Commit 1dce27c5 authored by David Howells's avatar David Howells Committed by H. Peter Anvin
Browse files

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: default avatarDavid Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20120216174942.23314.1364.stgit@warthog.procyon.org.uk


Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
parent 8b3d1cda

Documentation/filesystems/files.txt

+2 −2
Original line number Diff line number Diff line
@@ -113,8 +113,8 @@ the fdtable structure - 
	if (fd >= 0) {

		/* locate_fd() may have expanded fdtable, load the ptr */

		fdt = files_fdtable(files);

		FD_SET(fd, fdt->open_fds);

		FD_CLR(fd, fdt->close_on_exec);

		__set_open_fd(fd, fdt);

		__clear_close_on_exec(fd, fdt);

		spin_unlock(&files->file_lock);

	.....

arch/powerpc/platforms/cell/spufs/coredump.c

+1 −1
Original line number Diff line number Diff line
@@ -122,7 +122,7 @@ static struct spu_context *coredump_next_context(int *fd) 
	struct spu_context *ctx = NULL;



	for (; *fd < fdt->max_fds; (*fd)++) {

		if (!FD_ISSET(*fd, fdt->open_fds))

		if (!fd_is_open(*fd, fdt))

			continue;



		file = fcheck(*fd);

drivers/staging/android/binder.c

+5 −5
Original line number Diff line number Diff line
@@ -408,11 +408,11 @@ repeat: 
		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 task_fd_install( 
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 @@ static long task_close_fd(struct binder_proc *proc, unsigned int fd) 
	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);

fs/autofs4/dev-ioctl.c

+1 −1
Original line number Diff line number Diff line
@@ -230,7 +230,7 @@ static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file) 
	fdt = files_fdtable(files);

	BUG_ON(fdt->fd[fd] != NULL);

	rcu_assign_pointer(fdt->fd[fd], file);

	FD_SET(fd, fdt->close_on_exec);

	__set_close_on_exec(fd, fdt);

	spin_unlock(&files->file_lock);

}

fs/exec.c

+2 −2
Original line number Diff line number Diff line
@@ -2078,8 +2078,8 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) 
	fd_install(0, rp);

	spin_lock(&cf->file_lock);

	fdt = files_fdtable(cf);

	FD_SET(0, fdt->open_fds);

	FD_CLR(0, fdt->close_on_exec);

	__set_open_fd(0, fdt);

	__clear_close_on_exec(0, fdt);

	spin_unlock(&cf->file_lock);



	/* and disallow core files too */

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