firebird-mirror/src/jrd/blb.cpp

/*
 *	PROGRAM:	JRD Access Method
 *	MODULE:		blb.cpp
 *	DESCRIPTION:	Blob handler
 *
 * The contents of this file are subject to the Interbase Public
 * License Version 1.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy
 * of the License at http://www.Inprise.com/IPL.html
 *
 * Software distributed under the License is distributed on an
 * "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express
 * or implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code was created by Inprise Corporation
 * and its predecessors. Portions created by Inprise Corporation are
 * Copyright (C) Inprise Corporation.
 *
 * All Rights Reserved.
 * Contributor(s): ______________________________________.
 *
 * 2001.6.23 Claudio Valderrama: move_from_string to accept assignments
 * from string to blob field. First use was to allow inserting a literal string
 * in a blob field without requiring an UDF.
 *
 * 2001.07.06 Sean Leyne - Code Cleanup, removed "#ifdef READONLY_DATABASE"
 *                         conditionals, as the engine now fully supports
 *                         readonly databases.
 *
 * 2002.10.28 Sean Leyne - Code cleanup, removed obsolete "MPEXL" port
 * 2002.10.28 Sean Leyne - Code cleanup, removed obsolete "DecOSF" port
 *
 * Adriano dos Santos Fernandes
 *
 */

#include "firebird.h"
#include "memory_routines.h"
#include <string.h>
#include "../jrd/common.h"
#include "../jrd/ibase.h"

#include "../jrd/jrd.h"
#include "../jrd/tra.h"
#include "../jrd/val.h"
#include "../jrd/exe.h"
#include "../jrd/req.h"
#include "../jrd/blb.h"
#include "../jrd/ods.h"
#include "../jrd/lls.h"
#include "gen/iberror.h"
#include "../jrd/blob_filter.h"
#include "../jrd/sdl.h"
#include "../jrd/intl.h"
#include "../jrd/cch.h"
#include "../jrd/gdsassert.h"
#include "../jrd/blb_proto.h"
#include "../jrd/blf_proto.h"
#include "../jrd/cch_proto.h"
#include "../jrd/dpm_proto.h"
#include "../jrd/err_proto.h"
#include "../jrd/evl_proto.h"
#include "../jrd/filte_proto.h"
#include "../jrd/gds_proto.h"
#include "../jrd/intl_proto.h"
#include "../jrd/jrd_proto.h"
#include "../jrd/met_proto.h"
#include "../jrd/mov_proto.h"
#include "../jrd/pag_proto.h"
#include "../jrd/sdl_proto.h"
#include "../jrd/dsc_proto.h"
#include "../common/classes/array.h"
#include "../common/classes/VaryStr.h"

using namespace Jrd;
using namespace Firebird;
using Firebird::UCharBuffer;

typedef Ods::blob_page blob_page;

inline bool SEGMENTED(const blb* blob)
{
	return !(blob->blb_flags & BLB_stream);
}

static ArrayField* alloc_array(jrd_tra*, Ods::InternalArrayDesc*);
static blb* allocate_blob(thread_db*, jrd_tra*);
static ISC_STATUS blob_filter(USHORT, BlobControl*);
static blb* copy_blob(thread_db*, const bid*, bid*, USHORT, const UCHAR*, USHORT);
static void delete_blob(thread_db*, blb*, ULONG);
static void delete_blob_id(thread_db*, const bid*, SLONG, jrd_rel*);
static ArrayField* find_array(jrd_tra*, const bid*);
static BlobFilter* find_filter(thread_db*, SSHORT, SSHORT);
static blob_page* get_next_page(thread_db*, blb*, WIN *);
static void insert_page(thread_db*, blb*);
static void move_from_string(Jrd::thread_db*, const dsc*, dsc*, Jrd::jrd_nod*);
static void move_to_string(Jrd::thread_db*, dsc*, dsc*);
static void release_blob(blb*, const bool);
static void slice_callback(array_slice*, ULONG, dsc*);
static blb* store_array(thread_db*, jrd_tra*, bid*);


void BLB_cancel(thread_db* tdbb, blb* blob)
{
/**************************************
 *
 *      B L B _ c a n c e l
 *
 **************************************
 *
 * Functional description
 *      Abort a blob operation.  If the blob is a partially created
 *      temporary blob, free up any allocated pages.  In any case,
 *      get rid of the blob block.
 *
 **************************************/

	SET_TDBB(tdbb);

/* Release filter control resources */

	if (blob->blb_flags & BLB_temporary)
		delete_blob(tdbb, blob, 0);

	release_blob(blob, true);
}


void BLB_check_well_formed(Jrd::thread_db* tdbb, const dsc* desc, Jrd::blb* blob)
{
/**************************************
 *
 *      B L B _ c h e c k _ w e l l _ f o r m e d
 *
 **************************************
 *
 * Functional description
 *      Check if a text BLOB is well formed.
 *
 **************************************/

	SET_TDBB(tdbb);

	// Need to verify this to work in database creation, as the charsets didn't exist yet.
	if (desc->getCharSet() == CS_NONE || desc->getCharSet() == CS_BINARY)
		return;

	CharSet* charSet = INTL_charset_lookup(tdbb, desc->getCharSet());

	if (!charSet->shouldCheckWellFormedness())
		return;

	HalfStaticArray<UCHAR, BUFFER_MEDIUM> buffer;
	ULONG pos = 0;

	while (!(blob->blb_flags & BLB_eof))
	{
		const ULONG len = BLB_get_data(tdbb, blob,
			buffer.getBuffer(buffer.getCapacity()) + pos, buffer.getCapacity() - pos, false);
		buffer.resize(pos + len);

		if (charSet->wellFormed(pos + len, buffer.begin(), &pos))
			pos = 0;
		else
		{
			if (pos == 0)
				status_exception::raise(Arg::Gds(isc_malformed_string));
			else
			{
				buffer.removeCount(0, pos);
				pos = buffer.getCount();
			}
		}
	}

	if (pos != 0)
		status_exception::raise(Arg::Gds(isc_malformed_string));
}


void BLB_close(thread_db* tdbb, Jrd::blb* blob)
{
/**************************************
 *
 *      B L B _ c l o s e
 *
 **************************************
 *
 * Functional description
 *      Close a blob.  If the blob is open for retrieval, release the
 *      blob block.  If it's a temporary blob, flush out the last page
 *      (if necessary) in preparation for materialization.
 *
 **************************************/

	SET_TDBB(tdbb);

/* Release filter control resources */

	if (blob->blb_filter)
		BLF_close_blob(tdbb, &blob->blb_filter);

	blob->blb_flags |= BLB_closed;

	if (!(blob->blb_flags & BLB_temporary)) {
		release_blob(blob, true);
		return;
	}

	if (blob->blb_level == 0)
	{
		//Database* dbb = tdbb->getDatabase();

		blob->blb_temp_size = blob->blb_clump_size - blob->blb_space_remaining;

		if (blob->blb_temp_size > 0)
		{
			blob->blb_temp_size += BLP_SIZE;
			jrd_tra* transaction = blob->blb_transaction;
			TempSpace* const tempSpace = transaction->getBlobSpace();

			blob->blb_temp_offset = tempSpace->allocateSpace(blob->blb_temp_size);
			tempSpace->write(blob->blb_temp_offset, blob->getBuffer(), blob->blb_temp_size);
		}
	}
	else if (blob->blb_level >= 1 &&
			 blob->blb_space_remaining < blob->blb_clump_size)
	{
		insert_page(tdbb, blob);
	}

	blob->freeBuffer();
}


blb* BLB_create(thread_db* tdbb, jrd_tra* transaction, bid* blob_id)
{
/**************************************
 *
 *      B L B _ c r e a t e
 *
 **************************************
 *
 * Functional description
 *      Create a shiney, new, empty blob.
 *
 **************************************/

	SET_TDBB(tdbb);
	return BLB_create2(tdbb, transaction, blob_id, 0, NULL);
}


blb* BLB_create2(thread_db* tdbb,
				jrd_tra* transaction, bid* blob_id,
				USHORT bpb_length, const UCHAR* bpb)
{
/**************************************
 *
 *      B L B _ c r e a t e 2
 *
 **************************************
 *
 * Functional description
 *      Create a shiney, new, empty blob.
 *      Basically BLB_create() with BPB structure.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();
	CHECK_DBB(dbb);

/* Create a blob large enough to hold a single data page */
	SSHORT from, to;
	SSHORT from_charset, to_charset;
	const SSHORT type = gds__parse_bpb2(bpb_length,
						   bpb,
						   &from,
						   &to,
						   reinterpret_cast<USHORT*>(&from_charset),	// safe - alignment not changed
						   reinterpret_cast<USHORT*>(&to_charset),		// safe - alignment not changed
						   NULL, NULL, NULL, NULL);
	blb* blob = allocate_blob(tdbb, transaction);

	if (type & isc_bpb_type_stream)
		blob->blb_flags |= BLB_stream;

	if ((type & isc_bpb_storage_temp) || (dbb->dbb_flags & DBB_read_only)) {
		blob->blb_pg_space_id = dbb->dbb_page_manager.getTempPageSpaceID(tdbb);
	}
	else {
		blob->blb_pg_space_id = DB_PAGE_SPACE;
	}

	//blob->blb_source_interp = from_charset;
	//blob->blb_target_interp = to_charset;
	blob->blb_sub_type = to;

	bool filter_required = false;
	BlobFilter* filter = NULL;
	if (to && from != to)
	{
		// ASF: filter_text is not supported for write operations
		if (!(from == 0 && to == 1))
		{
			filter = find_filter(tdbb, from, to);
			filter_required = true;
		}
	}
	else if (to == isc_blob_text && (from_charset != to_charset))
	{
		if (from_charset == CS_dynamic)
			from_charset = tdbb->getAttachment()->att_charset;
		if (to_charset == CS_dynamic)
			to_charset = tdbb->getAttachment()->att_charset;

		if ((to_charset != CS_NONE) && (from_charset != CS_NONE) &&
			(to_charset != CS_BINARY) && (from_charset != CS_BINARY) &&
			(from_charset != to_charset))
		{
			filter = FB_NEW(*dbb->dbb_permanent) BlobFilter(*dbb->dbb_permanent);
			filter->blf_filter = filter_transliterate_text;
			filter_required = true;
		}
	}

	blob->blb_space_remaining = blob->blb_clump_size;

	if (filter_required)
	{
		BLF_create_blob(tdbb,
						transaction,
						&blob->blb_filter,
						blob_id,
						bpb_length,
						bpb,
						blob_filter,
						filter);
		blob->blb_flags |= BLB_temporary;
		return blob;
	}

	blob->blb_flags |= BLB_temporary;

/* Set up for a "small" blob -- a blob that fits on an ordinary blob page */

	blob_page* page = (blob_page*) blob->getBuffer();
	memset(page, 0, BLP_SIZE);	// initialize page header with NULLs
	page->blp_header.pag_type = pag_blob;
	blob->blb_segment = (UCHAR *) page->blp_page;

