From cf171317670de8760897f30e99d74b4073cf4874 Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Fri, 2 Dec 2005 02:49:11 +0000
Subject: [PATCH] Remove comment on errno=0 lines, but add mention to
 port/strtol.c function.

---
 src/backend/utils/adt/datetime.c | 22 +++++++++++-----------
 src/backend/utils/adt/float.c    | 26 +++++++++++++-------------
 src/backend/utils/adt/numutils.c |  4 ++--
 src/port/strtol.c                |  9 +++++++++
 4 files changed, 35 insertions(+), 26 deletions(-)

diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 8238b33196..a10caf602d 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.164 2005/12/01 21:11:58 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.165 2005/12/02 02:49:11 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1013,7 +1013,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 					if (tzp == NULL)
 						return DTERR_BAD_FORMAT;
 
-					errno = 0;	/* avoid having to check the result for failure */
+					errno = 0;
 					val = strtol(field[i], &cp, 10);
 					if (errno == ERANGE)
 						return DTERR_FIELD_OVERFLOW;
@@ -1161,7 +1161,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 					char	   *cp;
 					int			val;
 
-					errno = 0;	/* avoid having to check the result for failure */
+					errno = 0;
 					val = strtol(field[i], &cp, 10);
 					if (errno == ERANGE)
 						return DTERR_FIELD_OVERFLOW;
@@ -1921,7 +1921,7 @@ DecodeTimeOnly(char **field, int *ftype, int nf,
 							break;
 					}
 
-					errno = 0;	/* avoid having to check the result for failure */
+					errno = 0;
 					val = strtol(field[i], &cp, 10);
 					if (errno == ERANGE)
 						return DTERR_FIELD_OVERFLOW;
@@ -2465,14 +2465,14 @@ DecodeTime(char *str, int fmask, int *tmask, struct pg_tm * tm, fsec_t *fsec)
 
 	*tmask = DTK_TIME_M;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	tm->tm_hour = strtol(str, &cp, 10);
 	if (errno == ERANGE)
 		return DTERR_FIELD_OVERFLOW;
 	if (*cp != ':')
 		return DTERR_BAD_FORMAT;
 	str = cp + 1;
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	tm->tm_min = strtol(str, &cp, 10);
 	if (errno == ERANGE)
 		return DTERR_FIELD_OVERFLOW;
@@ -2486,7 +2486,7 @@ DecodeTime(char *str, int fmask, int *tmask, struct pg_tm * tm, fsec_t *fsec)
 	else
 	{
 		str = cp + 1;
-		errno = 0;	/* avoid having to check the result for failure */
+		errno = 0;
 		tm->tm_sec = strtol(str, &cp, 10);
 		if (errno == ERANGE)
 			return DTERR_FIELD_OVERFLOW;
@@ -2540,7 +2540,7 @@ DecodeNumber(int flen, char *str, bool haveTextMonth, int fmask,
 
 	*tmask = 0;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	val = strtol(str, &cp, 10);
 	if (errno == ERANGE)
 		return DTERR_FIELD_OVERFLOW;
@@ -2830,7 +2830,7 @@ DecodeTimezone(char *str, int *tzp)
 	if (*str != '+' && *str != '-')
 		return DTERR_BAD_FORMAT;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	hr = strtol(str + 1, &cp, 10);
 	if (errno == ERANGE)
 		return DTERR_TZDISP_OVERFLOW;
@@ -2838,7 +2838,7 @@ DecodeTimezone(char *str, int *tzp)
 	/* explicit delimiter? */
 	if (*cp == ':')
 	{
-		errno = 0;	/* avoid having to check the result for failure */
+		errno = 0;
 		min = strtol(cp + 1, &cp, 10);
 		if (errno == ERANGE)
 			return DTERR_TZDISP_OVERFLOW;
@@ -3085,7 +3085,7 @@ DecodeInterval(char **field, int *ftype, int nf, int *dtype, struct pg_tm * tm,
 
 			case DTK_DATE:
 			case DTK_NUMBER:
-				errno = 0;	/* avoid having to check the result for failure */
+				errno = 0;
 				val = strtol(field[i], &cp, 10);
 				if (errno == ERANGE)
 					return DTERR_FIELD_OVERFLOW;
diff --git a/src/backend/utils/adt/float.c b/src/backend/utils/adt/float.c
index 1ba9107bc9..d50e4eaf6f 100644
--- a/src/backend/utils/adt/float.c
+++ b/src/backend/utils/adt/float.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.118 2005/12/01 21:11:58 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.119 2005/12/02 02:49:11 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -278,7 +278,7 @@ float4in(PG_FUNCTION_ARGS)
 	while (*num != '\0' && isspace((unsigned char) *num))
 		num++;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	val = strtod(num, &endptr);
 
