Fix array_out's failure to backslash backslashes, per bug# 524. Also,

remove brain-dead rule that double quotes are needed if and only if the
datatype is pass-by-reference; neither direction of the implication holds
water.  Instead, examine the actual data string to see if it contains
any characters that force us to quote it.
Add some documentation about quoting of array values, which was previously
explained nowhere AFAICT.

1 files changed, 57 insertions, 39 deletions

diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index f6687847144..0cfa371c998 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.71 2001/10/25 05:49:43 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.72 2001/11/29 21:02:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -346,6 +346,7 @@ ArrayCount(char *str, int *dim, int typdelim)
  *	 If element type is pass-by-ref, the Datums point to palloc'd values.
  *	 *nbytes is set to the amount of data space needed for the array,
  *	 including alignment padding but not including array header overhead.
+ *	 CAUTION: the contents of "arrayStr" may be modified!
  *---------------------------------------------------------------------------
  */
 static Datum *
@@ -564,16 +565,13 @@ array_out(PG_FUNCTION_ARGS)
 	char	   *p,
 			   *tmp,
 			   *retval,
-			  **values,
-				delim[2];
+			  **values;
+	bool	   *needquotes;
 	int			nitems,
 				overall_length,
 				i,
 				j,
 				k,
-#ifndef TCL_ARRAYS
-				l,
-#endif
 				indx[MAXDIM];
 	int			ndim,
 			   *dim;
@@ -581,26 +579,29 @@ array_out(PG_FUNCTION_ARGS)
 	system_cache_lookup(element_type, false, &typlen, &typbyval,
 						&typdelim, &typelem, &typoutput, &typalign);
 	fmgr_info(typoutput, &outputproc);
-	sprintf(delim, "%c", typdelim);
 	ndim = ARR_NDIM(v);
 	dim = ARR_DIMS(v);
 	nitems = ArrayGetNItems(ndim, dim);
 
 	if (nitems == 0)
 	{
-		retval = (char *) palloc(3);
-		retval[0] = '{';
-		retval[1] = '}';
-		retval[2] = '\0';
+		retval = pstrdup("{}");
 		PG_RETURN_CSTRING(retval);
 	}
 
+	/*
+	 * Convert all values to string form, count total space needed
+	 * (including any overhead such as escaping backslashes),
+	 * and detect whether each item needs double quotes.
+	 */
+	values = (char **) palloc(nitems * sizeof(char *));
+	needquotes = (bool *) palloc(nitems * sizeof(bool));
 	p = ARR_DATA_PTR(v);
 	overall_length = 1;			/* [TRH] don't forget to count \0 at end. */
-	values = (char **) palloc(nitems * sizeof(char *));
 	for (i = 0; i < nitems; i++)
 	{
 		Datum		itemvalue;
+		bool		nq;
 
 		itemvalue = fetch_att(p, typbyval, typlen);
 		values[i] = DatumGetCString(FunctionCall3(&outputproc,
@@ -612,20 +613,32 @@ array_out(PG_FUNCTION_ARGS)
 		else
 			p += INTALIGN(*(int32 *) p);
 
-		/*
-		 * For the pair of double quotes
-		 */
-		if (!typbyval)
-			overall_length += 2;
-
+		/* count data plus backslashes; detect chars needing quotes */
+		nq = (values[i][0] == '\0');	/* force quotes for empty string */
 		for (tmp = values[i]; *tmp; tmp++)
 		{
+			char	ch = *tmp;
+
 			overall_length += 1;
+			if (ch == '"' || ch == '\\')
+			{
+				nq = true;
 #ifndef TCL_ARRAYS
-			if (*tmp == '"')
 				overall_length += 1;
 #endif
+			}
+			else if (ch == '{' || ch == '}' || ch == typdelim ||
+					 isspace((unsigned char) ch))
+				nq = true;
 		}
+
+		needquotes[i] = nq;
+
+		/* Count the pair of double quotes, if needed */
+		if (nq)
+			overall_length += 2;
+
+		/* and the comma */
 		overall_length += 1;
 	}
 
@@ -634,41 +647,41 @@ array_out(PG_FUNCTION_ARGS)
 	 */
 	for (i = j = 0, k = 1; i < ndim; k *= dim[i++], j += k);
 
-	p = (char *) palloc(overall_length + 2 * j);
-	retval = p;
+	retval = (char *) palloc(overall_length + 2 * j);
+	p = retval;
+
+#define APPENDSTR(str)	(strcpy(p, (str)), p += strlen(p))
+#define APPENDCHAR(ch)	(*p++ = (ch), *p = '\0')
 
-	strcpy(p, "{");
+	APPENDCHAR('{');
 	for (i = 0; i < ndim; indx[i++] = 0);
 	j = 0;
 	k = 0;
 	do
 	{
 		for (i = j; i < ndim - 1; i++)
-			strcat(p, "{");
+			APPENDCHAR('{');
 
-		/*
-		 * Surround anything that is not passed by value in double quotes.
-		 * See above for more details.
-		 */
-		if (!typbyval)
+		if (needquotes[k])
 		{
-			strcat(p, "\"");
+			APPENDCHAR('"');
 #ifndef TCL_ARRAYS
-			l = strlen(p);
 			for (tmp = values[k]; *tmp; tmp++)
 			{
-				if (*tmp == '"')
-					p[l++] = '\\';
-				p[l++] = *tmp;
+				char	ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					*p++ = '\\';
+				*p++ = ch;
 			}
-			p[l] = '\0';
+			*p = '\0';
 #else
-			strcat(p, values[k]);
+			APPENDSTR(values[k]);
 #endif
-			strcat(p, "\"");
+			APPENDCHAR('"');
 		}
 		else
-			strcat(p, values[k]);
+			APPENDSTR(values[k]);
 		pfree(values[k++]);
 
 		for (i = ndim - 1; i >= 0; i--)
@@ -676,16 +689,21 @@ array_out(PG_FUNCTION_ARGS)
 			indx[i] = (indx[i] + 1) % dim[i];
 			if (indx[i])
 			{
-				strcat(p, delim);
+				APPENDCHAR(typdelim);
 				break;
 			}
 			else
-				strcat(p, "}");
+				APPENDCHAR('}');
 		}
 		j = i;
 	} while (j != -1);
 
+#undef APPENDSTR
+#undef APPENDCHAR
+
 	pfree(values);
+	pfree(needquotes);
+
 	PG_RETURN_CSTRING(retval);
 }