/* Format blob id and return blob handle */

	blob_id->set_temporary(blob->blb_temp_id);

	return blob;
}


//
// This function makes linear stacks lookup. Therefore
// in case of big stacks garbage collection speed may become
// real problem. Stacks should be sorted before run?
// 2006.03.17 hvlad: it is sorted now
void BLB_garbage_collect(thread_db* tdbb,
						 RecordStack& going,
						 RecordStack& staying,
						 SLONG prior_page, jrd_rel* relation)
{
/**************************************
 *
 *      B L B _ g a r b a g e _ c o l l e c t
 *
 **************************************
 *
 * Functional description
 *      Garbage collect indices and blobs.  Garbage_collect is passed a
 *      stack of record blocks of records that are being deleted and a stack
 *      of records blocks of records that are staying.  Garbage_collect
 *      can be called from four operations:
 *
 *              VIO_backout     -- removing top record
 *              expunge         -- removing all versions of a record
 *              purge           -- removing all but top version of a record
 *              update_in_place -- replace the top level record.
 *
 *	hvlad: note that same blob_id can be reused by the staying record version
 *		in the different field than it was in going record. This is happening
 *		with 3 blob fields and update_in_place
 *
 **************************************/
	SET_TDBB(tdbb);

	RecordBitmap bmGoing;
	ULONG cntGoing = 0;

	// Loop thru records on the way out looking for blobs to garbage collect
	for (RecordStack::iterator stack1(going); stack1.hasData(); ++stack1)
	{
		Record* rec = stack1.object();
		if (!rec)
			continue;

		// Look for active blob records
		const Format* format = rec->rec_format;
		for (USHORT id = 0; id < format->fmt_count; id++)
		{
			DSC desc;
			if (DTYPE_IS_BLOB(format->fmt_desc[id].dsc_dtype) && EVL_field(0, rec, id, &desc))
			{
				const bid* blob = (bid*) desc.dsc_address;
				if (!blob->isEmpty())
				{
					if (blob->bid_internal.bid_relation_id == relation->rel_id)
					{
						const RecordNumber number = blob->get_permanent_number();
						bmGoing.set(number.getValue());
						cntGoing++;
					}
					else
					{
						// hvlad: blob_id in descriptor is not from our relation. Yes, it is
						// garbage in user data but we can handle it without bugcheck - just
						// ignore it. To be reconsider latter based on real user reports.
						// The same about staying blob few lines below
						gds__log("going blob (%ld:%ld) is not owned by relation (id = %d), ignored",
							blob->bid_quad.bid_quad_high, blob->bid_quad.bid_quad_low, relation->rel_id);
					}
				}
			}
		}
	}

	if (!cntGoing)
		return;

	// Make sure the blob doesn't stay in any record remaining
	for (RecordStack::iterator stack2(staying); stack2.hasData(); ++stack2)
	{
		Record* rec = stack2.object();
		if (!rec)
			continue;

		const Format* format = rec->rec_format;
		for (USHORT id = 0; id < format->fmt_count; id++)
		{
			DSC desc;
			if (DTYPE_IS_BLOB(format->fmt_desc[id].dsc_dtype) && EVL_field(0, rec, id, &desc))
			{
				const bid* blob = (bid*) desc.dsc_address;
				if (!blob->isEmpty())
				{
					if (blob->bid_internal.bid_relation_id == relation->rel_id)
					{
						const RecordNumber number = blob->get_permanent_number();
						if (bmGoing.test(number.getValue()))
						{
							bmGoing.clear(number.getValue());
							if (!--cntGoing)
								return;
						}
					}
					else
					{
						gds__log("staying blob (%ld:%ld) is not owned by relation (id = %d), ignored",
							blob->bid_quad.bid_quad_high, blob->bid_quad.bid_quad_low, relation->rel_id);
					}
				}
			}
		}
	}

	// Get rid of blob
	if (bmGoing.getFirst())
	{
		do {
			const FB_UINT64 id = bmGoing.current();

			bid blob;
			blob.set_permanent(relation->rel_id, RecordNumber(id));

			delete_blob_id(tdbb, &blob, prior_page, relation);
		} while (bmGoing.getNext());
	}
}


void BLB_gen_bpb(SSHORT source, SSHORT target, UCHAR sourceCharset, UCHAR targetCharset, UCharBuffer& bpb)
{
	bpb.resize(15);

	UCHAR* p = bpb.begin();
	*p++ = isc_bpb_version1;

	*p++ = isc_bpb_source_type;
	*p++ = 2;
	put_vax_short(p, source);
	p += 2;
	if (source == isc_blob_text)
	{
		*p++ = isc_bpb_source_interp;
		*p++ = 1;
		*p++ = sourceCharset;
	}

	*p++ = isc_bpb_target_type;
	*p++ = 2;
	put_vax_short(p, target);
	p += 2;
	if (target == isc_blob_text)
	{
		*p++ = isc_bpb_target_interp;
		*p++ = 1;
		*p++ = targetCharset;
	}
	fb_assert(static_cast<size_t>(p - bpb.begin()) <= bpb.getCount());

	// set the array count to the number of bytes we used
	bpb.shrink(p - bpb.begin());
}


void BLB_gen_bpb_from_descs(const dsc* fromDesc, const dsc* toDesc, UCharBuffer& bpb)
{
	BLB_gen_bpb(fromDesc->getBlobSubType(), toDesc->getBlobSubType(),
		fromDesc->getCharSet(), toDesc->getCharSet(), bpb);
}


blb* BLB_get_array(thread_db* tdbb, jrd_tra* transaction, const bid* blob_id,
				   Ods::InternalArrayDesc* desc)
{
/**************************************
 *
 *      B L B _ g e t _ a r r a y
 *
 **************************************
 *
 * Functional description
 *      Get array blob and array descriptor.
 *
 **************************************/
	SET_TDBB(tdbb);

	blb* blob = BLB_open2(tdbb, transaction, blob_id, 0, 0);

	if (blob->blb_length < sizeof(Ods::InternalArrayDesc)) {
		BLB_close(tdbb, blob);
		IBERROR(193);			/* msg 193 null or invalid array */
	}

	BLB_get_segment(tdbb, blob, reinterpret_cast<UCHAR*>(desc), sizeof(Ods::InternalArrayDesc));

	const USHORT n = desc->iad_length - sizeof(Ods::InternalArrayDesc);
	if (n) {
		BLB_get_segment(tdbb, blob, reinterpret_cast<UCHAR*>(desc) + sizeof(Ods::InternalArrayDesc), n);
	}

	return blob;
}


ULONG BLB_get_data(thread_db* tdbb, blb* blob, UCHAR* buffer, SLONG length, bool close)
{
/**************************************
 *
 *      B L B _ g e t _ d a t a
 *
 **************************************
 *
 * Functional description
 *      Get a large hunk of data from a blob, which can then be
 *      closed (if close == true).  Return total number of bytes read.
 *      Don't worry about segment boundaries.
 *
 **************************************/
	SET_TDBB(tdbb);
	BLOB_PTR* p = buffer;

	while (length > 0)
	{
		/* I have no idea why this limit is 32768 instead of 32767
		 * 1994-August-12 David Schnepper
		 */
		USHORT n = (USHORT) MIN(length, (SLONG) 32768);
		n = BLB_get_segment(tdbb, blob, p, n);
		p += n;
		length -= n;
		if (blob->blb_flags & BLB_eof)
			break;
	}

	if (close)
		BLB_close(tdbb, blob);

	return (ULONG)(p - buffer);
}


USHORT BLB_get_segment(thread_db* tdbb, blb* blob, UCHAR* segment, USHORT buffer_length)
{
/**************************************
 *
 *      B L B _ g e t _ s e g m e n t
 *
 **************************************
 *
 * Functional description
 *      Get next segment or fragment from a blob.  Return the number
 *      of bytes returned.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();

	if (--tdbb->tdbb_quantum < 0)
		JRD_reschedule(tdbb, 0, true);

/* If we reached end of file, we're still there */

	if (blob->blb_flags & BLB_eof)
		return 0;

	if (blob->blb_filter)
	{
		blob->blb_fragment_size = 0;
		USHORT tmp_len = 0;
		const ISC_STATUS status =
			BLF_get_segment(tdbb, &blob->blb_filter, &tmp_len, buffer_length, segment);

		switch (status)
		{
			case isc_segstr_eof:
				blob->blb_flags |= BLB_eof;
				break;
			case isc_segment:
				blob->blb_fragment_size = 1;
				break;
			default:
				fb_assert(status == 0);
		}

		return tmp_len;
	}

/* If there is a seek pending, handle it here */

	USHORT seek = 0;

	if (blob->blb_flags & BLB_seek)
	{
		if (blob->blb_seek >= blob->blb_length) {
			blob->blb_flags |= BLB_eof;
			return 0;
		}
		const USHORT l = dbb->dbb_page_size - BLP_SIZE;
		blob->blb_sequence = blob->blb_seek / l;
		seek = (USHORT)(blob->blb_seek % l);	// safe cast
		blob->blb_flags &= ~BLB_seek;
		blob->blb_fragment_size = 0;
		if (blob->blb_level) {
			blob->blb_space_remaining = 0;
			blob->blb_segment = NULL;
		}
		else {
			blob->blb_space_remaining = blob->blb_length - seek;
			blob->blb_segment = blob->getBuffer() + seek;
		}
	}

	if (!blob->blb_space_remaining && blob->blb_segment) {
		blob->blb_flags |= BLB_eof;
		return 0;
	}

/* Figure out how much data is to be moved, move it, and if necessary,
   advance to the next page.  The length is a function of segment
   size (or fragment size), buffer size, and amount of data left
   in the blob. */

	BLOB_PTR* to = segment;
	const BLOB_PTR* from = blob->blb_segment;
	USHORT length = blob->blb_space_remaining;
	bool active_page = false;
	fb_assert(blob->blb_pg_space_id);
	WIN window(blob->blb_pg_space_id, -1); // there was no initialization of win_page here.
	if (blob->blb_flags & BLB_large_scan) {
		window.win_flags = WIN_large_scan;
		window.win_scans = 1;
	}

	while (true)
	{
		/* If the blob is segmented, and this isn't a fragment, pick up
		   the length of the next segment. */

		if (SEGMENTED(blob) && !blob->blb_fragment_size)
		{
			while (length < 2)
			{
				if (active_page) {
					if (window.win_flags & WIN_large_scan)
						CCH_RELEASE_TAIL(tdbb, &window);
					else
						CCH_RELEASE(tdbb, &window);
				}
				const blob_page* page = get_next_page(tdbb, blob, &window);
				if (!page) {
					blob->blb_flags |= BLB_eof;
					return 0;
				}
				from = (const UCHAR*) page->blp_page;
				length = page->blp_length;
				active_page = true;
			}

