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https://github.com/torvalds/linux.git
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0565103d1a
The reverse case of this race (you must msync before read) is well known. This is the not so common one. It can be triggered only on systems which do a lot of task switching and only at UML startup. If you are starting 200+ UMLs ~ 0.5% will always die without this fix. Signed-off-by: Anton Ivanov <antivano@cisco.com> [rw: minor whitespace fixes] Signed-off-by: Richard Weinberger <richard@nod.at>
592 lines
10 KiB
C
592 lines
10 KiB
C
/*
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* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <sys/ioctl.h>
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#include <sys/mount.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <sys/un.h>
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#include <os.h>
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static void copy_stat(struct uml_stat *dst, const struct stat64 *src)
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{
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*dst = ((struct uml_stat) {
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.ust_dev = src->st_dev, /* device */
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.ust_ino = src->st_ino, /* inode */
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.ust_mode = src->st_mode, /* protection */
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.ust_nlink = src->st_nlink, /* number of hard links */
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.ust_uid = src->st_uid, /* user ID of owner */
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.ust_gid = src->st_gid, /* group ID of owner */
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.ust_size = src->st_size, /* total size, in bytes */
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.ust_blksize = src->st_blksize, /* blocksize for filesys I/O */
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.ust_blocks = src->st_blocks, /* number of blocks allocated */
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.ust_atime = src->st_atime, /* time of last access */
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.ust_mtime = src->st_mtime, /* time of last modification */
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.ust_ctime = src->st_ctime, /* time of last change */
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});
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}
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int os_stat_fd(const int fd, struct uml_stat *ubuf)
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{
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struct stat64 sbuf;
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int err;
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CATCH_EINTR(err = fstat64(fd, &sbuf));
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if (err < 0)
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return -errno;
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if (ubuf != NULL)
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copy_stat(ubuf, &sbuf);
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return err;
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}
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int os_stat_file(const char *file_name, struct uml_stat *ubuf)
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{
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struct stat64 sbuf;
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int err;
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CATCH_EINTR(err = stat64(file_name, &sbuf));
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if (err < 0)
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return -errno;
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if (ubuf != NULL)
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copy_stat(ubuf, &sbuf);
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return err;
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}
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int os_access(const char *file, int mode)
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{
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int amode, err;
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amode = (mode & OS_ACC_R_OK ? R_OK : 0) |
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(mode & OS_ACC_W_OK ? W_OK : 0) |
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(mode & OS_ACC_X_OK ? X_OK : 0) |
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(mode & OS_ACC_F_OK ? F_OK : 0);
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err = access(file, amode);
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if (err < 0)
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return -errno;
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return 0;
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}
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/* FIXME? required only by hostaudio (because it passes ioctls verbatim) */
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int os_ioctl_generic(int fd, unsigned int cmd, unsigned long arg)
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{
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int err;
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err = ioctl(fd, cmd, arg);
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if (err < 0)
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return -errno;
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return err;
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}
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/* FIXME: ensure namebuf in os_get_if_name is big enough */
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int os_get_ifname(int fd, char* namebuf)
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{
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if (ioctl(fd, SIOCGIFNAME, namebuf) < 0)
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return -errno;
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return 0;
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}
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int os_set_slip(int fd)
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{
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int disc, sencap;
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disc = N_SLIP;
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if (ioctl(fd, TIOCSETD, &disc) < 0)
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return -errno;
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sencap = 0;
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if (ioctl(fd, SIOCSIFENCAP, &sencap) < 0)
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return -errno;
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return 0;
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}
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int os_mode_fd(int fd, int mode)
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{
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int err;
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CATCH_EINTR(err = fchmod(fd, mode));
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if (err < 0)
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return -errno;
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return 0;
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}
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int os_file_type(char *file)
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{
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struct uml_stat buf;
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int err;
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err = os_stat_file(file, &buf);
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if (err < 0)
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return err;
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if (S_ISDIR(buf.ust_mode))
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return OS_TYPE_DIR;
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else if (S_ISLNK(buf.ust_mode))
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return OS_TYPE_SYMLINK;
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else if (S_ISCHR(buf.ust_mode))
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return OS_TYPE_CHARDEV;
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else if (S_ISBLK(buf.ust_mode))
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return OS_TYPE_BLOCKDEV;
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else if (S_ISFIFO(buf.ust_mode))
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return OS_TYPE_FIFO;
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else if (S_ISSOCK(buf.ust_mode))
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return OS_TYPE_SOCK;
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else return OS_TYPE_FILE;
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}
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int os_file_mode(const char *file, struct openflags *mode_out)
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{
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int err;
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*mode_out = OPENFLAGS();
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err = access(file, W_OK);
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if (err && (errno != EACCES))
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return -errno;
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else if (!err)
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*mode_out = of_write(*mode_out);
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err = access(file, R_OK);
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if (err && (errno != EACCES))
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return -errno;
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else if (!err)
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*mode_out = of_read(*mode_out);
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return err;
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}
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int os_open_file(const char *file, struct openflags flags, int mode)
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{
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int fd, err, f = 0;
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if (flags.r && flags.w)
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f = O_RDWR;
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else if (flags.r)
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f = O_RDONLY;
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else if (flags.w)
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f = O_WRONLY;
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else f = 0;
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if (flags.s)
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f |= O_SYNC;
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if (flags.c)
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f |= O_CREAT;
