pg_backup_custom.c

PostgreSQL7.4.6 for Linux

_PrintData(ArchiveHandle *AH)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	z_streamp	zp = ctx->zp;
	size_t		blkLen;
	char	   *in = ctx->zlibIn;
	size_t		cnt;

#ifdef HAVE_LIBZ
	int			res;
	char	   *out = ctx->zlibOut;
#endif

#ifdef HAVE_LIBZ

	res = Z_OK;

	if (AH->compression != 0)
	{
		zp->zalloc = Z_NULL;
		zp->zfree = Z_NULL;
		zp->opaque = Z_NULL;

		if (inflateInit(zp) != Z_OK)
			die_horribly(AH, modulename, "could not initialize compression library: %s\n", zp->msg);
	}
#endif

	blkLen = ReadInt(AH);
	while (blkLen != 0)
	{
		if (blkLen + 1 > ctx->inSize)
		{
			free(ctx->zlibIn);
			ctx->zlibIn = NULL;
			ctx->zlibIn = (char *) malloc(blkLen + 1);
			if (!ctx->zlibIn)
				die_horribly(AH, modulename, "out of memory\n");

			ctx->inSize = blkLen + 1;
			in = ctx->zlibIn;
		}

		cnt = fread(in, 1, blkLen, AH->FH);
		if (cnt != blkLen)
			die_horribly(AH, modulename,
				  "could not read data block -- expected %lu, got %lu\n",
						 (unsigned long) blkLen, (unsigned long) cnt);

		ctx->filePos += blkLen;

		zp->next_in = in;
		zp->avail_in = blkLen;

#ifdef HAVE_LIBZ

		if (AH->compression != 0)
		{
			while (zp->avail_in != 0)
			{
				zp->next_out = out;
				zp->avail_out = zlibOutSize;
				res = inflate(zp, 0);
				if (res != Z_OK && res != Z_STREAM_END)
					die_horribly(AH, modulename, "could not uncompress data: %s\n", zp->msg);

				out[zlibOutSize - zp->avail_out] = '\0';
				ahwrite(out, 1, zlibOutSize - zp->avail_out, AH);
			}
		}
		else
		{
#endif
			in[zp->avail_in] = '\0';
			ahwrite(in, 1, zp->avail_in, AH);
			zp->avail_in = 0;

#ifdef HAVE_LIBZ
		}
#endif
		blkLen = ReadInt(AH);
	}

#ifdef HAVE_LIBZ
	if (AH->compression != 0)
	{
		zp->next_in = NULL;
		zp->avail_in = 0;
		while (res != Z_STREAM_END)
		{
			zp->next_out = out;
			zp->avail_out = zlibOutSize;
			res = inflate(zp, 0);
			if (res != Z_OK && res != Z_STREAM_END)
				die_horribly(AH, modulename, "could not uncompress data: %s\n", zp->msg);

			out[zlibOutSize - zp->avail_out] = '\0';
			ahwrite(out, 1, zlibOutSize - zp->avail_out, AH);
		}
		if (inflateEnd(zp) != Z_OK)
			die_horribly(AH, modulename, "could not close compression library: %s\n", zp->msg);
	}
#endif
}

static void
_LoadBlobs(ArchiveHandle *AH)
{
	Oid			oid;

	StartRestoreBlobs(AH);

	oid = ReadInt(AH);
	while (oid != 0)
	{
		StartRestoreBlob(AH, oid);
		_PrintData(AH);
		EndRestoreBlob(AH, oid);
		oid = ReadInt(AH);
	}

	EndRestoreBlobs(AH);
}

/*
 * Skip the BLOBs from the current file position.
 * BLOBS are written sequentially as data blocks (see below).
 * Each BLOB is preceded by it's original OID.
 * A zero OID indicated the end of the BLOBS
 */
static void
_skipBlobs(ArchiveHandle *AH)
{
	Oid			oid;

	oid = ReadInt(AH);
	while (oid != 0)
	{
		_skipData(AH);
		oid = ReadInt(AH);
	}
}

