fis-gtm/sr_port_cm/gtcmtr_zprevious.c

/****************************************************************
 *								*
 *	Copyright 2001, 2009 Fidelity Information Services, Inc	*
 *								*
 *	This source code contains the intellectual property	*
 *	of its copyright holder(s), and is made available	*
 *	under a license.  If you do not know the terms of	*
 *	the license, please stop and do not read further.	*
 *								*
 ****************************************************************/

#include "mdef.h"

#include <stddef.h>

#include "gtm_string.h"

#include "copy.h"
#include "gdsroot.h"
#include "gtm_facility.h"
#include "fileinfo.h"
#include "gdsbt.h"
#include "gdsfhead.h"
#include "filestruct.h"
#include "cmidef.h"
#include "hashtab_mname.h"	/* needed for cmmdef.h */
#include "cmmdef.h"
#include "gvcst_protos.h"	/* for gvcst_data,gvcst_zprevious prototype */
#include "gv_xform_key.h"
#include "gtcm_find_region.h"
#include "gtcm_bind_name.h"
#include "gtcmtr_protos.h"
#include "gdscc.h"
#include "jnl.h"

GBLREF connection_struct *curr_entry;
GBLREF gv_namehead	*gv_target;
GBLREF gv_namehead	*reset_gv_target;
GBLREF gv_key		*gv_currkey;
GBLREF gv_key		*gv_altkey;
GBLREF sgmnt_addrs	*cs_addrs;
GBLREF gd_region        *gv_cur_region;

bool gtcmtr_zprevious(void)
{
	boolean_t		found, is_null;
	unsigned char		*ptr, regnum, *kprev, *kcur, *ktop;
	unsigned short		top, old_top;
	unsigned short		len, tmp_len;
	gv_key			*save_key;
	cm_region_list		*reg_ref;
	cm_region_head		*cm_reg_head;

	error_def(ERR_UNIMPLOP);
	error_def(ERR_TEXT);

