[fuse-devel] Partial read() hanging on /dev/fuse?

[Gregory H. <gre...@gm...>]

Hi all,

I am writing a native erlang libfuse (https://github.com/ghaskins/efuse)
framework, and I ran into an issue coming out of the gate that perhaps
someone here can explain.

So, I know that the fuse_in_header is 40-bytes, and the fuse_init_in
payload is 16.  So when I first connect to the fd returned from
fuse_mount(), the kernel tries to send me a FUSE_INIT packet.  The thing
I can't wrap my head around atm is if I do a read(fd, 56), I get back
the 56 byte FUSE_INIT packet, but if I do a read(fd, 40) the kernel blocks.

What I expect is that I can do a partial read to get the header,
including the .len field, and then do a subsequent read to get the
remainer.  Is that not supported, or am I doing something wrong?

In case it matters, I am on OpenSUSE 11.4, Linux linux-mp
2.6.37.6-0.5-desktop #1 SMP PREEMPT 2011-04-25 21:48:33 +0200 x86_64
x86_64 x86_64 GNU/Linux

Kind Regards,
-Greg