/*
 * Skip data from current file position.
 * Data blocks are formatted as an integer length, followed by data.
 * A zero length denoted the end of the block.
*/
static void
_skipData(ArchiveHandle *AH)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	size_t		blkLen;
	char	   *in = ctx->zlibIn;
	size_t		cnt;

	blkLen = ReadInt(AH);
	while (blkLen != 0)
	{
		if (blkLen > ctx->inSize)
		{
			free(ctx->zlibIn);
			ctx->zlibIn = (char *) malloc(blkLen);
			ctx->inSize = blkLen;
			in = ctx->zlibIn;
		}
		cnt = fread(in, 1, blkLen, AH->FH);
		if (cnt != blkLen)
			die_horribly(AH, modulename,
				  "could not read data block -- expected %lu, got %lu\n",
						 (unsigned long) blkLen, (unsigned long) cnt);

		ctx->filePos += blkLen;

		blkLen = ReadInt(AH);
	}
}

/*
 * Write a byte of data to the archive.
 *
 * Mandatory.
 *
 * Called by the archiver to do integer & byte output to the archive.
 * These routines are only used to read & write headers & TOC.
 *
 */
static int
_WriteByte(ArchiveHandle *AH, const int i)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	int			res;

	res = fputc(i, AH->FH);
	if (res != EOF)
		ctx->filePos += 1;
	else
		die_horribly(AH, modulename, "could not write byte: %s\n", strerror(errno));
	return res;
}

/*
 * Read a byte of data from the archive.
 *
 * Mandatory
 *
 * Called by the archiver to read bytes & integers from the archive.
 * These routines are only used to read & write headers & TOC.
 *
 */
static int
_ReadByte(ArchiveHandle *AH)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	int			res;

	res = fgetc(AH->FH);
	if (res != EOF)
		ctx->filePos += 1;
	return res;
}

/*
 * Write a buffer of data to the archive.
 *
 * Mandatory.
 *
 * Called by the archiver to write a block of bytes to the archive.
 * These routines are only used to read & write headers & TOC.
 *
 */
static size_t
_WriteBuf(ArchiveHandle *AH, const void *buf, size_t len)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	size_t		res;

	res = fwrite(buf, 1, len, AH->FH);

	if (res != len)
		die_horribly(AH, modulename,
					 "write error in _WriteBuf (%lu != %lu)\n",
					 (unsigned long) res, (unsigned long) len);

	ctx->filePos += res;
	return res;
}

/*
 * Read a block of bytes from the archive.
 *
 * Mandatory.
 *
 * Called by the archiver to read a block of bytes from the archive
 * These routines are only used to read & write headers & TOC.
 *
 */
static size_t
_ReadBuf(ArchiveHandle *AH, void *buf, size_t len)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	size_t		res;

	res = fread(buf, 1, len, AH->FH);
	ctx->filePos += res;

	return res;
}

/*
 * Close the archive.
 *
 * Mandatory.
 *
 * When writing the archive, this is the routine that actually starts
 * the process of saving it to files. No data should be written prior
 * to this point, since the user could sort the TOC after creating it.
 *
 * If an archive is to be written, this toutine must call:
 *		WriteHead			to save the archive header
 *		WriteToc			to save the TOC entries
 *		WriteDataChunks		to save all DATA & BLOBs.
 *
 */
static void
_CloseArchive(ArchiveHandle *AH)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	off_t		tpos;

	if (AH->mode == archModeWrite)
	{
		WriteHead(AH);
		tpos = ftello(AH->FH);
		WriteToc(AH);
		ctx->dataStart = _getFilePos(AH, ctx);
		WriteDataChunks(AH);

		/*
		 * This is not an essential operation - it is really only needed
		 * if we expect to be doing seeks to read the data back - it may
		 * be ok to just use the existing self-consistent block
		 * formatting.
		 */
		if (ctx->hasSeek)
		{
			fseeko(AH->FH, tpos, SEEK_SET);
			WriteToc(AH);
		}
	}

	if (fclose(AH->FH) != 0)
		die_horribly(AH, modulename, "could not close archive file: %s\n", strerror(errno));

	AH->FH = NULL;
}

/*--------------------------------------------------
 * END OF FORMAT CALLBACKS
 *--------------------------------------------------
 */

/*
 * Get the current position in the archive file.
 */
static off_t
_getFilePos(ArchiveHandle *AH, lclContext *ctx)
{
	off_t		pos;

	if (ctx->hasSeek)
	{
		pos = ftello(AH->FH);
		if (pos != ctx->filePos)
		{
			write_msg(modulename, "WARNING: ftell mismatch with expected position -- ftell used\n");

			/*
			 * Prior to 1.7 (pg7.3) we relied on the internally maintained
			 * pointer. Now we rely on off_t always. pos = ctx->filePos;
			 */
		}
	}
	else
		pos = ctx->filePos;
	return pos;
}

