xref: /linux/arch/um/drivers/pty.c (revision 976e3645923bdd2fe7893aae33fd7a21098bfb28)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  */
5 
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <unistd.h>
9 #include <errno.h>
10 #include <fcntl.h>
11 #include <string.h>
12 #include <termios.h>
13 #include <sys/stat.h>
14 #include "chan_user.h"
15 #include <os.h>
16 #include <um_malloc.h>
17 
18 struct pty_chan {
19 	void (*announce)(char *dev_name, int dev);
20 	int dev;
21 	int raw;
22 	struct termios tt;
23 	char dev_name[sizeof("/dev/pts/0123456\0")];
24 };
25 
pty_chan_init(char * str,int device,const struct chan_opts * opts)26 static void *pty_chan_init(char *str, int device, const struct chan_opts *opts)
27 {
28 	struct pty_chan *data;
29 
30 	data = uml_kmalloc(sizeof(*data), UM_GFP_KERNEL);
31 	if (data == NULL)
32 		return NULL;
33 
34 	*data = ((struct pty_chan) { .announce  	= opts->announce,
35 				     .dev  		= device,
36 				     .raw  		= opts->raw });
37 	return data;
38 }
39 
pts_open(int input,int output,int primary,void * d,char ** dev_out)40 static int pts_open(int input, int output, int primary, void *d,
41 		    char **dev_out)
42 {
43 	struct pty_chan *data = d;
44 	char *dev;
45 	int fd, err;
46 
47 	fd = get_pty();
48 	if (fd < 0) {
49 		err = -errno;
50 		printk(UM_KERN_ERR "open_pts : Failed to open pts\n");
51 		return err;
52 	}
53 
54 	if (data->raw) {
55 		CATCH_EINTR(err = tcgetattr(fd, &data->tt));
56 		if (err)
57 			goto out_close;
58 
59 		err = raw(fd);
60 		if (err)
61 			goto out_close;
62 	}
63 
64 	dev = ptsname(fd);
65 	sprintf(data->dev_name, "%s", dev);
66 	*dev_out = data->dev_name;
67 
68 	if (data->announce)
69 		(*data->announce)(dev, data->dev);
70 
71 	return fd;
72 
73 out_close:
74 	close(fd);
75 	return err;
76 }
77 
getmaster(char * line)78 static int getmaster(char *line)
79 {
80 	struct stat buf;
81 	char *pty, *bank, *cp;
82 	int master, err;
83 
84 	pty = &line[strlen("/dev/ptyp")];
85 	for (bank = "pqrs"; *bank; bank++) {
86 		line[strlen("/dev/pty")] = *bank;
87 		*pty = '0';
88 		/* Did we hit the end ? */
89 		if ((stat(line, &buf) < 0) && (errno == ENOENT))
90 			break;
91 
92 		for (cp = "0123456789abcdef"; *cp; cp++) {
93 			*pty = *cp;
94 			master = open(line, O_RDWR);
95 			if (master >= 0) {
96 				char *tp = &line[strlen("/dev/")];
97 
98 				/* verify slave side is usable */
99 				*tp = 't';
100 				err = access(line, R_OK | W_OK);
101 				*tp = 'p';
102 				if (!err)
103 					return master;
104 				close(master);
105 			}
106 		}
107 	}
108 
109 	printk(UM_KERN_ERR "getmaster - no usable host pty devices\n");
110 	return -ENOENT;
111 }
112 
pty_open(int input,int output,int primary,void * d,char ** dev_out)113 static int pty_open(int input, int output, int primary, void *d,
114 		    char **dev_out)
115 {
116 	struct pty_chan *data = d;
117 	int fd, err;
118 	char dev[sizeof("/dev/ptyxx\0")] = "/dev/ptyxx";
119 
120 	fd = getmaster(dev);
121 	if (fd < 0)
122 		return fd;
123 
124 	if (data->raw) {
125 		err = raw(fd);
126 		if (err) {
127 			close(fd);
128 			return err;
129 		}
130 	}
131 
132 	if (data->announce)
133 		(*data->announce)(dev, data->dev);
134 
135 	sprintf(data->dev_name, "%s", dev);
136 	*dev_out = data->dev_name;
137 
138 	return fd;
139 }
140 
141 const struct chan_ops pty_ops = {
142 	.type		= "pty",
143 	.init		= pty_chan_init,
144 	.open		= pty_open,
145 	.close		= generic_close,
146 	.read		= generic_read,
147 	.write		= generic_write,
148 	.console_write	= generic_console_write,
149 	.window_size	= generic_window_size,
150 	.free		= generic_free,
151 	.winch		= 0,
152 };
153 
154 const struct chan_ops pts_ops = {
155 	.type		= "pts",
156 	.init		= pty_chan_init,
157 	.open		= pts_open,
158 	.close		= generic_close,
159 	.read		= generic_read,
160 	.write		= generic_write,
161 	.console_write	= generic_console_write,
162 	.window_size	= generic_window_size,
163 	.free		= generic_free,
164 	.winch		= 0,
165 };
166