Improve the FileNotFoundExceptions thrown by OSFileSystem.open.

When I improved the internals of java.io.File, I failed to keep
OSFileSystem.open (which uses the internals of java.io.File) in
sync, leading to misleading error reporting. java.io.File's
internals now include a trailing NUL, which is useful for the
native code but confuses Java if it tries to decode the byte[]
as a UTF-8 sequence.

This patch fixes the bug and also improves OSFileSystem.open's
error reporting to include the reason for the failure.

Bug: 2313271

1 files changed, 53 insertions, 0 deletions

diff --git a/include/ScopedByteArray.h b/include/ScopedByteArray.h
new file mode 100644
index 0000000..bcbee99
--- /dev/null
+++ b/include/ScopedByteArray.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SCOPED_BYTE_ARRAY_H_included
+#define SCOPED_BYTE_ARRAY_H_included
+
+#include "JNIHelp.h"
+
+// A smart pointer that provides read-only access to a Java byte[].
+class ScopedByteArray {
+public:
+    ScopedByteArray(JNIEnv* env, jbyteArray byteArray)
+    : mEnv(env), mByteArray(byteArray), mBytes(NULL)
+    {
+        mBytes = env->GetByteArrayElements(mByteArray, NULL);
+    }
+
+    ~ScopedByteArray() {
+        if (mBytes) {
+            mEnv->ReleaseByteArrayElements(mByteArray, mBytes, JNI_ABORT);
+        }
+    }
+
+    const jbyte* bytes() const {
+        return mBytes;
+    }
+
+    // Element access.
+    const char& operator[](size_t n) const {
+        const char* array = reinterpret_cast<const char*>(mBytes);
+        return array[n];
+    }
+
+private:
+    JNIEnv* mEnv;
+    jbyteArray mByteArray;
+    jbyte* mBytes;
+};
+
+#endif  // SCOPED_BYTE_ARRAY_H_included