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