Re: [PATCH 07/15] python/aqmp: add send_fd_scm

[John Snow]

On Fri, Sep 17, 2021 at 9:34 AM Hanna Reitz  wrote:

> On 17.09.21 07:40, John Snow wrote:
> > The single space is indeed required to successfully transmit the file
> > descriptor to QEMU.
>
> Yeah, socket_scm_helper.c said “Send a blank to notify qemu”.
>
> > Signed-off-by: John Snow 
> > ---
> >   python/qemu/aqmp/qmp_client.py | 17 +
> >   1 file changed, 17 insertions(+)
> >
> > diff --git a/python/qemu/aqmp/qmp_client.py
> b/python/qemu/aqmp/qmp_client.py
> > index d2ad7459f9..58f85990bc 100644
> > --- a/python/qemu/aqmp/qmp_client.py
> > +++ b/python/qemu/aqmp/qmp_client.py
> > @@ -9,6 +9,8 @@
> >
> >   import asyncio
> >   import logging
> > +import socket
> > +import struct
> >   from typing import (
> >   Dict,
> >   List,
> > @@ -624,3 +626,18 @@ async def execute(self, cmd: str,
> >   """
> >   msg = self.make_execute_msg(cmd, arguments, oob=oob)
> >   return await self.execute_msg(msg)
> > +
> > +@upper_half
> > +@require(Runstate.RUNNING)
> > +def send_fd_scm(self, fd: int) -> None:
> > +"""
> > +Send a file descriptor to the remote via SCM_RIGHTS.
> > +"""
> > +assert self._writer is not None
> > +sock = self._writer.transport.get_extra_info('socket')
> > +
> > +# Python 3.9+ adds socket.send_fds(...)
> > +sock.sendmsg(
> > +[b' '],
> > +[(socket.SOL_SOCKET, socket.SCM_RIGHTS, struct.pack('@i',
> fd))]
> > +)
>
> AFAIU the socket can be either TCP or a UNIX socket
> (AsyncProtocol._do_accept’s docstring sounds this way), so should we
> check that this is a UNIX socket?  (Or is it fine to just run into the
> error that I suspect we would get with a TCP socket?)
>
> Hanna
>
>
Uhh, hm. I was going to say "Yeah, just let it fail!" but ... upon going to
document what error to expect in this case, I am realizing it fails
silently. So, uh, that's not ideal.

I'll fix this to make it bark.

--js

Re: [PATCH 07/15] python/aqmp: add send_fd_scm

[Hanna Reitz]

On 17.09.21 07:40, John Snow wrote:

The single space is indeed required to successfully transmit the file
descriptor to QEMU.


Yeah, socket_scm_helper.c said “Send a blank to notify qemu”.


Signed-off-by: John Snow 
---
  python/qemu/aqmp/qmp_client.py | 17 +
  1 file changed, 17 insertions(+)

diff --git a/python/qemu/aqmp/qmp_client.py b/python/qemu/aqmp/qmp_client.py
index d2ad7459f9..58f85990bc 100644
--- a/python/qemu/aqmp/qmp_client.py
+++ b/python/qemu/aqmp/qmp_client.py
@@ -9,6 +9,8 @@
  
  import asyncio

  import logging
+import socket
+import struct
  from typing import (
  Dict,
  List,
@@ -624,3 +626,18 @@ async def execute(self, cmd: str,
  """
  msg = self.make_execute_msg(cmd, arguments, oob=oob)
  return await self.execute_msg(msg)
+
+@upper_half
+@require(Runstate.RUNNING)
+def send_fd_scm(self, fd: int) -> None:
+"""
+Send a file descriptor to the remote via SCM_RIGHTS.
+"""
+assert self._writer is not None
+sock = self._writer.transport.get_extra_info('socket')
+
+# Python 3.9+ adds socket.send_fds(...)
+sock.sendmsg(
+[b' '],
+[(socket.SOL_SOCKET, socket.SCM_RIGHTS, struct.pack('@i', fd))]
+)


AFAIU the socket can be either TCP or a UNIX socket 
(AsyncProtocol._do_accept’s docstring sounds this way), so should we 
check that this is a UNIX socket?  (Or is it fine to just run into the 
error that I suspect we would get with a TCP socket?)


Hanna

[PATCH 07/15] python/aqmp: add send_fd_scm

[John Snow]

The single space is indeed required to successfully transmit the file
descriptor to QEMU.

Signed-off-by: John Snow 
---
 python/qemu/aqmp/qmp_client.py | 17 +
 1 file changed, 17 insertions(+)

diff --git a/python/qemu/aqmp/qmp_client.py b/python/qemu/aqmp/qmp_client.py
index d2ad7459f9..58f85990bc 100644
--- a/python/qemu/aqmp/qmp_client.py
+++ b/python/qemu/aqmp/qmp_client.py
@@ -9,6 +9,8 @@
 
 import asyncio
 import logging
+import socket
+import struct
 from typing import (
 Dict,
 List,
@@ -624,3 +626,18 @@ async def execute(self, cmd: str,
 """
 msg = self.make_execute_msg(cmd, arguments, oob=oob)
 return await self.execute_msg(msg)
+
+@upper_half
+@require(Runstate.RUNNING)
+def send_fd_scm(self, fd: int) -> None:
+"""
+Send a file descriptor to the remote via SCM_RIGHTS.
+"""
+assert self._writer is not None
+sock = self._writer.transport.get_extra_info('socket')
+
+# Python 3.9+ adds socket.send_fds(...)
+sock.sendmsg(
+[b' '],
+[(socket.SOL_SOCKET, socket.SCM_RIGHTS, struct.pack('@i', fd))]
+)
-- 
2.31.1