/// <summary>
/// Reads a record stream field into a file.
/// </summary>
/// <param name="field">Specifies the field of the Record to get.</param>
/// <param name="filePath">Specifies the path to the file to contain the stream.</param>
/// <exception cref="ArgumentOutOfRangeException">The field is less than 0 or greater than the
/// number of fields in the Record.</exception>
/// <exception cref="NotSupportedException">Attempt to extract a storage from a database open
/// in read-write mode, or from a database without an associated file path</exception>
/// <remarks><p>
/// This method is capable of directly extracting substorages. To do so, first select both the
/// `Name` and `Data` column of the `_Storages` table, then get the stream of the `Data` field.
/// However, substorages may only be extracted from a database that is open in read-only mode.
/// </p><p>
/// Win32 MSI API:
/// <a href="http://msdn.microsoft.com/library/en-us/msi/setup/msirecordreadstream.asp">MsiRecordReadStream</a>
/// </p></remarks>
public void GetStream(int field, string filePath)
{
if (string.IsNullOrWhiteSpace(filePath))
{
throw new ArgumentNullException("filePath");
}
IList <TableInfo> tables = (this.view != null ? this.view.Tables : null);
if (tables != null && tables.Count == 1 && tables[0].Name == "_Storages" && field == this.FindColumn("Data"))
{
if (!this.view.Database.IsReadOnly)
{
throw new NotSupportedException("Database must be opened read-only to support substorage extraction.");
}
else if (this.view.Database.FilePath == null)
{
throw new NotSupportedException("Database must have an associated file path to support substorage extraction.");
}
else if (this.FindColumn("Name") <= 0)
{
throw new NotSupportedException("Name column must be part of the Record in order to extract substorage.");
}
else
{
Record.ExtractSubStorage(this.view.Database.FilePath, this.GetString("Name"), filePath);
}
}
else
{
if (!this.IsNull(field))
{
Stream readStream = null, writeStream = null;
try
{
readStream = new RecordStream(this, field);
writeStream = new FileStream(filePath, FileMode.Create, FileAccess.Write);
int count = 512;
byte[] buf = new byte[count];
while (count == buf.Length)
{
if ((count = readStream.Read(buf, 0, buf.Length)) > 0)
{
writeStream.Write(buf, 0, count);
}
}
}
finally
{
if (readStream != null)
{
readStream.Close();
}
if (writeStream != null)
{
writeStream.Close();
}
}
}
}
}