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 20 struct helper_data { 21 void (*pre_exec)(void*); 22 void *pre_data; 23 char **argv; 24 int fd; 25 char *buf; 26 }; 27 28 static 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 44 /* Returns either the pid of the child process we run or -E* on failure. 45 * XXX The alloc_stack here breaks if this is called in the tracing thread, so 46 * we need to receive a preallocated stack (a local buffer is ok). */ 47 int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) 48 { 49 struct helper_data data; 50 unsigned long stack, sp; 51 int pid, fds[2], ret, n; 52 53 stack = alloc_stack(0, __cant_sleep()); 54 if (stack == 0) 55 return -ENOMEM; 56 57 ret = os_pipe(fds, 1, 0); 58 if (ret < 0) { 59 printk("run_helper : pipe failed, ret = %d\n", -ret); 60 goto out_free; 61 } 62 63 ret = os_set_exec_close(fds[1], 1); 64 if (ret < 0) { 65 printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n", 66 -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() ? kmalloc(PATH_MAX, UM_GFP_ATOMIC) : 76 kmalloc(PATH_MAX, UM_GFP_KERNEL); 77 pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data); 78 if (pid < 0) { 79 ret = -errno; 80 printk("run_helper : clone failed, errno = %d\n", errno); 81 goto out_free2; 82 } 83 84 close(fds[1]); 85 fds[1] = -1; 86 87 /* 88 * Read the errno value from the child, if the exec failed, or get 0 if 89 * the exec succeeded because the pipe fd was set as close-on-exec. 90 */ 91 n = read(fds[0], &ret, sizeof(ret)); 92 if (n == 0) { 93 ret = pid; 94 } else { 95 if (n < 0) { 96 n = -errno; 97 printk("run_helper : read on pipe failed, ret = %d\n", 98 -n); 99 ret = n; 100 kill(pid, SIGKILL); 101 } 102 CATCH_EINTR(waitpid(pid, NULL, 0)); 103 } 104 105 out_free2: 106 kfree(data.buf); 107 out_close: 108 if (fds[1] != -1) 109 close(fds[1]); 110 close(fds[0]); 111 out_free: 112 free_stack(stack, 0); 113 return ret; 114 } 115 116 int 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 | SIGCHLD, arg); 128 if (pid < 0) { 129 err = -errno; 130 printk("run_helper_thread : clone failed, errno = %d\n", 131 errno); 132 return err; 133 } 134 if (stack_out == NULL) { 135 CATCH_EINTR(pid = waitpid(pid, &status, 0)); 136 if (pid < 0) { 137 err = -errno; 138 printk("run_helper_thread - wait failed, errno = %d\n", 139 errno); 140 pid = err; 141 } 142 if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) 143 printk("run_helper_thread - thread returned status " 144 "0x%x\n", status); 145 free_stack(stack, 0); 146 } else 147 *stack_out = stack; 148 return pid; 149 } 150 151 int helper_wait(int pid) 152 { 153 int ret; 154 155 CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG)); 156 if (ret < 0) { 157 ret = -errno; 158 printk("helper_wait : waitpid failed, errno = %d\n", errno); 159 } 160 return ret; 161 } 162