src/bin/pg_dump/pg_backup_null.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pg_backup_null.c
   4  *
   5  *      Implementation of an archive that is never saved; it is used by
   6  *      pg_dump to output a plain text SQL script instead of saving
   7  *      a real archive.
   8  *
   9  *      See the headers to pg_restore for more details.
  10  *
  11  * Copyright (c) 2000, Philip Warner
  12  *              Rights are granted to use this software in any way so long
  13  *              as this notice is not removed.
  14  *
  15  *      The author is not responsible for loss or damages that may
  16  *      result from its use.
  17  *
  18  *
  19  * IDENTIFICATION
  20  *              src/bin/pg_dump/pg_backup_null.c
  21  *
  22  *-------------------------------------------------------------------------
  23  */
  24 #include "postgres_fe.h"
  25
  26 #include "fe_utils/string_utils.h"
  27 #include "libpq/libpq-fs.h"
  28 #include "pg_backup_archiver.h"
  29 #include "pg_backup_utils.h"
  30
  31 static void _WriteData(ArchiveHandle *AH, const void *data, size_t dLen);
  32 static void _WriteLOData(ArchiveHandle *AH, const void *data, size_t dLen);
  33 static void _EndData(ArchiveHandle *AH, TocEntry *te);
  34 static int      _WriteByte(ArchiveHandle *AH, const int i);
  35 static void _WriteBuf(ArchiveHandle *AH, const void *buf, size_t len);
  36 static void _CloseArchive(ArchiveHandle *AH);
  37 static void _PrintTocData(ArchiveHandle *AH, TocEntry *te);
  38 static void _StartLOs(ArchiveHandle *AH, TocEntry *te);
  39 static void _StartLO(ArchiveHandle *AH, TocEntry *te, Oid oid);
  40 static void _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid);
  41 static void _EndLOs(ArchiveHandle *AH, TocEntry *te);
  42
  43
  44 /*
  45  *      Initializer
  46  */
  47 void
  48 InitArchiveFmt_Null(ArchiveHandle *AH)
  49 {
  50         /* Assuming static functions, this can be copied for each format. */
  51         AH->WriteDataPtr = _WriteData;
  52         AH->EndDataPtr = _EndData;
  53         AH->WriteBytePtr = _WriteByte;
  54         AH->WriteBufPtr = _WriteBuf;
  55         AH->ClosePtr = _CloseArchive;
  56         AH->ReopenPtr = NULL;
  57         AH->PrintTocDataPtr = _PrintTocData;
  58
  59         AH->StartLOsPtr = _StartLOs;
  60         AH->StartLOPtr = _StartLO;
  61         AH->EndLOPtr = _EndLO;
  62         AH->EndLOsPtr = _EndLOs;
  63         AH->ClonePtr = NULL;
  64         AH->DeClonePtr = NULL;
  65
  66         /*
  67          * Now prevent reading...
  68          */
  69         if (AH->mode == archModeRead)
  70                 pg_fatal("this format cannot be read");
  71 }
  72
  73 /*
  74  * - Start a new TOC entry
  75  */
  76
  77 /*
  78  * Called by dumper via archiver from within a data dump routine
  79  */
  80 static void
  81 _WriteData(ArchiveHandle *AH, const void *data, size_t dLen)
  82 {
  83         /* Just send it to output, ahwrite() already errors on failure */
  84         ahwrite(data, 1, dLen, AH);
  85 }
  86
  87 /*
  88  * Called by dumper via archiver from within a data dump routine
  89  * We substitute this for _WriteData while emitting a LO
  90  */
  91 static void
  92 _WriteLOData(ArchiveHandle *AH, const void *data, size_t dLen)
  93 {
  94         if (dLen > 0)
  95         {
  96                 PQExpBuffer buf = createPQExpBuffer();
  97
  98                 appendByteaLiteralAHX(buf,
  99                                                           (const unsigned char *) data,
 100                                                           dLen,
 101                                                           AH);
 102
 103                 ahprintf(AH, "SELECT pg_catalog.lowrite(0, %s);\n", buf->data);
 104
 105                 destroyPQExpBuffer(buf);
 106         }
 107 }
 108
 109 static void
 110 _EndData(ArchiveHandle *AH, TocEntry *te)
 111 {
 112         ahprintf(AH, "\n\n");
 113 }
 114
 115 /*
 116  * Called by the archiver when starting to save BLOB DATA (not schema).
