ltree_io.c

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/*
 * in/out function for ltree and lquery
 * Teodor Sigaev <teodor@stack.net>
 * contrib/ltree/ltree_io.c
 */
#include "postgres.h"
 
#include <ctype.h>
 
#include "common/int.h"
#include "crc32.h"
#include "libpq/pqformat.h"
#include "ltree.h"
#include "varatt.h"
 
 
typedef struct
{
    const char *start;
    int         len;            /* length in bytes */
    int         flag;
    int         wlen;           /* length in characters */
} nodeitem;
 
#define LTPRS_WAITNAME  0
#define LTPRS_WAITDELIM 1
 
static bool finish_nodeitem(nodeitem *lptr, const char *ptr,
                            bool is_lquery, int pos, struct Node *escontext);
 
 
/*
 * expects a null terminated string
 * returns an ltree
 */
static ltree *
parse_ltree(const char *buf, struct Node *escontext)
{
    const char *ptr;
    nodeitem   *list,
               *lptr;
    int         num = 0,
                totallen = 0;
    int         state = LTPRS_WAITNAME;
    ltree      *result;
    ltree_level *curlevel;
    int         charlen;
    int         pos = 1;        /* character position for error messages */
 
#define UNCHAR ereturn(escontext, NULL,\
                       errcode(ERRCODE_SYNTAX_ERROR), \
                       errmsg("ltree syntax error at character %d", \
                              pos))
 
    ptr = buf;
    while (*ptr)
    {
        charlen = pg_mblen_cstr(ptr);
        if (t_iseq(ptr, '.'))
            num++;
        ptr += charlen;
    }
 
    if (num + 1 > LTREE_MAX_LEVELS)
        ereturn(escontext, NULL,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("number of ltree labels (%d) exceeds the maximum allowed (%d)",
                        num + 1, LTREE_MAX_LEVELS)));
    list = lptr = palloc_array(nodeitem, num + 1);
    ptr = buf;
    while (*ptr)
    {
        charlen = pg_mblen_cstr(ptr);
 
        switch (state)
        {
            case LTPRS_WAITNAME:
                if (ISLABEL(ptr))
                {
                    lptr->start = ptr;
                    lptr->wlen = 0;
                    state = LTPRS_WAITDELIM;
                }
                else
                    UNCHAR;
                break;
            case LTPRS_WAITDELIM:
                if (t_iseq(ptr, '.'))
                {
                    if (!finish_nodeitem(lptr, ptr, false, pos, escontext))
                        return NULL;
                    totallen += MAXALIGN(lptr->len + LEVEL_HDRSIZE);
                    lptr++;
                    state = LTPRS_WAITNAME;
                }
                else if (!ISLABEL(ptr))
                    UNCHAR;
                break;
            default:
                elog(ERROR, "internal error in ltree parser");
        }
 
        ptr += charlen;
        lptr->wlen++;
        pos++;
    }
 
    if (state == LTPRS_WAITDELIM)
    {
        if (!finish_nodeitem(lptr, ptr, false, pos, escontext))
            return NULL;
        totallen += MAXALIGN(lptr->len + LEVEL_HDRSIZE);
        lptr++;
    }
    else if (!(state == LTPRS_WAITNAME && lptr == list))
        ereturn(escontext, NULL,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("ltree syntax error"),
                 errdetail("Unexpected end of input.")));
 
    result = (ltree *) palloc0(LTREE_HDRSIZE + totallen);
    SET_VARSIZE(result, LTREE_HDRSIZE + totallen);
    result->numlevel = lptr - list;
    curlevel = LTREE_FIRST(result);
    lptr = list;
    while (lptr - list < result->numlevel)
    {
        curlevel->len = (uint16) lptr->len;
        memcpy(curlevel->name, lptr->start, lptr->len);
        curlevel = LEVEL_NEXT(curlevel);
        lptr++;
    }
 
    pfree(list);
    return result;
 
