first cut: establishes base helper classes and main

platform_reader.h

Index: platform_reader.h
diff --git a/platform_reader.h b/platform_reader.h
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+// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// Defines the PlatformReader base class.  It provides a default file reading
+// implementation that pulls in the contents of the given platform_file_path.
+// This content is passed to a subclass-defined Process() helper which will
+// return an int.  This int should map to the anonymous enum in the
+// PlatformReader class or to an extension to that enum in the subclass.
+#ifndef CROS_BOOT_MODE_PLATFORM_READER_H_
+#define CROS_BOOT_MODE_PLATFORM_READER_H_
+
+#include <sys/types.h>
+#include <string>
+
+#include "helpers.h"
+
+namespace cros_boot_mode {
+
+class PlatformReader {
+ public:
+  enum { kUnsupported = -1 };  // All subclasses should extend this enum.
+  PlatformReader();
+  virtual ~PlatformReader();
+  // Provides a default file reader which then calls an override-able
+  // function for processing.  Initialize must leave the class in a usable
+  // state even on failure.
+  virtual void Initialize();
+
+  // To be provided by the implementation
+
+  // The name of the concrete class.
+  virtual const char *name() const = 0;
+  // c_str() should return the conversion of the given enum to a lowercase
+  // char array with no spaces.
+  virtual const char *c_str() const = 0;
+  // max_size should return the maximum size that will be read.
+  virtual size_t max_size() const = 0;
+  // default_platform_file_path should return the char array of the
+  // path to the file to be processed.
+  virtual const char *default_platform_file_path() const = 0;
+  // Called from initialize over the contents of the platform file. It
+  // should return an int that matches either kUnsupported or an extension
+  // of the anonymous enum.  If the file does not exist, cannot be read,
+  // or exceeds the max_size(), Process will be called with (buf, 0) arguments.
+  virtual int Process(const char *file_contents, size_t length) = 0;
+
+  // Accessors for the private value.
+  // These are largely used for internal references, but kept in public
+  // to allow for direct unit testing.
+  virtual int value() const {
+    return value_;
+  }
+  virtual void set_value(int value) {
+    value_ = value;
+  }
+
+  virtual const char *platform_file_path() const;
+  virtual void set_platform_file_path(const char *path) {
+    platform_file_path_ = path;
+  }
+
+ private:
+   int value_;
+   const char *platform_file_path_;
+};
+
+}  // namespace cros_boot_mode
+#endif  // CROS_BOOT_MODE_PLATFORM_READER_H_