Re: [PATCH v3 1/1] python/machine: Fix AF_UNIX path too long on macOS

[John Snow]

On Mon, Jul 25, 2022 at 5:06 AM Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> On Fri, Jul 22, 2022 at 11:25:08AM -0700, Peter Delevoryas wrote:
> > On macOS, private $TMPDIR's are the default. These $TMPDIR's are
> > generated from a user's unix UID and UUID [1], which can create a
> > relatively long path:
> >
> >     /var/folders/d7/rz20f6hd709c1ty8f6_6y_z40000gn/T/
> >
> > QEMU's avocado tests create a temporary directory prefixed by
> > "avo_qemu_sock_", and create QMP sockets within _that_ as well.
> > The QMP socket is unnecessarily long, because a temporary directory
> > is created for every QEMUMachine object.
> >
> >     /avo_qemu_sock_uh3w_dgc/qemu-37331-10bacf110-monitor.sock
> >
> > The path limit for unix sockets on macOS is 104: [2]
> >
> >     /*
> >      * [XSI] Definitions for UNIX IPC domain.
> >      */
> >     struct  sockaddr_un {
> >         unsigned char   sun_len;        /* sockaddr len including null */
> >         sa_family_t     sun_family;     /* [XSI] AF_UNIX */
> >         char            sun_path[104];  /* [XSI] path name (gag) */
> >     };
> >
> > This results in avocado tests failing on macOS because the QMP unix
> > socket can't be created, because the path is too long:
> >
> >     ERROR| Failed to establish connection: OSError: AF_UNIX path too long
> >
> > This change resolves by reducing the size of the socket directory prefix
> > and the suffix on the QMP and console socket names.
> >
> > The result is paths like this:
> >
> >     pdel@pdel-mbp:/var/folders/d7/rz20f6hd709c1ty8f6_6y_z40000gn/T
> >     $ tree qemu*
> >     qemu_df4evjeq
> >     qemu_jbxel3gy
> >     qemu_ml9s_gg7
> >     qemu_oc7h7f3u
> >     qemu_oqb1yf97
> >     ├── 10a004050.con
> >     └── 10a004050.qmp
> >
> > [1] 
> > https://apple.stackexchange.com/questions/353832/why-is-mac-osx-temp-directory-in-weird-path
> > [2] 
> > /Library/Developer/CommandLineTools/SDKs/MacOSX12.3.sdk/usr/include/sys/un.h
> >
> > Signed-off-by: Peter Delevoryas <peter@pjd.dev>
> > ---
> >  python/qemu/machine/machine.py         | 6 +++---
> >  tests/avocado/avocado_qemu/__init__.py | 2 +-
> >  2 files changed, 4 insertions(+), 4 deletions(-)
>
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

My apologies, I missed this update because it appeared in a thread
underneath the old version.

Peter, may I please ask for you to kindly re-submit this patch with an
incremented version number?

--js