From 81453854081bfb83be782c3bf8fb77a5dfea4841 Mon Sep 17 00:00:00 2001
From: Ken Brown <kbrown@cornell.edu>
Date: Tue, 23 Feb 2021 11:48:46 -0500
Subject: [PATCH] Cygwin: AF_UNIX: allow opening with the O_PATH flag

This was done for the fhandler_socket_local class in commits
3a2191653a, 141437d374, and 477121317d, but the fhandler_socket_unix
class was overlooked.
---
 winsup/cygwin/fhandler.h              |  1 +
 winsup/cygwin/fhandler_socket_unix.cc | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h
index 397762be8..29907a707 100644
--- a/winsup/cygwin/fhandler.h
+++ b/winsup/cygwin/fhandler.h
@@ -1249,6 +1249,7 @@ class fhandler_socket_unix : public fhandler_socket
   int saw_shutdown () const { return shmem->shutdown (); }
   bool saw_shutdown_read () const { return !!(saw_shutdown () & _SHUT_RECV); }
 
+  int open (int flags, mode_t mode = 0);
   int close ();
   int getpeereid (pid_t *pid, uid_t *euid, gid_t *egid);
   void *serialize (int fd);
diff --git a/winsup/cygwin/fhandler_socket_unix.cc b/winsup/cygwin/fhandler_socket_unix.cc
index 1f8767667..bc67b70b1 100644
--- a/winsup/cygwin/fhandler_socket_unix.cc
+++ b/winsup/cygwin/fhandler_socket_unix.cc
@@ -1298,6 +1298,11 @@ fhandler_socket_unix::~fhandler_socket_unix ()
 int
 fhandler_socket_unix::dup (fhandler_base *child, int flags, DWORD src_pid)
 {
+  if (get_flags () & O_PATH)
+    /* We're viewing the socket as a disk file, but fhandler_base::dup
+       suffices here. */
+    return fhandler_base::dup (child, flags, src_pid);
+
   int ret = -1;
   HANDLE src_proc = GetCurrentProcess ();
   fhandler_socket_unix *fhs = (fhandler_socket_unix *) child;
@@ -1906,9 +1911,23 @@ fhandler_socket_unix::shutdown (int how)
   return 0;
 }
 
+int
+fhandler_socket_unix::open (int flags, mode_t mode)
+{
+  /* We don't support opening sockets unless O_PATH is specified. */
+  if (flags & O_PATH)
+    return open_fs (flags, mode);
+
+  set_errno (EOPNOTSUPP);
+  return 0;
+}
+
 int
 fhandler_socket_unix::close ()
 {
+  if (get_flags () & O_PATH)
+    return fhandler_base::close ();
+
   HANDLE evt = InterlockedExchangePointer (&cwt_termination_evt, NULL);
   HANDLE thr = InterlockedExchangePointer (&connect_wait_thr, NULL);
   if (thr)
@@ -3537,6 +3556,11 @@ fhandler_socket_unix::ioctl (unsigned int cmd, void *p)
 int
 fhandler_socket_unix::fcntl (int cmd, intptr_t arg)
 {
+  if (get_flags () & O_PATH)
+    /* We're viewing the socket as a disk file, but
+       fhandler_base::fcntl suffices here. */
+    return fhandler_base::fcntl (cmd, arg);
+
   int ret = -1;
 
   switch (cmd)