Free unmanaged memory

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

shadowsocks-csharp/Util/ProcessManagement/Job.cs

@@ -12,17 +12,17 @@ namespace Shadowsocks.Util.ProcessManagement
     public class Job : IDisposable
     {
         [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
-        static extern IntPtr CreateJobObject(IntPtr a, string lpName);
+        private static extern IntPtr CreateJobObject(IntPtr a, string lpName);
 
         [DllImport("kernel32.dll")]
-        static extern bool SetInformationJobObject(IntPtr hJob, JobObjectInfoType infoType, IntPtr lpJobObjectInfo, UInt32 cbJobObjectInfoLength);
+        private static extern bool SetInformationJobObject(IntPtr hJob, JobObjectInfoType infoType, IntPtr lpJobObjectInfo, UInt32 cbJobObjectInfoLength);
 
         [DllImport("kernel32.dll", SetLastError = true)]
-        static extern bool AssignProcessToJobObject(IntPtr job, IntPtr process);
+        private static extern bool AssignProcessToJobObject(IntPtr job, IntPtr process);
 
         [DllImport("kernel32.dll", SetLastError = true)]
         [return: MarshalAs(UnmanagedType.Bool)]
-        static extern bool CloseHandle(IntPtr hObject);
+        private static extern bool CloseHandle(IntPtr hObject);
 
         private IntPtr handle;
         private bool disposed;
@@ -30,7 +30,7 @@ namespace Shadowsocks.Util.ProcessManagement
         public Job()
         {
             handle = CreateJobObject(IntPtr.Zero, null);
-
+            var extendedInfoPtr = IntPtr.Zero;
             var info = new JOBOBJECT_BASIC_LIMIT_INFORMATION
             {
                 LimitFlags = 0x2000
@@ -41,12 +41,25 @@ namespace Shadowsocks.Util.ProcessManagement
                 BasicLimitInformation = info
             };
 
-            int length = Marshal.SizeOf(typeof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION));
-            IntPtr extendedInfoPtr = Marshal.AllocHGlobal(length);
-            Marshal.StructureToPtr(extendedInfo, extendedInfoPtr, false);
-
-            if (!SetInformationJobObject(handle, JobObjectInfoType.ExtendedLimitInformation, extendedInfoPtr, (uint)length))
-                throw new Exception(string.Format("Unable to set information.  Error: {0}", Marshal.GetLastWin32Error()));
+            try
+            {
+                int length = Marshal.SizeOf(typeof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION));
+                extendedInfoPtr = Marshal.AllocHGlobal(length);
+                Marshal.StructureToPtr(extendedInfo, extendedInfoPtr, false);
+
+                if (!SetInformationJobObject(handle, JobObjectInfoType.ExtendedLimitInformation, extendedInfoPtr,
+                        (uint) length))
+                    throw new Exception(string.Format("Unable to set information.  Error: {0}",
+                        Marshal.GetLastWin32Error()));
+            }
+            finally
+            {
+                if (extendedInfoPtr != IntPtr.Zero)
+                {
+                    Marshal.FreeHGlobal(extendedInfoPtr);
+                    extendedInfoPtr = IntPtr.Zero;
+                }
+            }
         }
 
         public void Dispose()
@@ -78,8 +91,7 @@ namespace Shadowsocks.Util.ProcessManagement
 
             if (!succ)
             {
-                var err = Marshal.GetLastWin32Error();
-                Logging.Error("Failed to call AssignProcessToJobObject! GetLastError=" + err);
+                Logging.Error("Failed to call AssignProcessToJobObject! GetLastError=" + Marshal.GetLastWin32Error());
             }
 
             return succ;