src/backend/utils/adt/quote.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * quote.c
   4  *        Functions for quoting identifiers and literals
   5  *
   6  * Portions Copyright (c) 2000-2009, PostgreSQL Global Development Group
   7  *
   8  *
   9  * IDENTIFICATION
  10  *        $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #include "postgres.h"
  15
  16 #include "utils/builtins.h"
  17
  18
  19 /*
  20  * quote_ident -
  21  *        returns a properly quoted identifier
  22  */
  23 Datum
  24 quote_ident(PG_FUNCTION_ARGS)
  25 {
  26         text       *t = PG_GETARG_TEXT_PP(0);
  27         const char *qstr;
  28         char       *str;
  29
  30         str = text_to_cstring(t);
  31         qstr = quote_identifier(str);
  32         PG_RETURN_TEXT_P(cstring_to_text(qstr));
  33 }
  34
  35 /*
  36  * quote_literal -
  37  *        returns a properly quoted literal
  38  *
  39  * NOTE: think not to make this function's behavior change with
  40  * standard_conforming_strings.  We don't know where the result
  41  * literal will be used, and so we must generate a result that
  42  * will work with either setting.  Take a look at what dblink
  43  * uses this for before thinking you know better.
  44  */
  45 Datum
  46 quote_literal(PG_FUNCTION_ARGS)
  47 {
  48         text       *t = PG_GETARG_TEXT_P(0);
  49         text       *result;
  50         char       *cp1;
  51         char       *cp2;
  52         int                     len;
  53
  54         len = VARSIZE(t) - VARHDRSZ;
  55         /* We make a worst-case result area; wasting a little space is OK */
  56         result = (text *) palloc(len * 2 + 3 + VARHDRSZ);
  57
  58         cp1 = VARDATA(t);
  59         cp2 = VARDATA(result);
  60
  61         for (; len-- > 0; cp1++)
  62         {
  63                 if (*cp1 == '\\')
  64                 {
  65                         *cp2++ = ESCAPE_STRING_SYNTAX;
  66                         break;
  67                 }
  68         }
  69
  70         len = VARSIZE(t) - VARHDRSZ;
  71         cp1 = VARDATA(t);
  72
  73         *cp2++ = '\'';
  74         while (len-- > 0)
  75         {
  76                 if (SQL_STR_DOUBLE(*cp1, true))
  77                         *cp2++ = *cp1;
  78                 *cp2++ = *cp1++;
  79         }
  80         *cp2++ = '\'';
  81
  82         SET_VARSIZE(result, cp2 - ((char *) result));
  83
  84         PG_RETURN_TEXT_P(result);
  85 }
  86
  87 /*
  88  * quote_nullable -
  89  *        Returns a properly quoted literal, with null values returned
  90  *        as the text string 'NULL'.
  91  */
  92 Datum
  93 quote_nullable(PG_FUNCTION_ARGS)
  94 {
  95         if (PG_ARGISNULL(0))
  96                 PG_RETURN_TEXT_P(cstring_to_text("NULL"));
  97         else
  98                 PG_RETURN_DATUM(DirectFunctionCall1(quote_literal,
  99                                                                                         PG_GETARG_DATUM(0)));
 100 }