mirror of https://github.com/postgres/postgres
4TB large objects (standard 8KB BLCKSZ case). For this purpose new libpq API lo_lseek64, lo_tell64 and lo_truncate64 are added. Also corresponding new backend functions lo_lseek64, lo_tell64 and lo_truncate64 are added. inv_api.c is changed to handle 64-bit offsets. Patch contributed by Nozomi Anzai (backend side) and Yugo Nagata (frontend side, docs, regression tests and example program). Reviewed by Kohei Kaigai. Committed by Tatsuo Ishii with minor editings.pull/3/head
Tatsuo Ishii
13 years ago
parent
ae835c7d6e
commit
461ef73f09
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/*-------------------------------------------------------------------------
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* |
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* testlo64.c |
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* test using large objects with libpq using 64-bit APIs |
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* |
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* Portions Copyright (c) 1996-2005, 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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* src/test/examples/testlo64.c |
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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, pg_int64 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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pg_int64 pos; |
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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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if (lo_tell64(conn, lobj_fd) < 0) |
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{ |
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fprintf(stderr, "error lo_tell64: %s\n", PQerrorMessage(conn)); |
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} |
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if ((pos=lo_lseek64(conn, lobj_fd, start, SEEK_SET)) < 0) |
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{ |
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fprintf(stderr, "error lo_lseek64: %s\n", PQerrorMessage(conn)); |
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return; |
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} |
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fprintf(stderr, "before read: retval of lo_lseek64 : %lld\n", (long long int) pos); |
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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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free(buf); |
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fprintf(stderr, "\n"); |
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pos = lo_tell64(conn, lobj_fd); |
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fprintf(stderr, "after read: retval of lo_tell64 : %lld\n\n", (long long int) pos); |
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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, pg_int64 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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pg_int64 pos; |
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lobj_fd = lo_open(conn, lobjId, INV_READ | INV_WRITE); |
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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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if ((pos=lo_lseek64(conn, lobj_fd, start, SEEK_SET)) < 0) |
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{ |
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fprintf(stderr, "error lo_lseek64: %s\n", PQerrorMessage(conn)); |
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return; |
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} |
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fprintf(stderr, "before write: retval of lo_lseek64 : %lld\n", (long long int) pos); |
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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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free(buf); |
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pos = lo_tell64(conn, lobj_fd); |
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fprintf(stderr, "after write: retval of lo_tell64 : %lld\n\n", (long long int) pos); |
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lo_close(conn, lobj_fd); |
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} |
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static void |
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my_truncate(PGconn *conn, Oid lobjId, size_t len) |
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{ |
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int lobj_fd; |
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lobj_fd = lo_open(conn, lobjId, INV_READ | INV_WRITE); |
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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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if (lo_truncate64(conn, lobj_fd, len) < 0) |
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{ |
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fprintf(stderr, "error lo_truncate64: %s\n", PQerrorMessage(conn)); |
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return; |
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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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*out_filename2; |
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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 != 5) |
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{ |
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fprintf(stderr, "Usage: %s database_name in_filename out_filename out_filename2\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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out_filename2 = argv[4]; |
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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_OK) |
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{ |
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fprintf(stderr, "Connection to database failed: %s", |
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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 4294967000-4294968000 of the large object\n"); |
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pickout(conn, lobjOid, 4294967000ULL, 1000); |
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printf("overwriting bytes 4294967000-4294968000 of the large object with X's\n"); |
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overwrite(conn, lobjOid, 4294967000ULL, 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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printf("truncating to 3294968000 byte\n"); |
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my_truncate(conn, lobjOid, 3294968000ULL); |
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printf("exporting truncated large object to file \"%s\" ...\n", out_filename2); |
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if (!lo_export(conn, lobjOid, out_filename2)) |
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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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