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 <sys/socket.h> 15 #include "user.h" 16 #include "kern_util.h" 17 #include "os.h" 18 #include "um_malloc.h" 19 #include "kern_constants.h" 20 21 struct helper_data { 22 void (*pre_exec)(void*); 23 void *pre_data; 24 char **argv; 25 int fd; 26 char *buf; 27 }; 28 29 static int helper_child(void *arg) 30 { 31 struct helper_data *data = arg; 32 char **argv = data->argv; 33 int errval; 34 35 if (data->pre_exec != NULL) 36 (*data->pre_exec)(data->pre_data); 37 errval = execvp_noalloc(data->buf, argv[0], argv); 38 printk("helper_child - execvp of '%s' failed - errno = %d\n", argv[0], 39 -errval); 40 write(data->fd, &errval, sizeof(errval)); 41 kill(os_getpid(), SIGKILL); 42 return 0; 43 } 44 45 /* Returns either the pid of the child process we run or -E* on failure. 46 * XXX The alloc_stack here breaks if this is called in the tracing thread, so 47 * we need to receive a preallocated stack (a local buffer is ok). */ 48 int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) 49 { 50 struct helper_data data; 51 unsigned long stack, sp; 52 int pid, fds[2], ret, n; 53 54 stack = alloc_stack(0, __cant_sleep()); 55 if (stack == 0) 56 return -ENOMEM; 57 58 ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds); 59 if (ret < 0) { 60 ret = -errno; 61 printk("run_helper : pipe failed, errno = %d\n", errno); 62 goto out_free; 63 } 64 65 ret = os_set_exec_close(fds[1]); 66 if (ret < 0) { 67 printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n", 68 -ret); 69 goto out_close; 70 } 71 72 sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *); 73 data.pre_exec = pre_exec; 74 data.pre_data = pre_data; 75 data.argv = argv; 76 data.fd = fds[1]; 77 data.buf = __cant_sleep() ? kmalloc(PATH_MAX, UM_GFP_ATOMIC) : 78 kmalloc(PATH_MAX, UM_GFP_KERNEL); 79 pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data); 80 if (pid < 0) { 81 ret = -errno; 82 printk("run_helper : clone failed, errno = %d\n", errno); 83 goto out_free2; 84 } 85 86 close(fds[1]); 87 fds[1] = -1; 88 89 /* 90 * Read the errno value from the child, if the exec failed, or get 0 if 91 * the exec succeeded because the pipe fd was set as close-on-exec. 92 */ 93 n = read(fds[0], &ret, sizeof(ret)); 94 if (n == 0) { 95 ret = pid; 96 } else { 97 if (n < 0) { 98 n = -errno; 99 printk("run_helper : read on pipe failed, ret = %d\n", 100 -n); 101 ret = n; 102 kill(pid, SIGKILL); 103 } 104 CATCH_EINTR(waitpid(pid, NULL, 0)); 105 } 106 107 out_free2: 108 kfree(data.buf); 109 out_close: 110 if (fds[1] != -1) 111 close(fds[1]); 112 close(fds[0]); 113 out_free: 114 free_stack(stack, 0); 115 return ret; 116 } 117 118 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 119 unsigned long *stack_out) 120 { 121 unsigned long stack, sp; 122 int pid, status, err; 123 124 stack = alloc_stack(0, __cant_sleep()); 125 if (stack == 0) 126 return -ENOMEM; 127 128 sp = stack + UM_KERN_PAGE_SIZE - 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, 0); 148 } else 149 *stack_out = stack; 150 return pid; 151 } 152 153 int 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