#undef UNCHAR
}
 
/*
 * expects an ltree
 * returns a null terminated string
 */
static char *
deparse_ltree(const ltree *in)
{
    char       *buf,
               *ptr;
    int         i;
    ltree_level *curlevel;
 
    ptr = buf = (char *) palloc(VARSIZE(in));
    curlevel = LTREE_FIRST(in);
    for (i = 0; i < in->numlevel; i++)
    {
        if (i != 0)
        {
            *ptr = '.';
            ptr++;
        }
        memcpy(ptr, curlevel->name, curlevel->len);
        ptr += curlevel->len;
        curlevel = LEVEL_NEXT(curlevel);
    }
 
    *ptr = '\0';
    return buf;
}
 
/*
 * Basic ltree I/O functions
 */
PG_FUNCTION_INFO_V1(ltree_in);
Datum
ltree_in(PG_FUNCTION_ARGS)
{
    char       *buf = (char *) PG_GETARG_POINTER(0);
    ltree      *res;
 
    if ((res = parse_ltree(buf, fcinfo->context)) == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_POINTER(res);
}
 
PG_FUNCTION_INFO_V1(ltree_out);
Datum
ltree_out(PG_FUNCTION_ARGS)
{
    ltree      *in = PG_GETARG_LTREE_P(0);
 
    PG_RETURN_POINTER(deparse_ltree(in));
}
 
/*
 * ltree type send function
 *
 * The type is sent as text in binary mode, so this is almost the same
 * as the output function, but it's prefixed with a version number so we
 * can change the binary format sent in future if necessary. For now,
 * only version 1 is supported.
 */
PG_FUNCTION_INFO_V1(ltree_send);
Datum
ltree_send(PG_FUNCTION_ARGS)
{
    ltree      *in = PG_GETARG_LTREE_P(0);
    StringInfoData buf;
    int         version = 1;
    char       *res = deparse_ltree(in);
 
    pq_begintypsend(&buf);
    pq_sendint8(&buf, version);
    pq_sendtext(&buf, res, strlen(res));
    pfree(res);
 
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
 
/*
 * ltree type recv function
 *
 * The type is sent as text in binary mode, so this is almost the same
 * as the input function, but it's prefixed with a version number so we
 * can change the binary format sent in future if necessary. For now,
 * only version 1 is supported.
 */
PG_FUNCTION_INFO_V1(ltree_recv);
Datum
ltree_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
    int         version = pq_getmsgint(buf, 1);
    char       *str;
    int         nbytes;
    ltree      *res;
 
    if (version != 1)
        elog(ERROR, "unsupported ltree version number %d", version);
 
    str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
    res = parse_ltree(str, NULL);
    pfree(str);
 
    PG_RETURN_POINTER(res);
}
 
 
#define LQPRS_WAITLEVEL 0
#define LQPRS_WAITDELIM 1
#define LQPRS_WAITOPEN  2
#define LQPRS_WAITFNUM  3
#define LQPRS_WAITSNUM  4
#define LQPRS_WAITND    5
#define LQPRS_WAITCLOSE 6
#define LQPRS_WAITEND   7
#define LQPRS_WAITVAR   8
 
 
#define GETVAR(x) ( *((nodeitem**)LQL_FIRST(x)) )
#define ITEMSIZE    MAXALIGN(LQL_HDRSIZE+sizeof(nodeitem*))
#define NEXTLEV(x) ( (lquery_level*)( ((char*)(x)) + ITEMSIZE) )
 
/*
 * expects a null terminated string
 * returns an lquery
 */
static lquery *
parse_lquery(const char *buf, struct Node *escontext)
{
    const char *ptr;
    int         num = 0,
                totallen = 0,
                numOR = 0;
    int         state = LQPRS_WAITLEVEL;
    lquery     *result;
    nodeitem   *lptr = NULL;
    lquery_level *cur,
               *curqlevel,
               *tmpql;
    lquery_variant *lrptr = NULL;
    bool        hasnot = false;
    bool        wasbad = false;
    int         charlen;
    int         pos = 1;        /* character position for error messages */
 
