SabreTools.Serialization/SabreTools.Data.Models/PKZIP/InfoZIPUnicodeCommentExtraField.cs

namespace SabreTools.Data.Models.PKZIP
{
    /// <summary>
    /// Stores the UTF-8 version of the file comment as stored in the
    /// central directory header. (Last Revision 20070912)
    ///
    /// Currently Version is set to the number 1.  If there is a need
    /// to change this field, the version will be incremented.  Changes
    /// MAY NOT be backward compatible so this extra field SHOULD NOT be
    /// used if the version is not recognized.
    ///
    /// The ComCRC32 is the standard zip CRC32 checksum of the File Comment
    /// field in the central directory header.  This is used to verify that
    /// the comment field has not changed since the Unicode Comment extra field
    /// was created.  This can happen if a utility changes the File Comment
    /// field but does not update the UTF-8 Comment extra field.  If the CRC
    /// check fails, this Unicode Comment extra field SHOULD be ignored and
    /// the File Comment field in the header SHOULD be used instead.
    ///
    /// The UnicodeCom field is the UTF-8 version of the File Comment field
    /// in the header.  As UnicodeCom is defined to be UTF-8, no UTF-8 byte
    /// order mark (BOM) is used.  The length of this field is determined by
    /// subtracting the size of the previous fields from TSize.  If both the
    /// File Name and Comment fields are UTF-8, the new General Purpose Bit
    /// Flag, bit 11 (Language encoding flag (EFS)), can be used to indicate
    /// both the header File Name and Comment fields are UTF-8 and, in this
    /// case, the Unicode Path and Unicode Comment extra fields are not
    /// needed and SHOULD NOT be created.  Note that, for backward
    /// compatibility, bit 11 SHOULD only be used if the native character set
    /// of the paths and comments being zipped up are already in UTF-8. It is
    /// expected that the same file comment storage method, either general
    /// purpose bit 11 or extra fields, be used in both the Local and Central
    /// Directory Header for a file.
    /// </summary>
    /// <remarks>Header ID = 0x6375</remarks>
    /// <see href="https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT"/>
    public class InfoZIPUnicodeCommentExtraField : ExtensibleDataField
    {
        /// <summary>
        /// Version of this extra field, currently 1
        /// </summary>
        public byte Version { get; set; }

        /// <summary>
        /// Comment Field CRC32 Checksum
        /// </summary>
        public uint ComCRC32 { get; set; }

        /// <summary>
        /// UTF-8 version of the entry comment
        /// </summary>
        public string UnicodeCom { get; set; } = string.Empty;
    }
}