fe-lobj.c

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * fe-lobj.c
 *	  Front-end large object interface
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /usr/local/cvsroot/pgsql/src/interfaces/libpq/fe-lobj.c,v 1.20 1999/05/10 00:46:26 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "libpq-fe.h"
#include "libpq-int.h"
#include "postgres.h"

#ifdef WIN32
#include "win32.h"
#include <io.h>
#else
#if !defined(NO_UNISTD_H)
#include <unistd.h>
#endif
#endif
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>

#include "libpq/libpq-fs.h"		/* must come after sys/stat.h */


#define LO_BUFSIZE		  1024

static int	lo_initialize(PGconn *conn);

/*
 * lo_open
 *	  opens an existing large object
 *
 * returns the file descriptor for use in later lo_* calls
 * return -1 upon failure.
 */
int
lo_open(PGconn *conn, Oid lobjId, int mode)
{
	int			fd;
	int			result_len;
	PQArgBlock	argv[2];
	PGresult   *res;

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = lobjId;

	argv[1].isint = 1;
	argv[1].len = 4;
	argv[1].u.integer = mode;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	res = PQfn(conn, conn->lobjfuncs->fn_lo_open, &fd, &result_len, 1, argv, 2);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);

		/* have to do this to reset offset in shared fd cache */
		/* but only if fd is valid */
		if (fd >= 0 && lo_lseek(conn, fd, 0L, SEEK_SET) < 0)
			return -1;
		return fd;
	}
	else
	{
		PQclear(res);
		return -1;
	}
}

/*
 * lo_close
 *	  closes an existing large object
 *
 * returns 0 upon success
 * returns -1 upon failure.
 */
int
lo_close(PGconn *conn, int fd)
{
	PQArgBlock	argv[1];
	PGresult   *res;
	int			retval;
	int			result_len;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = fd;
	res = PQfn(conn, conn->lobjfuncs->fn_lo_close,
			   &retval, &result_len, 1, argv, 1);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);
		return retval;
	}
	else
	{
		PQclear(res);
		return -1;
	}
}

/*
 * lo_read
 *	  read len bytes of the large object into buf
 *
 * returns the length of bytes read.
 * the CALLER must have allocated enough space to hold the result returned
 */

int
lo_read(PGconn *conn, int fd, char *buf, int len)
{
	PQArgBlock	argv[2];
	PGresult   *res;
	int			result_len;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = fd;

	argv[1].isint = 1;
	argv[1].len = 4;
	argv[1].u.integer = len;

	res = PQfn(conn, conn->lobjfuncs->fn_lo_read,
			   (int *) buf, &result_len, 0, argv, 2);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);
		return result_len;
	}
	else
	{
		PQclear(res);
		return -1;
	}
}

/*
 * lo_write
 *	  write len bytes of buf into the large object fd
 *
 */
int
lo_write(PGconn *conn, int fd, char *buf, int len)
{
	PQArgBlock	argv[2];
	PGresult   *res;
	int			result_len;
	int			retval;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	if (len <= 0)
		return 0;

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = fd;

	argv[1].isint = 0;
	argv[1].len = len;
	argv[1].u.ptr = (int *) buf;

	res = PQfn(conn, conn->lobjfuncs->fn_lo_write,
			   &retval, &result_len, 1, argv, 2);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);
		return retval;
	}
	else
	{
		PQclear(res);
		return -1;
	}
}

/*
 * lo_lseek
 *	  change the current read or write location on a large object
 * currently, only L_SET is a legal value for whence
 *
 */

int
lo_lseek(PGconn *conn, int fd, int offset, int whence)
{
	PQArgBlock	argv[3];
	PGresult   *res;
	int			retval;
	int			result_len;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = fd;

	argv[1].isint = 1;
	argv[1].len = 4;
	argv[1].u.integer = offset;

	argv[2].isint = 1;
	argv[2].len = 4;
	argv[2].u.integer = whence;

	res = PQfn(conn, conn->lobjfuncs->fn_lo_lseek,
			   &retval, &result_len, 1, argv, 3);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);
		return retval;
	}
	else
	{
		PQclear(res);
		return -1;
	}
}

/*
 * lo_creat
 *	  create a new large object
 * the mode is a bitmask describing different attributes of the new object
 *
 * returns the oid of the large object created or
 * InvalidOid upon failure
 */

