1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
/*
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sched.h>
#include <linux/limits.h>
#include <linux/slab.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include "kern_constants.h"
#include "kern_util.h"
#include "os.h"
#include "um_malloc.h"
#include "user.h"
struct helper_data {
void (*pre_exec)(void*);
void *pre_data;
char **argv;
int fd;
char *buf;
};
static int helper_child(void *arg)
{
struct helper_data *data = arg;
char **argv = data->argv;
int err;
if (data->pre_exec != NULL)
(*data->pre_exec)(data->pre_data);
err = execvp_noalloc(data->buf, argv[0], argv);
/* If the exec succeeds, we don't get here */
write(data->fd, &err, sizeof(err));
return 0;
}
/* Returns either the pid of the child process we run or -E* on failure. */
int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
{
struct helper_data data;
unsigned long stack, sp;
int pid, fds[2], ret, n;
stack = alloc_stack(0, __cant_sleep());
if (stack == 0)
return -ENOMEM;
ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
if (ret < 0) {
ret = -errno;
printk(UM_KERN_ERR "run_helper : pipe failed, errno = %d\n",
errno);
goto out_free;
}
ret = os_set_exec_close(fds[1]);
if (ret < 0) {
printk(UM_KERN_ERR "run_helper : setting FD_CLOEXEC failed, "
"ret = %d\n", -ret);
goto out_close;
}
sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
data.pre_exec = pre_exec;
data.pre_data = pre_data;
data.argv = argv;
data.fd = fds[1];
data.buf = __cant_sleep() ? uml_kmalloc(PATH_MAX, UM_GFP_ATOMIC) :
uml_kmalloc(PATH_MAX, UM_GFP_KERNEL);
pid = clone(helper_child, (void *) sp, CLONE_VM, &data);
if (pid < 0) {
ret = -errno;
printk(UM_KERN_ERR "run_helper : clone failed, errno = %d\n",
errno);
goto out_free2;
}
close(fds[1]);
fds[1] = -1;
/*
* Read the errno value from the child, if the exec failed, or get 0 if
* the exec succeeded because the pipe fd was set as close-on-exec.
*/
n = read(fds[0], &ret, sizeof(ret));
if (n == 0) {
ret = pid;
} else {
if (n < 0) {
n = -errno;
printk(UM_KERN_ERR "run_helper : read on pipe failed, "
"ret = %d\n", -n);
ret = n;
}
CATCH_EINTR(waitpid(pid, NULL, __WCLONE));
}
out_free2:
kfree(data.buf);
out_close:
if (fds[1] != -1)
close(fds[1]);
close(fds[0]);
out_free:
free_stack(stack, 0);
return ret;
}
int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
unsigned long *stack_out)
{
unsigned long stack, sp;
int pid, status, err;
stack = alloc_stack(0, __cant_sleep());
if (stack == 0)
return -ENOMEM;
sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
pid = clone(proc, (void *) sp, flags, arg);
if (pid < 0) {
err = -errno;
printk(UM_KERN_ERR "run_helper_thread : clone failed, "
"errno = %d\n", errno);
return err;
}
if (stack_out == NULL) {
CATCH_EINTR(pid = waitpid(pid, &status, __WCLONE));
if (pid < 0) {
err = -errno;
printk(UM_KERN_ERR "run_helper_thread - wait failed, "
"errno = %d\n", errno);
pid = err;
}
if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
printk(UM_KERN_ERR "run_helper_thread - thread "
"returned status 0x%x\n", status);
free_stack(stack, 0);
} else
*stack_out = stack;
return pid;
}
int helper_wait(int pid)
{
int ret, status;
int wflags = __WCLONE;
CATCH_EINTR(ret = waitpid(pid, &status, wflags));
if (ret < 0) {
printk(UM_KERN_ERR "helper_wait : waitpid process %d failed, "
"errno = %d\n", pid, errno);
return -errno;
} else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
printk(UM_KERN_ERR "helper_wait : process %d exited with "
"status 0x%x\n", pid, status);
return -ECHILD;
} else
return 0;
}
|
