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rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable).  these days, people use source.  these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

/*	$OpenBSD: popen.c,v 1.35 2009/10/27 23:59:40 deraadt 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. 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.
 */

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

#define READ 0
#define WRITE 1

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

struct child {
	pid_t pid;
	char done;
	char free;
	int status;
	struct child *link;
};
static struct child *child, *child_freelist = NULL;

static struct child *findchild(pid_t, int);
static void delchild(struct child *);
static pid_t file_pid(FILE *);
static int handle_spool_locks(int);

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

	unregister_file(fp);
	return(fclose(fp));
}

FILE *
Popen(char *cmd, char *mode)
{
	int p[2];
	int myside, hisside, fd0, fd1;
	pid_t 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];
		hisside = fd0 = fd1 = p[WRITE];
	} else {
		myside = p[WRITE];
		hisside = fd0 = p[READ];
		fd1 = -1;
	}
	sigemptyset(&nset);
	pid = start_command(value("SHELL"), &nset, fd0, fd1, "-c", cmd, NULL);
	if (pid < 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(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(void)
{

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

void
register_file(FILE *fp, int pipe, pid_t 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(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 pid_t
file_pid(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 (-1 means none) 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".
 */
pid_t
start_commandv(char *cmd, sigset_t *nset, int infd, int outfd, va_list args)
{
	pid_t pid;

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

		while ((argv[i++] = va_arg(args, char *)))
			;
		argv[i] = NULL;
		prepare_child(nset, infd, outfd);
		execvp(argv[0], argv);
		warn("%s", argv[0]);
		_exit(1);
	}
	return(pid);
}

int
run_command(char *cmd, sigset_t *nset, int infd, int outfd, ...)
{
	pid_t pid;
	va_list args;

	va_start(args, outfd);
	pid = start_commandv(cmd, nset, infd, outfd, args);
	va_end(args);
	if (pid < 0)
		return(-1);
	return(wait_command(pid));
}

int
start_command(char *cmd, sigset_t *nset, int infd, int outfd, ...)
{
	va_list args;
	int r;

	va_start(args, outfd);
	r = start_commandv(cmd, nset, infd, outfd, args);
	va_end(args);
	return(r);
}

void
prepare_child(sigset_t *nset, int infd, int 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);
	} else if (infd != 0) {
		/* we don't want the child stealing my stdin input */
		close(0);
		open(_PATH_DEVNULL, O_RDONLY, 0);
	}
	if (outfd >= 0 && outfd != 1)
		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_t pid)
{

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

static struct child *
findchild(pid_t 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));
			if (*cpp == NULL)
				errx(1, "Out of memory");
		}
		(*cpp)->pid = pid;
		(*cpp)->done = (*cpp)->free = 0;
		(*cpp)->link = NULL;
	}
	return(*cpp);
}

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

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

/* ARGSUSED */
void
sigchild(int signo)
{
	pid_t 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_t pid)
{
	struct child *cp;
	sigset_t nset, oset;
	pid_t 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_t 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(int action)
{
	static FILE *lockfp = NULL;

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

		/* XXX - lockspool requires root for user arg, we do not */
		if (uflag) {
			snprintf(buf, sizeof(buf), "%s %s", _PATH_LOCKSPOOL,
			    myname);
			cmd = buf;
		} else
			cmd = _PATH_LOCKSPOOL;

		/* Create the lock */
		lockfp = Popen(cmd, "r");
		if (lockfp == NULL)
			return(0);
		if (getc(lockfp) != '1') {
			Pclose(lockfp);
			lockfp = NULL;
			return(0);
		}
	} else {
		(void)fprintf(stderr, "handle_spool_locks: unknown action %d\n",
		    action);
		return(-1);
	}

	return(1);
}

int
spool_lock(void)
{

	return(handle_spool_locks(1));
}

int
spool_unlock(void)
{

	return(handle_spool_locks(0));
}