1 files changed, 134 insertions, 0 deletions
diff --git a/include/utils/FileMap.h b/include/utils/FileMap.h
new file mode 100644
index 0000000..8dfd3be
--- /dev/null
+++ b/include/utils/FileMap.h
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2006 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.
+ */
+
+//
+// Encapsulate a shared file mapping.
+//
+#ifndef __LIBS_FILE_MAP_H
+#define __LIBS_FILE_MAP_H
+
+#include <sys/types.h>
+
+#ifdef HAVE_WIN32_FILEMAP
+#include <windows.h>
+#endif
+
+namespace android {
+
+/*
+ * This represents a memory-mapped file.  It might be the entire file or
+ * only part of it.  This requires a little bookkeeping because the mapping
+ * needs to be aligned on page boundaries, and in some cases we'd like to
+ * have multiple references to the mapped area without creating additional
+ * maps.
+ *
+ * This always uses MAP_SHARED.
+ *
+ * TODO: we should be able to create a new FileMap that is a subset of
+ * an existing FileMap and shares the underlying mapped pages.  Requires
+ * completing the refcounting stuff and possibly introducing the notion
+ * of a FileMap hierarchy.
+ */
+class FileMap {
+public:
+    FileMap(void);
+
+    /*
+     * Create a new mapping on an open file.
+     *
+     * Closing the file descriptor does not unmap the pages, so we don't
+     * claim ownership of the fd.
+     *
+     * Returns "false" on failure.
+     */
+    bool create(const char* origFileName, int fd,
+                off_t offset, size_t length, bool readOnly);
+
+    /*
+     * Return the name of the file this map came from, if known.
+     */
+    const char* getFileName(void) const { return mFileName; }
+    
+    /*
+     * Get a pointer to the piece of the file we requested.
+     */
+    void* getDataPtr(void) const { return mDataPtr; }
+
+    /*
+     * Get the length we requested.
+     */
+    size_t getDataLength(void) const { return mDataLength; }
+
+    /*
+     * Get the data offset used to create this map.
+     */
+    off_t getDataOffset(void) const { return mDataOffset; }
+
+    /*
+     * Get a "copy" of the object.
+     */
+    FileMap* acquire(void) { mRefCount++; return this; }
+
+    /*
+     * Call this when mapping is no longer needed.
+     */
+    void release(void) {
+        if (--mRefCount <= 0)
+            delete this;
+    }
+
+    /*
+     * This maps directly to madvise() values, but allows us to avoid
+     * including <sys/mman.h> everywhere.
+     */
+    enum MapAdvice {
+        NORMAL, RANDOM, SEQUENTIAL, WILLNEED, DONTNEED
+    };
+
+    /*
+     * Apply an madvise() call to the entire file.
+     *
+     * Returns 0 on success, -1 on failure.
+     */
+    int advise(MapAdvice advice);
+
+protected:
+    // don't delete objects; call release()
+    ~FileMap(void);
+
+private:
+    // these are not implemented
+    FileMap(const FileMap& src);
+    const FileMap& operator=(const FileMap& src);
+
+    int         mRefCount;      // reference count
+    char*       mFileName;      // original file name, if known
+    void*       mBasePtr;       // base of mmap area; page aligned
+    size_t      mBaseLength;    // length, measured from "mBasePtr"
+    off_t       mDataOffset;    // offset used when map was created
+    void*       mDataPtr;       // start of requested data, offset from base
+    size_t      mDataLength;    // length, measured from "mDataPtr"
+#ifdef HAVE_WIN32_FILEMAP
+    HANDLE      mFileHandle;    // Win32 file handle
+    HANDLE      mFileMapping;   // Win32 file mapping handle
+#endif
+
+    static long mPageSize;
+};
+
+}; // namespace android
+
+#endif // __LIBS_FILE_MAP_H