common: Add bootSessionUUID to SNTSystemInfo

Source/common/SNTSystemInfo.h

@@ -29,6 +29,14 @@
 ///
 + (NSString *)hardwareUUID;
 
+///
+///  The boot session UUID is generated by IOKit during early startup and is
+///  persistent until the system reboots.
+///
+///  @return Boot Session UUID
+///
++ (NSString *)bootSessionUUID;
+
 ///
 ///  @return OS Version, e.g.: 10.10.2
 ///

Source/common/SNTSystemInfo.m

@@ -18,34 +18,51 @@
 @implementation SNTSystemInfo
 
 + (NSString *)serialNumber {
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wdeprecated-declarations"
-  io_service_t platformExpert = IOServiceGetMatchingService(
-      kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
-#pragma clang diagnostic pop
-  if (!platformExpert) return nil;
-
-  NSString *serial = CFBridgingRelease(IORegistryEntryCreateCFProperty(
-      platformExpert, CFSTR(kIOPlatformSerialNumberKey), kCFAllocatorDefault, 0));
-
-  IOObjectRelease(platformExpert);
-
+  static NSString *serial;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    io_service_t platformExpert = IOServiceGetMatchingService(
+        kIOMainPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
+    if (!platformExpert) return;
+
+    serial = CFBridgingRelease(IORegistryEntryCreateCFProperty(
+        platformExpert, CFSTR(kIOPlatformSerialNumberKey), kCFAllocatorDefault, 0));
+
+    IOObjectRelease(platformExpert);
+  });
   return serial;
 }
 
 + (NSString *)hardwareUUID {
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wdeprecated-declarations"
-  io_service_t platformExpert = IOServiceGetMatchingService(
-      kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
-#pragma clang diagnostic pop
-  if (!platformExpert) return nil;
+  static NSString *uuid;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    io_service_t platformExpert = IOServiceGetMatchingService(
+        kIOMainPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
+    if (!platformExpert) return;
 
-  NSString *uuid = CFBridgingRelease(IORegistryEntryCreateCFProperty(
-      platformExpert, CFSTR(kIOPlatformUUIDKey), kCFAllocatorDefault, 0));
+    uuid = CFBridgingRelease(IORegistryEntryCreateCFProperty(
+        platformExpert, CFSTR(kIOPlatformUUIDKey), kCFAllocatorDefault, 0));
 
-  IOObjectRelease(platformExpert);
+    IOObjectRelease(platformExpert);
+  });
+
+  return uuid;
+}
 
++ (NSString *)bootSessionUUID {
+  static NSString *uuid;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    uuid_string_t bootSessionUUID = {};
+    size_t uuidLength = sizeof(bootSessionUUID);
+    // If this fails, bootSessionUUID is left as a fixed stack array of 0's,
+    // so the line following will create a zero-length NSString. There's not
+    // much we can really do if this fails, there are no other ways to get this
+    // information.
+    sysctlbyname("kern.bootsessionuuid", bootSessionUUID, &uuidLength, NULL, 0);
+    uuid = @(bootSessionUUID);
+  });
   return uuid;
 }