#define UNCHAR ereturn(escontext, NULL,\
                       errcode(ERRCODE_SYNTAX_ERROR), \
                       errmsg("lquery syntax error at character %d", \
                              pos))
 
    ptr = buf;
    while (*ptr)
    {
        charlen = pg_mblen_cstr(ptr);
 
        if (t_iseq(ptr, '.'))
            num++;
        else if (t_iseq(ptr, '|'))
            numOR++;
 
        ptr += charlen;
    }
 
    num++;
    if (num > LQUERY_MAX_LEVELS)
        ereturn(escontext, NULL,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("number of lquery items (%d) exceeds the maximum allowed (%d)",
                        num, LQUERY_MAX_LEVELS)));
    curqlevel = tmpql = (lquery_level *) palloc0(ITEMSIZE * num);
    ptr = buf;
    while (*ptr)
    {
        charlen = pg_mblen_cstr(ptr);
 
        switch (state)
        {
            case LQPRS_WAITLEVEL:
                if (ISLABEL(ptr))
                {
                    GETVAR(curqlevel) = lptr = palloc0_array(nodeitem, numOR + 1);
                    lptr->start = ptr;
                    state = LQPRS_WAITDELIM;
                    curqlevel->numvar = 1;
                }
                else if (t_iseq(ptr, '!'))
                {
                    GETVAR(curqlevel) = lptr = palloc0_array(nodeitem, numOR + 1);
                    lptr->start = ptr + 1;
                    lptr->wlen = -1;    /* compensate for counting ! below */
                    state = LQPRS_WAITDELIM;
                    curqlevel->numvar = 1;
                    curqlevel->flag |= LQL_NOT;
                    hasnot = true;
                }
                else if (t_iseq(ptr, '*'))
                    state = LQPRS_WAITOPEN;
                else
                    UNCHAR;
                break;
            case LQPRS_WAITVAR:
                if (ISLABEL(ptr))
                {
                    lptr++;
                    lptr->start = ptr;
                    state = LQPRS_WAITDELIM;
                    if (pg_add_u16_overflow(curqlevel->numvar, 1, &curqlevel->numvar))
                        ereturn(escontext, NULL,
                                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                                 errmsg("lquery level has too many variants"),
                                 errdetail("Number of variants exceeds the maximum allowed (%d).",
                                           PG_UINT16_MAX)));
                }
                else
                    UNCHAR;
                break;
            case LQPRS_WAITDELIM:
                if (t_iseq(ptr, '@'))
                {
                    lptr->flag |= LVAR_INCASE;
                    curqlevel->flag |= LVAR_INCASE;
                }
                else if (t_iseq(ptr, '*'))
                {
                    lptr->flag |= LVAR_ANYEND;
                    curqlevel->flag |= LVAR_ANYEND;
                }
                else if (t_iseq(ptr, '%'))
                {
                    lptr->flag |= LVAR_SUBLEXEME;
                    curqlevel->flag |= LVAR_SUBLEXEME;
                }
                else if (t_iseq(ptr, '|'))
                {
                    if (!finish_nodeitem(lptr, ptr, true, pos, escontext))
                        return NULL;
                    state = LQPRS_WAITVAR;
                }
                else if (t_iseq(ptr, '{'))
                {
                    if (!finish_nodeitem(lptr, ptr, true, pos, escontext))
                        return NULL;
                    curqlevel->flag |= LQL_COUNT;
                    state = LQPRS_WAITFNUM;
                }
                else if (t_iseq(ptr, '.'))
                {
                    if (!finish_nodeitem(lptr, ptr, true, pos, escontext))
                        return NULL;
                    state = LQPRS_WAITLEVEL;
                    curqlevel = NEXTLEV(curqlevel);
                }
                else if (ISLABEL(ptr))
                {
                    /* disallow more chars after a flag */
                    if (lptr->flag)
                        UNCHAR;
                }
                else
                    UNCHAR;
                break;
            case LQPRS_WAITOPEN:
                if (t_iseq(ptr, '{'))
                    state = LQPRS_WAITFNUM;
                else if (t_iseq(ptr, '.'))
                {
                    /* We only get here for '*', so these are correct defaults */
                    curqlevel->low = 0;
                    curqlevel->high = LTREE_MAX_LEVELS;
                    curqlevel = NEXTLEV(curqlevel);
                    state = LQPRS_WAITLEVEL;
                }
                else
                    UNCHAR;
                break;
            case LQPRS_WAITFNUM:
                if (t_iseq(ptr, ','))
                    state = LQPRS_WAITSNUM;
                else if (isdigit((unsigned char) *ptr))
                {
                    int         low = atoi(ptr);
 
