Adds some error handling to the socket implementation.

runtime/bin/fdutils_macos.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_MACOS)
 
 #include "bin/fdutils.h"
 
 #include <errno.h>      // NOLINT
 #include <fcntl.h>      // NOLINT
 #include <sys/ioctl.h>  // NOLINT
 #include <unistd.h>     // NOLINT
 
 #include "platform/signal_blocker.h"
 
 namespace dart {
 namespace bin {
 
 bool FDUtils::SetCloseOnExec(intptr_t fd) {
   intptr_t status;
   status = NO_RETRY_EXPECTED(fcntl(fd, F_GETFD));
   if (status < 0) {
+    perror("fcntl(F_GETFD) failed");
     return false;
   }
   status |= FD_CLOEXEC;
   if (NO_RETRY_EXPECTED(fcntl(fd, F_SETFD, status)) < 0) {
+    perror("fcntl(F_SETFD, FD_CLOEXEC) failed");
     return false;
   }
   return true;
 }
 
 
 static bool SetBlockingHelper(intptr_t fd, bool blocking) {
   intptr_t status;
   status = NO_RETRY_EXPECTED(fcntl(fd, F_GETFL));
   if (status < 0) {
+    perror("fcntl(F_GETFL) failed");
     return false;
   }
   status = blocking ? (status & ~O_NONBLOCK) : (status | O_NONBLOCK);
   if (NO_RETRY_EXPECTED(fcntl(fd, F_SETFL, status)) < 0) {
+    perror("fcntl(F_SETFL, O_NONBLOCK) failed");
     return false;
   }
   return true;
 }
 
 
 bool FDUtils::SetNonBlocking(intptr_t fd) {
   return SetBlockingHelper(fd, false);
 }
 
@@ skipping 78 matching lines @@
       buffer_pos += bytes_written;
     }
   }
   return count;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_MACOS)