Wrap accesses to the fd_sets in struct fdtable
Wrap accesses to the fd_sets in struct fdtable (for recording open files and
close-on-exec flags) so that we can move away from using fd_sets since we
abuse the fd_set structs by not allocating the full-sized structure under
normal circumstances and by non-core code looking at the internals of the
fd_sets.
The first abuse means that use of FD_ZERO() on these fd_sets is not permitted,
since that cannot be told about their abnormal lengths.
This introduces six wrapper functions for setting, clearing and testing
close-on-exec flags and fd-is-open flags:
void __set_close_on_exec(int fd, struct fdtable *fdt);
void __clear_close_on_exec(int fd, struct fdtable *fdt);
bool close_on_exec(int fd, const struct fdtable *fdt);
void __set_open_fd(int fd, struct fdtable *fdt);
void __clear_open_fd(int fd, struct fdtable *fdt);
bool fd_is_open(int fd, const struct fdtable *fdt);
Note that I've prepended '__' to the names of the set/clear functions because
they require the caller to hold a lock to use them.
Note also that I haven't added wrappers for looking behind the scenes at the
the array. Possibly that should exist too.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20120216174942.23314.1364.stgit@warthog.procyon.org.uk
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/staging/android/binder.c b/drivers/staging/android/binder.c
index 7491801..35dd9c3 100644
--- a/drivers/staging/android/binder.c
+++ b/drivers/staging/android/binder.c
@@ -408,11 +408,11 @@
goto repeat;
}
- FD_SET(fd, fdt->open_fds);
+ __set_open_fd(fd, fdt);
if (flags & O_CLOEXEC)
- FD_SET(fd, fdt->close_on_exec);
+ __set_close_on_exec(fd, fdt);
else
- FD_CLR(fd, fdt->close_on_exec);
+ __clear_close_on_exec(fd, fdt);
files->next_fd = fd + 1;
#if 1
/* Sanity check */
@@ -453,7 +453,7 @@
static void __put_unused_fd(struct files_struct *files, unsigned int fd)
{
struct fdtable *fdt = files_fdtable(files);
- __FD_CLR(fd, fdt->open_fds);
+ __clear_open_fd(fd, fdt);
if (fd < files->next_fd)
files->next_fd = fd;
}
@@ -479,7 +479,7 @@
if (!filp)
goto out_unlock;
rcu_assign_pointer(fdt->fd[fd], NULL);
- FD_CLR(fd, fdt->close_on_exec);
+ __clear_close_on_exec(fd, fdt);
__put_unused_fd(files, fd);
spin_unlock(&files->file_lock);
retval = filp_close(filp, files);