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if (flags.t)
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f |= O_TRUNC;
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if (flags.e)
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f |= O_EXCL;
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if (flags.a)
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f |= O_APPEND;
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fd = open64(file, f, mode);
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if (fd < 0)
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return -errno;
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if (flags.cl && fcntl(fd, F_SETFD, 1)) {
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err = -errno;
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close(fd);
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return err;
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}
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return fd;
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}
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int os_connect_socket(const char *name)
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{
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struct sockaddr_un sock;
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int fd, err;
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sock.sun_family = AF_UNIX;
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snprintf(sock.sun_path, sizeof(sock.sun_path), "%s", name);
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fd = socket(AF_UNIX, SOCK_STREAM, 0);
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if (fd < 0) {
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err = -errno;
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goto out;
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}
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err = connect(fd, (struct sockaddr *) &sock, sizeof(sock));
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if (err) {
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err = -errno;
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goto out_close;
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}
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return fd;
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out_close:
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close(fd);
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out:
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return err;
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}
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void os_close_file(int fd)
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{
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close(fd);
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}
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int os_fsync_file(int fd)
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{
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if (fsync(fd) < 0)
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return -errno;
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return 0;
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}
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int os_seek_file(int fd, unsigned long long offset)
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{
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unsigned long long actual;
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actual = lseek64(fd, offset, SEEK_SET);
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if (actual != offset)
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return -errno;
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return 0;
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}
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int os_read_file(int fd, void *buf, int len)
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{
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int n = read(fd, buf, len);
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if (n < 0)
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return -errno;
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return n;
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}
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int os_write_file(int fd, const void *buf, int len)
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{
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int n = write(fd, (void *) buf, len);
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if (n < 0)
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return -errno;
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return n;
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}
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int os_sync_file(int fd)
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{
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int n = fsync(fd);
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if (n < 0)
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return -errno;
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return n;
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}
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int os_file_size(const char *file, unsigned long long *size_out)
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{
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struct uml_stat buf;
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int err;
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err = os_stat_file(file, &buf);
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if (err < 0) {
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printk(UM_KERN_ERR "Couldn't stat \"%s\" : err = %d\n", file,
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-err);
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return err;
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}
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if (S_ISBLK(buf.ust_mode)) {
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int fd;
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long blocks;
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fd = open(file, O_RDONLY, 0);
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if (fd < 0) {
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err = -errno;
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printk(UM_KERN_ERR "Couldn't open \"%s\", "
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"errno = %d\n", file, errno);
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return err;
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}
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if (ioctl(fd, BLKGETSIZE, &blocks) < 0) {
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err = -errno;
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printk(UM_KERN_ERR "Couldn't get the block size of "
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"\"%s\", errno = %d\n", file, errno);
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close(fd);
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return err;
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}
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*size_out = ((long long) blocks) * 512;
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close(fd);
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}
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else *size_out = buf.ust_size;
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return 0;
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}
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int os_file_modtime(const char *file, unsigned long *modtime)
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{
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struct uml_stat buf;
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int err;
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err = os_stat_file(file, &buf);
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if (err < 0) {
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printk(UM_KERN_ERR "Couldn't stat \"%s\" : err = %d\n", file,
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-err);
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return err;
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}
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*modtime = buf.ust_mtime;
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return 0;
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}
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int os_set_exec_close(int fd)
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{
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int err;
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CATCH_EINTR(err = fcntl(fd, F_SETFD, FD_CLOEXEC));
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if (err < 0)
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return -errno;
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return err;
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}
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int os_pipe(int *fds, int stream, int close_on_exec)
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{
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int err, type = stream ? SOCK_STREAM : SOCK_DGRAM;
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err = socketpair(AF_UNIX, type, 0, fds);
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if (err < 0)
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return -errno;
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if (!close_on_exec)
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return 0;
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err = os_set_exec_close(fds[0]);
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if (err < 0)
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goto error;
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err = os_set_exec_close(fds[1]);
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if (err < 0)
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goto error;
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return 0;
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error:
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printk(UM_KERN_ERR "os_pipe : Setting FD_CLOEXEC failed, err = %d\n",
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-err);
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close(fds[1]);
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close(fds[0]);
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return err;
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}
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int os_set_fd_async(int fd)
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{
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int err, flags;
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flags = fcntl(fd, F_GETFL);
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if (flags < 0)
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return -errno;
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flags |= O_ASYNC | O_NONBLOCK;
