diff options
Diffstat (limited to 'arch/um/os-Linux/helper.c')
| -rw-r--r-- | arch/um/os-Linux/helper.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c new file mode 100644 index 00000000..b6b10961 --- /dev/null +++ b/arch/um/os-Linux/helper.c @@ -0,0 +1,166 @@ +/* + * 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_constants.h" +#include "kern_util.h" +#include "os.h" +#include "um_malloc.h" +#include "user.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; + + 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 */ + 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; +} |