We'd like to use inotify to get notified when AF_UNIX sockets become
connectable. That happens at the moment of listen(), but this is doesn't
necessarily create in a watchable inotify event. Hence, let's synthesize
one whenever we generically create a socket, or when we know we created
it for a D-Bus server.
Ideally we wouldn't have to do this, and the kernel would generate an
event anyway for this. Doing this explicitly isn't too bad however, as
the event is still nicely associated with the AF_UNIX socket node, and
we generate all D-Bus sockets in our code hence it's safe.
This changes two things when binding to AF_UNIX file system sockets:
1. When wethe socket already exists in the fs, and unlink() on it fails,
don't bother to bind() a second time: since nothing changed it won't
work either.
2. Also use SELinux-aware bind() for the second attempt.
Currently socket_address_listen() calls mac_selinux_bind() to bind a UNIX
socket and checks its return value and errno for EADDRINUSE. This is not
correct. When there's an SELinux context change made for the new socket,
bind() is not the last function called in mac_selinux_bind(). In that
case the last call is setfscreatecon() from libselinux which can change
errno as it uses access() to check if /proc/thread-self is available.
It fails on kernels before 3.17 and errno is set to ENOENT.
It's safe to check only the return value at it's set to -errno.
core: Add flexible way to provide socket type
the socket type should be a diffrent argumet
in make_socket_fd . In this way we can set the socket
type like SOCK_STREAM SOCK_DGRAM in the address.
journal-remote: modify make_socket_fd
bind() fails if it is called before setting SO_REUSEPORT and another
process is already binded to the same addess.
A new reuse_port option has been introduced to socket_address_listen()
to set the option as part of socket initialization.
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Petr Lautrbach
Daniel Mack
Susant Sahani
Thomas Hindoe Paaboel Andersen
Christos Trochalakis
Kay Sievers