/*
 * File:	EncoreBootImageReader.h
 *
 * Copyright (c) Freescale Semiconductor, Inc. All rights reserved.
 * See included license file for license details.
 */
#if !defined(_EncoreBootImageReader_h_)
#define _EncoreBootImageReader_h_

#include "EncoreBootImage.h"

namespace elftosb
{
/*!
 * \brief Reads a Piano/Encore boot image from an input stream.
 */
class EncoreBootImageReader
{
public:
    /*!
     * \brief Exception class used for error found while reading a boot image.
     */
    class read_error : public std::runtime_error
    {
    public:
        //! \brief Constructor.
        read_error(const std::string &msg)
            : std::runtime_error(msg)
        {
        }
    };

    //! \brief An array of section headers.
    typedef std::vector<EncoreBootImage::section_header_t> section_array_t;

    //! \brief An array of boot tags.
    typedef std::vector<EncoreBootImage::boot_command_t> boot_tag_array_t;

public:
    //! \brief Default constructor.
    EncoreBootImageReader(std::istream &stream)
        : m_stream(stream)
    {
    }

    //! \brief Destructor.
    virtual ~EncoreBootImageReader() {}
    //! \name Decryption key
    //! These methods provide access to the Data Encryption Key (DEK). Normally
    //! the DEK is discovered using the readKeyDictionary() method.
    //@{
    inline void setKey(const AESKey<128> &key) { m_dek = key; }
    inline const AESKey<128> &getKey() const { return m_dek; }
    //@}

    //! \name Readers
    //! This group of methods is responsible for reading and parsing different
    //! pieces and parts of the boot image file.
    //@{
    //! \brief Reads the header from the image.
    void readImageHeader();

    //! \brief Computes the actual SHA-1 digest of the image header.
    void computeHeaderDigest(sha1_digest_t &digest);

    //! \brief Reads the digest at the end of the image.
    void readImageDigest();

    //! \brief Run a SHA-1 digest over the entire image.
    void computeImageDigest(sha1_digest_t &digest);

    //! \brief Read the plaintext section table entries.
    void readSectionTable();

    //! \brief Reads the key dictionary, if the image is encrypted.
    bool readKeyDictionary(const AESKey<128> &kek);

    //! \brief
    void readBootTags();

    //! \brief
    EncoreBootImage::Section *readSection(unsigned index);
    //@}

    //! \name Accessors
    //! Information retrieved with reader methods is accessible through
    //! these methods.
    //@{
    //! \brief Returns whether the image is encrypted or not.
    //! \pre The header must have been read already.
    inline bool isEncrypted() const { return m_header.m_keyCount > 0; }
    //! \brief Returns a reference to the image's header.
    const EncoreBootImage::boot_image_header_t &getHeader() const { return m_header; }
    //! \brief Returns a reference to the SHA-1 digest read from the image.
    const sha1_digest_t &getDigest() const { return m_digest; }
    //! \brief Returns a reference to the STL container holding the section headers.
    inline const section_array_t &getSections() const { return m_sections; }
    //! \brief Returns a reference to the STL container holding the boot tags.
    inline const boot_tag_array_t &getBootTags() const { return m_bootTags; }
    //@}

protected:
    std::istream &m_stream;                        //!< The input stream to read the image from.
    AESKey<128> m_dek;                             //!< DEK (data encryption key) read from the key dictionary.
    EncoreBootImage::boot_image_header_t m_header; //!< Header from the boot image.
    sha1_digest_t m_digest;                        //!< SHA-1 digest as read from the image.
    section_array_t m_sections;                    //!< The section table.
    boot_tag_array_t m_bootTags;                   //!< The array of boot tags read from the image.

protected:
    //! \brief Calculates the 8-bit checksum on a boot command header.
    uint8_t calculateCommandChecksum(EncoreBootImage::boot_command_t &header);
};

}; // namespace elftosb

#endif // _EncoreBootImageReader_h_