			UCHAR* p = (UCHAR *) & blob->blb_fragment_size;
			*p++ = *from++;
			*p++ = *from++;
			length -= 2;
		}

		/* Figure out how much data can be moved.  Then account for the
		   space, and move the data */

		USHORT l = MIN(buffer_length, length);

		if (SEGMENTED(blob)) {
			l = MIN(l, blob->blb_fragment_size);
			blob->blb_fragment_size -= l;
		}

		length -= l;
		buffer_length -= l;

		memcpy(to, from, l);

		to += l;
		from += l;

		/* If we ran out of space in the data clump, and there is a next
		   clump, get it. */

		if (!length)
		{
			if (active_page) {
				if (window.win_flags & WIN_large_scan)
					CCH_RELEASE_TAIL(tdbb, &window);
				else
					CCH_RELEASE(tdbb, &window);
			}
			const blob_page* page = get_next_page(tdbb, blob, &window);
			if (!page) {
				active_page = false;
				break;
			}
			from = reinterpret_cast<const UCHAR*>(page->blp_page) + seek;
			length = page->blp_length - seek;
			seek = 0;
			active_page = true;
		}

		/* If either the buffer or the fragment is exhausted, we're
		   done. */

		if (!buffer_length || (SEGMENTED(blob) && !blob->blb_fragment_size))
			break;
	}

	if (active_page)
	{
		UCHAR* buffer = blob->getBuffer();
		memcpy(buffer, from, length);
		from = buffer;

		if (window.win_flags & WIN_large_scan)
			CCH_RELEASE_TAIL(tdbb, &window);
		else
			CCH_RELEASE(tdbb, &window);
	}

	blob->blb_segment = const_cast<BLOB_PTR*>(from); // safe cast
	blob->blb_space_remaining = length;
	length = to - segment;
	blob->blb_seek += length;

/* If this is a stream blob, fake fragment unless we're at the end */

	if (!SEGMENTED(blob)) { // stream blob
		blob->blb_fragment_size = (blob->blb_seek == blob->blb_length) ? 0 : 1;
	}

	return length;
}


SLONG BLB_get_slice(thread_db* tdbb,
					jrd_tra* transaction,
					const bid* blob_id,
					const UCHAR* sdl,
					USHORT param_length,
					const UCHAR* param, SLONG slice_length, UCHAR* slice_addr)
{
/**************************************
 *
 *      B L B _ g e t _ s l i c e
 *
 **************************************
 *
 * Functional description
 *      Fetch a slice of an array.
 *
 **************************************/
	SET_TDBB(tdbb);
    //Database* database = GET_DBB();
	Jrd::ContextPoolHolder context(tdbb, transaction->tra_pool);

/* Checkout slice description language */
	SLONG variables[64];
	sdl_info info;
	memcpy(variables, param, MIN(sizeof(variables), param_length));

	if (SDL_info(tdbb->tdbb_status_vector, sdl, &info, variables)) {
		ERR_punt();
	}

	SLONG stuff[IAD_LEN(16) / 4];
	Ods::InternalArrayDesc* desc = (Ods::InternalArrayDesc*) stuff;
	blb* blob = BLB_get_array(tdbb, transaction, blob_id, desc);
	SLONG length = desc->iad_total_length;

/* Get someplace to put data */

	UCharBuffer data_buffer;
	UCHAR* const data = data_buffer.getBuffer(desc->iad_total_length);

/* zero out memory, so that it does not have to be done for each element */

	memset(data, 0, desc->iad_total_length);

	SLONG offset = 0;

	array_slice arg;

/* If we know something about the subscript bounds, prepare
   to fetch only stuff we really care about */

	if (info.sdl_info_dimensions)
	{
		const SLONG from = SDL_compute_subscript(tdbb->tdbb_status_vector, desc,
								  				 info.sdl_info_dimensions, info.sdl_info_lower);
		const SLONG to = SDL_compute_subscript(tdbb->tdbb_status_vector, desc,
								  			   info.sdl_info_dimensions, info.sdl_info_upper);
		if (from != -1 && to != -1) {
			if (from) {
				offset = from * desc->iad_element_length;
				BLB_lseek(blob, 0, offset + (SLONG) desc->iad_length);
			}
			length = (to - from + 1) * desc->iad_element_length;
		}
	}

	length = BLB_get_data(tdbb, blob, data + offset, length) + offset;

/* Walk array */
	arg.slice_desc = info.sdl_info_element;
	arg.slice_desc.dsc_address = slice_addr;
	arg.slice_end = slice_addr + slice_length;
	arg.slice_count = 0;
	arg.slice_element_length = info.sdl_info_element.dsc_length;
	arg.slice_direction = array_slice::slc_reading_array;	// fetching from array
	arg.slice_high_water = data + length;
	arg.slice_base = data + offset;

	ISC_STATUS status = SDL_walk(tdbb->tdbb_status_vector, sdl,
								 data, desc, variables, slice_callback, &arg);

	if (status) {
		ERR_punt();
	}

	return (SLONG) (arg.slice_count * arg.slice_element_length);
}


SLONG BLB_lseek(blb* blob, USHORT mode, SLONG offset)
{
/**************************************
 *
 *      B L B _ l s e e k
 *
 **************************************
 *
 * Functional description
 *      Position a blob for direct access.  Seek is only defined for stream
 *      type blobs.
 *
 **************************************/

	if (!(blob->blb_flags & BLB_stream))
		ERR_post(Arg::Gds(isc_bad_segstr_type));

	if (mode == 1)
		offset += blob->blb_seek;
	else if (mode == 2)
		offset = blob->blb_length + offset;

	if (offset < 0)
		offset = 0;

	if (offset > (SLONG) blob->blb_length)
		offset = blob->blb_length;

	blob->blb_seek = offset;
	blob->blb_flags |= BLB_seek;
	blob->blb_flags &= ~BLB_eof;

	return offset;
}


// This function can't take from_desc as const because it may call store_array,
// which in turn calls BLB_create2 that writes in the blob id. Although the
// compiler allows to modify from_desc->dsc_address' contents when from_desc is
// constant, this is misleading so I didn't make the source descriptor constant.
void BLB_move(thread_db* tdbb, dsc* from_desc, dsc* to_desc, jrd_nod* field)
{
/**************************************
 *
 *      B L B _ m o v e
 *
 **************************************
 *
 * Functional description
 *      Perform an assignment to a blob field or a blob descriptor.
 *      When assigning to a field, unless the blob is null,
 *      this requires that either a temporary blob be materialized or that
 *      a permanent blob be copied.  Note: it is illegal to have a blob
 *      field in a message.
 *
 **************************************/
	SET_TDBB(tdbb);

	if (to_desc->dsc_dtype == dtype_array)
	{
		// only array->array conversions are allowed
		if (from_desc->dsc_dtype != dtype_array && from_desc->dsc_dtype != dtype_quad)
		{
			ERR_post(Arg::Gds(isc_array_convert_error));
		}
	}
	else if (DTYPE_IS_BLOB_OR_QUAD(to_desc->dsc_dtype))
	{
		if (!DTYPE_IS_BLOB_OR_QUAD(from_desc->dsc_dtype))
		{
			// anything that can be copied into a string can be copied into a blob
			move_from_string(tdbb, from_desc, to_desc, field);
			return;
		}
	}
	else if (DTYPE_IS_BLOB_OR_QUAD(from_desc->dsc_dtype))
	{
		move_to_string(tdbb, from_desc, to_desc);
		return;
	}
	else
		fb_assert(false);

	bool simpleMove = true;

	// If the target node is a field, we need more work to do.
	if (field)
	{
		switch (field->nod_type)
		{
			case nod_field:
				// We should not materialize the blob if the destination field
				// stream (nod_union, for example) doesn't have a relation.
				simpleMove =
					tdbb->getRequest()->req_rpb[(IPTR)field->nod_arg[e_fld_stream]].rpb_relation == NULL;
				break;
			case nod_argument:
			case nod_variable:
				break;
			default:
				BUGCHECK(199);			/* msg 199 expected field node */
		}
	}

	bid* source = (bid*) from_desc->dsc_address;
	bid* destination = (bid*) to_desc->dsc_address;

	// If nothing changed, do nothing.  If it isn't broken, don't fix it.
	if (*source == *destination)
		return;

	const bool needFilter =
		(from_desc->dsc_sub_type != isc_blob_untyped && to_desc->dsc_sub_type != isc_blob_untyped &&
			(from_desc->dsc_sub_type != to_desc->dsc_sub_type ||
		 		(from_desc->dsc_sub_type == isc_blob_text &&
		 		from_desc->dsc_scale != to_desc->dsc_scale &&
				to_desc->dsc_scale != CS_NONE && to_desc->dsc_scale != CS_BINARY)));

	if (!needFilter && to_desc->isBlob() &&
        (from_desc->getCharSet() == CS_NONE || from_desc->getCharSet() == CS_BINARY) &&
        (to_desc->getCharSet() != CS_NONE && to_desc->getCharSet() != CS_BINARY))
	{
		AutoBlb blob(tdbb, BLB_open(tdbb, tdbb->getTransaction(), source));
		BLB_check_well_formed(tdbb, to_desc, blob.getBlb());
	}

	// If the target node is not a field, just copy the blob id and return.
	if (simpleMove)
	{
		// But if the sub_type or charset is different, create a new blob.
		if (DTYPE_IS_BLOB_OR_QUAD(from_desc->dsc_dtype) &&
			DTYPE_IS_BLOB_OR_QUAD(to_desc->dsc_dtype) &&
			needFilter)
		{
			UCharBuffer bpb;
			BLB_gen_bpb_from_descs(from_desc, to_desc, bpb);

			Database* dbb = tdbb->getDatabase();
			const USHORT pageSpace = dbb->dbb_flags & DBB_read_only ?
				dbb->dbb_page_manager.getTempPageSpaceID(tdbb) : DB_PAGE_SPACE;

			copy_blob(tdbb, source, destination, bpb.getCount(), bpb.begin(), pageSpace);
		}
		else
			*destination = *source;

		return;
	}

	jrd_req* request = tdbb->getRequest();
	const USHORT id = (USHORT) (IPTR) field->nod_arg[e_fld_id];
	record_param* rpb = &request->req_rpb[(IPTR)field->nod_arg[e_fld_stream]];
	jrd_rel* relation = rpb->rpb_relation;

	if (relation->isVirtual()) {
		ERR_post(Arg::Gds(isc_read_only));
	}

	RelationPages* relPages = relation->getPages(tdbb);
	Record* record = rpb->rpb_record;

	// If either the source value is null or the blob id itself is null
	// (all zeros), then the blob is null.

	if ((request->req_flags & req_null) || source->isEmpty())
	{
		SET_NULL(record, id);
		destination->clear();
		return;
	}

	CLEAR_NULL(record, id);
	jrd_tra* transaction = request->req_transaction;

	// If the target is a view, this must be from a view update trigger.
	// Just pass the blob id thru.

	if (relation->rel_view_rse) {
		*destination = *source;
		return;
	}

	// If the source is a permanent blob, then the blob must be copied.
	// Otherwise find the temporary blob referenced.

