Fuchsia: Partial implementation of dart:io sockets

runtime/bin/fdutils_macos.cc

Index: runtime/bin/fdutils_macos.cc
diff --git a/runtime/bin/fdutils_macos.cc b/runtime/bin/fdutils_macos.cc
index ab1a603e91277fdcd66180bbeffb4f60cd5bf46c..4a0e3c09c8864fa14e93b8b6f7e315b77a1a67ef 100644
--- a/runtime/bin/fdutils_macos.cc
+++ b/runtime/bin/fdutils_macos.cc
@@ -137,6 +137,13 @@ ssize_t FDUtils::WriteToBlocking(int fd, const void* buffer, size_t count) {
   return count;
 }
 
+
+void FDUtils::SaveErrorAndClose(intptr_t fd) {
+  int err = errno;
+  VOID_TEMP_FAILURE_RETRY(close(fd));
+  errno = err;
+}
+
 }  // namespace bin
 }  // namespace dart