From 425203384a6c3e19af782c86570740464423eb4d Mon Sep 17 00:00:00 2001 From: Ken Brown Date: Wed, 24 Feb 2021 10:43:15 -0500 Subject: [PATCH] Cygwin: fix linkat(2) on sockets that are not socket files If linkat(2) is called with AT_EMPTY_PATH on an AF_LOCAL or AF_UNIX socket that is not a socket file, the current code calls fhandler_disk_file::link in most cases. The latter expects to be operating on a disk file and uses the socket's io_handle, which is not a file handle. Fix this by calling fhandler_disk_file::link only if the fhandler_socket object is a file (determined by testing dev().isfs()). Also fix the case of a socket file opened with O_PATH by setting the fhandler_disk_file's io_handle. --- winsup/cygwin/fhandler_socket_local.cc | 7 ++++++- winsup/cygwin/fhandler_socket_unix.cc | 9 ++++++--- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/winsup/cygwin/fhandler_socket_local.cc b/winsup/cygwin/fhandler_socket_local.cc index 22586c0dd..ad7dd0a98 100644 --- a/winsup/cygwin/fhandler_socket_local.cc +++ b/winsup/cygwin/fhandler_socket_local.cc @@ -750,9 +750,14 @@ fhandler_socket_local::facl (int cmd, int nentries, aclent_t *aclbufp) int fhandler_socket_local::link (const char *newpath) { - if (get_sun_path () && get_sun_path ()[0] == '\0') + if (!dev ().isfs ()) + /* linkat w/ AT_EMPTY_PATH called on a socket not opened w/ O_PATH. */ return fhandler_socket_wsock::link (newpath); + /* link on a socket file or linkat w/ AT_EMPTY_PATH called on a + socket opened w/ O_PATH. */ fhandler_disk_file fh (pc); + if (get_flags () & O_PATH) + fh.set_handle (get_handle ()); return fh.link (newpath); } diff --git a/winsup/cygwin/fhandler_socket_unix.cc b/winsup/cygwin/fhandler_socket_unix.cc index fae07367d..252bcd9a9 100644 --- a/winsup/cygwin/fhandler_socket_unix.cc +++ b/winsup/cygwin/fhandler_socket_unix.cc @@ -2421,11 +2421,14 @@ fhandler_socket_unix::facl (int cmd, int nentries, aclent_t *aclbufp) int fhandler_socket_unix::link (const char *newpath) { - if (sun_path () - && (sun_path ()->un_len <= (socklen_t) sizeof (sa_family_t) - || sun_path ()->un.sun_path[0] == '\0')) + if (!dev ().isfs ()) + /* linkat w/ AT_EMPTY_PATH called on a socket not opened w/ O_PATH. */ return fhandler_socket::link (newpath); + /* link on a socket file or linkat w/ AT_EMPTY_PATH called on a + socket opened w/ O_PATH. */ fhandler_disk_file fh (pc); + if (get_flags () & O_PATH) + fh.set_handle (get_handle ()); return fh.link (newpath); } -- 2.43.5