	ArrayField* array = NULL;
	BlobIndex* blobIndex;
	blb* blob = NULL;
	bool materialized_blob; // Set if we materialized temporary blob in this routine

	UCharBuffer bpb;
	if (needFilter)
		BLB_gen_bpb_from_descs(from_desc, to_desc, bpb);

	while (true)
	{
		materialized_blob = false;
		blobIndex = NULL;
		if (source->bid_internal.bid_relation_id || needFilter)
		{
			blob = copy_blob(tdbb, source, destination,
							 bpb.getCount(), bpb.begin(), relPages->rel_pg_space_id);
		}
		else if ((to_desc->dsc_dtype == dtype_array) && (array = find_array(transaction, source)) &&
			(blob = store_array(tdbb, transaction, source)))
		{
			materialized_blob = true;
		}
		else
		{
			if (transaction->tra_blobs->locate(source->bid_temp_id()))
			{
				blobIndex = &transaction->tra_blobs->current();
				if (blobIndex->bli_materialized)
				{
					if (blobIndex->bli_request) {
						// Walk through call stack looking if our BLOB is
						// owned by somebody from our call chain
						jrd_req* temp_req = request;
						do {
							if (blobIndex->bli_request == temp_req)
								break;
							temp_req = temp_req->req_caller;
						} while (temp_req);
						if (!temp_req) {
							// Trying to use temporary id of materialized blob from another request
							ERR_post(Arg::Gds(isc_bad_segstr_id));
						}
					}
					source = &blobIndex->bli_blob_id;
					continue;
				}

				materialized_blob = true;
				blob = blobIndex->bli_blob_object;

				if (!blob || !(blob->blb_flags & BLB_closed))
				{
					ERR_post(Arg::Gds(isc_bad_segstr_id));
				}

				if (blob->blb_level && (blob->blb_pg_space_id != relPages->rel_pg_space_id))
				{
					const ULONG oldTempID = blob->blb_temp_id;
					blb* newBlob = copy_blob(tdbb, source, destination,
						bpb.getCount(), bpb.begin(), relPages->rel_pg_space_id);

					transaction->tra_blobs->locate(newBlob->blb_temp_id);
					BlobIndex* newBlobIndex = &transaction->tra_blobs->current();

					transaction->tra_blobs->locate(oldTempID);
					blobIndex = &transaction->tra_blobs->current();

					newBlobIndex->bli_blob_object = blob;
					blobIndex->bli_blob_object = newBlob;

					blob->blb_temp_id = newBlob->blb_temp_id;
					newBlob->blb_temp_id = oldTempID;

					BLB_cancel(tdbb, blob);
					blob = newBlob;

					transaction->tra_blobs->locate(blob->blb_temp_id);
					blobIndex = &transaction->tra_blobs->current();
				}
			}
		}

		if (!blob || !(blob->blb_flags & BLB_closed))
		{
			ERR_post(Arg::Gds(isc_bad_segstr_id));
		}

		break;
	}

	blob->blb_relation = relation;
	blob->blb_sub_type = to_desc->getBlobSubType();
	blob->blb_charset = to_desc->getCharSet();
	destination->set_permanent(relation->rel_id, DPM_store_blob(tdbb, blob, record));
	// This is the only place in the engine where blobs are materialized
	// If new places appear code below should transform to common sub-routine
	if (materialized_blob)
	{
		// hvlad: we have possible thread switch in DPM_store_blob above and somebody
		// can modify transaction->tra_blobs therefore we must update our blobIndex
		if (!transaction->tra_blobs->locate(blob->blb_temp_id)) {
			// If we didn't find materialized blob in transaction blob index it
			// means memory structures are inconsistent and crash is appropriate
			BUGCHECK(305); // msg 305 Blobs accounting is inconsistent
		}
		blobIndex = &transaction->tra_blobs->current();

		blobIndex->bli_materialized = true;
		blobIndex->bli_blob_id = *destination;
		// Assign temporary BLOB ownership to top-level request if it is not assigned yet
		jrd_req* own_request;
		if (blobIndex->bli_request) {
			own_request = blobIndex->bli_request;
		}
		else {
			own_request = request;
			while (own_request->req_caller)
				own_request = own_request->req_caller;
			blobIndex->bli_request = own_request;
			own_request->req_blobs.add(blob->blb_temp_id);
		}
		// Not sure that this ownership is entirely correct for arrays, but
		// even if I make mistake here widening array lifetime this should not hurt much
		if (array)
			array->arr_request = own_request;
	}

	release_blob(blob, !materialized_blob);
}


blb* BLB_open(thread_db* tdbb, jrd_tra* transaction, const bid* blob_id)
{
/**************************************
 *
 *      B L B _ o p e n
 *
 **************************************
 *
 * Functional description
 *      Open an existing blob.
 *
 **************************************/

	SET_TDBB(tdbb);
	return BLB_open2(tdbb, transaction, blob_id, 0, 0);
}


blb* BLB_open2(thread_db* tdbb,
			  jrd_tra* transaction, const bid* blob_id,
			  USHORT bpb_length, const UCHAR* bpb,
			  bool external_call)
{
/**************************************
 *
 *      B L B _ o p e n 2
 *
 **************************************
 *
 * Functional description
 *      Open an existing blob.
 *      Basically BLB_open() with BPB structure.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();

/* Handle filter case */
	SSHORT from, to;
	SSHORT from_charset, to_charset;
	bool from_type_specified;
	bool from_charset_specified;
	bool to_type_specified;
	bool to_charset_specified;

	gds__parse_bpb2(bpb_length,
					bpb,
					&from,
					&to,
					reinterpret_cast<USHORT*>(&from_charset),	// safe - alignment not changed
					reinterpret_cast<USHORT*>(&to_charset),		// safe - alignment not changed
					&from_type_specified, &from_charset_specified,
					&to_type_specified, &to_charset_specified);

	blb* const blob = allocate_blob(tdbb, transaction);

	bool try_relations = false;
	BlobIndex* current = NULL;

	if (!blob_id->bid_internal.bid_relation_id)
	{
		if (blob_id->isEmpty())
			blob->blb_flags |= BLB_eof;
		else
		{
			/* Note: Prior to 1991, we would immediately report bad_segstr_id here,
			 * but then we decided to allow a newly created blob to be opened,
			 * leaving the possibility of receiving a garbage blob ID from
			 * the application.
			 * The following does some checks to try and product ourselves
			 * better.  94-Jan-07 Daves.
			 */

			/* Search the index of transaction blobs for a match */
			const blb* new_blob = NULL;
			if (transaction->tra_blobs->locate(blob_id->bid_temp_id())) {
				current = &transaction->tra_blobs->current();
				if (!current->bli_materialized)
					new_blob = current->bli_blob_object;
				else
					blob_id = &current->bli_blob_id;
			}

			if (!current || !current->bli_materialized)
			{
				if (!new_blob || !(new_blob->blb_flags & BLB_temporary) ||
					!(new_blob->blb_flags & BLB_closed))
				{
					ERR_post(Arg::Gds(isc_bad_segstr_id));
				}

				blob->blb_lead_page = new_blob->blb_lead_page;
				blob->blb_max_sequence = new_blob->blb_max_sequence;
				blob->blb_count = new_blob->blb_count;
				blob->blb_length = new_blob->blb_length;
				blob->blb_max_segment = new_blob->blb_max_segment;
				blob->blb_level = new_blob->blb_level;
				blob->blb_flags = new_blob->blb_flags & BLB_stream;
				blob->blb_pg_space_id = new_blob->blb_pg_space_id;

				if (new_blob->blb_temp_size > 0)
				{
					transaction->getBlobSpace()->read(new_blob->blb_temp_offset,
						blob->getBuffer(), new_blob->blb_temp_size);
				}

				const vcl* pages = new_blob->blb_pages;
				if (pages)
				{
					vcl* new_pages = vcl::newVector(*transaction->tra_pool, *pages);
					blob->blb_pages = new_pages;
				}

				if (blob->blb_level == 0)
				{
					blob->blb_space_remaining =
						new_blob->blb_clump_size - new_blob->blb_space_remaining;
					blob->blb_segment =
						(UCHAR*) ((blob_page*) blob->getBuffer())->blp_page;
				}
			}
			else
				try_relations = true;
		}
	}
	else
		try_relations = true;

	if (try_relations)
	{
		// Ordinarily, we would call MET_relation to get the relation id.
		// However, since the blob id must be consider suspect, this is
		// not a good idea.  On the other hand, if we don't already
		// know about the relation, the blob id has got to be invalid
		// anyway.

		vec<jrd_rel*>* vector = dbb->dbb_relations;

		if (blob_id->bid_internal.bid_relation_id >= vector->count() ||
			!(blob->blb_relation = (*vector)[blob_id->bid_internal.bid_relation_id] ) )
		{
				ERR_post(Arg::Gds(isc_bad_segstr_id));
		}

		blob->blb_pg_space_id = blob->blb_relation->getPages(tdbb)->rel_pg_space_id;
		DPM_get_blob(tdbb, blob, blob_id->get_permanent_number(), false, (SLONG) 0);

		// If the blob is known to be damaged, ignore it.

		if (blob->blb_flags & BLB_damaged)
		{
			if (!(dbb->dbb_flags & DBB_damaged))
				IBERROR(194);	// msg 194 blob not found

			blob->blb_flags |= BLB_eof;
			blob->blb_count = 0;
			blob->blb_max_segment = 0;
			blob->blb_length = 0;
			return blob;
		}

		// Get first data page in anticipation of reading.

		if (blob->blb_level == 0)
			blob->blb_segment = blob->getBuffer();
	}

	UCharBuffer new_bpb;

	if (external_call && ENCODE_ODS(dbb->dbb_ods_version, dbb->dbb_minor_original) >= ODS_11_1)
	{
		if (!from_type_specified)
			from = blob->blb_sub_type;
		if (!from_charset_specified)
			from_charset = blob->blb_charset;

		if (!to_type_specified && from == isc_blob_text)
			to = isc_blob_text;
		if (!to_charset_specified && from == isc_blob_text)
			to_charset = CS_dynamic;

		BLB_gen_bpb(from, to, from_charset, to_charset, new_bpb);
		bpb = new_bpb.begin();
		bpb_length = new_bpb.getCount();
	}

	//blob->blb_target_interp = to_charset;
	//blob->blb_source_interp = from_charset;