                    if (low < 0 || low > LTREE_MAX_LEVELS)
                        ereturn(escontext, NULL,
                                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                                 errmsg("lquery syntax error"),
                                 errdetail("Low limit (%d) exceeds the maximum allowed (%d), at character %d.",
                                           low, LTREE_MAX_LEVELS, pos)));
 
                    curqlevel->low = (uint16) low;
                    state = LQPRS_WAITND;
                }
                else
                    UNCHAR;
                break;
            case LQPRS_WAITSNUM:
                if (isdigit((unsigned char) *ptr))
                {
                    int         high = atoi(ptr);
 
                    if (high < 0 || high > LTREE_MAX_LEVELS)
                        ereturn(escontext, NULL,
                                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                                 errmsg("lquery syntax error"),
                                 errdetail("High limit (%d) exceeds the maximum allowed (%d), at character %d.",
                                           high, LTREE_MAX_LEVELS, pos)));
                    else if (curqlevel->low > high)
                        ereturn(escontext, NULL,
                                (errcode(ERRCODE_SYNTAX_ERROR),
                                 errmsg("lquery syntax error"),
                                 errdetail("Low limit (%d) is greater than high limit (%d), at character %d.",
                                           curqlevel->low, high, pos)));
 
                    curqlevel->high = (uint16) high;
                    state = LQPRS_WAITCLOSE;
                }
                else if (t_iseq(ptr, '}'))
                {
                    curqlevel->high = LTREE_MAX_LEVELS;
                    state = LQPRS_WAITEND;
                }
                else
                    UNCHAR;
                break;
            case LQPRS_WAITCLOSE:
                if (t_iseq(ptr, '}'))
                    state = LQPRS_WAITEND;
                else if (!isdigit((unsigned char) *ptr))
                    UNCHAR;
                break;
            case LQPRS_WAITND:
                if (t_iseq(ptr, '}'))
                {
                    curqlevel->high = curqlevel->low;
                    state = LQPRS_WAITEND;
                }
                else if (t_iseq(ptr, ','))
                    state = LQPRS_WAITSNUM;
                else if (!isdigit((unsigned char) *ptr))
                    UNCHAR;
                break;
            case LQPRS_WAITEND:
                if (t_iseq(ptr, '.'))
                {
                    state = LQPRS_WAITLEVEL;
                    curqlevel = NEXTLEV(curqlevel);
                }
                else
                    UNCHAR;
                break;
            default:
                elog(ERROR, "internal error in lquery parser");
        }
 
        ptr += charlen;
        if (state == LQPRS_WAITDELIM)
            lptr->wlen++;
        pos++;
    }
 
    if (state == LQPRS_WAITDELIM)
    {
        if (!finish_nodeitem(lptr, ptr, true, pos, escontext))
            return NULL;
    }
    else if (state == LQPRS_WAITOPEN)
        curqlevel->high = LTREE_MAX_LEVELS;
    else if (state != LQPRS_WAITEND)
        ereturn(escontext, NULL,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("lquery syntax error"),
                 errdetail("Unexpected end of input.")));
 
    curqlevel = tmpql;
    totallen = LQUERY_HDRSIZE;
    while ((char *) curqlevel - (char *) tmpql < num * ITEMSIZE)
    {
        totallen += LQL_HDRSIZE;
        if (curqlevel->numvar)
        {
            lptr = GETVAR(curqlevel);
            while (lptr - GETVAR(curqlevel) < curqlevel->numvar)
            {
                totallen += MAXALIGN(LVAR_HDRSIZE + lptr->len);
                lptr++;
            }
        }
        curqlevel = NEXTLEV(curqlevel);
    }
 
