Beginnings of a debugger wire protocol

runtime/bin/fdutils_macos.cc

Index: runtime/bin/fdutils_macos.cc
===================================================================
--- runtime/bin/fdutils_macos.cc	(revision 7329)
+++ runtime/bin/fdutils_macos.cc	(working copy)
@@ -10,14 +10,14 @@
 #include "bin/fdutils.h"
 
 
-bool FDUtils::SetNonBlocking(intptr_t fd) {
+static bool SetBlockingHelper(intptr_t fd, bool blocking) {
   intptr_t status;
   status = TEMP_FAILURE_RETRY(fcntl(fd, F_GETFL));
   if (status < 0) {
     perror("fcntl F_GETFL failed");
     return false;
   }
-  status = (status | O_NONBLOCK);
+  status = blocking ? (status & ~O_NONBLOCK) : (status | O_NONBLOCK);
   if (TEMP_FAILURE_RETRY(fcntl(fd, F_SETFL, status)) < 0) {
     perror("fcntl F_SETFL failed");
     return false;
@@ -26,6 +26,16 @@
 }
 
 
+bool FDUtils::SetNonBlocking(intptr_t fd) {
+  return SetBlockingHelper(fd, false);
+}
+
+
+bool FDUtils::SetBlocking(intptr_t fd) {
+  return SetBlockingHelper(fd, true);
+}
+
+
 bool FDUtils::IsBlocking(intptr_t fd, bool* is_blocking) {
   intptr_t status;
   status = TEMP_FAILURE_RETRY(fcntl(fd, F_GETFL));