Incorrect behavior about AsyncSeek of TokioCompatFile

[silver-ymz]

Sometimes AsyncSeek to TokioCompatFile will set the offset to the wrong place. This error occurs in apache/opendal#2263 https://github.com/apache/incubator-opendal/actions/runs/4976970726/jobs/8905529556

I guess the problem is about

openssh-sftp-client/src/file/tokio_compat_file.rs

Line 354 in ec57895

self.consume(offset);

openssh-sftp-client/src/file/tokio_compat_file.rs

Lines 383 to 391 in ec57895

	fn consume(self: Pin<&mut Self>, amt: usize) {
	let this = self.project();
	let buffer = this.buffer;
	let amt = min(buffer.len(), amt);
	buffer.advance(amt);
	this.inner.offset += amt as u64;
	}

When the offset amount is larger than buffer.len(), it will only offset to the end of buffer.

I haven't found the code which can reproduce stably. I will try to fix it these days.

[NobodyXu]

Note that File::start_seek does not support SeekFrom::End, since I'm not sure how to implement it in a race-free manner

[NobodyXu]

Also, in

openssh-sftp-client/src/file/tokio_compat_file.rs

Line 354 in ec57895

self.consume(offset);

offset can be larger than the self.buffer.len(), this is a UB according to AsyncBufRead interface.

[NobodyXu]

However, our AsyncBufRead impl is also wrong

openssh-sftp-client/src/file/tokio_compat_file.rs

Lines 383 to 391 in ec57895

	fn consume(self: Pin<&mut Self>, amt: usize) {
	let this = self.project();
	let buffer = this.buffer;
	let amt = min(buffer.len(), amt);
	buffer.advance(amt);
	this.inner.offset += amt as u64;
	}

It should panic if amt is more than self.buffer.len()

[NobodyXu]

What I suggest you to do is to advance the buffer and increase offset manually in

openssh-sftp-client/src/file/tokio_compat_file.rs

Line 354 in ec57895

self.consume(offset);

[silver-ymz]

What I suggest you to do is to advance the buffer and increase offset manually in

I think so. I'll complete it tomorrow.

[NobodyXu]

What I suggest you to do is to advance the buffer and increase offset manually in

I think so. I'll complete it tomorrow.

It will also be great if you can fix ::consume