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if (fcntl(fd, F_SETFL, flags) < 0) {
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err = -errno;
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printk(UM_KERN_ERR "os_set_fd_async : failed to set O_ASYNC "
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"and O_NONBLOCK on fd # %d, errno = %d\n", fd, errno);
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return err;
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}
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if ((fcntl(fd, F_SETSIG, SIGIO) < 0) ||
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(fcntl(fd, F_SETOWN, os_getpid()) < 0)) {
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err = -errno;
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printk(UM_KERN_ERR "os_set_fd_async : Failed to fcntl F_SETOWN "
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"(or F_SETSIG) fd %d, errno = %d\n", fd, errno);
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return err;
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}
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return 0;
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}
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int os_clear_fd_async(int fd)
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{
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int flags;
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flags = fcntl(fd, F_GETFL);
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if (flags < 0)
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return -errno;
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flags &= ~(O_ASYNC | O_NONBLOCK);
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if (fcntl(fd, F_SETFL, flags) < 0)
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return -errno;
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return 0;
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}
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int os_set_fd_block(int fd, int blocking)
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{
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int flags;
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flags = fcntl(fd, F_GETFL);
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if (flags < 0)
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return -errno;
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if (blocking)
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flags &= ~O_NONBLOCK;
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else
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flags |= O_NONBLOCK;
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if (fcntl(fd, F_SETFL, flags) < 0)
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return -errno;
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return 0;
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}
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int os_accept_connection(int fd)
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{
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int new;
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new = accept(fd, NULL, 0);
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if (new < 0)
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return -errno;
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return new;
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}
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#ifndef SHUT_RD
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#define SHUT_RD 0
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#endif
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#ifndef SHUT_WR
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#define SHUT_WR 1
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#endif
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#ifndef SHUT_RDWR
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#define SHUT_RDWR 2
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#endif
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int os_shutdown_socket(int fd, int r, int w)
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{
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int what, err;
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if (r && w)
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what = SHUT_RDWR;
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else if (r)
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what = SHUT_RD;
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else if (w)
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what = SHUT_WR;
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else
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return -EINVAL;
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err = shutdown(fd, what);
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if (err < 0)
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return -errno;
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return 0;
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}
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int os_rcv_fd(int fd, int *helper_pid_out)
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{
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int new, n;
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char buf[CMSG_SPACE(sizeof(new))];
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struct msghdr msg;
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struct cmsghdr *cmsg;
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struct iovec iov;
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msg.msg_name = NULL;
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msg.msg_namelen = 0;
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iov = ((struct iovec) { .iov_base = helper_pid_out,
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.iov_len = sizeof(*helper_pid_out) });
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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msg.msg_control = buf;
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msg.msg_controllen = sizeof(buf);
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msg.msg_flags = 0;
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n = recvmsg(fd, &msg, 0);
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if (n < 0)
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return -errno;
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else if (n != iov.iov_len)
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*helper_pid_out = -1;
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cmsg = CMSG_FIRSTHDR(&msg);
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if (cmsg == NULL) {
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printk(UM_KERN_ERR "rcv_fd didn't receive anything, "
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"error = %d\n", errno);
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return -1;
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}
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if ((cmsg->cmsg_level != SOL_SOCKET) ||
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(cmsg->cmsg_type != SCM_RIGHTS)) {
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printk(UM_KERN_ERR "rcv_fd didn't receive a descriptor\n");
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return -1;
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}
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new = ((int *) CMSG_DATA(cmsg))[0];
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return new;
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}
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int os_create_unix_socket(const char *file, int len, int close_on_exec)
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{
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struct sockaddr_un addr;
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int sock, err;
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sock = socket(PF_UNIX, SOCK_DGRAM, 0);
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if (sock < 0)
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return -errno;
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if (close_on_exec) {
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err = os_set_exec_close(sock);
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if (err < 0)
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printk(UM_KERN_ERR "create_unix_socket : "
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"close_on_exec failed, err = %d", -err);
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}
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addr.sun_family = AF_UNIX;
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snprintf(addr.sun_path, len, "%s", file);
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err = bind(sock, (struct sockaddr *) &addr, sizeof(addr));
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if (err < 0)
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return -errno;
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return sock;
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}
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void os_flush_stdout(void)
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{
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fflush(stdout);
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}
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int os_lock_file(int fd, int excl)
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{
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int type = excl ? F_WRLCK : F_RDLCK;
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struct flock lock = ((struct flock) { .l_type = type,
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.l_whence = SEEK_SET,
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.l_start = 0,
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.l_len = 0 } );
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int err, save;
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err = fcntl(fd, F_SETLK, &lock);
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if (!err)
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goto out;
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save = -errno;
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err = fcntl(fd, F_GETLK, &lock);
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if (err) {
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err = -errno;
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goto out;
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}
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|
printk(UM_KERN_ERR "F_SETLK failed, file already locked by pid %d\n",
|
|
lock.l_pid);
|
|
err = save;
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
unsigned os_major(unsigned long long dev)
|
|
{
|
|
return major(dev);
|
|
}
|
|
|
|
unsigned os_minor(unsigned long long dev)
|
|
{
|
|
return minor(dev);
|
|
}
|
|
|
|
unsigned long long os_makedev(unsigned major, unsigned minor)
|
|
{
|
|
return makedev(major, minor);
|
|
}
|