 117  * This routine should save whatever format-specific information is needed
 118  * to read the LOs back into memory.
 119  *
 120  * It is called just prior to the dumper's DataDumper routine.
 121  *
 122  * Optional, but strongly recommended.
 123  */
 124 static void
 125 _StartLOs(ArchiveHandle *AH, TocEntry *te)
 126 {
 127         ahprintf(AH, "BEGIN;\n\n");
 128 }
 129
 130 /*
 131  * Called by the archiver when the dumper calls StartLO.
 132  *
 133  * Mandatory.
 134  *
 135  * Must save the passed OID for retrieval at restore-time.
 136  */
 137 static void
 138 _StartLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
 139 {
 140         bool            old_lo_style = (AH->version < K_VERS_1_12);
 141
 142         if (oid == 0)
 143                 pg_fatal("invalid OID for large object");
 144
 145         /* With an old archive we must do drop and create logic here */
 146         if (old_lo_style && AH->public.ropt->dropSchema)
 147                 DropLOIfExists(AH, oid);
 148
 149         if (old_lo_style)
 150                 ahprintf(AH, "SELECT pg_catalog.lo_open(pg_catalog.lo_create('%u'), %d);\n",
 151                                  oid, INV_WRITE);
 152         else
 153                 ahprintf(AH, "SELECT pg_catalog.lo_open('%u', %d);\n",
 154                                  oid, INV_WRITE);
 155
 156         AH->WriteDataPtr = _WriteLOData;
 157 }
 158
 159 /*
 160  * Called by the archiver when the dumper calls EndLO.
 161  *
 162  * Optional.
 163  */
 164 static void
 165 _EndLO(ArchiveHandle *AH, TocEntry *te, Oid oid)
 166 {
 167         AH->WriteDataPtr = _WriteData;
 168
 169         ahprintf(AH, "SELECT pg_catalog.lo_close(0);\n\n");
 170 }
 171
 172 /*
 173  * Called by the archiver when finishing saving BLOB DATA.
 174  *
 175  * Optional.
 176  */
 177 static void
 178 _EndLOs(ArchiveHandle *AH, TocEntry *te)
 179 {
 180         ahprintf(AH, "COMMIT;\n\n");
 181 }
 182
 183 /*------
 184  * Called as part of a RestoreArchive call; for the NULL archive, this
 185  * just sends the data for a given TOC entry to the output.
 186  *------
 187  */
 188 static void
 189 _PrintTocData(ArchiveHandle *AH, TocEntry *te)
 190 {
 191         if (te->dataDumper)
 192         {
 193                 AH->currToc = te;
 194
 195                 if (strcmp(te->desc, "BLOBS") == 0)
 196                         _StartLOs(AH, te);
 197
 198                 te->dataDumper((Archive *) AH, te->dataDumperArg);
 199
 200                 if (strcmp(te->desc, "BLOBS") == 0)
 201                         _EndLOs(AH, te);
 202
 203                 AH->currToc = NULL;
 204         }
 205 }
 206
 207 static int
 208 _WriteByte(ArchiveHandle *AH, const int i)
 209 {
 210         /* Don't do anything */
 211         return 0;
 212 }
 213
 214 static void
 215 _WriteBuf(ArchiveHandle *AH, const void *buf, size_t len)
 216 {
 217         /* Don't do anything */
 218 }
 219
 220 static void
 221 _CloseArchive(ArchiveHandle *AH)
 222 {
 223         /* Nothing to do */
 224 }