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261 lines
5.2 KiB
C
261 lines
5.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* testlo.c
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* test using large objects with libpq
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*
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* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/test/examples/testlo.c,v 1.22 2004/08/29 04:13:12 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "libpq-fe.h"
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#include "libpq/libpq-fs.h"
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#define BUFSIZE 1024
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/*
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* importFile -
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* import file "in_filename" into database as large object "lobjOid"
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*
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*/
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static Oid
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importFile(PGconn *conn, char *filename)
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{
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Oid lobjId;
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int lobj_fd;
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char buf[BUFSIZE];
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int nbytes,
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tmp;
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int fd;
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/*
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* open the file to be read in
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*/
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fd = open(filename, O_RDONLY, 0666);
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if (fd < 0)
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{ /* error */
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fprintf(stderr, "can't open unix file\"%s\"\n", filename);
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}
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/*
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* create the large object
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*/
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lobjId = lo_creat(conn, INV_READ | INV_WRITE);
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if (lobjId == 0)
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fprintf(stderr, "can't create large object");
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lobj_fd = lo_open(conn, lobjId, INV_WRITE);
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/*
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* read in from the Unix file and write to the inversion file
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*/
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while ((nbytes = read(fd, buf, BUFSIZE)) > 0)
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{
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tmp = lo_write(conn, lobj_fd, buf, nbytes);
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if (tmp < nbytes)
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fprintf(stderr, "error while reading \"%s\"", filename);
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}
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close(fd);
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lo_close(conn, lobj_fd);
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return lobjId;
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}
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static void
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pickout(PGconn *conn, Oid lobjId, int start, int len)
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{
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int lobj_fd;
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char *buf;
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int nbytes;
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int nread;
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lobj_fd = lo_open(conn, lobjId, INV_READ);
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if (lobj_fd < 0)
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fprintf(stderr, "can't open large object %u", lobjId);
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lo_lseek(conn, lobj_fd, start, SEEK_SET);
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buf = malloc(len + 1);
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nread = 0;
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while (len - nread > 0)
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{
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nbytes = lo_read(conn, lobj_fd, buf, len - nread);
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buf[nbytes] = '\0';
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fprintf(stderr, ">>> %s", buf);
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nread += nbytes;
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if (nbytes <= 0)
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break; /* no more data? */
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}
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fprintf(stderr, "\n");
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lo_close(conn, lobj_fd);
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}
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static void
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overwrite(PGconn *conn, Oid lobjId, int start, int len)
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{
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int lobj_fd;
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char *buf;
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int nbytes;
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int nwritten;
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int i;
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lobj_fd = lo_open(conn, lobjId, INV_READ);
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if (lobj_fd < 0)
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fprintf(stderr, "can't open large object %u", lobjId);
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lo_lseek(conn, lobj_fd, start, SEEK_SET);
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buf = malloc(len + 1);
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for (i = 0; i < len; i++)
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buf[i] = 'X';
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buf[i] = '\0';
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nwritten = 0;
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while (len - nwritten > 0)
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{
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nbytes = lo_write(conn, lobj_fd, buf + nwritten, len - nwritten);
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nwritten += nbytes;
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if (nbytes <= 0)
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{
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fprintf(stderr, "\nWRITE FAILED!\n");
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break;
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}
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}
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fprintf(stderr, "\n");
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lo_close(conn, lobj_fd);
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}
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/*
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* exportFile -
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* export large object "lobjOid" to file "out_filename"
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*
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*/
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static void
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exportFile(PGconn *conn, Oid lobjId, char *filename)
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{
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int lobj_fd;
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char buf[BUFSIZE];
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int nbytes,
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tmp;
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int fd;
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/*
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* create an inversion "object"
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*/
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lobj_fd = lo_open(conn, lobjId, INV_READ);
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if (lobj_fd < 0)
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fprintf(stderr, "can't open large object %u", lobjId);
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/*
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* open the file to be written to
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*/
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fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
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if (fd < 0)
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{ /* error */
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fprintf(stderr, "can't open unix file\"%s\"",
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filename);
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}
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/*
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* read in from the Unix file and write to the inversion file
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*/
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while ((nbytes = lo_read(conn, lobj_fd, buf, BUFSIZE)) > 0)
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{
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tmp = write(fd, buf, nbytes);
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if (tmp < nbytes)
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{
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fprintf(stderr, "error while writing \"%s\"",
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filename);
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}
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}
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lo_close(conn, lobj_fd);
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close(fd);
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return;
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}
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static void
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exit_nicely(PGconn *conn)
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{
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PQfinish(conn);
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exit(1);
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}
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int
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main(int argc, char **argv)
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{
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char *in_filename,
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*out_filename;
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char *database;
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Oid lobjOid;
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PGconn *conn;
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PGresult *res;
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if (argc != 4)
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{
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fprintf(stderr, "Usage: %s database_name in_filename out_filename\n",
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argv[0]);
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exit(1);
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}
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database = argv[1];
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in_filename = argv[2];
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out_filename = argv[3];
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/*
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* set up the connection
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*/
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conn = PQsetdb(NULL, NULL, NULL, NULL, database);
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/* check to see that the backend connection was successfully made */
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if (PQstatus(conn) == CONNECTION_BAD)
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{
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fprintf(stderr, "Connection to database '%s' failed.\n", database);
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fprintf(stderr, "%s", PQerrorMessage(conn));
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exit_nicely(conn);
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}
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res = PQexec(conn, "begin");
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PQclear(res);
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printf("importing file \"%s\" ...\n", in_filename);
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/* lobjOid = importFile(conn, in_filename); */
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lobjOid = lo_import(conn, in_filename);
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if (lobjOid == 0)
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fprintf(stderr, "%s\n", PQerrorMessage(conn));
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else
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{
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printf("\tas large object %u.\n", lobjOid);
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printf("picking out bytes 1000-2000 of the large object\n");
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pickout(conn, lobjOid, 1000, 1000);
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printf("overwriting bytes 1000-2000 of the large object with X's\n");
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overwrite(conn, lobjOid, 1000, 1000);
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printf("exporting large object to file \"%s\" ...\n", out_filename);
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/* exportFile(conn, lobjOid, out_filename); */
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if (!lo_export(conn, lobjOid, out_filename))
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fprintf(stderr, "%s\n", PQerrorMessage(conn));
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}
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res = PQexec(conn, "end");
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PQclear(res);
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PQfinish(conn);
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return 0;
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}
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