Be more paranoid about monitor info

These function are not guaranteed to succeed, and we've had reports that
they fail on ARM. So make sure we more properly check return values.

diff --git a/vncviewer/MonitorArrangement.cxx b/vncviewer/MonitorArrangement.cxx
index e075d17331fd20171664d96664787111f89ea8d1..055a91ccbbfe6b5deab82d70ee799b7bdefd625d 100644 (file)
--- a/vncviewer/MonitorArrangement.cxx
+++ b/vncviewer/MonitorArrangement.cxx
@@ -406,6 +406,12 @@ std::string MonitorArrangement::get_monitor_name(int m)
 #elif defined(__APPLE__)
   CGDisplayCount count;
   CGDirectDisplayID displays[16];
+
+  CGDirectDisplayID displayID;
+  CFDictionaryRef info;
+  CFDictionaryRef dict;
+  CFIndex dict_len;
+
   std::string name;
 
   if (CGGetActiveDisplayList(16, displays, &count) != kCGErrorSuccess)
@@ -418,14 +424,20 @@ std::string MonitorArrangement::get_monitor_name(int m)
     return "";
 
   // Notice: Here we assume indices to be ordered the same as in FLTK (we rely on that in cocoa.mm as well).
-  CGDirectDisplayID displayID = displays[m];
+  displayID = displays[m];
+
+  info = IODisplayCreateInfoDictionary(CGDisplayIOServicePort(displayID),
+                                       kIODisplayOnlyPreferredName);
+  if (info == NULL)
+    return "";
 
-  CFDictionaryRef info = IODisplayCreateInfoDictionary(
-    /* display = */ CGDisplayIOServicePort(displayID),
-    /* options = */ kIODisplayOnlyPreferredName);
+  dict = (CFDictionaryRef) CFDictionaryGetValue(info, CFSTR(kDisplayProductName));
+  if (dict == NULL) {
+    CFRelease(info);
+    return "";
+  }
 
-  CFDictionaryRef dict = (CFDictionaryRef) CFDictionaryGetValue(info, CFSTR(kDisplayProductName));
-  CFIndex dict_len = CFDictionaryGetCount(dict);
+  dict_len = CFDictionaryGetCount(dict);
 
   if (dict_len > 0) {
     CFTypeRef * names = new CFTypeRef[dict_len];