	BlobFilter* filter = NULL;
	bool filter_required = false;
	if (to && from != to) {
		filter = find_filter(tdbb, from, to);
		filter_required = true;
	}
	else if (to == isc_blob_text && (from_charset != to_charset))
	{
		if (from_charset == CS_dynamic)
			from_charset = tdbb->getAttachment()->att_charset;
		if (to_charset == CS_dynamic)
			to_charset = tdbb->getAttachment()->att_charset;

		if ((to_charset != CS_NONE) && (from_charset != CS_NONE) &&
			(to_charset != CS_BINARY) && (from_charset != CS_BINARY) &&
			(from_charset != to_charset))
		{
			filter = FB_NEW(*dbb->dbb_permanent) BlobFilter(*dbb->dbb_permanent);
			filter->blf_filter = filter_transliterate_text;
			filter_required = true;
		}
	}

	if (filter_required)
	{
		BlobControl* control = 0;
		BLF_open_blob(tdbb, transaction, &control, blob_id, bpb_length, bpb,
					  blob_filter, filter);
		blob->blb_filter = control;
		blob->blb_max_segment = control->ctl_max_segment;
		blob->blb_count = control->ctl_number_segments;
		blob->blb_length = control->ctl_total_length;
		return blob;
	}

	return blob;
}


void BLB_put_data(thread_db* tdbb, blb* blob, const UCHAR* buffer, SLONG length)
{
/**************************************
 *
 *      B L B _ p u t _ d a t a
 *
 **************************************
 *
 * Functional description
 *      Write data to a blob.
 *      Don't worry about segment boundaries.
 *
 **************************************/
	SET_TDBB(tdbb);
	const BLOB_PTR* p = buffer;

	while (length > 0)
	{
		// ASF: the comment below was copied from BLB_get_data
		// I have no idea why this limit is 32768 instead of 32767
		// 1994-August-12 David Schnepper
		const USHORT n = (USHORT) MIN(length, (SLONG) 32768);
		BLB_put_segment(tdbb, blob, p, n);
		p += n;
		length -= n;
	}
}


void BLB_put_segment(thread_db* tdbb, blb* blob, const UCHAR* seg, USHORT segment_length)
{
/**************************************
 *
 *      B L B _ p u t _ s e g m e n t
 *
 **************************************
 *
 * Functional description
 *      Add a segment to a blob.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();
	const BLOB_PTR* segment = seg;

/* Make sure blob is a temporary blob.  If not, complain bitterly. */

	if (!(blob->blb_flags & BLB_temporary))
		IBERROR(195);			/* msg 195 cannot update old blob */

	if (blob->blb_filter) {
		BLF_put_segment(tdbb, &blob->blb_filter, segment_length, segment);
		return;
	}

	/* Account for new segment */

	blob->blb_count++;
	blob->blb_length += segment_length;

	if (segment_length > blob->blb_max_segment)
		blob->blb_max_segment = segment_length;

/* Compute the effective length of the segment (counts length unless
   the blob is a stream blob). */

	ULONG length;				// length of segment + overhead
	bool length_flag;
	if (SEGMENTED(blob)) {
		length = segment_length + 2;
		length_flag = true;
	}
	else {
		length = segment_length;
		length_flag = false;
	}

/* Case 0: Transition from small blob to medium size blob.  This really
   just does a form transformation and drops into the next case. */

	if (blob->blb_level == 0 && length > (ULONG) blob->blb_space_remaining)
	{
		jrd_tra* transaction = blob->blb_transaction;
		blob->blb_pages = vcl::newVector(*transaction->tra_pool, 0);
		const USHORT l = dbb->dbb_page_size - BLP_SIZE;
		blob->blb_space_remaining += l - blob->blb_clump_size;
		blob->blb_clump_size = l;
		blob->blb_level = 1;
	}

/* Case 1: The segment fits.  In what is immaterial.  Just move the segment
   and get out! */

	BLOB_PTR* p = blob->blb_segment;

	if (length_flag && blob->blb_space_remaining >= 2)
	{
		const BLOB_PTR* q = (UCHAR*) &segment_length;
		*p++ = *q++;
		*p++ = *q++;
		blob->blb_space_remaining -= 2;
		length_flag = false;
	}

	if (!length_flag && segment_length <= blob->blb_space_remaining)
	{
		blob->blb_space_remaining -= segment_length;
		memcpy(p, segment, segment_length);
		blob->blb_segment = p + segment_length;
		return;
	}

/* The segment cannot be contained in the current clump.  What does
   bit is copied to the current page image.  Then allocate a page to
   hold the current page, copy the page image to the buffer, and release
   the page.  Since a segment can be much larger than a page, this whole
   mess is done in a loop. */

	while (length_flag || segment_length)
	{
		/* Move what fits.  At this point, the length is known not to fit. */

		const USHORT l = MIN(segment_length, blob->blb_space_remaining);

		if (!length_flag && l)
		{
			segment_length -= l;
			blob->blb_space_remaining -= l;

			memcpy(p, segment, l);
			p += l;
			segment += l;

			if (segment_length == 0)
			{
				blob->blb_segment = p;
				return;
			}
		}

		/* Data page is full.  Add the page to the blob data structure. */

		insert_page(tdbb, blob);
		blob->blb_sequence++;

		/* Get ready to start filling the next page. */

		blob_page* page = (blob_page*) blob->getBuffer();
		p = blob->blb_segment = (UCHAR *) page->blp_page;
		blob->blb_space_remaining = blob->blb_clump_size;

		/* If there's still a length waiting to be moved, move it already! */

		if (length_flag) {
			const BLOB_PTR* q = (UCHAR*) &segment_length;
			*p++ = *q++;
			*p++ = *q++;
			blob->blb_space_remaining -= 2;
			length_flag = false;
			blob->blb_segment = p;
		}
	}

}


void BLB_put_slice(	thread_db*	tdbb,
					jrd_tra*		transaction,
					bid*		blob_id,
					const UCHAR*	sdl,
					USHORT	param_length,
					const UCHAR*	param,
					SLONG	slice_length,
					UCHAR*	slice_addr)
{
/**************************************
 *
 *      B L B _ p u t _ s l i c e
 *
 **************************************
 *
 * Functional description
 *      Put a slice of an array.
 *
 **************************************/
	SET_TDBB(tdbb);
	Jrd::ContextPoolHolder context(tdbb, transaction->tra_pool);

/* Do initial parse of slice description to get relation and field identification */
	sdl_info info;
	if (SDL_info(tdbb->tdbb_status_vector, sdl, &info, 0))
		ERR_punt();

	jrd_rel* relation;
	if (info.sdl_info_relation.length()) {
		relation = MET_lookup_relation(tdbb, info.sdl_info_relation);
	}
	else {
		relation = MET_relation(tdbb, info.sdl_info_rid);
	}

	if (!relation) {
		IBERROR(196);			/* msg 196 relation for array not known */
	}

	SSHORT	n;
	if (info.sdl_info_field.length()) {
	    n = MET_lookup_field(tdbb, relation, info.sdl_info_field, 0);
	}
	else {
		n = info.sdl_info_fid;
	}

/* Make sure relation is scanned */
	MET_scan_relation(tdbb, relation);

	jrd_fld* field;
	if (n < 0 || !(field = MET_get_field(relation, n))) {
		IBERROR(197);			/* msg 197 field for array not known */
	}

	ArrayField* array_desc = field->fld_array;
	if (!array_desc)
	{
		ERR_post(Arg::Gds(isc_invalid_dimension) << Arg::Num(0) << Arg::Num(1));
	}

/* Find and/or allocate array block.  There are three distinct cases:

	1.  Array is totally new.
	2.  Array is still in "temporary" state.
	3.  Array exists and is being updated.
*/
	ArrayField* array = 0;
	array_slice arg;
	if (blob_id->bid_internal.bid_relation_id)
	{
		for (array = transaction->tra_arrays; array; array = array->arr_next)
		{
			if (array->arr_blob && array->arr_blob->blb_blob_id == *blob_id)
			{
				break;
			}
		}
		if (array)
		{
			arg.slice_high_water = array->arr_data + array->arr_effective_length;
		}
		else
		{
			// CVC: maybe char temp[IAD_LEN(16)]; may work but it won't be aligned.
			SLONG temp[IAD_LEN(16) / 4];
			Ods::InternalArrayDesc* p_ads = reinterpret_cast<Ods::InternalArrayDesc*>(temp);
			blb* blob = BLB_get_array(tdbb, transaction, blob_id, p_ads);
			array =	alloc_array(transaction, p_ads);
			array->arr_effective_length = blob->blb_length - array->arr_desc.iad_length;
			BLB_get_data(tdbb, blob, array->arr_data, array->arr_desc.iad_total_length);
			arg.slice_high_water = array->arr_data + array->arr_effective_length;
			array->arr_blob = allocate_blob(tdbb, transaction);
			(array->arr_blob)->blb_blob_id = *blob_id;
		}
	}
	else if (blob_id->bid_temp_id())
	{
		array = find_array(transaction, blob_id);
		if (!array) {
			ERR_post(Arg::Gds(isc_invalid_array_id));
		}

		arg.slice_high_water = array->arr_data + array->arr_effective_length;
	}
	else {
		array = alloc_array(transaction, &array_desc->arr_desc);
		arg.slice_high_water = array->arr_data;
	}

/* Walk array */

	arg.slice_desc = info.sdl_info_element;
	arg.slice_desc.dsc_address = slice_addr;
	arg.slice_end = slice_addr + slice_length;
	arg.slice_count = 0;
	arg.slice_element_length = info.sdl_info_element.dsc_length;
	arg.slice_direction = array_slice::slc_writing_array;	// storing INTO array
	arg.slice_base = array->arr_data;

	SLONG variables[64];
	memcpy(variables, param, MIN(sizeof(variables), param_length));

	if (SDL_walk(tdbb->tdbb_status_vector, sdl, array->arr_data, &array_desc->arr_desc,
				 variables, slice_callback, &arg))
	{
		ERR_punt();
	}

	const SLONG length = arg.slice_high_water - array->arr_data;

	if (length > array->arr_effective_length) {
		array->arr_effective_length = length;
	}

	blob_id->set_temporary(array->arr_temp_id);
}


void BLB_release_array(ArrayField* array)
{
/**************************************
 *
 *      B L B _ r e l e a s e _ a r r a y
 *
 **************************************
 *
 * Functional description
 *      Release an array block and friends and relations.
 *
 **************************************/

	delete[] array->arr_data;

	jrd_tra* transaction = array->arr_transaction;
	if (transaction)
	{
		for (ArrayField** ptr = &transaction->tra_arrays; *ptr; ptr = &(*ptr)->arr_next)
		{
			if (*ptr == array) {
				*ptr = array->arr_next;
				break;
			}
		}
	}

	delete array;
}


void BLB_scalar(thread_db*		tdbb,
				jrd_tra*		transaction,
				const bid*		blob_id,
				USHORT			count,
				const SLONG*	subscripts,
				impure_value*	value)
{
/**************************************
 *
 *      B L B _ s c a l a r
 *
 **************************************
 *
 * Functional description
 *
 **************************************/

