Be proactive about checking for error codes.

LibGit2Sharp/Core/Ensure.cs

@@ -38,34 +38,11 @@ public static void ArgumentNotNullOrEmptyString(string argumentValue, string arg
             }
         }
 
-        /// <summary>
-        ///   Check that the result of a C call was successful
-        ///   <para>
-        ///     This usually means that the method is expected to return 0.
-        ///     In some rare cases, some methods may return negative values for errors and
-        ///     positive values carrying information. Those positive values should be interpreted
-        ///     as successful calls as well.
-        ///   </para>
-        /// </summary>
-        /// <param name = "result">The result to examine.</param>
-        /// <param name = "allowPositiveResult">False to only allow success when comparing against 0,
-        ///   True when positive values are allowed as well.</param>
-        public static void Success(int result, bool allowPositiveResult = false)
+        private static void HandleError(int result)
         {
-            if (result == (int)GitErrorCode.Ok)
-            {
-                return;
-            }
-
-            if (allowPositiveResult && result > (int)GitErrorCode.Ok)
-            {
-                return;
-            }
-
             string errorMessage;
             GitError error = NativeMethods.giterr_last().MarshalAsGitError();
 
-
             if (error == null)
             {
                 error = new GitError { Category = GitErrorCategory.Unknown, Message = IntPtr.Zero };
@@ -98,6 +75,62 @@ public static void Success(int result, bool allowPositiveResult = false)
             }
         }
 
+        /// <summary>
+        ///   Check that the result of a C call was successful
+        ///   <para>
+        ///     The native function is expected to return strictly 0 for
+        ///     success or a negative value in the case of failure.
+        ///   </para>
+        /// </summary>
+        /// <param name = "result">The result to examine.</param>
+        public static void ZeroResult(int result)
+        {
+            if (result == (int)GitErrorCode.Ok)
+            {
+                return;
+            }
+
+            HandleError(result);
+        }
+
+        /// <summary>
+        ///   Check that the result of a C call that returns a boolean value
+        ///   was successful
+        ///   <para>
+        ///     The native function is expected to return strictly 0 for
+        ///     success or a negative value in the case of failure.
+        ///   </para>
+        /// </summary>
+        /// <param name = "result">The result to examine.</param>
+        public static void BooleanResult(int result)
+        {
+            if (result == (int)GitErrorCode.Ok || result == 1)
+            {
+                return;
+            }
+
+            HandleError(result);
+        }
+
+        /// <summary>
+        ///   Check that the result of a C call that returns an integer value
+        ///   was successful
+        ///   <para>
+        ///     The native function is expected to return strictly 0 for
+        ///     success or a negative value in the case of failure.
+        ///   </para>
+        /// </summary>
+        /// <param name = "result">The result to examine.</param>
+        public static void Int32Result(int result)
+        {
+            if (result >= (int)GitErrorCode.Ok)
+            {
+                return;
+            }
+
+            HandleError(result);
+        }
+
         /// <summary>
         ///   Checks an argument by applying provided checker.
         /// </summary>

LibGit2Sharp/Core/NativeMethods.cs

@@ -26,7 +26,7 @@ private sealed class LibraryLifetimeObject : CriticalFinalizerObject
             // Ensure mono can JIT the .cctor and adjust the PATH before trying to load the native library.
             // See https://github.com/libgit2/libgit2sharp/pull/190
             [MethodImpl(MethodImplOptions.NoInlining)]
-            public LibraryLifetimeObject() { Ensure.Success(NativeMethods.git_threads_init()); }
+            public LibraryLifetimeObject() { Ensure.ZeroResult(NativeMethods.git_threads_init()); }
             ~LibraryLifetimeObject() { NativeMethods.git_threads_shutdown(); }
         }
 
@@ -988,7 +988,7 @@ internal static extern int git_treebuilder_insert(
         internal static extern void git_treebuilder_free(IntPtr bld);
 
         [DllImport(libgit2)]
-        internal static extern bool git_blob_is_binary(GitObjectSafeHandle blob);
+        internal static extern int git_blob_is_binary(GitObjectSafeHandle blob);
     }
 }
 // ReSharper restore InconsistentNaming