Introduce ObjectLoader and RSExecutable.

ObjectLoader loads an object file into memory.

ObjectLoaderImpl defines a set of format-independent interfaces
that a object file format loader has to provide.

ELFObjectLoaderImpl is a subclass of ObjectLoaderImpl and can be used
to load an ELF relocatable object built based on librsloader. It
directly uses the C++ APIs provided by librsloader instead of using
wrapped C APIs defined in librsloader.h

RSExecutable holds the build results of a RSScript.
diff --git a/lib/ExecutionEngine/ObjectLoader.cpp b/lib/ExecutionEngine/ObjectLoader.cpp
new file mode 100644
index 0000000..708ded3
--- /dev/null
+++ b/lib/ExecutionEngine/ObjectLoader.cpp
@@ -0,0 +1,157 @@
+/*
+ * Copyright 2012, 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.
+ */
+
+#include "ObjectLoader.h"
+
+#include <utils/FileMap.h>
+
+#include "DebugHelper.h"
+#include "ELFObjectLoaderImpl.h"
+#include "FileBase.h"
+#include "GDBJITRegistrar.h"
+
+using namespace bcc;
+
+ObjectLoader *ObjectLoader::Load(void *pMemStart, size_t pMemSize,
+                                 const char *pName,
+                                 SymbolResolverInterface &pResolver,
+                                 bool pEnableGDBDebug) {
+  ObjectLoader *result = NULL;
+
+  // Check parameters.
+  if ((pMemStart == NULL) || (pMemSize <= 0)) {
+    ALOGE("Invalid memory '%s' was given to load (memory addr: %p, size: %u)",
+          pName, pMemStart, static_cast<unsigned>(pMemSize));
+    goto bail;
+  }
+
+  // Create result object
+  result = new (std::nothrow) ObjectLoader();
+  if (result == NULL) {
+    ALOGE("Out of memory when create object loader for %s!", pName);
+    goto bail;
+  }
+
+  // Currently, only ELF object loader is supported. Therefore, there's no codes
+  // to detect the object file type and to select the one appropriated. Directly
+  // try out the ELF object loader.
+  result->mImpl = new (std::nothrow) ELFObjectLoaderImpl();
+  if (result->mImpl == NULL) {
+    ALOGE("Out of memory when create ELF object loader for %s", pName);
+    goto bail;
+  }
+
+  // Load the object file.
+  if (!result->mImpl->load(pMemStart, pMemSize)) {
+    ALOGE("Failed to load %s!", pName);
+    goto bail;
+  }
+
+  // Perform relocation.
+  if (!result->mImpl->relocate(pResolver)) {
+    ALOGE("Error occurred when performs relocation on %s!", pName);
+    goto bail;
+  }
+
+  // GDB debugging is enabled. Note that error occurrs during the setup of
+  // debugging won't failed the object load. Only a warning is issued to notify
+  // that the debugging is disabled due to the failure.
+  if (pEnableGDBDebug) {
+    // GDB's JIT debugging requires the source object file corresponded to the
+    // process image desired to debug with. And some fields in the object file
+    // must be updated to record the runtime information after it's loaded into
+    // memory. For example, GDB's JIT debugging requires an ELF file with the
+    // value of sh_addr in the section header to be the memory address that the
+    // section lives in the process image. Therefore, a writable memory with its
+    // contents initialized to the contents of pFile is created.
+    result->mDebugImage = new (std::nothrow) uint8_t [ pMemSize ];
+    if (result->mDebugImage != NULL) {
+      ::memcpy(result->mDebugImage, pMemStart, pMemSize);
+      if (!result->mImpl->prepareDebugImage(result->mDebugImage, pMemSize)) {
+        ALOGW("GDB debug for %s is enabled by the user but won't work due to "
+              "failure debug image preparation!", pName);
+      } else {
+        registerObjectWithGDB(
+            reinterpret_cast<const ObjectBuffer *>(result->mDebugImage),
+            pMemSize);
+      }
+    }
+  }
+
+  return result;
+
+bail:
+  delete result;
+  return NULL;
+}
+
+ObjectLoader *ObjectLoader::Load(FileBase &pFile,
+                                 SymbolResolverInterface &pResolver,
+                                 bool pEnableGDBDebug) {
+  size_t file_size;
+  android::FileMap *file_map = NULL;
+  const char *input_filename = pFile.getName().c_str();
+  ObjectLoader *result = NULL;
+
+  // Check the inputs.
+  if (pFile.hasError()) {
+    ALOGE("Input file %s to the object loader is in the invalid state! (%s)",
+          input_filename, pFile.getErrorMessage().c_str());
+    return NULL;
+  }
+
+  // Get the file size.
+  file_size = pFile.getSize();
+  if (pFile.hasError()) {
+    ALOGE("Failed to get size of file %s! (%s)", input_filename,
+          pFile.getErrorMessage().c_str());
+    return NULL;
+  }
+
+  // Abort on empty file.
+  if (file_size <= 0) {
+    ALOGE("Empty file %s to the object loader.", input_filename);
+    return NULL;
+  }
+
+  // Create memory map for the input file.
+  file_map = pFile.createMap(0, file_size, /* pIsReadOnly */true);
+  if ((file_map == NULL) || pFile.hasError())  {
+    ALOGE("Failed to map the file %s to the memory! (%s)", input_filename,
+          pFile.getErrorMessage().c_str());
+    return NULL;
+  }
+
+  // Delegate the load request.
+  result = Load(file_map->getDataPtr(), file_size, input_filename, pResolver,
+                pEnableGDBDebug);
+
+  // No whether the load is successful or not, file_map is no longer needed. On
+  // success, there's a copy of the object corresponded to the pFile in the
+  // memory. Therefore, file_map can be safely released.
+  file_map->release();
+
+  return result;
+}
+
+void *ObjectLoader::getSymbolAddress(const char *pName) const {
+  return mImpl->getSymbolAddress(pName);
+}
+
+ObjectLoader::~ObjectLoader() {
+  delete mImpl;
+  delete [] reinterpret_cast<uint8_t *>(mDebugImage);
+}