quote.c

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/*-------------------------------------------------------------------------
 *
 * quote.c
 *    Functions for quoting identifiers and literals
 *
 * Portions Copyright (c) 2000-2021, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/quote.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "utils/builtins.h"


/*
 * quote_ident -
 *    returns a properly quoted identifier
 */
Datum
quote_ident(PG_FUNCTION_ARGS)
{
    text       *t = PG_GETARG_TEXT_PP(0);
    const char *qstr;
    char       *str;

    str = text_to_cstring(t);
    qstr = quote_identifier(str);
    PG_RETURN_TEXT_P(cstring_to_text(qstr));
}

/*
 * quote_literal_internal -
 *    helper function for quote_literal and quote_literal_cstr
 *
 * NOTE: think not to make this function's behavior change with
 * standard_conforming_strings.  We don't know where the result
 * literal will be used, and so we must generate a result that
 * will work with either setting.  Take a look at what dblink
 * uses this for before thinking you know better.
 */
static size_t
quote_literal_internal(char *dst, const char *src, size_t len)
{
    const char *s;
    char       *savedst = dst;

    for (s = src; s < src + len; s++)
    {
        if (*s == '\\')
        {
            *dst++ = ESCAPE_STRING_SYNTAX;
            break;
        }
    }

    *dst++ = '\'';
    while (len-- > 0)
    {
        if (SQL_STR_DOUBLE(*src, true))
            *dst++ = *src;
        *dst++ = *src++;
    }
    *dst++ = '\'';

    return dst - savedst;
}

/*
 * quote_literal -
 *    returns a properly quoted literal
 */
Datum
quote_literal(PG_FUNCTION_ARGS)
{
    text       *t = PG_GETARG_TEXT_PP(0);
    text       *result;
    char       *cp1;
    char       *cp2;
    int         len;

    len = VARSIZE_ANY_EXHDR(t);
    /* We make a worst-case result area; wasting a little space is OK */
    result = (text *) palloc(len * 2 + 3 + VARHDRSZ);

    cp1 = VARDATA_ANY(t);
    cp2 = VARDATA(result);

    SET_VARSIZE(result, VARHDRSZ + quote_literal_internal(cp2, cp1, len));

    PG_RETURN_TEXT_P(result);
}

/*
 * quote_literal_cstr -
 *    returns a properly quoted literal
 */
char *
quote_literal_cstr(const char *rawstr)
{
    char       *result;
    int         len;
    int         newlen;

    len = strlen(rawstr);
    /* We make a worst-case result area; wasting a little space is OK */
    result = palloc(len * 2 + 3 + 1);

    newlen = quote_literal_internal(result, rawstr, len);
    result[newlen] = '\0';

    return result;
}

/*
 * quote_nullable -
 *    Returns a properly quoted literal, with null values returned
 *    as the text string 'NULL'.
 */
Datum
quote_nullable(PG_FUNCTION_ARGS)
{
    if (PG_ARGISNULL(0))
        PG_RETURN_TEXT_P(cstring_to_text("NULL"));
    else
        PG_RETURN_DATUM(DirectFunctionCall1(quote_literal,
                                            PG_GETARG_DATUM(0)));
}