Oid
lo_creat(PGconn *conn, int mode)
{
	PQArgBlock	argv[1];
	PGresult   *res;
	int			retval;
	int			result_len;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = mode;
	res = PQfn(conn, conn->lobjfuncs->fn_lo_creat,
			   &retval, &result_len, 1, argv, 1);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);
		return (Oid) retval;
	}
	else
	{
		PQclear(res);
		return InvalidOid;
	}
}


/*
 * lo_tell
 *	  returns the current seek location of the large object
 *
 */

int
lo_tell(PGconn *conn, int fd)
{
	int			retval;
	PQArgBlock	argv[1];
	PGresult   *res;
	int			result_len;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = fd;

	res = PQfn(conn, conn->lobjfuncs->fn_lo_tell,
			   &retval, &result_len, 1, argv, 1);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);
		return retval;
	}
	else
	{
		PQclear(res);
		return -1;
	}
}

/*
 * lo_unlink
 *	  delete a file
 *
 */

int
lo_unlink(PGconn *conn, Oid lobjId)
{
	PQArgBlock	argv[1];
	PGresult   *res;
	int			result_len;
	int			retval;

	if (conn->lobjfuncs == (PGlobjfuncs *) NULL)
	{
		if (lo_initialize(conn) < 0)
			return -1;
	}

	argv[0].isint = 1;
	argv[0].len = 4;
	argv[0].u.integer = lobjId;

	res = PQfn(conn, conn->lobjfuncs->fn_lo_unlink,
			   &retval, &result_len, 1, argv, 1);
	if (PQresultStatus(res) == PGRES_COMMAND_OK)
	{
		PQclear(res);
		return retval;
	}
	else
	{
		PQclear(res);
		return -1;
	}
}

/*
 * lo_import -
 *	  imports a file as an (inversion) large object.
 *		returns the oid of that object upon success,
 * returns InvalidOid upon failure
 *
 */

Oid
lo_import(PGconn *conn, char *filename)
{
	int			fd;
	int			nbytes,
				tmp;
	char		buf[LO_BUFSIZE];
	Oid			lobjOid;
	int			lobj;

	/*
	 * open the file to be read in
	 */
#ifndef __CYGWIN32__
	fd = open(filename, O_RDONLY, 0666);
#else
	fd = open(filename, O_RDONLY | O_BINARY, 0666);
#endif
	if (fd < 0)
	{							/* error */
		sprintf(conn->errorMessage,
				"lo_import: can't open unix file\"%s\"\n", filename);
		return InvalidOid;
	}

	/*
	 * create an inversion "object"
	 */
	lobjOid = lo_creat(conn, INV_READ | INV_WRITE);
	if (lobjOid == InvalidOid)
	{
		sprintf(conn->errorMessage,
			  "lo_import: can't create inv object for \"%s\"", filename);
		return InvalidOid;
	}

	lobj = lo_open(conn, lobjOid, INV_WRITE);
	if (lobj == -1)
	{
		sprintf(conn->errorMessage,
				"lo_import: could not open inv object oid %u", lobjOid);
		return InvalidOid;
	}

	/*
	 * read in from the Unix file and write to the inversion file
	 */
	while ((nbytes = read(fd, buf, LO_BUFSIZE)) > 0)
	{
		tmp = lo_write(conn, lobj, buf, nbytes);
		if (tmp < nbytes)
		{
			sprintf(conn->errorMessage,
					"lo_import: error while reading \"%s\"", filename);
			return InvalidOid;
		}
	}

	(void) close(fd);
	(void) lo_close(conn, lobj);

	return lobjOid;
}

/*
 * lo_export -
 *	  exports an (inversion) large object.
 * returns -1 upon failure, 1 otherwise
 */
int
lo_export(PGconn *conn, Oid lobjId, char *filename)
{
	int			fd;
	int			nbytes,
				tmp;
	char		buf[LO_BUFSIZE];
	int			lobj;

	/*
	 * create an inversion "object"
	 */
	lobj = lo_open(conn, lobjId, INV_READ);
	if (lobj == -1)
	{
		sprintf(conn->errorMessage,
				"lo_export: can't open inv object %u", lobjId);
		return -1;
	}

	/*
	 * open the file to be written to
	 */
#ifndef __CYGWIN32__
	fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
#else
	fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC | O_BINARY, 0666);
#endif
	if (fd < 0)
	{							/* error */
		sprintf(conn->errorMessage,
				"lo_export: can't open unix file\"%s\"", filename);
		return 0;
	}

