Re: [Qemu-devel] [PATCH] block/curl: Add support for Secure Shell (ssh/sftp) block device

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, Mar 22, 2013 at 01:04:55PM +0000, Richard W.M. Jones wrote:
> 
> I got it working with Curl, patch attached.
> 
> However there are multiple issues (these are mainly notes for myself):
> 
> (1) libcurl cannot read the size of the file.  I had to hard-code
> this.  This is probably just a shortcoming of libcurl (libssh2/sftp
> itself can read the size of files).  Will try to work on a patch for
> upstream.
> 
> (2) Fedora's curl (which is heavily patched) is broken in some way and
> deadlocks itself.  Upstream curl from git works better.  I haven't yet
> identified which patch/commit is responsible.
> 
> (3) ssh-agent authentication doesn't work.  It appears that either
> ssh-agent itself doesn't like multiple connections from a single
> process (qemu), or libcurl/libssh2 is having a problem with making
> multiple connections out to ssh-agent.  If I disable ssh-agent auth,
> it works.  Still investigating this.
> 
> (4) You must specify a user@ in the URL, else libcurl tries to
> authenticate as user "".  I will see if I can send a fix for this
> upstream.
> 
> (5) Although it gets much of the way through a boot of a guest, it
> eventually segfaults.  Still investigating this.
> 
> (6) There are several more issues marked by XXX's in the code.

Thank you for improving libcurl!  You're making it better for everybody.

A lot of people go back to NIH when they hit limitations in existing
software.

Stefan