[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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/fs/splice.c b/fs/splice.c
index ed91a62..a532612 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -680,7 +680,8 @@
* 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 @@
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 @@
/*
* 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 @@
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 @@
/*
* 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 @@
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);
}
}