    result = (lquery *) palloc0(totallen);
    SET_VARSIZE(result, totallen);
    result->numlevel = num;
    result->firstgood = 0;
    result->flag = 0;
    if (hasnot)
        result->flag |= LQUERY_HASNOT;
    cur = LQUERY_FIRST(result);
    curqlevel = tmpql;
    while ((char *) curqlevel - (char *) tmpql < num * ITEMSIZE)
    {
        memcpy(cur, curqlevel, LQL_HDRSIZE);
        cur->totallen = LQL_HDRSIZE;
        if (curqlevel->numvar)
        {
            lrptr = LQL_FIRST(cur);
            lptr = GETVAR(curqlevel);
            while (lptr - GETVAR(curqlevel) < curqlevel->numvar)
            {
                int         newlen = cur->totallen + MAXALIGN(LVAR_HDRSIZE + lptr->len);
 
                if (newlen > PG_UINT16_MAX)
                    ereturn(escontext, NULL,
                            (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                             errmsg("lquery level is too large"),
                             errdetail("Total size of level exceeds the maximum allowed (%d bytes).",
                                       PG_UINT16_MAX)));
                cur->totallen = (uint16) newlen;
 
                lrptr->len = lptr->len;
                lrptr->flag = lptr->flag;
                lrptr->val = ltree_crc32_sz(lptr->start, lptr->len);
                memcpy(lrptr->name, lptr->start, lptr->len);
                lptr++;
                lrptr = LVAR_NEXT(lrptr);
            }
            pfree(GETVAR(curqlevel));
            if (cur->numvar > 1 || cur->flag != 0)
            {
                /* Not a simple match */
                wasbad = true;
            }
            else if (wasbad == false)
            {
                /* count leading simple matches */
                (result->firstgood)++;
            }
        }
        else
        {
            /* '*', so this isn't a simple match */
            wasbad = true;
        }
        curqlevel = NEXTLEV(curqlevel);
        cur = LQL_NEXT(cur);
    }
 
    pfree(tmpql);
    return result;
 
#undef UNCHAR
}
 
/*
 * Close out parsing an ltree or lquery nodeitem:
 * compute the correct length, and complain if it's not OK
 */
static bool
finish_nodeitem(nodeitem *lptr, const char *ptr, bool is_lquery, int pos,
                struct Node *escontext)
{
    if (is_lquery)
    {
        /*
         * Back up over any flag characters, and discount them from length and
         * position.
         */
        while (ptr > lptr->start && strchr("@*%", ptr[-1]) != NULL)
        {
            ptr--;
            lptr->wlen--;
            pos--;
        }
    }
 
    /* Now compute the byte length, which we weren't tracking before. */
    lptr->len = ptr - lptr->start;
 
    /* Complain if it's empty or too long */
    if (lptr->len == 0)
        ereturn(escontext, false,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 is_lquery ?
                 errmsg("lquery syntax error at character %d", pos) :
                 errmsg("ltree syntax error at character %d", pos),
                 errdetail("Empty labels are not allowed.")));
    if (lptr->wlen > LTREE_LABEL_MAX_CHARS)
        ereturn(escontext, false,
                (errcode(ERRCODE_NAME_TOO_LONG),
                 errmsg("label string is too long"),
                 errdetail("Label length is %d, must be at most %d, at character %d.",
                           lptr->wlen, LTREE_LABEL_MAX_CHARS, pos)));
    return true;
}
 
/*
 * expects an lquery
 * returns a null terminated string
 */
static char *
deparse_lquery(const lquery *in)
{
    char       *buf,
               *ptr;
    int         i,
                j,
                totallen = 1;
    lquery_level *curqlevel;
    lquery_variant *curtlevel;
 
    curqlevel = LQUERY_FIRST(in);
    for (i = 0; i < in->numlevel; i++)
    {
        totallen++;
        if (curqlevel->numvar)
        {
            totallen += 1 + (curqlevel->numvar * 4) + curqlevel->totallen;
            if (curqlevel->flag & LQL_COUNT)
                totallen += 2 * 11 + 3;
        }
        else
            totallen += 2 * 11 + 4;
        curqlevel = LQL_NEXT(curqlevel);
    }
 
