to_char: revert cc0d90b

Revert "to_char(float4/8):  zero pad to specified length".  There are
too many platform-specific problems, and the proper rounding is missing.
Also revert companion patch 9d61b99.

Author: bmomjian

src/backend/utils/adt/formatting.c

@@ -113,6 +113,13 @@
 #define DCH_MAX_ITEM_SIZ	   12		/* max localized day name		*/
 #define NUM_MAX_ITEM_SIZ		8		/* roman number (RN has 15 chars)	*/
 
+/* ----------
+ * More is in float.c
+ * ----------
+ */
+#define MAXFLOATWIDTH	60
+#define MAXDOUBLEWIDTH	500
+
 
 /* ----------
  * Format parser structs
@@ -5207,7 +5214,8 @@ int4_to_char(PG_FUNCTION_ARGS)
 		/* we can do it easily because float8 won't lose any precision */
 		float8		val = (float8) value;
 
-		orgnum = psprintf("%+.*e", Num.post, val);
+		orgnum = (char *) palloc(MAXDOUBLEWIDTH + 1);
+		snprintf(orgnum, MAXDOUBLEWIDTH + 1, "%+.*e", Num.post, val);
 
 		/*
 		 * Swap a leading positive sign for a space.
@@ -5406,6 +5414,7 @@ float4_to_char(PG_FUNCTION_ARGS)
 		numstr = orgnum = int_to_roman((int) rint(value));
 	else if (IS_EEEE(&Num))
 	{
+		numstr = orgnum = (char *) palloc(MAXDOUBLEWIDTH + 1);
 		if (isnan(value) || is_infinite(value))
 		{
 			/*
@@ -5419,29 +5428,15 @@ float4_to_char(PG_FUNCTION_ARGS)
 		}
 		else
 		{
-			numstr = psprintf("%+.*e", Num.post, value);
-
-			/* prevent the display of imprecise/junk digits */
-			if (Num.pre + Num.post > FLT_DIG)
-			{
-				int		digits = 0;
-				char   *numstr_p;
-
-				for (numstr_p = numstr; *numstr_p && *numstr_p != 'e'; numstr_p++)
-				{
-					if (isdigit(*numstr_p))
-					{
-						if (++digits > FLT_DIG)
-							*numstr_p = '0';
-					}
-				}
-			}
+			snprintf(orgnum, MAXDOUBLEWIDTH + 1, "%+.*e", Num.post, value);
 
 			/*
 			 * Swap a leading positive sign for a space.
 			 */
-			if (*numstr == '+')
-				*numstr = ' ';
+			if (*orgnum == '+')
+				*orgnum = ' ';
+
+			numstr = orgnum;
 		}
 	}
 	else
@@ -5457,24 +5452,16 @@ float4_to_char(PG_FUNCTION_ARGS)
 			Num.pre += Num.multi;
 		}
 
-		/* let psprintf() do the rounding */
-		orgnum = psprintf("%.*f", Num.post, val);
+		orgnum = (char *) palloc(MAXFLOATWIDTH + 1);
+		snprintf(orgnum, MAXFLOATWIDTH + 1, "%.0f", fabs(val));
+		numstr_pre_len = strlen(orgnum);
 
-		/* prevent the display of imprecise/junk digits */
-		if (Num.pre + Num.post > FLT_DIG)
-		{
-			int 	digits = 0;
-			char   *orgnum_p;
-
-			for (orgnum_p = orgnum; *orgnum_p; orgnum_p++)
-			{
-				if (isdigit(*orgnum_p))
-				{
-					if (++digits > FLT_DIG)
-						*orgnum_p = '0';
-				}
-			}
-		}
+		/* adjust post digits to fit max float digits */
+		if (numstr_pre_len >= FLT_DIG)
+			Num.post = 0;
+		else if (numstr_pre_len + Num.post > FLT_DIG)
+			Num.post = FLT_DIG - numstr_pre_len;
+		snprintf(orgnum, MAXFLOATWIDTH + 1, "%.*f", Num.post, val);
 
 		if (*orgnum == '-')
 		{						/* < 0 */
@@ -5533,6 +5520,7 @@ float8_to_char(PG_FUNCTION_ARGS)
 		numstr = orgnum = int_to_roman((int) rint(value));
 	else if (IS_EEEE(&Num))
 	{
+		numstr = orgnum = (char *) palloc(MAXDOUBLEWIDTH + 1);
 		if (isnan(value) || is_infinite(value))
 		{
 			/*
@@ -5546,29 +5534,15 @@ float8_to_char(PG_FUNCTION_ARGS)
 		}
 		else
 		{
-			numstr = psprintf("%+.*e", Num.post, value);
-
-			/* prevent the display of imprecise/junk digits */
-			if (Num.pre + Num.post > DBL_DIG)
-			{
-				int		digits = 0;
-				char   *numstr_p;
-
-				for (numstr_p = numstr; *numstr_p && *numstr_p != 'e'; numstr_p++)
-				{
-					if (isdigit(*numstr_p))
-					{
-						if (++digits > DBL_DIG)
-							*numstr_p = '0';
-					}
-				}
-			}
+			snprintf(orgnum, MAXDOUBLEWIDTH + 1, "%+.*e", Num.post, value);
 
 			/*
 			 * Swap a leading positive sign for a space.
 			 */
-			if (*numstr == '+')
-				*numstr = ' ';
+			if (*orgnum == '+')
+				*orgnum = ' ';
+
+			numstr = orgnum;
 		}
 	}
 	else
@@ -5583,25 +5557,15 @@ float8_to_char(PG_FUNCTION_ARGS)
 			val = value * multi;
 			Num.pre += Num.multi;
 		}
-
-		/* let psprintf() do the rounding */
-		orgnum = psprintf("%.*f", Num.post, val);
-
-		/* prevent the display of imprecise/junk digits */
-		if (Num.pre + Num.post > DBL_DIG)
-		{
-			int 	digits = 0;
-			char   *orgnum_p;
-
-			for (orgnum_p = orgnum; *orgnum_p; orgnum_p++)
-			{
-				if (isdigit(*orgnum_p))
-				{
-					if (++digits > DBL_DIG)
-						*orgnum_p = '0';
-				}
-			}
-		}
+		orgnum = (char *) palloc(MAXDOUBLEWIDTH + 1);
+		numstr_pre_len = snprintf(orgnum, MAXDOUBLEWIDTH + 1, "%.0f", fabs(val));
+
+		/* adjust post digits to fit max double digits */
+		if (numstr_pre_len >= DBL_DIG)
+			Num.post = 0;
+		else if (numstr_pre_len + Num.post > DBL_DIG)
+			Num.post = DBL_DIG - numstr_pre_len;
+		snprintf(orgnum, MAXDOUBLEWIDTH + 1, "%.*f", Num.post, val);
 
 		if (*orgnum == '-')
 		{						/* < 0 */