/*-------------------------------------------------------------------------
 *
 * vacuumlo.c
 *	  This removes orphaned large objects from a database.
 *
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/contrib/vacuumlo/vacuumlo.c,v 1.35 2007/12/11 19:57:32 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"

#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#ifdef HAVE_TERMIOS_H
#include <termios.h>
#endif

#include "libpq-fe.h"
#include "libpq/libpq-fs.h"

#define atooid(x)  ((Oid) strtoul((x), NULL, 10))

#define BUFSIZE			1024

extern char *optarg;
extern int	optind,
			opterr,
			optopt;

struct _param
{
	char	   *pg_user;
	int			pg_prompt;
	char	   *pg_port;
	char	   *pg_host;
	int			verbose;
	int			dry_run;
};

int			vacuumlo(char *, struct _param *);
void		usage(void);



/*
 * This vacuums LOs of one database. It returns 0 on success, -1 on failure.
 */
int
vacuumlo(char *database, struct _param * param)
{
	PGconn	   *conn;
	PGresult   *res,
			   *res2;
	char		buf[BUFSIZE];
	int			matched;
	int			deleted;
	int			i;
	static char *password = NULL;
	bool		new_pass;

	if (param->pg_prompt && password == NULL)
		password = simple_prompt("Password: ", 100, false);

	/*
	 * Start the connection.  Loop until we have a password if requested by
	 * backend.
	 */
	do
	{
		new_pass = false;

		conn = PQsetdbLogin(param->pg_host,
							param->pg_port,
							NULL,
							NULL,
							database,
							param->pg_user,
							password);
		if (!conn)
		{
			fprintf(stderr, "Connection to database \"%s\" failed\n",
					database);
			return -1;
		}

		if (PQstatus(conn) == CONNECTION_BAD &&
			PQconnectionNeedsPassword(conn) &&
			password == NULL &&
			!feof(stdin))
		{
			PQfinish(conn);
			password = simple_prompt("Password: ", 100, false);
			new_pass = true;
		}
	} while (new_pass);

	/* check to see that the backend connection was successfully made */
	if (PQstatus(conn) == CONNECTION_BAD)
	{
		fprintf(stderr, "Connection to database \"%s\" failed:\n%s",
				database, PQerrorMessage(conn));
		PQfinish(conn);
		return -1;
	}

	if (param->verbose)
	{
		fprintf(stdout, "Connected to %s\n", database);
		if (param->dry_run)
			fprintf(stdout, "Test run: no large objects will be removed!\n");
	}

	/*
	 * Don't get fooled by any non-system catalogs
	 */
	res = PQexec(conn, "SET search_path = pg_catalog");
	if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "Failed to set search_path:\n");
		fprintf(stderr, "%s", PQerrorMessage(conn));
		PQclear(res);
		PQfinish(conn);
		return -1;
	}
	PQclear(res);

	/*
	 * First we create and populate the LO temp table
	 */
	buf[0] = '\0';
	strcat(buf, "CREATE TEMP TABLE vacuum_l AS ");
	strcat(buf, "SELECT DISTINCT loid AS lo FROM pg_largeobject ");
	res = PQexec(conn, buf);
	if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "Failed to create temp table:\n");
		fprintf(stderr, "%s", PQerrorMessage(conn));
		PQclear(res);
		PQfinish(conn);
		return -1;
	}
	PQclear(res);

	/*
	 * Vacuum the temp table so that planner will generate decent plans for
	 * the DELETEs below.
	 */
	buf[0] = '\0';
	strcat(buf, "VACUUM ANALYZE vacuum_l");
	res = PQexec(conn, buf);
	if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "Failed to vacuum temp table:\n");
		fprintf(stderr, "%s", PQerrorMessage(conn));
		PQclear(res);
		PQfinish(conn);
		return -1;
	}
	PQclear(res);

	/*
	 * Now find any candidate tables that have columns of type oid.
	 *
	 * NOTE: we ignore system tables and temp tables by the expedient of
	 * rejecting tables in schemas named 'pg_*'.  In particular, the temp
	 * table formed above is ignored, and pg_largeobject will be too. If
	 * either of these were scanned, obviously we'd end up with nothing to
	 * delete...
	 *
	 * NOTE: the system oid column is ignored, as it has attnum < 1. This
	 * shouldn't matter for correctness, but it saves time.
	 */
	buf[0] = '\0';
	strcat(buf, "SELECT s.nspname, c.relname, a.attname ");
	strcat(buf, "FROM pg_class c, pg_attribute a, pg_namespace s, pg_type t ");
	strcat(buf, "WHERE a.attnum > 0 AND NOT a.attisdropped ");
	strcat(buf, "      AND a.attrelid = c.oid ");
	strcat(buf, "      AND a.atttypid = t.oid ");
	strcat(buf, "      AND c.relnamespace = s.oid ");
	strcat(buf, "      AND t.typname in ('oid', 'lo') ");
	strcat(buf, "      AND c.relkind = 'r'");
	strcat(buf, "      AND s.nspname !~ '^pg_'");
	res = PQexec(conn, buf);
	if (PQresultStatus(res) != PGRES_TUPLES_OK)
	{
		fprintf(stderr, "Failed to find OID columns:\n");
		fprintf(stderr, "%s", PQerrorMessage(conn));
		PQclear(res);
		PQfinish(conn);
		return -1;
	}

	for (i = 0; i < PQntuples(res); i++)
	{
		char	   *schema,
				   *table,
				   *field;

		schema = PQgetvalue(res, i, 0);
		table = PQgetvalue(res, i, 1);
		field = PQgetvalue(res, i, 2);

		if (param->verbose)
			fprintf(stdout, "Checking %s in %s.%s\n", field, schema, table);

