/// <summary>
/// Read page bytes from disk
/// </summary>
public virtual byte[] ReadPage(uint pageID)
{
// if stream are not initialized but need header, create new header
if (_stream == null && pageID == 0)
{
var header = new HeaderPage
{
LastPageID = 1
};
return(header.WritePage());
}
else if (_stream == null)
{
this.InternalInitialize();
}
var buffer = new byte[BasePage.PAGE_SIZE];
var position = BasePage.GetSizeOfPages(pageID);
// position cursor
if (_stream.Position != position)
{
_stream.Seek(position, SeekOrigin.Begin);
}
// read bytes from data file
_stream.Read(buffer, 0, BasePage.PAGE_SIZE);
return(buffer);
}
/// <summary>
/// Initialize new datafile with header page + lock reserved area zone
/// </summary>
public static void CreateDatabase(Stream stream, string password = null, long initialSize = 0)
{
// calculate how many empty pages will be added on disk
var emptyPages = initialSize == 0 ? 0 : (initialSize - (2 * BasePage.PAGE_SIZE)) / BasePage.PAGE_SIZE;
// if too small size (less than 2 pages), assume no initial size
if (emptyPages < 0)
{
emptyPages = 0;
}
// create a new header page in bytes (keep second page empty)
var header = new HeaderPage
{
LastPageID = initialSize == 0 ? 1 : (uint)emptyPages + 1,
FreeEmptyPageID = initialSize == 0 ? uint.MaxValue : 2
};
if (password != null)
{
header.Password = AesEncryption.HashSHA1(password);
header.Salt = AesEncryption.Salt();
}
// point to begin file
stream.Seek(0, SeekOrigin.Begin);
// get header page in bytes
var buffer = header.WritePage();
stream.Write(buffer, 0, BasePage.PAGE_SIZE);
// write second page as an empty AREA (it's not a page) just to use as lock control
stream.Write(new byte[BasePage.PAGE_SIZE], 0, BasePage.PAGE_SIZE);
// create crypto class if has password
var crypto = password != null ? new AesEncryption(password, header.Salt) : null;
// if initial size is defined, lets create empty pages in a linked list
if (emptyPages > 0)
{
stream.SetLength(initialSize);
var pageID = 1u;
while (++pageID < (emptyPages + 2))
{
var empty = new EmptyPage(pageID)
{
PrevPageID = pageID == 2 ? 0 : pageID - 1,
NextPageID = pageID == emptyPages + 1 ? uint.MaxValue : pageID + 1
};
var bytes = empty.WritePage();
if (password != null)
{
bytes = crypto.Encrypt(bytes);
}
stream.Write(bytes, 0, BasePage.PAGE_SIZE);
}
}
if (crypto != null)
{
crypto.Dispose();
}
}