Merge branch 'accept-close-race-5279' of https://github.com/endragor/Nim into endragor-accept-close-race-5279

lib/pure/asyncdispatch.nim

@@ -753,26 +753,6 @@ when defined(windows) or defined(nimdoc):
     let dwLocalAddressLength = Dword(sizeof(Sockaddr_in) + 16)
     let dwRemoteAddressLength = Dword(sizeof(Sockaddr_in) + 16)
 
-    template completeAccept() {.dirty.} =
-      var listenSock = socket
-      let setoptRet = setsockopt(clientSock, SOL_SOCKET,
-          SO_UPDATE_ACCEPT_CONTEXT, addr listenSock,
-          sizeof(listenSock).SockLen)
-      if setoptRet != 0: raiseOSError(osLastError())
-
-      var localSockaddr, remoteSockaddr: ptr SockAddr
-      var localLen, remoteLen: int32
-      getAcceptExSockaddrs(addr lpOutputBuf[0], dwReceiveDataLength,
-                           dwLocalAddressLength, dwRemoteAddressLength,
-                           addr localSockaddr, addr localLen,
-                           addr remoteSockaddr, addr remoteLen)
-      register(clientSock.AsyncFD)
-      # TODO: IPv6. Check ``sa_family``. http://stackoverflow.com/a/9212542/492186
-      retFuture.complete(
-        (address: $inet_ntoa(cast[ptr Sockaddr_in](remoteSockAddr).sin_addr),
-         client: clientSock.AsyncFD)
-      )
-
     template failAccept(errcode) =
       if flags.isDisconnectionError(errcode):
         var newAcceptFut = acceptAddr(socket, flags)
@@ -785,6 +765,29 @@ when defined(windows) or defined(nimdoc):
       else:
         retFuture.fail(newException(OSError, osErrorMsg(errcode)))
 
+    template completeAccept() {.dirty.} =
+      var listenSock = socket
+      let setoptRet = setsockopt(clientSock, SOL_SOCKET,
+          SO_UPDATE_ACCEPT_CONTEXT, addr listenSock,
+          sizeof(listenSock).SockLen)
+      if setoptRet != 0:
+        let errcode = osLastError()
+        checkCloseError clientSock.closeSocket()
+        failAccept(errcode)
+      else:
+        var localSockaddr, remoteSockaddr: ptr SockAddr
+        var localLen, remoteLen: int32
+        getAcceptExSockaddrs(addr lpOutputBuf[0], dwReceiveDataLength,
+                             dwLocalAddressLength, dwRemoteAddressLength,
+                             addr localSockaddr, addr localLen,
+                             addr remoteSockaddr, addr remoteLen)
+        register(clientSock.AsyncFD)
+        # TODO: IPv6. Check ``sa_family``. http://stackoverflow.com/a/9212542/492186
+        retFuture.complete(
+          (address: $inet_ntoa(cast[ptr Sockaddr_in](remoteSockAddr).sin_addr),
+          client: clientSock.AsyncFD)
+        )
+
     var ol = PCustomOverlapped()
     GC_ref(ol)
     ol.data = CompletionData(fd: socket, cb:

lib/pure/nativesockets.nim

@@ -22,11 +22,12 @@ const useWinVersion = defined(Windows) or defined(nimdoc)
 when useWinVersion:
   import winlean
   export WSAEWOULDBLOCK, WSAECONNRESET, WSAECONNABORTED, WSAENETRESET,
+         WSANOTINITIALISED, WSAENOTSOCK, WSAEINPROGRESS, WSAEINTR,
          WSAEDISCON, ERROR_NETNAME_DELETED
 else:
   import posix
   export fcntl, F_GETFL, O_NONBLOCK, F_SETFL, EAGAIN, EWOULDBLOCK, MSG_NOSIGNAL,
-    EINTR, EINPROGRESS, ECONNRESET, EPIPE, ENETRESET
+    EINTR, EINPROGRESS, ECONNRESET, EPIPE, ENETRESET, EBADF
   export Sockaddr_storage, Sockaddr_un, Sockaddr_un_path_length
 
 export SocketHandle, Sockaddr_in, Addrinfo, INADDR_ANY, SockAddr, SockLen,
@@ -619,3 +620,28 @@ proc selectWrite*(writefds: var seq[SocketHandle],
 when defined(Windows):
   var wsa: WSAData
   if wsaStartup(0x0101'i16, addr wsa) != 0: raiseOSError(osLastError())
+
+proc checkCloseError*(ret: cint) =
+  ## Asserts that the return value of close() or closeSocket() syscall
+  ## does not indicate a programming error (such as invalid descriptor).
+  ## This must only be used when an error has already occurred and
+  ## you are performing a cleanup.
+  ## Otherwise, error handling must be performed as usual.
+  ##
+  ## This procedure must be called right after performing the syscall. Example:
+  ##
+  ## .. code-block:: nim
+  ##
+  ##  let ret = someSysCall()
+  ##  if ret != 0:
+  ##    let errcode = osLastError()
+  ##    checkCloseError sock.closeSocket()
+  ##    raise newException(OSError, osErrorMsg(errcode))
+
+  if ret != 0:
+    let errcode = osLastError()
+    when useWinVersion:
+      doAssert(errcode.int32 notin {WSANOTINITIALISED, WSAENOTSOCK,
+                                    WSAEINPROGRESS, WSAEINTR, WSAEWOULDBLOCK})
+    else:
+      doAssert(errcode.int32 notin {EBADF})