/*
 * Read a data block header. The format changed in V1.3, so we
 * put the code here for simplicity.
 */
static void
_readBlockHeader(ArchiveHandle *AH, int *type, int *id)
{
	if (AH->version < K_VERS_1_3)
		*type = BLK_DATA;
	else
		*type = _ReadByte(AH);;

	*id = ReadInt(AH);
}

/*
 * If zlib is available, then startit up. This is called from
 * StartData & StartBlob. The buffers are setup in the Init routine.
 *
 */
static void
_StartDataCompressor(ArchiveHandle *AH, TocEntry *te)
{
	lclContext *ctx = (lclContext *) AH->formatData;
	z_streamp	zp = ctx->zp;

#ifdef HAVE_LIBZ

	if (AH->compression < 0 || AH->compression > 9)
		AH->compression = Z_DEFAULT_COMPRESSION;

	if (AH->compression != 0)
	{
		zp->zalloc = Z_NULL;
		zp->zfree = Z_NULL;
		zp->opaque = Z_NULL;

		if (deflateInit(zp, AH->compression) != Z_OK)
			die_horribly(AH, modulename, "could not initialize compression library: %s\n", zp->msg);
	}

#else

	AH->compression = 0;
#endif

	/* Just be paranoid - maybe End is called after Start, with no Write */
	zp->next_out = ctx->zlibOut;
	zp->avail_out = zlibOutSize;
}

/*
 * Send compressed data to the output stream (via ahwrite).
 * Each data chunk is preceded by it's length.
 * In the case of Z0, or no zlib, just write the raw data.
 *
 */
static int
_DoDeflate(ArchiveHandle *AH, lclContext *ctx, int flush)
{
	z_streamp	zp = ctx->zp;

#ifdef HAVE_LIBZ
	char	   *out = ctx->zlibOut;
	int			res = Z_OK;

	if (AH->compression != 0)
	{
		res = deflate(zp, flush);
		if (res == Z_STREAM_ERROR)
			die_horribly(AH, modulename, "could not compress data: %s\n", zp->msg);

		if (((flush == Z_FINISH) && (zp->avail_out < zlibOutSize))
			|| (zp->avail_out == 0)
			|| (zp->avail_in != 0)
			)
		{
			/*
			 * Extra paranoia: avoid zero-length chunks since a zero
			 * length chunk is the EOF marker. This should never happen
			 * but...
			 */
			if (zp->avail_out < zlibOutSize)
			{
				/*
				 * printf("Wrote %lu byte deflated chunk\n", (unsigned
				 * long) (zlibOutSize - zp->avail_out));
				 */
				WriteInt(AH, zlibOutSize - zp->avail_out);
				if (fwrite(out, 1, zlibOutSize - zp->avail_out, AH->FH) != (zlibOutSize - zp->avail_out))
					die_horribly(AH, modulename, "could not write compressed chunk\n");
				ctx->filePos += zlibOutSize - zp->avail_out;
			}
			zp->next_out = out;
			zp->avail_out = zlibOutSize;
		}
	}
	else
#endif
	{
		if (zp->avail_in > 0)
		{
			WriteInt(AH, zp->avail_in);
			if (fwrite(zp->next_in, 1, zp->avail_in, AH->FH) != zp->avail_in)
				die_horribly(AH, modulename, "could not write uncompressed chunk\n");
			ctx->filePos += zp->avail_in;
			zp->avail_in = 0;
		}
		else
		{
#ifdef HAVE_LIBZ
			if (flush == Z_FINISH)
				res = Z_STREAM_END;
#endif
		}
	}

#ifdef HAVE_LIBZ
	return res;
#else
	return 1;
#endif
}

/*
 * Terminate zlib context and flush it's buffers. If no zlib
 * then just return.
 *
 */
static void
_EndDataCompressor(ArchiveHandle *AH, TocEntry *te)
{

#ifdef HAVE_LIBZ
	lclContext *ctx = (lclContext *) AH->formatData;
	z_streamp	zp = ctx->zp;
	int			res;

	if (AH->compression != 0)
	{
		zp->next_in = NULL;
		zp->avail_in = 0;

		do
		{
			/* printf("Ending data output\n"); */
			res = _DoDeflate(AH, ctx, Z_FINISH);
		} while (res != Z_STREAM_END);

		if (deflateEnd(zp) != Z_OK)
			die_horribly(AH, modulename, "could not close compression stream: %s\n", zp->msg);
	}
#endif

	/* Send the end marker */
	WriteInt(AH, 0);
}