Initialize errno before calling sscanf in json_parse_int64() so parsing valid numbers after parsing an out of range number works.

json_util.c

@@ -147,11 +147,14 @@ int json_parse_int64(const char *buf, int64_t *retval)
 	int64_t num64;
 	const char *buf_skip_space;
 	int orig_has_neg;
+	int _errno;
+	errno = 0; // sscanf won't always set errno, so initialize
 	if (sscanf(buf, "%" SCNd64, &num64) != 1)
 	{
 		MC_DEBUG("Failed to parse, sscanf != 1\n");
 		return 1;
 	}
+	_errno = errno;
 	buf_skip_space = buf;
 	orig_has_neg = 0;
 	// Skip leading spaces
@@ -168,7 +171,7 @@ int json_parse_int64(const char *buf, int64_t *retval)
 	if (buf_skip_space[0] == '0' && buf_skip_space[1] == '\0')
 		orig_has_neg = 0; // "-0" is the same as just plain "0"
 	
-	if (errno != ERANGE)
+	if (_errno != ERANGE)
 	{
 		char buf_cmp[100];
 		char *buf_cmp_start = buf_cmp;
@@ -196,10 +199,10 @@ int json_parse_int64(const char *buf, int64_t *retval)
 		    )
 		   )
 		{
-			errno = ERANGE;
+			_errno = ERANGE;
 		}
 	}
-	if (errno == ERANGE)
+	if (_errno == ERANGE)
 	{
 		if (orig_has_neg)
 			num64 = INT64_MIN;

tests/test_parse_int64.c

@@ -80,6 +80,9 @@ int main()
 	strcpy(buf, "-21474836480"); // INT32_MIN * 10
 	checkit(buf);
 
+	strcpy(buf, "9223372036854775806"); // INT64_MAX - 1
+	checkit(buf);
+
 	strcpy(buf, "9223372036854775807"); // INT64_MAX
 	checkit(buf);
 
@@ -92,6 +95,9 @@ int main()
 	strcpy(buf, "-9223372036854775809"); // INT64_MIN - 1
 	checkit(buf);
 
+	strcpy(buf, "18446744073709551614"); // UINT64_MAX - 1
+	checkit(buf);
+
 	strcpy(buf, "18446744073709551615"); // UINT64_MAX
 	checkit(buf);
 
@@ -101,5 +107,9 @@ int main()
 	strcpy(buf, "-18446744073709551616"); // -UINT64_MAX
 	checkit(buf);
 
+	// Ensure we can still parse valid numbers after parsing out of range ones.
+	strcpy(buf, "123");
+	checkit(buf);
+
 	return 0;
 }

tests/test_parse_int64.expected

@@ -17,10 +17,13 @@ buf=-2147483647 parseit=0, value=-2147483647
 buf=-2147483648 parseit=0, value=-2147483648 
 buf=-2147483649 parseit=0, value=-2147483649 
 buf=-21474836480 parseit=0, value=-21474836480 
+buf=9223372036854775806 parseit=0, value=9223372036854775806 
 buf=9223372036854775807 parseit=0, value=9223372036854775807 
 buf=9223372036854775808 parseit=0, value=9223372036854775807 
 buf=-9223372036854775808 parseit=0, value=-9223372036854775808 
 buf=-9223372036854775809 parseit=0, value=-9223372036854775808 
+buf=18446744073709551614 parseit=0, value=9223372036854775807 
 buf=18446744073709551615 parseit=0, value=9223372036854775807 
 buf=18446744073709551616 parseit=0, value=9223372036854775807 
 buf=-18446744073709551616 parseit=0, value=-9223372036854775808 
+buf=123 parseit=0, value=123