	/*
	 * read in from the Unix file and write to the inversion file
	 */
	while ((nbytes = lo_read(conn, lobj, buf, LO_BUFSIZE)) > 0)
	{
		tmp = write(fd, buf, nbytes);
		if (tmp < nbytes)
		{
			sprintf(conn->errorMessage,
					"lo_export: error while writing \"%s\"",
					filename);
			return -1;
		}
	}

	(void) lo_close(conn, lobj);
	(void) close(fd);

	return 1;
}


/* ----------------
 * lo_initialize
 *
 * Initialize the large object interface for an existing connection.
 * We ask the backend about the functions OID's in pg_proc for all
 * functions that are required for large object operations.
 * ----------------
 */
static int
lo_initialize(PGconn *conn)
{
	PGresult   *res;
	PGlobjfuncs *lobjfuncs;
	int			n;
	char	   *fname;
	Oid			foid;

	/* ----------------
	 * Allocate the structure to hold the functions OID's
	 * ----------------
	 */
	lobjfuncs = (PGlobjfuncs *) malloc(sizeof(PGlobjfuncs));
	if (lobjfuncs == (PGlobjfuncs *) NULL)
	{
		strcpy(conn->errorMessage,
			   "FATAL: malloc() failed in lo_initialize()\n");
		return -1;
	}
	MemSet((char *) lobjfuncs, 0, sizeof(PGlobjfuncs));

	/* ----------------
	 * Execute the query to get all the functions at once
	 * ----------------
	 */
	res = PQexec(conn, "select proname, oid from pg_proc	\
    		where 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 (res == (PGresult *) NULL)
	{
		free(lobjfuncs);
		return -1;
	}

	if (res->resultStatus != PGRES_TUPLES_OK)
	{
		free(lobjfuncs);
		PQclear(res);
		strcpy(conn->errorMessage,
			   "ERROR: SELECT didn't return data in lo_initialize()\n");
		return -1;
	}

	/* ----------------
	 * Examine the result and put the OID's into the struct
	 * ----------------
	 */
	for (n = 0; n < PQntuples(res); n++)
	{
		fname = PQgetvalue(res, n, 0);
		foid = (Oid) atoi(PQgetvalue(res, n, 1));
		if (!strcmp(fname, "lo_open"))
			lobjfuncs->fn_lo_open = foid;
		else if (!strcmp(fname, "lo_close"))
			lobjfuncs->fn_lo_close = foid;
		else if (!strcmp(fname, "lo_creat"))
			lobjfuncs->fn_lo_creat = foid;
		else if (!strcmp(fname, "lo_unlink"))
			lobjfuncs->fn_lo_unlink = foid;
		else if (!strcmp(fname, "lo_lseek"))
			lobjfuncs->fn_lo_lseek = foid;
		else if (!strcmp(fname, "lo_tell"))
			lobjfuncs->fn_lo_tell = foid;
		else if (!strcmp(fname, "loread"))
			lobjfuncs->fn_lo_read = foid;
		else if (!strcmp(fname, "lowrite"))
			lobjfuncs->fn_lo_write = foid;
	}

	PQclear(res);

	/* ----------------
	 * Finally check that we really got all large object
	 * interface functions.
	 * ----------------
	 */
	if (lobjfuncs->fn_lo_open == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function lo_open\n");
		free(lobjfuncs);
		return -1;
	}
	if (lobjfuncs->fn_lo_close == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function lo_close\n");
		free(lobjfuncs);
		return -1;
	}
	if (lobjfuncs->fn_lo_creat == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function lo_creat\n");
		free(lobjfuncs);
		return -1;
	}
	if (lobjfuncs->fn_lo_unlink == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function lo_unlink\n");
		free(lobjfuncs);
		return -1;
	}
	if (lobjfuncs->fn_lo_lseek == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function lo_lseek\n");
		free(lobjfuncs);
		return -1;
	}
	if (lobjfuncs->fn_lo_tell == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function lo_tell\n");
		free(lobjfuncs);
		return -1;
	}
	if (lobjfuncs->fn_lo_read == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function loread\n");
		free(lobjfuncs);
		return -1;
	}
	if (lobjfuncs->fn_lo_write == 0)
	{
		strcpy(conn->errorMessage,
			   "ERROR: Cannot determine OID for function lowrite\n");
		free(lobjfuncs);
		return -1;
	}

	/* ----------------
	 * Put the structure into the connection control
	 * ----------------
	 */
	conn->lobjfuncs = lobjfuncs;
	return 0;
}