    ptr = buf = (char *) palloc(totallen);
    curqlevel = LQUERY_FIRST(in);
    for (i = 0; i < in->numlevel; i++)
    {
        if (i != 0)
        {
            *ptr = '.';
            ptr++;
        }
        if (curqlevel->numvar)
        {
            if (curqlevel->flag & LQL_NOT)
            {
                *ptr = '!';
                ptr++;
            }
            curtlevel = LQL_FIRST(curqlevel);
            for (j = 0; j < curqlevel->numvar; j++)
            {
                if (j != 0)
                {
                    *ptr = '|';
                    ptr++;
                }
                memcpy(ptr, curtlevel->name, curtlevel->len);
                ptr += curtlevel->len;
                if ((curtlevel->flag & LVAR_SUBLEXEME))
                {
                    *ptr = '%';
                    ptr++;
                }
                if ((curtlevel->flag & LVAR_INCASE))
                {
                    *ptr = '@';
                    ptr++;
                }
                if ((curtlevel->flag & LVAR_ANYEND))
                {
                    *ptr = '*';
                    ptr++;
                }
                curtlevel = LVAR_NEXT(curtlevel);
            }
        }
        else
        {
            *ptr = '*';
            ptr++;
        }
 
        if ((curqlevel->flag & LQL_COUNT) || curqlevel->numvar == 0)
        {
            if (curqlevel->low == curqlevel->high)
            {
                sprintf(ptr, "{%d}", curqlevel->low);
            }
            else if (curqlevel->low == 0)
            {
                if (curqlevel->high == LTREE_MAX_LEVELS)
                {
                    if (curqlevel->numvar == 0)
                    {
                        /* This is default for '*', so print nothing */
                        *ptr = '\0';
                    }
                    else
                        sprintf(ptr, "{,}");
                }
                else
                    sprintf(ptr, "{,%d}", curqlevel->high);
            }
            else if (curqlevel->high == LTREE_MAX_LEVELS)
            {
                sprintf(ptr, "{%d,}", curqlevel->low);
            }
            else
                sprintf(ptr, "{%d,%d}", curqlevel->low, curqlevel->high);
            ptr = strchr(ptr, '\0');
        }
 
        curqlevel = LQL_NEXT(curqlevel);
    }
 
    *ptr = '\0';
    return buf;
}
 
/*
 * Basic lquery I/O functions
 */
PG_FUNCTION_INFO_V1(lquery_in);
Datum
lquery_in(PG_FUNCTION_ARGS)
{
    char       *buf = (char *) PG_GETARG_POINTER(0);
    lquery     *res;
 
    if ((res = parse_lquery(buf, fcinfo->context)) == NULL)
        PG_RETURN_NULL();
 
    PG_RETURN_POINTER(res);
}
 
PG_FUNCTION_INFO_V1(lquery_out);
Datum
lquery_out(PG_FUNCTION_ARGS)
{
    lquery     *in = PG_GETARG_LQUERY_P(0);
 
    PG_RETURN_POINTER(deparse_lquery(in));
}
 
/*
 * lquery type send function
 *
 * The type is sent as text in binary mode, so this is almost the same
 * as the output function, but it's prefixed with a version number so we
 * can change the binary format sent in future if necessary. For now,
 * only version 1 is supported.
 */
PG_FUNCTION_INFO_V1(lquery_send);
Datum
lquery_send(PG_FUNCTION_ARGS)
{
    lquery     *in = PG_GETARG_LQUERY_P(0);
    StringInfoData buf;
    int         version = 1;
    char       *res = deparse_lquery(in);
 
    pq_begintypsend(&buf);
    pq_sendint8(&buf, version);
    pq_sendtext(&buf, res, strlen(res));
    pfree(res);
 
    PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
 
/*
 * lquery type recv function
 *
 * The type is sent as text in binary mode, so this is almost the same
 * as the input function, but it's prefixed with a version number so we
 * can change the binary format sent in future if necessary. For now,
 * only version 1 is supported.
 */
PG_FUNCTION_INFO_V1(lquery_recv);
Datum
lquery_recv(PG_FUNCTION_ARGS)
{
    StringInfo  buf = (StringInfo) PG_GETARG_POINTER(0);
    int         version = pq_getmsgint(buf, 1);
    char       *str;
    int         nbytes;
    lquery     *res;
 
    if (version != 1)
        elog(ERROR, "unsupported lquery version number %d", version);
 
    str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
    res = parse_lquery(str, NULL);
    pfree(str);
 
    PG_RETURN_POINTER(res);
}