postgresql/src/tutorial/C-code/beard.c

/*-------------------------------------------------------------------------
 *
 * beard.c--
 *    sample routines to use large objects
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/tutorial/C-code/Attic/beard.c,v 1.1.1.1 1996/07/09 06:22:34 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */

typedef struct ImageHdr {
    int		size;
} ImageHdr;

#define BUFSIZE 10

/*
 * beard -
 *   clips lower 1/3 of picture and return as large object
 */
Oid
beard(Oid picture)
{
    Oid beard;
    int pic_fd, beard_fd;
    ImageHdr ihdr;
    char buf[BUFSIZE];
    int cc;

    if ((pic_fd = lo_open(picture, INV_READ)) == -1)
	elog(WARN, "Cannot access picture large object");

    if (lo_read(pic_fd, (char*)&ihdr, sizeof(ihdr)) != sizeof(ihdr))
	elog(WARN, "Picture large object corrupted");

    beardOffset = (ihdr.size / 3) * 2;

    /*
     * new large object
     */
    if ((beard = lo_creat(INV_MD)) == 0)  /* ?? is this right? */
	elog(WARN, "Cannot create new large object");

    if ((beard_fd = lo_open(beard, INV_WRITE)) == -1)
	elog(WARN, "Cannot access beard large object");

    lo_lseek(pic_fd, beardOffset, SET_CUR);
    while ((cc = lo_read(pic_fd, buf, BUFSIZE)) > 0) {
	if (lo_write(beard_fd, buf, cc) != cc)
	    elog(WARN, "error while writing large object");
    }

    lo_close(pic_fd);
    lo_close(beard_fd);

    return beard;
}