		/*
		 * The "IN" construct used here was horribly inefficient before
		 * Postgres 7.4, but should be now competitive if not better than the
		 * bogus join we used before.
		 */
		snprintf(buf, BUFSIZE,
				 "DELETE FROM vacuum_l "
				 "WHERE lo IN (SELECT \"%s\" FROM \"%s\".\"%s\")",
				 field, schema, table);
		res2 = PQexec(conn, buf);
		if (PQresultStatus(res2) != PGRES_COMMAND_OK)
		{
			fprintf(stderr, "Failed to check %s in table %s.%s:\n",
					field, schema, table);
			fprintf(stderr, "%s", PQerrorMessage(conn));
			PQclear(res2);
			PQclear(res);
			PQfinish(conn);
			return -1;
		}
		PQclear(res2);
	}
	PQclear(res);

	/*
	 * Run the actual deletes in a single transaction.	Note that this would
	 * be a bad idea in pre-7.1 Postgres releases (since rolling back a table
	 * delete used to cause problems), but it should be safe now.
	 */
	res = PQexec(conn, "begin");
	PQclear(res);

	/*
	 * Finally, those entries remaining in vacuum_l are orphans.
	 */
	buf[0] = '\0';
	strcat(buf, "SELECT lo ");
	strcat(buf, "FROM vacuum_l");
	res = PQexec(conn, buf);
	if (PQresultStatus(res) != PGRES_TUPLES_OK)
	{
		fprintf(stderr, "Failed to read temp table:\n");
		fprintf(stderr, "%s", PQerrorMessage(conn));
		PQclear(res);
		PQfinish(conn);
		return -1;
	}

	matched = PQntuples(res);
	deleted = 0;
	for (i = 0; i < matched; i++)
	{
		Oid			lo = atooid(PQgetvalue(res, i, 0));

		if (param->verbose)
		{
			fprintf(stdout, "\rRemoving lo %6u   ", lo);
			fflush(stdout);
		}

		if (param->dry_run == 0)
		{
			if (lo_unlink(conn, lo) < 0)
			{
				fprintf(stderr, "\nFailed to remove lo %u: ", lo);
				fprintf(stderr, "%s", PQerrorMessage(conn));
			}
			else
				deleted++;
		}
		else
			deleted++;
	}
	PQclear(res);

	/*
	 * That's all folks!
	 */
	res = PQexec(conn, "end");
	PQclear(res);

	PQfinish(conn);

	if (param->verbose)
		fprintf(stdout, "\r%s %d large objects from %s.\n",
		   (param->dry_run ? "Would remove" : "Removed"), deleted, database);

	return 0;
}

void
usage(void)
{
	fprintf(stdout, "vacuumlo removes unreferenced large objects from databases\n\n");
	fprintf(stdout, "Usage:\n  vacuumlo [options] dbname [dbname ...]\n\n");
	fprintf(stdout, "Options:\n");
	fprintf(stdout, "  -v\t\tWrite a lot of progress messages\n");
	fprintf(stdout, "  -n\t\tDon't remove large objects, just show what would be done\n");
	fprintf(stdout, "  -U username\tUsername to connect as\n");
	fprintf(stdout, "  -W\t\tForce password prompt\n");
	fprintf(stdout, "  -h hostname\tDatabase server host\n");
	fprintf(stdout, "  -p port\tDatabase server port\n\n");
}


int
main(int argc, char **argv)
{
	int			rc = 0;
	struct _param param;
	int			c;
	int			port;

	/* Parameter handling */
	param.pg_user = NULL;
	param.pg_prompt = 0;
	param.pg_host = NULL;
	param.pg_port = NULL;
	param.verbose = 0;
	param.dry_run = 0;

	while (1)
	{
		c = getopt(argc, argv, "?h:U:p:vnW");
		if (c == -1)
			break;

		switch (c)
		{
			case '?':
				if (optopt == '?')
				{
					usage();
					exit(0);
				}
				exit(1);
			case ':':
				exit(1);
			case 'v':
				param.verbose = 1;
				break;
			case 'n':
				param.dry_run = 1;
				param.verbose = 1;
				break;
			case 'U':
				param.pg_user = strdup(optarg);
				break;
			case 'W':
				param.pg_prompt = 1;
				break;
			case 'p':
				port = strtol(optarg, NULL, 10);
				if ((port < 1) || (port > 65535))
				{
					fprintf(stderr, "[%s]: invalid port number '%s'\n", argv[0], optarg);
					exit(1);
				}
				param.pg_port = strdup(optarg);
				break;
			case 'h':
				param.pg_host = strdup(optarg);
				break;
		}
	}

	/* No database given? Show usage */
	if (optind >= argc)
	{
		fprintf(stderr, "vacuumlo: missing required argument: database name\n");
		fprintf(stderr, "Try 'vacuumlo -?' for help.\n");
		exit(1);
	}

	for (c = optind; c < argc; c++)
	{
		/* Work on selected database */
		rc += (vacuumlo(argv[c], &param) != 0);
	}

	return rc;
}
