PostgreSQL Synchronization Tool

/* npq - A C# libpq wrapper
 * 
 * The contents of this file are subject to the terms
 * of the Common Development and Distribution License
 * (the "License").  You may not use this file except
 * in compliance with the License.
 *
 * You can obtain a copy of the license at
 * http://www.opensource.org/licenses/cddl1.php.
 * See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * Copyright 2009 by martin.faust@e56.de
 */
using System;
using System.Runtime.InteropServices;

namespace npq {

	/// <summary>
	/// Connection status
	/// </summary>
	public enum ConnStatusType {
		CONNECTION_OK,
		CONNECTION_BAD,
		CONNECTION_STARTED,
		CONNECTION_MADE,
		CONNECTION_AWAITING_RESPONSE,
		CONNECTION_AUTH_OK,
		CONNECTION_SETENV,
		CONNECTION_SSL_STARTUP,
		CONNECTION_NEEDED
	}
	
	/// <summary>
	/// Query status
	/// </summary>
	public enum ExecStatusType {
		PGRES_EMPTY_QUERY,
		PGRES_COMMAND_OK,
		PGRES_TUPLES_OK,
		PGRES_COPY_OUT,
		PGRES_COPY_IN,
		PGRES_BAD_RESPONSE,
		PGRES_NONFATAL_ERROR,
		PGRES_FATAL_ERROR
	}
	
	
	/// <summary>
	/// libpq wrapper
	/// </summary>
	public class PG {

		// Connection functions
		
		/// <summary>
		/// Makes a new connection to the database server.
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern IntPtr PQconnectdb(string conninfo);
		/// <summary>
		/// Close a connection
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern void PQfinish(IntPtr conn);
		
				
		/// <summary>
		/// Returns the connection status
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern ConnStatusType PQstatus(IntPtr conn);
		
		[DllImport("libpq.dll", EntryPoint="PQerrorMessage", CharSet=CharSet.Ansi)]
		private static extern IntPtr __PQerrorMessage(IntPtr conn);
		/// <summary>
		/// Returns the last error message
		/// </summary>
		public static string PQerrorMessage(IntPtr conn) { return Marshal.PtrToStringAnsi(__PQerrorMessage(conn)); }
		
		/// <summary>
		/// Returns the protocol version
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int PQprotocolVersion(IntPtr conn);
		/// <summary>
		/// Returns the server version
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int PQserverVersion(IntPtr conn);
		
		/// <summary>
		/// Execute a query
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern IntPtr PQexec(IntPtr conn, [MarshalAs(UnmanagedType.LPStr)] string query);	
		
		/// <summary>
		/// Returns the result status of a query
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern ExecStatusType PQresultStatus(IntPtr res);
		[DllImport("libpq.dll", EntryPoint="PQresultErrorMessage", CharSet=CharSet.Ansi)]
		private static extern IntPtr __PQresultErrorMessage(IntPtr res);
		public static string PQresultErrorMessage(IntPtr res) { return Marshal.PtrToStringAnsi(__PQresultErrorMessage(res)); }
		/// <summary>
		/// Frees the result
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern void PQclear(IntPtr res);
		
		/// <summary>
		/// The number of rows in the result
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int PQntuples(IntPtr res);
		/// <summary>
		/// The number of fields in the result
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int PQnfields(IntPtr res);
		
		[DllImport("libpq.dll", EntryPoint="PQfname",CharSet=CharSet.Ansi)]
		private static extern IntPtr __PQfname(IntPtr res, int field_num);
		/// <summary>
		/// Returns the field name
		/// </summary>
		public static string PQfname(IntPtr res, int field_num) { return Marshal.PtrToStringAnsi(__PQfname(res, field_num)); }
			
		/// <summary>
		/// Returns the field type
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int PQftype(IntPtr res, int field_num);
		/// <summary>
		/// Returns the field type as a string
		/// </summary>
		public static string PQftypename(IntPtr conn, int ftype) {
			IntPtr result = PQexec(conn, "select typname from pg_catalog.pg_type where oid = "+ftype);
			string name = PQgetvalue(result, 0, 0);
			PQclear(result);
			return name;
		}
		
		[DllImport("libpq.dll", EntryPoint="PQgetvalue",CharSet=CharSet.Ansi)]
		private static extern IntPtr __PQgetvalue(IntPtr res, int tup_num, int field_num);
		/// <summary>
		/// Gets the value of the result
		/// </summary>
		public static string PQgetvalue(IntPtr res, int tup_num, int field_num) { return Marshal.PtrToStringAnsi(__PQgetvalue(res, tup_num, field_num)); }
		
		[DllImport("libpq.dll", EntryPoint="PQcmdTuples",CharSet=CharSet.Ansi)]
		private static extern IntPtr __PQcmdTuples(IntPtr res);
		/// <summary>
		/// Gets the result for insert, update, or delete
		/// </summary>
		public static int PQcmdTuples(IntPtr res) { return int.Parse(Marshal.PtrToStringAnsi(__PQcmdTuples(res))); }
		
		// Large-object access routines
		
		/// <summary>
		/// Large Object Write Mode
		/// </summary>
		public const int INV_WRITE = 0x00020000;
		/// <summary>
		/// Large Object Read Mode
		/// </summary>
		public const int INV_READ = 0x00040000;

		/// <summary>
		/// Opens a large object and returns a file descriptor
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_open(IntPtr conn, int lobjId, int mode);
		/// <summary>
		/// Closes an opened large object
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_close(IntPtr conn, int fd);
		/// <summary>
		/// Read data from the large object
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_read(IntPtr conn, int fd, [MarshalAs(UnmanagedType.LPArray)] byte[] buf, int len);
		/// <summary>
		/// Write data into the large object
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_write(IntPtr conn, int fd, [MarshalAs(UnmanagedType.LPArray)] byte[] buf, int len);
		/// <summary>
		/// Seek inside the large object
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_lseek(IntPtr conn, int fd, int offset, int whence);
		/// <summary>
		/// Create a new large object
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_creat(IntPtr conn, int mode);
		/// <summary>
		/// Creates a new large object with a specified id
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_create(IntPtr conn, int lobjId);
		/// <summary>
		/// Tell me the position within the new large object
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_tell(IntPtr conn, int fd);
		/// <summary>
		/// Truncate a large object to a given length
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_truncate(IntPtr conn, int fd, int len);
		/// <summary>
		/// Delete a large object
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_unlink(IntPtr conn, int lobjId);
		/// <summary>
		/// Import a file and returns the large object id
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_import(IntPtr conn, [MarshalAs(UnmanagedType.LPStr)] string filename);
		/// <summary>
		/// Export a large object into a file
		/// </summary>
		[DllImport("libpq.dll")]
		public static extern int lo_export(IntPtr conn, int lobjId, [MarshalAs(UnmanagedType.LPStr)] string filename);

		/// <summary>
		/// Returns the length of a large object
		/// </summary>
		public static int lo_length(IntPtr conn, int fd) {
			lo_lseek(conn, fd, 0, 2);
			int len = lo_tell(conn, fd);
			lo_lseek(conn, fd, 0, 0);
			
			return len;
		}
	}
}