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LargeObjectManager.cs
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210 lines (187 loc) · 7.46 KB
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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
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph and the following two paragraphs appear in all copies.
//
// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
-------------------------------------------------------------------------
*/
using System;
using System.Data;
using System.Text;
using Npgsql;
namespace NpgsqlTypes
{
/// <summary>
/// Large Object Manager.
/// </summary>
public class LargeObjectManager
{
// the fastpath api for this connection
private readonly Fastpath fp;
/// <summary>
/// This mode indicates we want to write to an object
/// </summary>
public const Int32 WRITE = 0x00020000;
/// <summary>
/// This mode indicates we want to read an object
/// </summary>
public static Int32 READ = 0x00040000;
/// <summary>
/// This mode is the default. It indicates we want read and write access to
/// </summary>
public static Int32 READWRITE = READ | WRITE;
private LargeObjectManager()
{
/*
* This prevents us being created by mere mortals
*/
}
/// <summary>
/// Constructs the LargeObject API.
/// 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.
/// </summary>
/// <param name="conn"></param>
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;
StringBuilder sql = null;
try
{
sql = new StringBuilder();
if (conn.PostgreSqlVersion > new Version(7, 3, 0))
{
sql.Append("SELECT p.proname,p.oid ");
sql.Append(" FROM pg_catalog.pg_proc p, pg_catalog.pg_namespace n ");
sql.Append(" WHERE p.pronamespace=n.oid AND n.nspname='pg_catalog' AND (");
}
else
{
sql.Append("SELECT proname,oid FROM pg_proc WHERE ");
}
sql.Append(" proname = 'lo_open'");
sql.Append(" or proname = 'lo_close'");
sql.Append(" or proname = 'lo_creat'");
sql.Append(" or proname = 'lo_unlink'");
sql.Append(" or proname = 'lo_lseek'");
sql.Append(" or proname = 'lo_tell'");
sql.Append(" or proname = 'loread'");
sql.Append(" or proname = 'lowrite'");
if (conn.PostgreSqlVersion > new Version(7, 3, 0))
{
sql.Append(")");
}
using (IDbCommand cmd = new NpgsqlCommand(sql.ToString()))
{
cmd.Connection = conn;
this.fp = new Fastpath(conn, conn.Connector.Stream);
using (IDataReader res = cmd.ExecuteReader())
{
if (res == null)
{
throw new NpgsqlException("postgresql.lo.init");
}
fp.AddFunctions(res);
}
}
}
finally
{
sql = null;
}
}
/// <summary>
/// This opens an existing large object, based on its OID. This method
/// assumes that READ and WRITE access is required (the default).
/// </summary>
/// <param name="oid">OID of large object.</param>
/// <returns>LargeObject instance providing access to the object</returns>
public LargeObject Open(Int32 oid)
{
return new LargeObject(fp, oid, READWRITE);
}
/// <summary>
/// This opens an existing large object, based on its OID.
/// </summary>
/// <param name="oid">OID of large object.</param>
/// <param name="mode">Mode of open.</param>
/// <returns></returns>
public LargeObject Open(Int32 oid, Int32 mode)
{
return new LargeObject(fp, oid, mode);
}
/// <summary>
/// This creates a large object, returning its OID.
/// </summary>
/// <returns>OID of new object.</returns>
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 NpgsqlException on error
*/
/// <summary>
/// This creates a large object, returning its OID.
/// </summary>
/// <param name="mode">Bitmask describing different attributes of the new object.</param>
/// <returns>OID of new object.</returns>
public Int32 Create(Int32 mode)
{
FastpathArg[] args = new FastpathArg[1];
args[0] = new FastpathArg(mode);
return fp.GetInteger("lo_creat", args);
}
/// <summary>
/// This deletes a large object.
/// </summary>
/// <param name="oid">OID describing object to delete.</param>
public void Delete(Int32 oid)
{
FastpathArg[] args = new FastpathArg[1];
args[0] = new FastpathArg(oid);
fp.FastpathCall("lo_unlink", false, args);
}
/// <summary>
/// This deletes a large object.
/// It is identical to the Delete() method, and is supplied as the C API uses unlink.
/// </summary>
/// <param name="oid">OID describing object to delete.</param>
public void Unlink(Int32 oid)
{
Delete(oid);
}
}
}