pg_backup_null.c

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/*-------------------------------------------------------------------------
 *
 * pg_backup_null.c
 *
 *  Implementation of an archive that is never saved; it is used by
 *  pg_dump to output a plain text SQL script instead of saving
 *  a real archive.
 *
 *  See the headers to pg_restore for more details.
 *
 * Copyright (c) 2000, Philip Warner
 *      Rights are granted to use this software in any way so long
 *      as this notice is not removed.
 *
 *  The author is not responsible for loss or damages that may
 *  result from its use.
 *
 *
 * IDENTIFICATION
 *      src/bin/pg_dump/pg_backup_null.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"
 
#include "fe_utils/string_utils.h"
#include "libpq/libpq-fs.h"
#include "pg_backup_archiver.h"
#include "pg_backup_utils.h"
 
static void _WriteData(ArchiveHandle *AH, const void *data, size_t dLen);
static void _WriteLOData(ArchiveHandle *AH, const void *data, size_t dLen);
static void _EndData(ArchiveHandle *AH, TocEntry *te);
static int  _WriteByte(ArchiveHandle *AH, const int i);
static void _WriteBuf(ArchiveHandle *AH, const void *buf, size_t len);
static void _CloseArchive(ArchiveHandle *AH);
static void _PrintTocData(ArchiveHandle *AH, TocEntry *te);
static void _StartLOs(ArchiveHandle *AH, TocEntry *te);
static void _StartLO(ArchiveHandle *AH, TocEntry *te, Oid oid);
static void _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid);
static void _EndLOs(ArchiveHandle *AH, TocEntry *te);
 
 
/*
 *  Initializer
 */
void
InitArchiveFmt_Null(ArchiveHandle *AH)
{
    /* Assuming static functions, this can be copied for each format. */
    AH->WriteDataPtr = _WriteData;
    AH->EndDataPtr = _EndData;
    AH->WriteBytePtr = _WriteByte;
    AH->WriteBufPtr = _WriteBuf;
    AH->ClosePtr = _CloseArchive;
    AH->ReopenPtr = NULL;
    AH->PrintTocDataPtr = _PrintTocData;
 
    AH->StartLOsPtr = _StartLOs;
    AH->StartLOPtr = _StartLO;
    AH->EndLOPtr = _EndLO;
    AH->EndLOsPtr = _EndLOs;
    AH->ClonePtr = NULL;
    AH->DeClonePtr = NULL;
 
    /*
     * Now prevent reading...
     */
    if (AH->mode == archModeRead)
        pg_fatal("this format cannot be read");
}
 
/*
 * - Start a new TOC entry
 */
 
/*
 * Called by dumper via archiver from within a data dump routine
 */
static void
_WriteData(ArchiveHandle *AH, const void *data, size_t dLen)
{
    /* Just send it to output, ahwrite() already errors on failure */
    ahwrite(data, 1, dLen, AH);
}
 
/*
 * Called by dumper via archiver from within a data dump routine
 * We substitute this for _WriteData while emitting a LO
 */
static void
_WriteLOData(ArchiveHandle *AH, const void *data, size_t dLen)
{
    if (dLen > 0)
    {
        PQExpBuffer buf = createPQExpBuffer();
 
        appendByteaLiteralAHX(buf,
                              (const unsigned char *) data,
                              dLen,
                              AH);
 
        ahprintf(AH, "SELECT pg_catalog.lowrite(0, %s);\n", buf->data);
 
        destroyPQExpBuffer(buf);
    }
}
 
static void
_EndData(ArchiveHandle *AH, TocEntry *te)
{
    ahprintf(AH, "\n\n");
}
 
/*
 * Called by the archiver when starting to save BLOB DATA (not schema).
 * This routine should save whatever format-specific information is needed
 * to read the LOs back into memory.
 *
 * It is called just prior to the dumper's DataDumper routine.
 *
 * Optional, but strongly recommended.
 */
static void
_StartLOs(ArchiveHandle *AH, TocEntry *te)
{
    ahprintf(AH, "BEGIN;\n\n");
}
 
/*
 * Called by the archiver when the dumper calls StartLO.
 *
 * Mandatory.
 *
 * Must save the passed OID for retrieval at restore-time.
 */
static void
_StartLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
{
    bool        old_lo_style = (AH->version < K_VERS_1_12);
 
    if (oid == 0)
        pg_fatal("invalid OID for large object");
 
    /* With an old archive we must do drop and create logic here */
    if (old_lo_style && AH->public.ropt->dropSchema)
        DropLOIfExists(AH, oid);
 
    if (old_lo_style)
        ahprintf(AH, "SELECT pg_catalog.lo_open(pg_catalog.lo_create('%u'), %d);\n",
                 oid, INV_WRITE);
    else
        ahprintf(AH, "SELECT pg_catalog.lo_open('%u', %d);\n",
                 oid, INV_WRITE);
 
    AH->WriteDataPtr = _WriteLOData;
}
 
/*
 * Called by the archiver when the dumper calls EndLO.
 *
 * Optional.
 */
static void
_EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
{
    AH->WriteDataPtr = _WriteData;
 
    ahprintf(AH, "SELECT pg_catalog.lo_close(0);\n\n");
}
 
/*
 * Called by the archiver when finishing saving BLOB DATA.
 *
 * Optional.
 */
static void
_EndLOs(ArchiveHandle *AH, TocEntry *te)
{
    ahprintf(AH, "COMMIT;\n\n");
}
 
/*------
 * Called as part of a RestoreArchive call; for the NULL archive, this
 * just sends the data for a given TOC entry to the output.
 *------
 */
static void
_PrintTocData(ArchiveHandle *AH, TocEntry *te)
{
    if (te->dataDumper)
    {
        AH->currToc = te;
 
        if (strcmp(te->desc, "BLOBS") == 0)
            _StartLOs(AH, te);
 
        te->dataDumper((Archive *) AH, te->dataDumperArg);
 
        if (strcmp(te->desc, "BLOBS") == 0)
            _EndLOs(AH, te);
 
        AH->currToc = NULL;
    }
}
 
static int
_WriteByte(ArchiveHandle *AH, const int i)
{
    /* Don't do anything */
    return 0;
}
 
static void
_WriteBuf(ArchiveHandle *AH, const void *buf, size_t len)
{
    /* Don't do anything */
}
 
static void
_CloseArchive(ArchiveHandle *AH)
{
    /* Nothing to do */
}