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 "user_util.h" 17 #include "os.h" 18 #include "um_malloc.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 /* Debugging aid, changed only from gdb */ 29 int helper_pause = 0; 30 31 static void helper_hup(int sig) 32 { 33 } 34 35 static int helper_child(void *arg) 36 { 37 struct helper_data *data = arg; 38 char **argv = data->argv; 39 int errval; 40 41 if (helper_pause){ 42 signal(SIGHUP, helper_hup); 43 pause(); 44 } 45 if (data->pre_exec != NULL) 46 (*data->pre_exec)(data->pre_data); 47 errval = execvp_noalloc(data->buf, argv[0], argv); 48 printk("helper_child - execvp of '%s' failed - errno = %d\n", argv[0], -errval); 49 os_write_file(data->fd, &errval, sizeof(errval)); 50 kill(os_getpid(), SIGKILL); 51 return 0; 52 } 53 54 /* Returns either the pid of the child process we run or -E* on failure. 55 * XXX The alloc_stack here breaks if this is called in the tracing thread, so 56 * we need to receive a preallocated stack (a local buffer is ok). */ 57 int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv, 58 unsigned long *stack_out) 59 { 60 struct helper_data data; 61 unsigned long stack, sp; 62 int pid, fds[2], ret, n; 63 64 if ((stack_out != NULL) && (*stack_out != 0)) 65 stack = *stack_out; 66 else 67 stack = alloc_stack(0, __cant_sleep()); 68 if (stack == 0) 69 return -ENOMEM; 70 71 ret = os_pipe(fds, 1, 0); 72 if (ret < 0) { 73 printk("run_helper : pipe failed, ret = %d\n", -ret); 74 goto out_free; 75 } 76 77 ret = os_set_exec_close(fds[1], 1); 78 if (ret < 0) { 79 printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n", 80 -ret); 81 goto out_close; 82 } 83 84 sp = stack + page_size() - sizeof(void *); 85 data.pre_exec = pre_exec; 86 data.pre_data = pre_data; 87 data.argv = argv; 88 data.fd = fds[1]; 89 data.buf = __cant_sleep() ? um_kmalloc_atomic(PATH_MAX) : 90 um_kmalloc(PATH_MAX); 91 pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data); 92 if (pid < 0) { 93 ret = -errno; 94 printk("run_helper : clone failed, errno = %d\n", errno); 95 goto out_free2; 96 } 97 98 close(fds[1]); 99 fds[1] = -1; 100 101 /* Read the errno value from the child, if the exec failed, or get 0 if 102 * the exec succeeded because the pipe fd was set as close-on-exec. */ 103 n = os_read_file(fds[0], &ret, sizeof(ret)); 104 if (n == 0) { 105 ret = pid; 106 } else { 107 if (n < 0) { 108 printk("run_helper : read on pipe failed, ret = %d\n", 109 -n); 110 ret = n; 111 kill(pid, SIGKILL); 112 } 113 CATCH_EINTR(waitpid(pid, NULL, 0)); 114 } 115 116 out_free2: 117 kfree(data.buf); 118 out_close: 119 if (fds[1] != -1) 120 close(fds[1]); 121 close(fds[0]); 122 out_free: 123 if ((stack_out == NULL) || (*stack_out == 0)) 124 free_stack(stack, 0); 125 return ret; 126 } 127 128 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, 129 unsigned long *stack_out, int stack_order) 130 { 131 unsigned long stack, sp; 132 int pid, status, err; 133 134 stack = alloc_stack(stack_order, __cant_sleep()); 135 if (stack == 0) 136 return -ENOMEM; 137 138 sp = stack + (page_size() << stack_order) - sizeof(void *); 139 pid = clone(proc, (void *) sp, flags | SIGCHLD, arg); 140 if (pid < 0) { 141 err = -errno; 142 printk("run_helper_thread : clone failed, errno = %d\n", 143 errno); 144 return err; 145 } 146 if (stack_out == NULL) { 147 CATCH_EINTR(pid = waitpid(pid, &status, 0)); 148 if (pid < 0) { 149 err = -errno; 150 printk("run_helper_thread - wait failed, errno = %d\n", 151 errno); 152 pid = err; 153 } 154 if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) 155 printk("run_helper_thread - thread returned status " 156 "0x%x\n", status); 157 free_stack(stack, stack_order); 158 } else 159 *stack_out = stack; 160 return pid; 161 } 162 163 int helper_wait(int pid) 164 { 165 int ret; 166 167 CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG)); 168 if (ret < 0) { 169 ret = -errno; 170 printk("helper_wait : waitpid failed, errno = %d\n", errno); 171 } 172 return ret; 173 } 174