tap: Support for detection of existing sockets on ramfs

On ramfs, connecting to a non-existent UNIX domain socket yields
EACCESS, instead of ENOENT. This is visible if we use passt directly
on rootfs (a ramfs instance) from an initramfs image.

It's probably wrong for ramfs to return EACCES, but given the
simplicity of the filesystem, I doubt we should try to fix it there
at the possible cost of added complexity.

Also, this whole beauty should go away once qrap-less usage is
established, so just accept EACCES as indication that a conflicting
socket does not, in fact, exist.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 2 insertions, 1 deletions

diff --git a/tap.c b/tap.c
index 4dcff4f..0a3ccce 100644
--- a/tap.c
+++ b/tap.c
@@ -912,7 +912,8 @@ static void tap_sock_unix_init(struct ctx *c)
 		}
 
 		ret = connect(ex, (const struct sockaddr *)&addr, sizeof(addr));
-		if (!ret || (errno != ENOENT && errno != ECONNREFUSED)) {
+		if (!ret || (errno != ENOENT && errno != ECONNREFUSED &&
+			     errno != EACCES)) {
 			if (*c->sock_path) {
 				err("Socket path %s already in use", path);
 				exit(EXIT_FAILURE);