	SLONG stuff[IAD_LEN(16) / 4];

	SET_TDBB(tdbb);

	Ods::InternalArrayDesc* array_desc = (Ods::InternalArrayDesc*) stuff;
	blb* blob = BLB_get_array(tdbb, transaction, blob_id, array_desc);

// Get someplace to put data.
// We need DOUBLE_ALIGNed buffer, that's why some tricks
	HalfStaticArray<double, 64> temp;
	dsc desc = array_desc->iad_rpt[0].iad_desc;
	desc.dsc_address = reinterpret_cast<UCHAR*>(temp.getBuffer((desc.dsc_length / sizeof(double)) +
												(desc.dsc_length % sizeof(double) ? 1 : 0)));

	const SLONG number = SDL_compute_subscript(tdbb->tdbb_status_vector, array_desc, count, subscripts);
	if (number < 0) {
		BLB_close(tdbb, blob);
		ERR_punt();
	}

	const SLONG offset = number * array_desc->iad_element_length;
	BLB_lseek(blob, 0, offset + (SLONG) array_desc->iad_length);
	BLB_get_segment(tdbb, blob, desc.dsc_address, desc.dsc_length);

/* If we have run out of data, then clear the data buffer. */

	if (blob->blb_flags & BLB_eof) {
		memset(desc.dsc_address, 0, (int) desc.dsc_length);
	}
	EVL_make_value(tdbb, &desc, value);
	BLB_close(tdbb, blob);
}


static ArrayField* alloc_array(jrd_tra* transaction, Ods::InternalArrayDesc* proto_desc)
{
/**************************************
 *
 *      a l l o c _ a r r a y
 *
 **************************************
 *
 * Functional description
 *      Allocate an array block based on a prototype array descriptor.
 *
 **************************************/

	// Compute size and allocate block

	const USHORT n = MAX(proto_desc->iad_struct_count, proto_desc->iad_dimensions);
	ArrayField* array = FB_NEW_RPT(*transaction->tra_pool, n) ArrayField();

	// Copy prototype descriptor

	memcpy(&array->arr_desc, proto_desc, proto_desc->iad_length);

	// Link into transaction block

	array->arr_next = transaction->tra_arrays;
	transaction->tra_arrays = array;
	array->arr_transaction = transaction;

	// Allocate large block to hold array

	array->arr_data = FB_NEW(*transaction->tra_pool) UCHAR[array->arr_desc.iad_total_length];
	array->arr_temp_id = ++transaction->tra_next_blob_id;

	return array;
}


static blb* allocate_blob(thread_db* tdbb, jrd_tra* transaction)
{
/**************************************
 *
 *      a l l o c a t e _ b l o b
 *
 **************************************
 *
 * Functional description
 *      Create a shiney, new, empty blob.
 *
 **************************************/

	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();

	// If we are in an autonomous transaction, link the blob on the transaction started by the user.
	while (transaction->tra_outer)
		transaction = transaction->tra_outer;

	// Create a blob large enough to hold a single data page.

	blb* blob = FB_NEW(*transaction->tra_pool) blb(*transaction->tra_pool, dbb->dbb_page_size);
	blob->blb_attachment = tdbb->getAttachment();
	blob->blb_transaction = transaction;

	// Compute some parameters governing various maximum sizes based on
	// database page size.

	blob->blb_clump_size = dbb->dbb_page_size -
							sizeof(Ods::data_page) -
							sizeof(Ods::data_page::dpg_repeat) -
							sizeof(Ods::blh);
	blob->blb_max_pages = blob->blb_clump_size >> SHIFTLONG;
	blob->blb_pointers = (dbb->dbb_page_size - BLP_SIZE) >> SHIFTLONG;
	// This code is to handle huge number of blob updates done in one transaction.
	// Blob index counter may wrap in this case
	do {
		transaction->tra_next_blob_id++;
		// Do not generate null blob ID
		if (!transaction->tra_next_blob_id)
			transaction->tra_next_blob_id++;
	} while (!transaction->tra_blobs->add(BlobIndex(transaction->tra_next_blob_id, blob)));
	blob->blb_temp_id = transaction->tra_next_blob_id;

	return blob;
}


static ISC_STATUS blob_filter(USHORT	action,
							  BlobControl*	control)
{
/**************************************
 *
 *      b l o b _ f i l t e r
 *
 **************************************
 *
 * Functional description
 *      Filter of last resort for filtered blob access handled by Y-valve.
 *
 **************************************/

/* Note: Cannot remove this JRD_get_thread_data without API change to
   blob filter routines */

	thread_db* tdbb = JRD_get_thread_data();

	jrd_tra* const transaction = reinterpret_cast<jrd_tra*>(control->ctl_internal[1]);
	bid* blob_id = reinterpret_cast<bid*>(control->ctl_internal[2]);

#ifdef DEV_BUILD
	if (transaction) {
		BLKCHK(transaction, type_tra);
	}
#endif

	blb* blob = 0;

	switch (action)
	{
	case isc_blob_filter_open:
		blob = BLB_open2(tdbb, transaction, blob_id, 0, 0);
		control->source_handle = blob;
		control->ctl_total_length = blob->blb_length;
		control->ctl_max_segment = blob->blb_max_segment;
		control->ctl_number_segments = blob->blb_count;
		return FB_SUCCESS;

	case isc_blob_filter_get_segment:
		blob = control->source_handle;
		control->ctl_segment_length =
			BLB_get_segment(tdbb, blob, control->ctl_buffer, control->ctl_buffer_length);
		if (blob->blb_flags & BLB_eof) {
			return isc_segstr_eof;
		}
		if (blob->blb_fragment_size) {
			return isc_segment;
		}
		return FB_SUCCESS;

	case isc_blob_filter_create:
		control->source_handle = BLB_create2(tdbb, transaction, blob_id, 0, NULL);
		return FB_SUCCESS;

	case isc_blob_filter_put_segment:
		blob = control->source_handle;
		BLB_put_segment(tdbb, blob, control->ctl_buffer, control->ctl_buffer_length);
		return FB_SUCCESS;

	case isc_blob_filter_close:
		BLB_close(tdbb, control->source_handle);
		return FB_SUCCESS;

	case isc_blob_filter_alloc:
	    // pointer to ISC_STATUS!!!
		return (ISC_STATUS) FB_NEW(*transaction->tra_pool) BlobControl(*transaction->tra_pool);

	case isc_blob_filter_free:
		delete control;
		return FB_SUCCESS;

	case isc_blob_filter_seek:
		fb_assert(false);
		// fail through ...

	default:
		ERR_post(Arg::Gds(isc_uns_ext));
		return FB_SUCCESS;
	}
}


static blb* copy_blob(thread_db* tdbb, const bid* source, bid* destination,
					  USHORT bpb_length, const UCHAR* bpb,
					  USHORT destPageSpaceID)
{
/**************************************
 *
 *      c o p y _ b l o b
 *
 **************************************
 *
 * Functional description
 *      Make a copy of an existing blob.
 *
 **************************************/
	SET_TDBB(tdbb);

	jrd_req* request = tdbb->getRequest();
	blb* input = BLB_open2(tdbb, request->req_transaction, source, bpb_length, bpb);
	blb* output = BLB_create(tdbb, request->req_transaction, destination);
	output->blb_sub_type = input->blb_sub_type;
	if (destPageSpaceID) {
		output->blb_pg_space_id = destPageSpaceID;
	}

	if (input->blb_flags & BLB_stream) {
		output->blb_flags |= BLB_stream;
	}

	HalfStaticArray<UCHAR, 2048> buffer;
	UCHAR* buff = buffer.getBuffer(input->blb_max_segment);

	while (true)
	{
		const USHORT length = BLB_get_segment(tdbb, input, buff, input->blb_max_segment);
		if (input->blb_flags & BLB_eof) {
			break;
		}
		BLB_put_segment(tdbb, output, buff, length);
	}

	BLB_close(tdbb, input);
	BLB_close(tdbb, output);

	return output;
}


static void delete_blob(thread_db* tdbb, blb* blob, ULONG prior_page)
{
/**************************************
 *
 *      d e l e t e _ b l o b
 *
 **************************************
 *
 * Functional description
 *      Delete all disk storage associated with blob.  This can be used
 *      to either abort a temporary blob or get rid of an unwanted and
 *      unloved permanent blob.  The routine deletes only blob page --
 *      somebody else will have to worry about the blob root.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* const dbb = tdbb->getDatabase();
	CHECK_DBB(dbb);

	const USHORT pageSpaceID = blob->blb_pg_space_id;

	if (dbb->dbb_flags & DBB_read_only)
	{
		const USHORT tempSpaceID = dbb->dbb_page_manager.getTempPageSpaceID(tdbb);

		if (pageSpaceID != tempSpaceID)
		{
			ERR_post(Arg::Gds(isc_read_only_database));
		}
	}

	// Level 0 blobs don't need cleanup

	if (blob->blb_level == 0)
		return;

	const PageNumber prior(pageSpaceID, prior_page);

	// Level 1 blobs just need the root page level released

	vcl* vector = blob->blb_pages;
	vcl::iterator ptr = vector->begin();
	const vcl::iterator end = vector->end();

	if (blob->blb_level == 1)
	{
		for (; ptr < end; ++ptr) {
			if (*ptr) {
				PAG_release_page(tdbb, PageNumber(pageSpaceID, *ptr), prior);
			}
		}
		return;
	}

	// Level 2 blobs need a little more work to keep the page precedence
	// in order.  The basic problem is that the pointer page has to be
	// released before the data pages that it points to.  Sigh.

