
			return(p->pid);
	errx(1, "Invalid file pointer");
	/*NOTREACHED*/
}

/*
 * Run a command without a shell, with optional arguments and splicing
 * of stdin and stdout.  The command name can be a sequence of words.
 * Signals must be handled by the caller.
 * "nset" contains the signals to ignore in the new process.
 * SIGINT is enabled unless it's in "nset".
 */
/*VARARGS4*/
int
run_command(cmd, nset, infd, outfd, a0, a1, a2)
	char *cmd;
	sigset_t *nset;
	int infd, outfd;
	char *a0, *a1, *a2;
{
	int pid;

	if ((pid = start_command(cmd, nset, infd, outfd, a0, a1, a2)) < 0)
		return(-1);
	return(wait_command(pid));
}

/*VARARGS4*/
int
start_command(cmd, nset, infd, outfd, a0, a1, a2)
	char *cmd;
	sigset_t *nset;
	int infd, outfd;
	char *a0, *a1, *a2;
{
	int pid;

	if ((pid = vfork()) < 0) {
		warn("fork");
		return(-1);
	}
	if (pid == 0) {
		char *argv[100];
		int i = getrawlist(cmd, argv, sizeof(argv)/ sizeof(*argv));

		if ((argv[i++] = a0) != NULL &&
		    (argv[i++] = a1) != NULL &&
		    (argv[i++] = a2) != NULL)
			argv[i] = NULL;
		prepare_child(nset, infd, outfd);
		execvp(argv[0], argv);
		warn("%s", argv[0]);
		_exit(1);
	}
	return(pid);
}

void
prepare_child(nset, infd, outfd)
	sigset_t *nset;
	int infd, outfd;
{
	int i;
	sigset_t eset;

	/*
	 * All file descriptors other than 0, 1, and 2 are supposed to be
	 * close-on-exec.
	 */
	if (infd >= 0)
		dup2(infd, 0);
	if (outfd >= 0)
		dup2(outfd, 1);
	if (nset == NULL)
		return;
	if (nset != NULL) {
		for (i = 1; i < NSIG; i++)
			if (sigismember(nset, i))
				(void)signal(i, SIG_IGN);
	}
	if (nset == NULL || !sigismember(nset, SIGINT))
		(void)signal(SIGINT, SIG_DFL);
	sigemptyset(&eset);
	(void)sigprocmask(SIG_SETMASK, &eset, NULL);
}

int
wait_command(pid)
	int pid;
{

	if (wait_child(pid) < 0) {
		puts("Fatal error in process.");
		return(-1);
	}
	return(0);
}

static struct child *
findchild(pid, dont_alloc)
	int pid;
	int dont_alloc;
{
	struct child **cpp;

	for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
	     cpp = &(*cpp)->link)
			;
	if (*cpp == NULL) {
		if (dont_alloc)
			return(NULL);
		if (child_freelist) {
			*cpp = child_freelist;
			child_freelist = (*cpp)->link;
		} else
			*cpp = (struct child *)malloc(sizeof(struct child));
		(*cpp)->pid = pid;
		(*cpp)->done = (*cpp)->free = 0;
		(*cpp)->link = NULL;
	}
	return(*cpp);
}

static void
delchild(cp)
	struct child *cp;
{
	struct child **cpp;

	for (cpp = &child; *cpp != cp; cpp = &(*cpp)->link)
		;
	*cpp = cp->link;
	cp->link = child_freelist;
	child_freelist = cp;
}

void
sigchild(signo)
	int signo;
{
	int pid;
	int status;
	struct child *cp;
	int save_errno = errno;

	while ((pid =
	    waitpid((pid_t)-1, &status, WNOHANG)) > 0) {
		cp = findchild(pid, 1);
		if (!cp)
			continue;
		if (cp->free)
			delchild(cp);
		else {
			cp->done = 1;
			cp->status = status;
		}
	}
	errno = save_errno;
}

int wait_status;

/*
 * Wait for a specific child to die.
 */
int
wait_child(pid)
	int pid;
{
	struct child *cp;
	sigset_t nset, oset;
	int rv = 0;

	sigemptyset(&nset);
	sigaddset(&nset, SIGCHLD);
	sigprocmask(SIG_BLOCK, &nset, &oset);
	/*
	 * If we have not already waited on the pid (via sigchild)
	 * wait on it now.  Otherwise, use the wait status stashed
	 * by sigchild.
	 */
	cp = findchild(pid, 1);
	if (cp == NULL || !cp->done)
		rv = waitpid(pid, &wait_status, 0);
	else
		wait_status = cp->status;
	if (cp != NULL)
		delchild(cp);
	sigprocmask(SIG_SETMASK, &oset, NULL);
	if (rv == -1 || (WIFEXITED(wait_status) && WEXITSTATUS(wait_status)))
		return(-1);
	else
		return(0);
}

/*
 * Mark a child as don't care.
 */
void
free_child(pid)
	int pid;
{
	struct child *cp;
	sigset_t nset, oset;

	sigemptyset(&nset);
	sigaddset(&nset, SIGCHLD);
	sigprocmask(SIG_BLOCK, &nset, &oset);
	if ((cp = findchild(pid, 0)) != NULL) {
		if (cp->done)
			delchild(cp);
		else
			cp->free = 1;
	}
	sigprocmask(SIG_SETMASK, &oset, NULL);
}

/*
 * Lock(1)/unlock(0) mail spool using lockspool(1).
 * Returns 1 for success, 0 for failure, -1 for bad usage.
 */
static int
handle_spool_locks(action)
	int action;
{
	static FILE *lockfp = NULL;
	static int lock_pid;

	if (action == 0) {
		/* Clear the lock */
		if (lockfp == NULL) {
			fputs("handle_spool_locks: no spool lock to remove.\n",
			    stderr);
			return(-1);
		}
		(void)kill(lock_pid, SIGTERM);
		(void)Pclose(lockfp);
		lockfp = NULL;
	} else if (action == 1) {
		char *cmd = _PATH_LOCKSPOOL;

		/* XXX - lockspool requires root for user arg, we do not */
		if (uflag && asprintf(&cmd, "%s %s", _PATH_LOCKSPOOL,
		    myname) == -1)
			errx(1, "Out of memory");

		/* Create the lock */
		lockfp = Popen(cmd, "r");
		if (uflag)
			free(cmd);
		if (lockfp == NULL || getc(lockfp) != '1') {
			lockfp = NULL;
			return(0);
		}
		lock_pid = fp_head->pid;	/* new entries added at head */
	} else {
		(void)fprintf(stderr, "handle_spool_locks: unknown action %d\n",
		    action);
		return(-1);
	}

	return(1);
}

int
spool_lock()
{
	return(handle_spool_locks(1));
}

int
spool_unlock()
{
	return(handle_spool_locks(0));
}