/* * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) * Licensed under the GPL */ #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <sched.h> #include <linux/limits.h> #include <sys/socket.h> #include <sys/wait.h> #include <kern_util.h> #include <os.h> #include <um_malloc.h> struct helper_data { void (*pre_exec)(void*); void *pre_data; char **argv; int fd; char *buf; }; static int helper_child(void *arg) { struct helper_data *data = arg; char **argv = data->argv; int err, ret; if (data->pre_exec != NULL) (*data->pre_exec)(data->pre_data); err = execvp_noalloc(data->buf, argv[0], argv); /* If the exec succeeds, we don't get here */ CATCH_EINTR(ret = write(data->fd, &err, sizeof(err))); return 0; } /* Returns either the pid of the child process we run or -E* on failure. */ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) { struct helper_data data; unsigned long stack, sp; int pid, fds[2], ret, n; stack = alloc_stack(0, __cant_sleep()); if (stack == 0) return -ENOMEM; ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds); if (ret < 0) { ret = -errno; printk(UM_KERN_ERR "run_helper : pipe failed, errno = %d\n", errno); goto out_free; } ret = os_set_exec_close(fds[1]); if (ret < 0) { printk(UM_KERN_ERR "run_helper : setting FD_CLOEXEC failed, " "ret = %d\n", -ret); goto out_close; } sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *); data.pre_exec = pre_exec; data.pre_data = pre_data; data.argv = argv; data.fd = fds[1]; data.buf = __cant_sleep() ? uml_kmalloc(PATH_MAX, UM_GFP_ATOMIC) : uml_kmalloc(PATH_MAX, UM_GFP_KERNEL); pid = clone(helper_child, (void *) sp, CLONE_VM, &data); if (pid < 0) { ret = -errno; printk(UM_KERN_ERR "run_helper : clone failed, errno = %d\n", errno); goto out_free2; } close(fds[1]); fds[1] = -1; /* * Read the errno value from the child, if the exec failed, or get 0 if * the exec succeeded because the pipe fd was set as close-on-exec. */ n = read(fds[0], &ret, sizeof(ret)); if (n == 0) { ret = pid; } else { if (n < 0) { n = -errno; printk(UM_KERN_ERR "run_helper : read on pipe failed, " "ret = %d\n", -n); ret = n; } CATCH_EINTR(waitpid(pid, NULL, __WCLONE)); } out_free2: kfree(data.buf); out_close: if (fds[1] != -1) close(fds[1]); close(fds[0]); out_free: free_stack(stack, 0); return ret; } int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, unsigned long *stack_out) { unsigned long stack, sp; int pid, status, err; stack = alloc_stack(0, __cant_sleep()); if (stack == 0) return -ENOMEM; sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *); pid = clone(proc, (void *) sp, flags, arg); if (pid < 0) { err = -errno; printk(UM_KERN_ERR "run_helper_thread : clone failed, " "errno = %d\n", errno); return err; } if (stack_out == NULL) { CATCH_EINTR(pid = waitpid(pid, &status, __WCLONE)); if (pid < 0) { err = -errno; printk(UM_KERN_ERR "run_helper_thread - wait failed, " "errno = %d\n", errno); pid = err; } if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) printk(UM_KERN_ERR "run_helper_thread - thread " "returned status 0x%x\n", status); free_stack(stack, 0); } else *stack_out = stack; return pid; } int helper_wait(int pid) { int ret, status; int wflags = __WCLONE; CATCH_EINTR(ret = waitpid(pid, &status, wflags)); if (ret < 0) { printk(UM_KERN_ERR "helper_wait : waitpid process %d failed, " "errno = %d\n", pid, errno); return -errno; } else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { printk(UM_KERN_ERR "helper_wait : process %d exited with " "status 0x%x\n", pid, status); return -ECHILD; } else return 0; }