kludge to make undeleting an undeleted message work

[unix-history] / usr / src / usr.bin / mail / popen.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)popen.c	5.13 (Berkeley) %G%";
#endif /* not lint */

#include "rcv.h"
#include <sys/signal.h>
#include <sys/wait.h>

#define READ 0
#define WRITE 1
static int *pid;

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

	if (pid == 0)
		pid = (int *) malloc((unsigned) sizeof (int) * getdtablesize());
	if (pipe(p) < 0)
		return NULL;
	if (*mode == 'r') {
		myside = p[READ];
		fd0 = -1;
		hisside = fd1 = p[WRITE];
	} else {
		myside = p[WRITE];
		hisside = fd0 = p[READ];
		fd1 = -1;
	}
	if ((pid[myside] = start_command(cmd, 0, fd0, fd1, NOSTR)) < 0) {
		close(p[READ]);
		close(p[WRITE]);
		return NULL;
	}
	close(hisside);
	return fdopen(myside, mode);
}

Pclose(ptr)
	FILE *ptr;
{
	int i;
	int omask;

	i = fileno(ptr);
	fclose(ptr);
	omask = sigblock(sigmask(SIGINT)|sigmask(SIGHUP));
	i = wait_child(pid[i]);
	sigsetmask(omask);
	return i;
}

/*
 * 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.
 * "Mask" contains the signals to ignore in the new process.
 * SIGINT is enabled unless it's in the mask.
 */
/*VARARGS4*/
run_command(cmd, mask, infd, outfd, a0, a1, a2)
	char *cmd;
	int mask, infd, outfd;
	char *a0, *a1, *a2;
{
	int pid;

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

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

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

		if ((argv[i++] = a0) != NOSTR &&
		    (argv[i++] = a1) != NOSTR &&
		    (argv[i++] = a2) != NOSTR)
			argv[i] = NOSTR;
		prepare_child(mask, infd, outfd);
		execvp(argv[0], argv);
		perror(argv[0]);
		_exit(1);
	}
	return pid;
}

prepare_child(mask, infd, outfd)
	int mask, infd, outfd;
{
	int i;

	if (infd >= 0)
		dup2(infd, 0);
	if (outfd >= 0)
		dup2(outfd, 1);
	for (i = getdtablesize(); --i > 2;)
		close(i);
	for (i = 1; i <= NSIG; i++)
		if (mask & sigmask(i))
			(void) signal(i, SIG_IGN);
	if ((mask & sigmask(SIGINT)) == 0)
		(void) signal(SIGINT, SIG_DFL);
	(void) sigsetmask(0);
}

wait_command(pid)
	int pid;
{

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

struct child {
	int pid;
	char done;
	char free;
	union wait status;
	struct child *link;
};
static struct child *child;

struct child *
findchild(pid)
	int pid;
{
	register struct child **cpp;

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

delchild(cp)
	register struct child *cp;
{
	register struct child **cpp;

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

sigchild()
{
	int pid;
	union wait status;
	register struct child *cp;

	while ((pid = wait3(&status, WNOHANG, (struct timeval *)0)) > 0) {
		cp = findchild(pid);
		if (cp->free)
			delchild(cp);
		else {
			cp->done = 1;
			cp->status = status;
		}
	}
}

union wait wait_status;

/*
 * Wait for a specific child to die.
 */
wait_child(pid)
	int pid;
{
	int mask = sigblock(sigmask(SIGCHLD));
	register struct child *cp = findchild(pid);

	while (!cp->done)
		sigpause(mask);
	wait_status = cp->status;
	delchild(cp);
	sigsetmask(mask);
	return wait_status.w_status ? -1 : 0;
}

/*
 * Mark a child as don't care.
 */
free_child(pid)
	int pid;
{
	int mask = sigblock(sigmask(SIGCHLD));
	register struct child *cp = findchild(pid);

	if (cp->done)
		delchild(cp);
	else
		cp->free = 1;
	sigsetmask(mask);
}