qemu-patch-raspberry4/hw/9pfs/9p-util.h
Greg Kurz 3dbcf27334 9pfs: local: simplify file opening
The logic to open a path currently sits between local_open_nofollow() and
the relative_openat_nofollow() helper, which has no other user.

For the sake of clarity, this patch moves all the code of the helper into
its unique caller. While here we also:
- drop the code to skip leading "/" because the backend isn't supposed to
  pass anything but relative paths without consecutive slashes. The assert()
  is kept because we really don't want a buggy backend to pass an absolute
  path to openat().
- use strchrnul() to get a simpler code. This is ok since virtfs is for
  linux+glibc hosts only.
- don't dup() the initial directory and add an assert() to ensure we don't
  return the global mountfd to the caller. BTW, this would mean that the
  caller passed an empty path, which isn't supposed to happen either.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[groug: fixed typos in changelog]
2017-05-25 10:30:14 +02:00

59 lines
1.4 KiB
C

/*
* 9p utilities
*
* Copyright IBM, Corp. 2017
*
* Authors:
* Greg Kurz <groug@kaod.org>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_9P_UTIL_H
#define QEMU_9P_UTIL_H
static inline void close_preserve_errno(int fd)
{
int serrno = errno;
close(fd);
errno = serrno;
}
static inline int openat_dir(int dirfd, const char *name)
{
#ifdef O_PATH
#define OPENAT_DIR_O_PATH O_PATH
#else
#define OPENAT_DIR_O_PATH 0
#endif
return openat(dirfd, name,
O_DIRECTORY | O_RDONLY | O_NOFOLLOW | OPENAT_DIR_O_PATH);
}
static inline int openat_file(int dirfd, const char *name, int flags,
mode_t mode)
{
int fd, serrno, ret;
fd = openat(dirfd, name, flags | O_NOFOLLOW | O_NOCTTY | O_NONBLOCK,
mode);
if (fd == -1) {
return -1;
}
serrno = errno;
/* O_NONBLOCK was only needed to open the file. Let's drop it. */
ret = fcntl(fd, F_SETFL, flags);
assert(!ret);
errno = serrno;
return fd;
}
ssize_t fgetxattrat_nofollow(int dirfd, const char *path, const char *name,
void *value, size_t size);
int fsetxattrat_nofollow(int dirfd, const char *path, const char *name,
void *value, size_t size, int flags);
#endif