Initial error handling code

src/core/SkSecureReader32.h

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#ifndef SkSecureReader32_DEFINED
+#define SkSecureReader32_DEFINED
+
+#include "SkMatrix.h"
+#include "SkPath.h"
+#include "SkRegion.h"
+#include "SkRRect.h"
+#include "SkScalar.h"
+
+class SkString;
+
+class SkSecureReader32 : SkNoncopyable {
+public:
+    SkSecureReader32();
+    SkSecureReader32(const void* data, size_t size);
+
+    void setMemory(const void* data, size_t size);
+
+    uint32_t size() const;
+    uint32_t offset() const;
+    bool eof() const;
+    const void* base() const;
+    const void* peek() const;
+
+    bool readBool();
+
+    int32_t readInt();
+
+    SkScalar readScalar();
+
+    const void* skip(size_t size);
+
+    int32_t readS32();
+    uint32_t readU32();
+
+    void readPath(SkPath* path);
+
+    void readMatrix(SkMatrix* matrix);
+
+    void readRegion(SkRegion* rgn);
+
+    /**
+     *  Read the length of a string (written by SkWriter32::writeString) into
+     *  len (if len is not NULL) and return the null-ternimated address of the
+     *  string within the reader's buffer.
+     */
+    const char* readString(size_t* len = NULL);
+
+    void setError() { fError = true; }
+    bool getError() const { return fError; }
+
+private:
+    bool isAvailable(uint32_t size) const;
+
+    // these are always 4-byte aligned
+    const char* fCurr;  // current position within buffer
+    const char* fStop;  // end of buffer
+    const char* fBase;  // beginning of buffer
+    bool fError;
+
+    static bool ptr_align_4(const void* ptr) {
+        return (((const char*)ptr - (const char*)NULL) & 3) == 0;
+    }
+};
+
+#endif