	WIN window(pageSpaceID, -1);
	window.win_flags = WIN_large_scan;
	window.win_scans = 1;

	Array<UCHAR> data(dbb->dbb_page_size);
	UCHAR* const buffer = data.begin();

	for (; ptr < end; ptr++)
	{
		if ( (window.win_page = *ptr) )
		{
			const blob_page* page = (blob_page*) CCH_FETCH(tdbb, &window, LCK_read, pag_blob);
			memcpy(buffer, page, dbb->dbb_page_size);
			CCH_RELEASE_TAIL(tdbb, &window);

			const PageNumber page1(pageSpaceID, *ptr);
			PAG_release_page(tdbb, page1, prior);
			page = (blob_page*) buffer;
			const SLONG* ptr2 = page->blp_page;
			for (const SLONG* const end2 = ptr2 + blob->blb_pointers; ptr2 < end2; ptr2++)
			{
				if (*ptr2) {
					PAG_release_page(tdbb, PageNumber(pageSpaceID, *ptr2), page1);
				}
			}
		}
	}
}


static void delete_blob_id(thread_db* tdbb,
						   const bid* blob_id, SLONG prior_page, jrd_rel* relation)
{
/**************************************
 *
 *      d e l e t e _ b l o b _ i d
 *
 **************************************
 *
 * Functional description
 *      Delete an existing blob for purpose of garbage collection.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();
	CHECK_DBB(dbb);

	/* If the blob is null, don't bother to delete it.  Reasonable? */

	if (blob_id->isEmpty())
		return;

	if (blob_id->bid_internal.bid_relation_id != relation->rel_id)
		CORRUPT(200);			/* msg 200 invalid blob id */

	/* Fetch blob */

	blb* blob = allocate_blob(tdbb, dbb->dbb_sys_trans);
	blob->blb_relation = relation;
	blob->blb_pg_space_id = relation->getPages(tdbb)->rel_pg_space_id;
	prior_page = DPM_get_blob(tdbb, blob, blob_id->get_permanent_number(), true, prior_page);

	if (!(blob->blb_flags & BLB_damaged))
		delete_blob(tdbb, blob, prior_page);

	release_blob(blob, true);
}


static ArrayField* find_array(jrd_tra* transaction, const bid* blob_id)
{
/**************************************
 *
 *      f i n d _ a r r a y
 *
 **************************************
 *
 * Functional description
 *      Find array from temporary blob id.
 *
 **************************************/
	ArrayField* array = transaction->tra_arrays;

	for (; array; array = array->arr_next) {
		if (array->arr_temp_id == blob_id->bid_temp_id()) {
			break;
		}
	}

	return array;
}


static BlobFilter* find_filter(thread_db* tdbb, SSHORT from, SSHORT to)
{
/**************************************
 *
 *      f i n d _ f i l t e r
 *
 **************************************
 *
 * Functional description
 *      Find blob filter.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();
	CHECK_DBB(dbb);

	BlobFilter* cache = dbb->dbb_blob_filters;
	for (; cache; cache = cache->blf_next) {
		if (cache->blf_from == from && cache->blf_to == to)
			return cache;
	}

	cache = BLF_lookup_internal_filter(tdbb, from, to);
	if (!cache) {
		cache = MET_lookup_filter(tdbb, from, to);
	}

	if (cache) {
		cache->blf_next = dbb->dbb_blob_filters;
		dbb->dbb_blob_filters = cache;
	}

	return cache;
}


static blob_page* get_next_page(thread_db* tdbb, blb* blob, WIN * window)
{
/**************************************
 *
 *      g e t _ n e x t _ p a g e
 *
 **************************************
 *
 * Functional description
 *      Read a blob page and copy it into the blob data area.  Return
 *      the next page. if there's no next page, return NULL.
 *
 **************************************/
	if (blob->blb_level == 0 || blob->blb_sequence > blob->blb_max_sequence) {
		blob->blb_space_remaining = 0;
		return NULL;
	}

	SET_TDBB(tdbb);
#ifdef SUPERSERVER_V2
	Database* dbb = tdbb->getDatabase();
	SLONG pages[PREFETCH_MAX_PAGES];
#endif

	const vcl* vector = blob->blb_pages;

	blob_page* page = 0;
/* Level 1 blobs are much easier -- page number is in vector. */
	if (blob->blb_level == 1)
	{
#ifdef SUPERSERVER_V2
		/* Perform prefetch of blob level 1 data pages. */

		if (!(blob->blb_sequence % dbb->dbb_prefetch_sequence))
		{
			USHORT sequence = blob->blb_sequence;
			USHORT i = 0;
			while (i < dbb->dbb_prefetch_pages && sequence <= blob->blb_max_sequence)
			{
				 pages[i++] = (*vector)[sequence++];
			}

			CCH_PREFETCH(tdbb, pages, i);
		}
#endif
		window->win_page = (*vector)[blob->blb_sequence];
		page = (blob_page*) CCH_FETCH(tdbb, window, LCK_read, pag_blob);
	}
	else
	{
		window->win_page = (*vector)[blob->blb_sequence / blob->blb_pointers];
		page = (blob_page*) CCH_FETCH(tdbb, window, LCK_read, pag_blob);
#ifdef SUPERSERVER_V2
		/* Perform prefetch of blob level 2 data pages. */

		USHORT sequence = blob->blb_sequence % blob->blb_pointers;
		if (!(sequence % dbb->dbb_prefetch_sequence))
		{
			ULONG abs_sequence = blob->blb_sequence;
			USHORT i = 0;
			while (i < dbb->dbb_prefetch_pages && sequence < blob->blb_pointers &&
				abs_sequence <= blob->blb_max_sequence)
			{
				pages[i++] = page->blp_page[sequence++];
				abs_sequence++;
			}

			CCH_PREFETCH(tdbb, pages, i);
		}
#endif
		page = (blob_page*) CCH_HANDOFF(tdbb, window,
										page->blp_page[blob->blb_sequence % blob->blb_pointers],
										LCK_read, pag_blob);
	}

	if (page->blp_sequence != (SLONG) blob->blb_sequence)
		CORRUPT(201);			/* msg 201 cannot find blob page */

	blob->blb_sequence++;

	return page;
}


static void insert_page(thread_db* tdbb, blb* blob)
{
/**************************************
 *
 *      i n s e r t _ p a g e
 *
 **************************************
 *
 * Functional description
 *      A data page has been formatted.  Allocate a physical page,
 *      move the data page to the buffer, and insert the page number
 *      of the new page into the blob data structure.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();
	CHECK_DBB(dbb);

	const USHORT length = dbb->dbb_page_size - blob->blb_space_remaining;
	vcl* vector = blob->blb_pages;
	blob->blb_max_sequence = blob->blb_sequence;

/* Allocate a page for the now full blob data page.  Move the page
   image to the buffer, and release the page.  */

	const USHORT pageSpaceID = blob->blb_pg_space_id;

	WIN window(pageSpaceID, -1);
	blob_page* page = (blob_page*) DPM_allocate(tdbb, &window);
	const PageNumber page_number = window.win_page;

	if (blob->blb_sequence == 0)
		blob->blb_lead_page = page_number.getPageNum();

	// Page header is partially populated by DPM_allocate. Preserve it.
	memcpy(
		reinterpret_cast<char*>(page) + sizeof(Ods::pag),
		reinterpret_cast<const char*>(blob->getBuffer()) + sizeof(Ods::pag),
		length - sizeof(Ods::pag));
	page->blp_header.pag_type = pag_blob;

	page->blp_sequence = blob->blb_sequence;
	page->blp_lead_page = blob->blb_lead_page;
	page->blp_length = length - BLP_SIZE;
	CCH_RELEASE(tdbb, &window);

/* If the blob is at level 1, there are two cases.  First, and easiest,
   is that there is still room in the page vector to hold the pointer.
   The second case is that the vector is full, and the blob must be
   transformed into a level 2 blob. */

	if (blob->blb_level == 1)
	{
		/*  See if there is room in the page vector.  If so, just update
		   the vector. */

		if (blob->blb_sequence < blob->blb_max_pages) {
			if (blob->blb_sequence >= vector->count()) {
				vector->resize(blob->blb_sequence + 1);
			}
			(*vector)[blob->blb_sequence] = page_number.getPageNum();
			return;
		}

		/* The vector just overflowed.  Sigh.  Transform blob to level 2. */

		blob->blb_level = 2;
		page = (blob_page*) DPM_allocate(tdbb, &window);
		page->blp_header.pag_flags = Ods::blp_pointers;
		page->blp_header.pag_type = pag_blob;
		page->blp_lead_page = blob->blb_lead_page;
		page->blp_length = vector->count() << SHIFTLONG;
		memcpy(page->blp_page, vector->memPtr(), page->blp_length);
		vector->resize(1);
		(*vector)[0] = window.win_page.getPageNum();
		CCH_RELEASE(tdbb, &window);
	}

/* The blob must be level 2.  Find the appropriate pointer page (creating
   it if need be, and stick the pointer in the appropriate slot. */

	USHORT l = blob->blb_sequence / blob->blb_pointers;

	if (l < vector->count())
	{
		window.win_page = (*vector)[l];
		window.win_flags = 0;
		page = (blob_page*) CCH_FETCH(tdbb, &window, LCK_write, pag_blob);
	}
	else if (l < blob->blb_pointers)
	{
		page = (blob_page*) DPM_allocate(tdbb, &window);
		page->blp_header.pag_flags = Ods::blp_pointers;
		page->blp_header.pag_type = pag_blob;
		page->blp_lead_page = blob->blb_lead_page;
		vector->resize(l + 1);
		(*vector)[l] = window.win_page.getPageNum();
	}
	else {
		ERR_post(Arg::Gds(isc_imp_exc) << Arg::Gds(isc_blobtoobig));
	}

	CCH_precedence(tdbb, &window, page_number);
	CCH_MARK(tdbb, &window);
	l = blob->blb_sequence % blob->blb_pointers;
	page->blp_page[l] = page_number.getPageNum();
	page->blp_length = (l + 1) << SHIFTLONG;
	CCH_RELEASE(tdbb, &window);
}


static void move_from_string(thread_db* tdbb, const dsc* from_desc, dsc* to_desc, jrd_nod* field)
{
/**************************************
 *
 *      m o v e _ f r o m _ s t r i n g
 *
 **************************************
 *
 * Functional description
 *      Perform an assignment to a blob field.  It's capable of handling
 *      strings (and anything that could be converted to strings) by
 *      doing an internal conversion to blob and then calling BLB_move
 *      with that new blob.
 *
 **************************************/
	SET_TDBB (tdbb);

	const UCHAR charSet = INTL_GET_CHARSET(from_desc);
	UCHAR* fromstr = NULL;

	MoveBuffer buffer;
	const int length = MOV_make_string2(tdbb, from_desc, charSet, &fromstr, buffer);
	const UCHAR toCharSet = to_desc->getCharSet();

	if ((charSet == CS_NONE || charSet == CS_BINARY || charSet == toCharSet) &&
		toCharSet != CS_NONE && toCharSet != CS_BINARY)
	{
		if (!INTL_charset_lookup(tdbb, toCharSet)->wellFormed(length, fromstr))
			status_exception::raise(Arg::Gds(isc_malformed_string));
	}

	UCharBuffer bpb;
	BLB_gen_bpb_from_descs(from_desc, to_desc, bpb);

	bid temp_bid;
	temp_bid.clear();
	blb* blob = BLB_create2(tdbb, tdbb->getRequest()->req_transaction, &temp_bid, bpb.getCount(), bpb.begin());

	DSC blob_desc;
	blob_desc.clear();

	blob_desc.dsc_scale = to_desc->dsc_scale;	// blob charset
	blob_desc.dsc_flags = (blob_desc.dsc_flags & 0xFF) | (to_desc->dsc_flags & 0xFF00);	// blob collation
	blob_desc.dsc_sub_type = to_desc->dsc_sub_type;
	blob_desc.dsc_dtype = dtype_blob;
	blob_desc.dsc_length = sizeof(ISC_QUAD);
	blob_desc.dsc_address = reinterpret_cast<UCHAR*>(&temp_bid);
	BLB_put_segment(tdbb, blob, fromstr, length);
	BLB_close(tdbb, blob);
	ULONG blob_temp_id = blob->blb_temp_id;
	BLB_move(tdbb, &blob_desc, to_desc, field);

