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