Commit 529565dc authored by Ingo Molnar's avatar Ingo Molnar Committed by Jens Axboe
Browse files

[PATCH] splice: add optional input and output offsets 



add optional input and output offsets to sys_splice(), for seekable file
descriptors:

 asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
                            int fd_out, loff_t __user *off_out,
                            size_t len, unsigned int flags);

semantics are straightforward: f_pos will be updated with the offset
provided by user-space, before the splice transfer is about to begin.
Providing a NULL offset pointer means the existing f_pos will be used
(and updated in situ).  Providing an offset for a pipe results in
-ESPIPE. Providing an invalid offset pointer results in -EFAULT.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent 3a326a2c

fs/splice.c

+41 −13
Original line number Diff line number Diff line
@@ -680,7 +680,8 @@ EXPORT_SYMBOL(generic_splice_sendpage); 
 * Attempt to initiate a splice from pipe to file.

 */

static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,

			   size_t len, unsigned int flags)

			   loff_t __user *off_out, size_t len,

			   unsigned int flags)

{

	loff_t pos;

	int ret;
@@ -691,7 +692,11 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, 
	if (!(out->f_mode & FMODE_WRITE))

		return -EBADF;



	if (off_out && copy_from_user(&out->f_pos, off_out, sizeof(loff_t)))

		return -EFAULT;



	pos = out->f_pos;



	ret = rw_verify_area(WRITE, out, &pos, len);

	if (unlikely(ret < 0))

		return ret;
@@ -702,8 +707,9 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, 
/*

 * Attempt to initiate a splice from a file to a pipe.

 */

static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,

			 size_t len, unsigned int flags)

static long do_splice_to(struct file *in, loff_t __user *off_in,

			 struct pipe_inode_info *pipe, size_t len,

			 unsigned int flags)

{

	loff_t pos, isize, left;

	int ret;
@@ -714,7 +720,11 @@ static long do_splice_to(struct file *in, struct pipe_inode_info *pipe, 
	if (!(in->f_mode & FMODE_READ))

		return -EBADF;



	if (off_in && copy_from_user(&in->f_pos, off_in, sizeof(loff_t)))

		return -EFAULT;



	pos = in->f_pos;



	ret = rw_verify_area(READ, in, &pos, len);

	if (unlikely(ret < 0))

		return ret;
@@ -733,23 +743,39 @@ static long do_splice_to(struct file *in, struct pipe_inode_info *pipe, 
/*

 * Determine where to splice to/from.

 */

static long do_splice(struct file *in, struct file *out, size_t len,

		      unsigned int flags)

static long do_splice(struct file *in, loff_t __user *off_in,

		      struct file *out, loff_t __user *off_out,

		      size_t len, unsigned int flags)

{

	struct pipe_inode_info *pipe;



	if (off_out && out->f_op->llseek == no_llseek)

		return -EINVAL;

	if (off_in && in->f_op->llseek == no_llseek)

		return -EINVAL;



	pipe = in->f_dentry->d_inode->i_pipe;

	if (pipe)

		return do_splice_from(pipe, out, len, flags);

	if (pipe) {

		if (off_in)

			return -ESPIPE;



		return do_splice_from(pipe, out, off_out, len, flags);

	}



	pipe = out->f_dentry->d_inode->i_pipe;

	if (pipe)

		return do_splice_to(in, pipe, len, flags);

	if (pipe) {

		if (off_out)

			return -ESPIPE;



		return do_splice_to(in, off_in, pipe, len, flags);

	}



	return -EINVAL;

}



asmlinkage long sys_splice(int fdin, int fdout, size_t len, unsigned int flags)

asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,

			   int fd_out, loff_t __user *off_out,

			   size_t len, unsigned int flags)

{

	long error;

	struct file *in, *out;
@@ -759,13 +785,15 @@ asmlinkage long sys_splice(int fdin, int fdout, size_t len, unsigned int flags) 
		return 0;



	error = -EBADF;

	in = fget_light(fdin, &fput_in);

	in = fget_light(fd_in, &fput_in);

	if (in) {

		if (in->f_mode & FMODE_READ) {

			out = fget_light(fdout, &fput_out);

			out = fget_light(fd_out, &fput_out);

			if (out) {

				if (out->f_mode & FMODE_WRITE)

					error = do_splice(in, out, len, flags);

					error = do_splice(in, off_in,

							  out, off_out,

							  len, flags);

				fput_light(out, fput_out);

			}

		}

include/linux/syscalls.h

+5 −2
Original line number Diff line number Diff line
@@ -569,8 +569,11 @@ asmlinkage long compat_sys_newfstatat(unsigned int dfd, char __user * filename, 
asmlinkage long compat_sys_openat(unsigned int dfd, const char __user *filename,

				   int flags, int mode);

asmlinkage long sys_unshare(unsigned long unshare_flags);

asmlinkage long sys_splice(int fdin, int fdout, size_t len,

				unsigned int flags);



asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,

			   int fd_out, loff_t __user *off_out,

			   size_t len, unsigned int flags);



asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,

					int flags);

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