	ptr = curr_entry->clb_ptr->mbf;
	assert(CMMS_Q_PREV == *ptr);
	ptr++;
	GET_USHORT(len, ptr);
	ptr += SIZEOF(short);
	regnum = *ptr++;
	reg_ref = gtcm_find_region(curr_entry, regnum);
	len--;	/* subtract size of regnum */
	assert(0 == offsetof(gv_key, top));
	GET_USHORT(old_top, ptr); /* old_top = ((gv_key *)ptr)->top; */
	/* old_top is the size of the gv_currkey structure allocated on the client side.
	 * gv_currkey->top is the size of the corresponding gv_currkey structure allocated on the server side.
	 * Both could be different depending on the reg->max_key_size values across ALL databases that each of
	 * them have accessed till now. Use the client or server version of the "top" field as appropriate.
	 */
	CM_GET_GVCURRKEY(ptr, len);
	cm_reg_head = reg_ref->reghead;
	if (gv_currkey->prev)
	{
		gtcm_bind_name(cm_reg_head, FALSE); /* sets gv_target; do not use gv_target before gtcm_bind_name */
		if (gv_target->collseq || gv_target->nct)
		{	/* Need to convert subscript representation from client side to string representation
			 * so any collation transformations can happen on server side.
			 * First determine if last subscript is a NULL subscript. Code in op_zprevious uses same logic
			 */
			is_null = TRUE;
			kprev = &gv_currkey->base[gv_currkey->prev];
			for (kcur = kprev, ktop = &gv_currkey->base[old_top] - 1; kcur < ktop; kcur++)
			{
				if (STR_SUB_MAXVAL != *kcur)
				{
					is_null = FALSE;
					break;
				}
			}
			if (is_null)
			{	/* Last subscript of incoming key is a NULL subscript.
				 * Client would have represented it using a sequence of FF, FF, FF, ...
				 * Remove the representation temporarily before doing the gv_xform_key.
				 * Introduce the NULL subscript after the transformation.
				 * This is because we do NOT allow a null subsc to be transformed to a non null subsc
				 * 	so no need for that be part of the transformation.
				 */
				*kprev = KEY_DELIMITER;
				gv_currkey->end = gv_currkey->prev;
			}
			gv_xform_key(gv_currkey, FALSE);
			if (is_null)
			{	/* Insert the NULL subscript at the end just in time for the gvcst_zprevious call. */
				GVZPREVIOUS_APPEND_MAX_SUBS_KEY(gv_currkey, gv_target);
			}
		}
		found = (0 == gv_target->root) ? FALSE : gvcst_zprevious();
	} else
	{	/* name level */
		assert(2 <= gv_currkey->end);			/* at least one character of name, and 2 <NUL> delimiters */
		assert((MAX_MIDENT_LEN + 2) >= gv_currkey->end);/* no more than MAX_MIDENT_LEN (31),and two <NUL> delimiters */
		assert(INVALID_GV_TARGET == reset_gv_target);
		GTCM_CHANGE_REG(cm_reg_head);	/* sets gv_cur_region/cs_addrs/cs_data appropriately */
		for (;  ;)
		{
			reset_gv_target = gv_target;	/* for restoration, just in case something goes wrong before
							 * gtcm_bind_name() is called */
			gv_target = cs_addrs->dir_tree;
			found = gvcst_zprevious();
			if (!found)
				break;
			assert(2 <= gv_altkey->end);			/* at least one character of name and a <NUL> delimiter */
			assert((MAX_MIDENT_LEN + 2) >= gv_currkey->end);/* no more than MAX_MIDENT_LEN (31),
									 * and two <NUL> delimiters */
			if ((PRE_V5_MAX_MIDENT_LEN < strlen((char *)gv_altkey->base)) && !curr_entry->client_supports_long_names)
			{
				rts_error(VARLSTCNT(6) ERR_UNIMPLOP, 0,
					ERR_TEXT, 2,
					LEN_AND_LIT("GT.CM client does not support global names greater than 8 characters"));
			}
			save_key = gv_currkey;
			gv_currkey = gv_altkey;
			gv_altkey = save_key;
			gtcm_bind_name(cm_reg_head, TRUE);
			reset_gv_target = INVALID_GV_TARGET;
			if ((0 != gv_target->root) && (0 != gvcst_data()))
			{
				save_key = gv_currkey;
				gv_currkey = gv_altkey;
				gv_altkey = save_key;
				break;
			}
		}
	}
	if (!found)
		len = 0;
	else
	{
		gv_altkey->prev = gv_currkey->prev;
		if (gv_target->nct || gv_target->collseq)
			gv_xform_key(gv_altkey, TRUE);
		/* len = SIZEOF(gv_key) + gv_altkey->end; */
		len = gv_altkey->end + SIZEOF(unsigned short) + SIZEOF(unsigned short) + SIZEOF(unsigned short) + SIZEOF(char);
	}
	ptr = curr_entry->clb_ptr->mbf;
	*ptr++ = CMMS_R_PREV;
	tmp_len = len + 1;
	PUT_USHORT(ptr, tmp_len);
	ptr += SIZEOF(short);
	*ptr++ = regnum;
	if (len)
	{	/* memcpy(ptr, gv_altkey, len); */ /* this memcpy modified to the following PUTs and memcpy; vinu, 07/18/01 */
		/* we are goint to restore top from old_top, why even bother setting it now? vinu, 07/18/01 */
		/* PUT_USHORT(ptr, gv_altkey->top); */
		PUT_USHORT(ptr + SIZEOF(unsigned short), gv_altkey->end);
		PUT_USHORT(ptr + SIZEOF(unsigned short) + SIZEOF(unsigned short), gv_altkey->prev);
		memcpy(ptr + SIZEOF(unsigned short) + SIZEOF(unsigned short) + SIZEOF(unsigned short), gv_altkey->base,
		       len - SIZEOF(unsigned short) - SIZEOF(unsigned short) - SIZEOF(unsigned short));
	}
	PUT_USHORT(ptr, old_top); /* ((gv_key *)ptr)->top = old_top; */
	curr_entry->clb_ptr->cbl = SIZEOF(unsigned char) + SIZEOF(unsigned short) + SIZEOF(unsigned char) + len;
	reset_gv_target = INVALID_GV_TARGET;
	return TRUE;
}