 	/* did we not see anything that looks like a double? */
@@ -445,7 +445,7 @@ float8in(PG_FUNCTION_ARGS)
 	while (*num != '\0' && isspace((unsigned char) *num))
 		num++;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	val = strtod(num, &endptr);
 
 	/* did we not see anything that looks like a double? */
@@ -1476,7 +1476,7 @@ dpow(PG_FUNCTION_ARGS)
 	 * We must check both for errno getting set and for a NaN result, in order
 	 * to deal with the vagaries of different platforms...
 	 */
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = pow(arg1, arg2);
 	if (errno != 0
 #ifdef HAVE_FINITE
@@ -1506,7 +1506,7 @@ dexp(PG_FUNCTION_ARGS)
 	 * to deal with the vagaries of different platforms. Also, a zero result
 	 * implies unreported underflow.
 	 */
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = exp(arg1);
 	if (errno != 0 || result == 0.0
 #ifdef HAVE_FINITE
@@ -1590,7 +1590,7 @@ dacos(PG_FUNCTION_ARGS)
 	float8		arg1 = PG_GETARG_FLOAT8(0);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = acos(arg1);
 	if (errno != 0
 #ifdef HAVE_FINITE
@@ -1615,7 +1615,7 @@ dasin(PG_FUNCTION_ARGS)
 	float8		arg1 = PG_GETARG_FLOAT8(0);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = asin(arg1);
 	if (errno != 0
 #ifdef HAVE_FINITE
@@ -1640,7 +1640,7 @@ datan(PG_FUNCTION_ARGS)
 	float8		arg1 = PG_GETARG_FLOAT8(0);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = atan(arg1);
 	if (errno != 0
 #ifdef HAVE_FINITE
@@ -1666,7 +1666,7 @@ datan2(PG_FUNCTION_ARGS)
 	float8		arg2 = PG_GETARG_FLOAT8(1);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = atan2(arg1, arg2);
 	if (errno != 0
 #ifdef HAVE_FINITE
@@ -1691,7 +1691,7 @@ dcos(PG_FUNCTION_ARGS)
 	float8		arg1 = PG_GETARG_FLOAT8(0);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = cos(arg1);
 	if (errno != 0
 #ifdef HAVE_FINITE
@@ -1716,7 +1716,7 @@ dcot(PG_FUNCTION_ARGS)
 	float8		arg1 = PG_GETARG_FLOAT8(0);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = tan(arg1);
 	if (errno != 0 || result == 0.0
 #ifdef HAVE_FINITE
@@ -1742,7 +1742,7 @@ dsin(PG_FUNCTION_ARGS)
 	float8		arg1 = PG_GETARG_FLOAT8(0);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = sin(arg1);
 	if (errno != 0
 #ifdef HAVE_FINITE
@@ -1767,7 +1767,7 @@ dtan(PG_FUNCTION_ARGS)
 	float8		arg1 = PG_GETARG_FLOAT8(0);
 	float8		result;
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	result = tan(arg1);
 	if (errno != 0
 #ifdef HAVE_FINITE
diff --git a/src/backend/utils/adt/numutils.c b/src/backend/utils/adt/numutils.c
index 6d27160e03..c3a83f203f 100644
--- a/src/backend/utils/adt/numutils.c
+++ b/src/backend/utils/adt/numutils.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/numutils.c,v 1.71 2005/12/01 21:16:13 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/numutils.c,v 1.72 2005/12/02 02:49:11 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -73,7 +73,7 @@ pg_atoi(char *s, int size, int c)
 				 errmsg("invalid input syntax for integer: \"%s\"",
 						s)));
 
-	errno = 0;	/* avoid having to check the result for failure */
+	errno = 0;
 	l = strtol(s, &badp, 10);
 
 	/* We made no progress parsing the string, so bail out */
diff --git a/src/port/strtol.c b/src/port/strtol.c
index a103b446e6..866dad03e7 100644
--- a/src/port/strtol.c
+++ b/src/port/strtol.c
@@ -44,6 +44,15 @@ static char sccsid[] = "@(#)strtol.c	5.4 (Berkeley) 2/23/91";
 
 #define const
 
+/*
+ *	Usage Tip:
+ *
+ *	strtol() doesn't give a unique return value to indicate that errno
+ *	should be consulted, so in most cases it is best to set errno = 0
+ *	before calling this function, and then errno != 0 can be tested
+ *	after the function completes.
+ */
+ 
 /*
  * Convert a string to a long integer.
  *
-- 
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