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 unsigned long *stack_out) 49 { 50 struct helper_data data; 51 unsigned long stack, sp; 52 int pid, fds[2], ret, n; 53 54 if ((stack_out != NULL) && (*stack_out != 0)) 55 stack = *stack_out; 56 else 57 stack = alloc_stack(0, __cant_sleep()); 58 if (stack == 0) 59 return -ENOMEM; 60 61 ret = os_pipe(fds, 1, 0); 62 if (ret < 0) { 63 printk("run_helper : pipe failed, ret = %d\n", -ret); 64 goto out_free; 65 } 66 67 ret = os_set_exec_close(fds[1], 1); 68 if (ret < 0) { 69 printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n", 70 -ret); 71 goto out_close; 72 } 73 74 sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *); 75 data.pre_exec = pre_exec; 76 data.pre_data = pre_data; 77 data.argv = argv; 78 data.fd = fds[1]; 79 data.buf = __cant_sleep() ? um_kmalloc_atomic(PATH_MAX) : 80 um_kmalloc(PATH_MAX); 81 pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data); 82 if (pid < 0) { 83 ret = -errno; 84 printk("run_helper : clone failed, errno = %d\n", errno); 85 goto out_free2; 86 } 87 88 close(fds[1]); 89 fds[1] = -1; 90 91 /* 92 * Read the errno value from the child, if the exec failed, or get 0 if 93 * the exec succeeded because the pipe fd was set as close-on-exec. 94 */ 95 n = read(fds[0], &ret, sizeof(ret)); 96 if (n == 0) { 97 ret = pid; 98 } else { 99 if (n < 0) { 100 n = -errno; 101 printk("run_helper : read on pipe failed, ret = %d\n", 102 -n); 103 ret = n; 104 kill(pid, SIGKILL); 105 } 106 CATCH_EINTR(waitpid(pid, NULL, 0)); 107 } 108 109 out_free2: 110 kfree(data.buf); 111 out_close: 112 if (fds[1] != -1) 113 close(fds[1]); 114 close(fds[0]); 115 out_free: 116 if ((stack_out == NULL) || (*stack_out == 0)) 117 free_stack(stack, 0); 118 return ret; 119 } 120 121 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 122 unsigned long *stack_out, int stack_order) 123 { 124 unsigned long stack, sp; 125 int pid, status, err; 126 127 stack = alloc_stack(stack_order, __cant_sleep()); 128 if (stack == 0) 129 return -ENOMEM; 130 131 sp = stack + (UM_KERN_PAGE_SIZE << stack_order) - sizeof(void *); 132 pid = clone(proc, (void *) sp, flags | SIGCHLD, arg); 133 if (pid < 0) { 134 err = -errno; 135 printk("run_helper_thread : clone failed, errno = %d\n", 136 errno); 137 return err; 138 } 139 if (stack_out == NULL) { 140 CATCH_EINTR(pid = waitpid(pid, &status, 0)); 141 if (pid < 0) { 142 err = -errno; 143 printk("run_helper_thread - wait failed, errno = %d\n", 144 errno); 145 pid = err; 146 } 147 if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) 148 printk("run_helper_thread - thread returned status " 149 "0x%x\n", status); 150 free_stack(stack, stack_order); 151 } else 152 *stack_out = stack; 153 return pid; 154 } 155 156 int helper_wait(int pid) 157 { 158 int ret; 159 160 CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG)); 161 if (ret < 0) { 162 ret = -errno; 163 printk("helper_wait : waitpid failed, errno = %d\n", errno); 164 } 165 return ret; 166 } 167