1/*
2 * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
4 */
5
6#include <stdio.h>
7#include <stdlib.h>
8#include <unistd.h>
9#include <errno.h>
10#include <sched.h>
11#include <limits.h>
12#include <sys/signal.h>
13#include <sys/wait.h>
14#include "user.h"
15#include "kern_util.h"
16#include "os.h"
17#include "um_malloc.h"
18#include "kern_constants.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 errval;
33
34	if (data->pre_exec != NULL)
35		(*data->pre_exec)(data->pre_data);
36	errval = execvp_noalloc(data->buf, argv[0], argv);
37	printk("helper_child - execvp of '%s' failed - errno = %d\n", argv[0],
38	       -errval);
39	write(data->fd, &errval, sizeof(errval));
40	kill(os_getpid(), SIGKILL);
41	return 0;
42}
43
44int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
45	       unsigned long *stack_out)
46{
47	struct helper_data data;
48	unsigned long stack, sp;
49	int pid, fds[2], ret, n;
50
51	if ((stack_out != NULL) && (*stack_out != 0))
52		stack = *stack_out;
53	else
54		stack = alloc_stack(0, __cant_sleep());
55	if (stack == 0)
56		return -ENOMEM;
57
58	ret = os_pipe(fds, 1, 0);
59	if (ret < 0) {
60		printk("run_helper : pipe failed, ret = %d\n", -ret);
61		goto out_free;
62	}
63
64	ret = os_set_exec_close(fds[1], 1);
65	if (ret < 0) {
66		printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n",
67		       -ret);
68		goto out_close;
69	}
70
71	sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
72	data.pre_exec = pre_exec;
73	data.pre_data = pre_data;
74	data.argv = argv;
75	data.fd = fds[1];
76	data.buf = __cant_sleep() ? um_kmalloc_atomic(PATH_MAX) :
77					um_kmalloc(PATH_MAX);
78	pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data);
79	if (pid < 0) {
80		ret = -errno;
81		printk("run_helper : clone failed, errno = %d\n", 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("run_helper : read on pipe failed, ret = %d\n",
99			       -n);
100			ret = n;
101			kill(pid, SIGKILL);
102		}
103		CATCH_EINTR(waitpid(pid, NULL, 0));
104	}
105
106out_free2:
107	kfree(data.buf);
108out_close:
109	if (fds[1] != -1)
110		close(fds[1]);
111	close(fds[0]);
112out_free:
113	if ((stack_out == NULL) || (*stack_out == 0))
114		free_stack(stack, 0);
115	return ret;
116}
117
118int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
119		      unsigned long *stack_out, int stack_order)
120{
121	unsigned long stack, sp;
122	int pid, status, err;
123
124	stack = alloc_stack(stack_order, __cant_sleep());
125	if (stack == 0)
126		return -ENOMEM;
127
128	sp = stack + (UM_KERN_PAGE_SIZE << stack_order) - sizeof(void *);
129	pid = clone(proc, (void *) sp, flags | SIGCHLD, arg);
130	if (pid < 0) {
131		err = -errno;
132		printk("run_helper_thread : clone failed, errno = %d\n",
133		       errno);
134		return err;
135	}
136	if (stack_out == NULL) {
137		CATCH_EINTR(pid = waitpid(pid, &status, 0));
138		if (pid < 0) {
139			err = -errno;
140			printk("run_helper_thread - wait failed, errno = %d\n",
141			       errno);
142			pid = err;
143		}
144		if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
145			printk("run_helper_thread - thread returned status "
146			       "0x%x\n", status);
147		free_stack(stack, stack_order);
148	} else
149		*stack_out = stack;
150	return pid;
151}
152
153int helper_wait(int pid)
154{
155	int ret;
156
157	CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG));
158	if (ret < 0) {
159		ret = -errno;
160		printk("helper_wait : waitpid failed, errno = %d\n", errno);
161	}
162	return ret;
163}
164