src/kernel/linux/v4.19/arch/um/drivers/pty.c

/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <termios.h>
#include <sys/stat.h>
#include "chan_user.h"
#include <os.h>
#include <um_malloc.h>

struct pty_chan {
	void (*announce)(char *dev_name, int dev);
	int dev;
	int raw;
	struct termios tt;
	char dev_name[sizeof("/dev/pts/0123456\0")];
};

static void *pty_chan_init(char *str, int device, const struct chan_opts *opts)
{
	struct pty_chan *data;

	data = uml_kmalloc(sizeof(*data), UM_GFP_KERNEL);
	if (data == NULL)
		return NULL;

	*data = ((struct pty_chan) { .announce  	= opts->announce,
				     .dev  		= device,
				     .raw  		= opts->raw });
	return data;
}

static int pts_open(int input, int output, int primary, void *d,
		    char **dev_out)
{
	struct pty_chan *data = d;
	char *dev;
	int fd, err;

	fd = get_pty();
	if (fd < 0) {
		err = -errno;
		printk(UM_KERN_ERR "open_pts : Failed to open pts\n");
		return err;
	}

	if (data->raw) {
		CATCH_EINTR(err = tcgetattr(fd, &data->tt));
		if (err)
			goto out_close;

		err = raw(fd);
		if (err)
			goto out_close;
	}

	dev = ptsname(fd);
	sprintf(data->dev_name, "%s", dev);
	*dev_out = data->dev_name;

	if (data->announce)
		(*data->announce)(dev, data->dev);

	return fd;

out_close:
	close(fd);
	return err;
}

static int getmaster(char *line)
{
	struct stat buf;
	char *pty, *bank, *cp;
	int master, err;

	pty = &line[strlen("/dev/ptyp")];
	for (bank = "pqrs"; *bank; bank++) {
		line[strlen("/dev/pty")] = *bank;
		*pty = '0';
		/* Did we hit the end ? */
		if ((stat(line, &buf) < 0) && (errno == ENOENT))
			break;

		for (cp = "0123456789abcdef"; *cp; cp++) {
			*pty = *cp;
			master = open(line, O_RDWR);
			if (master >= 0) {
				char *tp = &line[strlen("/dev/")];

				/* verify slave side is usable */
				*tp = 't';
				err = access(line, R_OK | W_OK);
				*tp = 'p';
				if (!err)
					return master;
				close(master);
			}
		}
	}

	printk(UM_KERN_ERR "getmaster - no usable host pty devices\n");
	return -ENOENT;
}

static int pty_open(int input, int output, int primary, void *d,
		    char **dev_out)
{
	struct pty_chan *data = d;
	int fd, err;
	char dev[sizeof("/dev/ptyxx\0")] = "/dev/ptyxx";

	fd = getmaster(dev);
	if (fd < 0)
		return fd;

	if (data->raw) {
		err = raw(fd);
		if (err) {
			close(fd);
			return err;
		}
	}

	if (data->announce)
		(*data->announce)(dev, data->dev);

	sprintf(data->dev_name, "%s", dev);
	*dev_out = data->dev_name;

	return fd;
}

const struct chan_ops pty_ops = {
	.type		= "pty",
	.init		= pty_chan_init,
	.open		= pty_open,
	.close		= generic_close,
	.read		= generic_read,
	.write		= generic_write,
	.console_write	= generic_console_write,
	.window_size	= generic_window_size,
	.free		= generic_free,
	.winch		= 0,
};

const struct chan_ops pts_ops = {
	.type		= "pts",
	.init		= pty_chan_init,
	.open		= pts_open,
	.close		= generic_close,
	.read		= generic_read,
	.write		= generic_write,
	.console_write	= generic_console_write,
	.window_size	= generic_window_size,
	.free		= generic_free,
	.winch		= 0,
};