	// 14-June-2004. Nickolay Samofatov
	// The code below saves a lot of memory when bunches of records are
	// converted to blobs from strings. If BLB_move is materialized blob we
	// can discard it without consequences since we know there are no other
	// descriptors using temporary ID of blob we just created. If blob is
	// still temporary we cannot free it as it may now be used inside
	// trigger for updatable view. In theory we could make this decision
	// solely via checking that destination field belongs to updatable
	// view, but direct check that blob is fully materialized should be
	// more future proof.
	// ASF: Blob ID could now be stored in any descriptor of parameters or
	// variables. - 2007-03-24

	jrd_tra* transaction = tdbb->getRequest()->req_transaction;
	if (transaction->tra_blobs->locate(blob_temp_id))
	{
		BlobIndex* current = &transaction->tra_blobs->current();
		if (current->bli_materialized)
		{
			// Delete BLOB from request owned blob list
			jrd_req* blob_request = current->bli_request;
			if (blob_request) {
				if (blob_request->req_blobs.locate(blob_temp_id)) {
					blob_request->req_blobs.fastRemove();
				}
				else {
					// We should never get here because when bli_request is assigned
					// item should be added to req_blobs array
					fb_assert(false);
				}
			}

			// Free materialized blob handle
			transaction->tra_blobs->fastRemove();
		}
		else
		{
			// But even in bad case when we cannot free blob immediately
			// we may still bind lifetime of blob to current top level request.
			if (!current->bli_request)
			{
				jrd_req* blob_request = tdbb->getRequest();
				while (blob_request->req_caller)
					blob_request = blob_request->req_caller;

				current->bli_request = blob_request;
				current->bli_request->req_blobs.add(blob_temp_id);
			}
		}
	}
}


static void move_to_string(thread_db* tdbb, dsc* fromDesc, dsc* toDesc)
{
/**************************************
 *
 *      m o v e _ t o _ s t r i n g
 *
 **************************************
 *
 * Functional description
 *      Perform an assignment from a blob to another datatype.
 *
 **************************************/
	SET_TDBB(tdbb);

	fb_assert(DTYPE_IS_BLOB_OR_QUAD(fromDesc->dsc_dtype));
	fb_assert(!DTYPE_IS_BLOB_OR_QUAD(toDesc->dsc_dtype));

	dsc blobAsText;
	blobAsText.dsc_dtype = dtype_text;

	if (DTYPE_IS_TEXT(toDesc->dsc_dtype))
		blobAsText.dsc_ttype() = toDesc->dsc_ttype();
	else
		blobAsText.dsc_ttype() = ttype_ascii;

	UCharBuffer bpb;
	BLB_gen_bpb_from_descs(fromDesc, &blobAsText, bpb);

	blb* blob = BLB_open2(tdbb, tdbb->getRequest()->req_transaction,
		(bid*) fromDesc->dsc_address, bpb.getCount(), bpb.begin());

	const CharSet* fromCharSet = INTL_charset_lookup(tdbb, fromDesc->dsc_scale);
	const CharSet* toCharSet = INTL_charset_lookup(tdbb, INTL_GET_CHARSET(&blobAsText));

	HalfStaticArray<UCHAR, BUFFER_SMALL> buffer;
	buffer.getBuffer((blob->blb_length / fromCharSet->minBytesPerChar()) * toCharSet->maxBytesPerChar());
	const ULONG len = BLB_get_data(tdbb, blob, buffer.begin(), buffer.getCapacity(), true);

	if (len > MAX_COLUMN_SIZE - sizeof(USHORT))
		ERR_post(Arg::Gds(isc_arith_except) << Arg::Gds(isc_blob_truncation));

	blobAsText.dsc_address = buffer.begin();
	blobAsText.dsc_length = (USHORT) len;

	MOV_move(tdbb, &blobAsText, toDesc);
}


static void release_blob(blb* blob, const bool purge_flag)
{
/**************************************
 *
 *      r e l e a s e _ b l o b
 *
 **************************************
 *
 * Functional description
 *      Release a blob and associated blocks.  Among other things,
 *      disconnect it from the transaction.  However, if purge_flag
 *      is false, then only release the associated blocks.
 *
 **************************************/
	jrd_tra* const transaction = blob->blb_transaction;

	// Disconnect blob from transaction block.

	if (purge_flag)
	{
		if (transaction->tra_blobs->locate(blob->blb_temp_id))
		{
			jrd_req* blob_request = transaction->tra_blobs->current().bli_request;

			if (blob_request)
			{
				if (blob_request->req_blobs.locate(blob->blb_temp_id))
					blob_request->req_blobs.fastRemove();
				else
				{
					// We should never get here because when bli_request is assigned
					// item should be added to req_blobs array
					fb_assert(false);
				}
			}

			transaction->tra_blobs->fastRemove();
		}
		else
		{
			// We should never get here because allocate_blob stores each blob object
			// in tra_blobs
			fb_assert(false);
		}
	}

	delete blob->blb_pages;
	blob->blb_pages = NULL;

	if ((blob->blb_flags & BLB_temporary) && blob->blb_temp_size > 0)
	{
		blob->blb_transaction->getBlobSpace()->releaseSpace(blob->blb_temp_offset, blob->blb_temp_size);
	}

	delete blob;
}


static void slice_callback(array_slice* arg, ULONG /*count*/, DSC* descriptors)
{
/**************************************
 *
 *      s l i c e _ c a l l b a c k
 *
 **************************************
 *
 * Functional description
 *      Perform slice assignment.
 *
 **************************************/
	thread_db* tdbb = JRD_get_thread_data();

	dsc* array_desc = descriptors;
	dsc* slice_desc = &arg->slice_desc;
	BLOB_PTR* const next = slice_desc->dsc_address + arg->slice_element_length;

	if (next > arg->slice_end)
		ERR_post(Arg::Gds(isc_out_of_bounds));

	if (array_desc->dsc_address < arg->slice_base)
		ERR_error(198);			/* msg 198 array subscript computation error */

	if (arg->slice_direction == array_slice::slc_writing_array)
	{
		/* Storing INTO array */
		/* FROM slice_desc TO array_desc */

		/* If storing beyond the high-water mark, ensure elements
		 * from the high-water mark to current position are zeroed
		 */

		// Since we are only initializing, it makes sense to throw away
		// the constness of arg->slice_high_water.
		const SLONG l = array_desc->dsc_address - arg->slice_high_water;
		if (l > 0)
			memset(const_cast<BLOB_PTR*>(arg->slice_high_water), 0, l);

		/* The individual elements of a varying string array may not be aligned
		   correctly.  If they aren't, some RISC machines may break.  In those
		   cases, calculate the actual length and then move the length and
		   text manually. */

		if (array_desc->dsc_dtype == dtype_varying &&
			(U_IPTR) array_desc->dsc_address !=
				FB_ALIGN((U_IPTR) array_desc->dsc_address, (MIN(sizeof(USHORT), FB_ALIGNMENT))))
		{
			/* Note: cannot remove this JRD_get_thread_data without api change
			   to slice callback routines */
			/*thread_db* tdbb = */ JRD_get_thread_data();

			DynamicVaryStr<1024> tmp_buffer;
			const USHORT tmp_len = array_desc->dsc_length;
			const char* p;
			const USHORT len = MOV_make_string(slice_desc, INTL_TEXT_TYPE(*array_desc), &p,
											   tmp_buffer.getBuffer(tmp_len), tmp_len);
			memcpy(array_desc->dsc_address, &len, sizeof(USHORT));
			memcpy(array_desc->dsc_address + sizeof(USHORT), p, (int) len);
		}
		else
		{
			MOV_move(tdbb, slice_desc, array_desc);
		}
		const BLOB_PTR* const end = array_desc->dsc_address + array_desc->dsc_length;
		if (end > arg->slice_high_water)
			arg->slice_high_water = end;
	}
	else
	{
		/* Fetching FROM array */
		/* FROM array_desc TO slice_desc */

		/* If the element is under the high-water mark, fetch it,
		 * otherwise just zero it
		 */
		if (array_desc->dsc_address < arg->slice_high_water)
		{
			/* If a varying string isn't aligned correctly, calculate the actual
			   length and then treat the string as if it had type text. */

			if (array_desc->dsc_dtype == dtype_varying &&
				(U_IPTR) array_desc->dsc_address !=
					FB_ALIGN((U_IPTR) array_desc->dsc_address, (MIN(sizeof(USHORT), FB_ALIGNMENT))))
			{
			    // temp_desc will vanish at the end of the block, but it's used
			    // only as a way to transfer blocks of memory.
				dsc temp_desc;
				temp_desc.dsc_dtype = dtype_text;
				temp_desc.dsc_sub_type = array_desc->dsc_sub_type;
				temp_desc.dsc_scale = array_desc->dsc_scale;
				temp_desc.dsc_flags = array_desc->dsc_flags;
				memcpy(&temp_desc.dsc_length, array_desc->dsc_address, sizeof(USHORT));
				temp_desc.dsc_address = array_desc->dsc_address + sizeof(USHORT);
				MOV_move(tdbb, &temp_desc, slice_desc);
			}
			else
				MOV_move(tdbb, array_desc, slice_desc);
			++arg->slice_count;
		}
		else {
		    const SLONG l = slice_desc->dsc_length;
			if (l)
				memset(slice_desc->dsc_address, 0, l);
		}
	}

	slice_desc->dsc_address = next;
}


static blb* store_array(thread_db* tdbb, jrd_tra* transaction, bid* blob_id)
{
/**************************************
 *
 *      s t o r e _ a r r a y
 *
 **************************************
 *
 * Functional description
 *      Actually store an array.  Oh boy!
 *
 **************************************/
	SET_TDBB(tdbb);

/* Validate array */

	const ArrayField* array = find_array(transaction, blob_id);
	if (!array)
		return NULL;

/* Create blob for array */

	blb* blob = BLB_create2(tdbb, transaction, blob_id, 0, NULL);
	blob->blb_flags |= BLB_stream;

/* Write out array descriptor */

	BLB_put_segment(tdbb, blob, reinterpret_cast<const UCHAR*>(&array->arr_desc),
					array->arr_desc.iad_length);

/* Write out actual array */
	const USHORT seg_limit = 32768;
	const BLOB_PTR* p = array->arr_data;
	SLONG length = array->arr_effective_length;
	while (length > seg_limit) {
		BLB_put_segment(tdbb, blob, p, seg_limit);
		length -= seg_limit;
		p += seg_limit;
	}

	if (length)
		BLB_put_segment(tdbb, blob, p, (USHORT) length);

	BLB_close(tdbb, blob);

	return blob;
}