Avoid flush in Socket and IO::FileDescriptor finalizer

spec/std/io/file_descriptor_spec.cr

@@ -64,15 +64,15 @@ describe IO::FileDescriptor do
       end
     end
 
-    it "flushes" do
+    it "does not flush" do
       with_tempfile "fd-finalize-flush" do |path|
         file = File.new(path, "w")
         file << "foo"
         file.flush
         file << "bar"
         file.finalize
 
-        File.read(path).should eq "foobar"
+        File.read(path).should eq "foo"
       ensure
         file.try(&.close) rescue nil
       end

spec/std/socket/socket_spec.cr

@@ -171,7 +171,7 @@ describe Socket, tags: "network" do
   {% end %}
 
   describe "#finalize" do
-    it "flushes" do
+    it "does not flush" do
       port = unused_local_port
       server = Socket.tcp(Socket::Family::INET)
       server.bind("127.0.0.1", port)
@@ -190,7 +190,8 @@ describe Socket, tags: "network" do
 
       socket = Socket.tcp(Socket::Family::INET)
       socket.connect(Socket::IPAddress.new("127.0.0.1", port))
-      socket.gets.should eq "foobar"
+
+      socket.gets.should eq "foo"
     ensure
       socket.try &.close
       server.try &.close

src/crystal/system/unix/file_descriptor.cr

@@ -120,7 +120,7 @@ module Crystal::System::FileDescriptor
     file_descriptor_close
   end
 
-  def file_descriptor_close : Nil
+  def file_descriptor_close(&) : Nil
     # Clear the @volatile_fd before actually closing it in order to
     # reduce the chance of reading an outdated fd value
     _fd = @volatile_fd.swap(-1)
@@ -130,11 +130,17 @@ module Crystal::System::FileDescriptor
       when Errno::EINTR, Errno::EINPROGRESS
         # ignore
       else
-        raise IO::Error.from_errno("Error closing file", target: self)
+        yield
       end
     end
   end
 
+  def file_descriptor_close
+    file_descriptor_close do
+      raise IO::Error.from_errno("Error closing file", target: self)
+    end
+  end
+
   private def system_flock_shared(blocking)
     flock LibC::FlockOp::SH, blocking
   end

src/crystal/system/unix/socket.cr

@@ -208,6 +208,10 @@ module Crystal::System::Socket
     # always lead to undefined results. This is not specific to libevent.
     event_loop.close(self)
 
+    socket_close
+  end
+
+  private def socket_close(&)
     # Clear the @volatile_fd before actually closing it in order to
     # reduce the chance of reading an outdated fd value
     fd = @volatile_fd.swap(-1)
@@ -219,11 +223,17 @@ module Crystal::System::Socket
       when Errno::EINTR, Errno::EINPROGRESS
         # ignore
       else
-        raise ::Socket::Error.from_errno("Error closing socket")
+        yield
       end
     end
   end
 
+  private def socket_close
+    socket_close do
+      raise ::Socket::Error.from_errno("Error closing socket")
+    end
+  end
+
   private def system_local_address
     sockaddr6 = uninitialized LibC::SockaddrIn6
     sockaddr = pointerof(sockaddr6).as(LibC::Sockaddr*)

src/crystal/system/win32/file_descriptor.cr

@@ -178,6 +178,12 @@ module Crystal::System::FileDescriptor
 
   def file_descriptor_close
     if LibC.CloseHandle(windows_handle) == 0
+      yield
+    end
+  end
+
+  def file_descriptor_close
+    file_descriptor_close do
       raise IO::Error.from_winerror("Error closing file", target: self)
     end
   end

src/crystal/system/win32/socket.cr

@@ -375,11 +375,17 @@ module Crystal::System::Socket
       when WinError::WSAEINTR, WinError::WSAEINPROGRESS
         # ignore
       else
-        raise ::Socket::Error.from_os_error("Error closing socket", err)
+        yield err
       end
     end
   end
 
+  def system_close
+    system_close do |err|
+      raise ::Socket::Error.from_os_error("Error closing socket", err)
+    end
+  end
+
   private def system_local_address
     sockaddr6 = uninitialized LibC::SockaddrIn6
     sockaddr = pointerof(sockaddr6).as(LibC::Sockaddr*)

src/io/file_descriptor.cr

@@ -236,7 +236,7 @@ class IO::FileDescriptor < IO
   def finalize
     return if closed? || !close_on_finalize?
 
-    close rescue nil
+    file_descriptor_close { } # ignore error
   end
 
   def closed? : Bool

src/socket.cr

@@ -422,7 +422,7 @@ class Socket < IO
   def finalize
     return if closed?
 
-    close rescue nil
+    socket_close { } # ignore error
   end
 
   def closed? : Bool