1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <stdio.h>
7#include <unistd.h>
8#include <errno.h>
9#include <os.h>
10#include "harddog.h"
11
12struct dog_data {
13 int stdin_fd;
14 int stdout_fd;
15 int close_me[2];
16};
17
18static void pre_exec(void *d)
19{
20 struct dog_data *data = d;
21
22 dup2(data->stdin_fd, 0);
23 dup2(data->stdout_fd, 1);
24 dup2(data->stdout_fd, 2);
25 close(data->stdin_fd);
26 close(data->stdout_fd);
27 close(data->close_me[0]);
28 close(data->close_me[1]);
29}
30
31int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock)
32{
33 struct dog_data data;
34 int in_fds[2], out_fds[2], pid, n, err;
35 char pid_buf[sizeof("nnnnnnn\0")], c;
36 char *pid_args[] = { "/usr/bin/uml_watchdog", "-pid", pid_buf, NULL };
37 char *mconsole_args[] = { "/usr/bin/uml_watchdog", "-mconsole", NULL,
38 NULL };
39 char **args = NULL;
40
41 err = os_pipe(in_fds, 1, 0);
42 if (err < 0) {
43 printk("harddog_open - os_pipe failed, err = %d\n", -err);
44 goto out;
45 }
46
47 err = os_pipe(out_fds, 1, 0);
48 if (err < 0) {
49 printk("harddog_open - os_pipe failed, err = %d\n", -err);
50 goto out_close_in;
51 }
52
53 data.stdin_fd = out_fds[0];
54 data.stdout_fd = in_fds[1];
55 data.close_me[0] = out_fds[1];
56 data.close_me[1] = in_fds[0];
57
58 if (sock != NULL) {
59 mconsole_args[2] = sock;
60 args = mconsole_args;
61 }
62 else {
63 /* XXX The os_getpid() is not SMP correct */
64 sprintf(pid_buf, "%d", os_getpid());
65 args = pid_args;
66 }
67
68 pid = run_helper(pre_exec, &data, args);
69
70 close(out_fds[0]);
71 close(in_fds[1]);
72
73 if (pid < 0) {
74 err = -pid;
75 printk("harddog_open - run_helper failed, errno = %d\n", -err);
76 goto out_close_out;
77 }
78
79 n = read(in_fds[0], &c, sizeof(c));
80 if (n == 0) {
81 printk("harddog_open - EOF on watchdog pipe\n");
82 helper_wait(pid);
83 err = -EIO;
84 goto out_close_out;
85 }
86 else if (n < 0) {
87 printk("harddog_open - read of watchdog pipe failed, "
88 "err = %d\n", errno);
89 helper_wait(pid);
90 err = n;
91 goto out_close_out;
92 }
93 *in_fd_ret = in_fds[0];
94 *out_fd_ret = out_fds[1];
95 return 0;
96
97 out_close_in:
98 close(in_fds[0]);
99 close(in_fds[1]);
100 out_close_out:
101 close(out_fds[0]);
102 close(out_fds[1]);
103 out:
104 return err;
105}
106
107void stop_watchdog(int in_fd, int out_fd)
108{
109 close(in_fd);
110 close(out_fd);
111}
112
113int ping_watchdog(int fd)
114{
115 int n;
116 char c = '\n';
117
118 n = write(fd, &c, sizeof(c));
119 if (n != sizeof(c)) {
120 printk("ping_watchdog - write failed, ret = %d, err = %d\n",
121 n, errno);
122 if (n < 0)
123 return n;
124 return -EIO;
125 }
126 return 1;
127
128}
129

source code of linux/arch/um/drivers/harddog_user.c