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/*-------------------------------------------------------------------------
LargeObjectManager.cs
This class is a port of the class LargeObjectManager.java implemented by
PostgreSQL Global Development Group
Copyright (c) 2004, Emiliano Necciari
Original Code: Copyright (c) 2003, PostgreSQL Global Development Group
Note: (Francisco Figueiredo Jr.)
Changed case of method names to conform to .Net names standard.
Also changed type names to their true names. i.e. int -> Int32
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-------------------------------------------------------------------------
*/
using System;
using System.Data;
using Npgsql;
namespace NpgsqlTypes
{
/// <summary>
/// Summary description for LargeObjectManager.
/// </summary>
public class LargeObjectManager
{
// the fastpath api for this connection
private Fastpath fp;
/*
* This mode indicates we want to write to an object
*/
public const Int32 WRITE = 0x00020000;
/*
* This mode indicates we want to read an object
*/
public static Int32 READ = 0x00040000;
/*
* This mode is the default. It indicates we want read and write access to
* a large object
*/
public static Int32 READWRITE = READ | WRITE;
/*
* This prevents us being created by mere mortals
*/
private LargeObjectManager()
{}
/*
* Constructs the LargeObject API.
*
* <p><b>Important Notice</b>
* <br>This method should only be called by org.postgresql.Connection
*
* <p>There should only be one LargeObjectManager per Connection. The
* org.postgresql.Connection class keeps track of the various extension API's
* and it's advised you use those to gain access, and not going direct.
*/
public LargeObjectManager(NpgsqlConnection conn)
{
// We need Fastpath to do anything
// Now get the function oid's for the api
//
// This is an example of Fastpath.addFunctions();
//
String sql;
if (conn.ServerVersion > new ServerVersion(7,3,0) )
{
sql = "SELECT p.proname,p.oid "+
" FROM pg_catalog.pg_proc p, pg_catalog.pg_namespace n "+
" WHERE p.pronamespace=n.oid AND n.nspname='pg_catalog' AND (";
}
else
{
sql = "SELECT proname,oid FROM pg_proc WHERE ";
}
sql += " proname = 'lo_open'" +
" or proname = 'lo_close'" +
" or proname = 'lo_creat'" +
" or proname = 'lo_unlink'" +
" or proname = 'lo_lseek'" +
" or proname = 'lo_tell'" +
" or proname = 'loread'" +
" or proname = 'lowrite'";
if (conn.ServerVersion > new ServerVersion(7,3,0) )
{
sql += ")";
}
IDbCommand cmd = new NpgsqlCommand(sql);
cmd.Connection = conn;
this.fp = new Fastpath(conn,conn.Connector.Stream);
IDataReader res = cmd.ExecuteReader(CommandBehavior.CloseConnection);
if (res == null)
throw new Exception("postgresql.lo.init");
fp.AddFunctions(res);
}
/*
* This opens an existing large object, based on its OID. This method
* assumes that READ and WRITE access is required (the default).
*
* @param oid of large object
* @return LargeObject instance providing access to the object
* @exception SQLException on error
*/
public LargeObject Open(Int32 oid)
{
return new LargeObject(fp, oid, READWRITE);
}
/*
* This opens an existing large object, based on its OID
*
* @param oid of large object
* @param mode mode of open
* @return LargeObject instance providing access to the object
* @exception SQLException on error
*/
public LargeObject Open(Int32 oid, Int32 mode)
{
return new LargeObject(fp, oid, mode);
}
/*
* This creates a large object, returning its OID.
*
* <p>It defaults to READWRITE for the new object's attributes.
*
* @return oid of new object
* @exception SQLException on error
*/
public Int32 Create()
{
FastpathArg[] args = new FastpathArg[1];
args[0] = new FastpathArg(READWRITE);
return fp.GetInteger("lo_creat", args);
}
/*
* This creates a large object, returning its OID
*
* @param mode a bitmask describing different attributes of the new object
* @return oid of new object
* @exception SQLException on error
*/
public Int32 Create(Int32 mode)
{
FastpathArg[] args = new FastpathArg[1];
args[0] = new FastpathArg(mode);
return fp.GetInteger("lo_creat", args);
}
/*
* This deletes a large object.
*
* @param oid describing object to delete
* @exception SQLException on error
*/
public void Delete(Int32 oid)
{
FastpathArg[] args = new FastpathArg[1];
args[0] = new FastpathArg(oid);
fp.FastpathCall("lo_unlink", false, args);
}
/*
* This deletes a large object.
*
* <p>It is identical to the delete method, and is supplied as the C API uses
* unlink.
*
* @param oid describing object to delete
* @exception SQLException on error
*/
public void Unlink(Int32 oid)
{
Delete(oid);
}
}
}
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