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 it's use.
  17  *
  18  *
  19  * IDENTIFICATION
  20  *              $PostgreSQL$
  21  *
  22  *-------------------------------------------------------------------------
  23  */
  24
  25 #include "pg_backup_archiver.h"
  26
  27 #include <unistd.h>                             /* for dup */
  28
  29 #include "libpq/libpq-fs.h"
  30
  31
  32 static size_t _WriteData(ArchiveHandle *AH, const void *data, size_t dLen);
  33 static size_t _WriteBlobData(ArchiveHandle *AH, const void *data, size_t dLen);
  34 static void _EndData(ArchiveHandle *AH, TocEntry *te);
  35 static int      _WriteByte(ArchiveHandle *AH, const int i);
  36 static size_t _WriteBuf(ArchiveHandle *AH, const void *buf, size_t len);
  37 static void _CloseArchive(ArchiveHandle *AH);
  38 static void _PrintTocData(ArchiveHandle *AH, TocEntry *te, RestoreOptions *ropt);
  39 static void _StartBlobs(ArchiveHandle *AH, TocEntry *te);
  40 static void _StartBlob(ArchiveHandle *AH, TocEntry *te, Oid oid);
  41 static void _EndBlob(ArchiveHandle *AH, TocEntry *te, Oid oid);
  42 static void _EndBlobs(ArchiveHandle *AH, TocEntry *te);
  43
  44
  45 /*
  46  *      Initializer
  47  */
  48 void
  49 InitArchiveFmt_Null(ArchiveHandle *AH)
  50 {
  51         /* Assuming static functions, this can be copied for each format. */
  52         AH->WriteDataPtr = _WriteData;
  53         AH->EndDataPtr = _EndData;
  54         AH->WriteBytePtr = _WriteByte;
  55         AH->WriteBufPtr = _WriteBuf;
  56         AH->ClosePtr = _CloseArchive;
  57         AH->ReopenPtr = NULL;
  58         AH->PrintTocDataPtr = _PrintTocData;
  59
  60         AH->StartBlobsPtr = _StartBlobs;
  61         AH->StartBlobPtr = _StartBlob;
  62         AH->EndBlobPtr = _EndBlob;
  63         AH->EndBlobsPtr = _EndBlobs;
  64         AH->ClonePtr = NULL;
  65         AH->DeClonePtr = NULL;
  66
  67         /* Initialize LO buffering */
  68         AH->lo_buf_size = LOBBUFSIZE;
  69         AH->lo_buf = (void *) malloc(LOBBUFSIZE);
  70         if (AH->lo_buf == NULL)
  71                 die_horribly(AH, NULL, "out of memory\n");
  72
  73         /*
  74          * Now prevent reading...
  75          */
  76         if (AH->mode == archModeRead)
  77                 die_horribly(AH, NULL, "this format cannot be read\n");
  78 }
  79
  80 /*
  81  * - Start a new TOC entry
  82  */
  83
  84 /*
  85  * Called by dumper via archiver from within a data dump routine
  86  */
  87 static size_t
  88 _WriteData(ArchiveHandle *AH, const void *data, size_t dLen)
  89 {
  90         /* Just send it to output */
  91         ahwrite(data, 1, dLen, AH);
  92         return dLen;
  93 }
  94
  95 /*
  96  * Called by dumper via archiver from within a data dump routine
  97  * We substitute this for _WriteData while emitting a BLOB
  98  */
  99 static size_t
 100 _WriteBlobData(ArchiveHandle *AH, const void *data, size_t dLen)
 101 {
 102         if (dLen > 0)
 103         {
 104                 unsigned char *str;
 105                 size_t          len;
 106
 107                 str = PQescapeBytea((const unsigned char *) data, dLen, &len);
 108                 if (!str)
 109                         die_horribly(AH, NULL, "out of memory\n");
 110
 111                 ahprintf(AH, "SELECT lowrite(0, '%s');\n", str);
 112
 113                 free(str);
 114         }
 115         return dLen;
 116 }
 117
 118 static void
 119 _EndData(ArchiveHandle *AH, TocEntry *te)
 120 {
 121         ahprintf(AH, "\n\n");
 122 }
 123
 124 /*
 125  * Called by the archiver when starting to save all BLOB DATA (not schema).
 126  * This routine should save whatever format-specific information is needed
 127  * to read the BLOBs back into memory.
 128  *
 129  * It is called just prior to the dumper's DataDumper routine.
 130  *
 131  * Optional, but strongly recommended.
 132  */
 133 static void
 134 _StartBlobs(ArchiveHandle *AH, TocEntry *te)
 135 {
 136         ahprintf(AH, "BEGIN;\n\n");
 137 }
 138
 139 /*
 140  * Called by the archiver when the dumper calls StartBlob.
 141  *
 142  * Mandatory.
 143  *
 144  * Must save the passed OID for retrieval at restore-time.
 145  */
 146 static void
 147 _StartBlob(ArchiveHandle *AH, TocEntry *te, Oid oid)
 148 {
 149         if (oid == 0)
 150                 die_horribly(AH, NULL, "invalid OID for large object\n");
 151
 152         ahprintf(AH, "SELECT lo_open(lo_create(%u), %d);\n", oid, INV_WRITE);
 153
 154         AH->WriteDataPtr = _WriteBlobData;
 155 }
 156
 157 /*
 158  * Called by the archiver when the dumper calls EndBlob.
 159  *
 160  * Optional.
 161  */
 162 static void
 163 _EndBlob(ArchiveHandle *AH, TocEntry *te, Oid oid)
 164 {
 165         AH->WriteDataPtr = _WriteData;
 166
 167         ahprintf(AH, "SELECT lo_close(0);\n\n");
 168 }
 169
 170 /*
 171  * Called by the archiver when finishing saving all BLOB DATA.
 172  *
 173  * Optional.
 174  */
 175 static void
 176 _EndBlobs(ArchiveHandle *AH, TocEntry *te)
 177 {
 178         ahprintf(AH, "COMMIT;\n\n");
 179 }
 180
 181 /*------
 182  * Called as part of a RestoreArchive call; for the NULL archive, this
 183  * just sends the data for a given TOC entry to the output.
 184  *------
 185  */
 186 static void
 187 _PrintTocData(ArchiveHandle *AH, TocEntry *te, RestoreOptions *ropt)
 188 {
 189         if (te->dataDumper)
 190         {
 191                 AH->currToc = te;
 192
 193                 if (strcmp(te->desc, "BLOBS") == 0)
 194                         _StartBlobs(AH, te);
 195
 196                 (*te->dataDumper) ((Archive *) AH, te->dataDumperArg);
 197
 198                 if (strcmp(te->desc, "BLOBS") == 0)
 199                         _EndBlobs(AH, te);
 200
 201                 AH->currToc = NULL;
 202         }
 203 }
 204
 205 static int
 206 _WriteByte(ArchiveHandle *AH, const int i)
 207 {
 208         /* Don't do anything */
 209         return 0;
 210 }
 211
 212 static size_t
 213 _WriteBuf(ArchiveHandle *AH, const void *buf, size_t len)
 214 {
 215         /* Don't do anything */
 216         return len;
 217 }
 218
 219 static void
 220 _CloseArchive(ArchiveHandle *AH)
 221 {
 222         /* Nothing to do */
 223 }