Support marking a file-descriptor as blocking via fcntl

Summary: Previously, only marking it as non-blocking was supported.

Reviewed By: simpkins

Differential Revision: D5307769

fbshipit-source-id: 03ed7c35632dbc9551552b21c401ea709bd6eaaa

folly/portability/Fcntl.cpp

@@ -61,24 +61,23 @@ int fcntl(int fd, int cmd, ...) {
     }
     case F_SETFL: {
       int flags = va_arg(args, int);
-      if (flags & O_NONBLOCK) {
       // If it's not a socket, it's probably a pipe.
       if (folly::portability::sockets::is_fh_socket(fd)) {
         SOCKET s = (SOCKET)_get_osfhandle(fd);
         if (s != INVALID_SOCKET) {
-            u_long nonBlockingEnabled = 1;
+          u_long nonBlockingEnabled = (flags & O_NONBLOCK) ? 1 : 0;
           res = ioctlsocket(s, FIONBIO, &nonBlockingEnabled);
         }
       } else {
         HANDLE p = (HANDLE)_get_osfhandle(fd);
         if (GetFileType(p) == FILE_TYPE_PIPE) {
-            DWORD newMode = PIPE_READMODE_BYTE | PIPE_NOWAIT;
+          DWORD newMode = PIPE_READMODE_BYTE;
+          newMode |= (flags & O_NONBLOCK) ? PIPE_NOWAIT : PIPE_WAIT;
           if (SetNamedPipeHandleState(p, &newMode, nullptr, nullptr)) {
             res = 0;
           }
         }
       }
-      }
       break;
     }
   }