btrfs-progs: use parse_u64() to implement arg_strtou64()

Both functions are just doing the same thing, the only difference is
only in error handling, as parse_u64() requires callers to handle it,
meanwhile arg_strtou64() would call exit(1).

This patch would convert arg_strtou64() to utilize parse_u64(), and use
the return value to output different error messages.

This also means the return value of parse_u64() would be more than just
0 or 1, but -EINVAL for invalid string (including no numeric string at
all, has any tailing characters, or minus value), and -ERANGE for
overflow.

The existing callers are only checking if the return value is 0, thus
not really affected.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

common/parse-utils.c

@@ -31,14 +31,31 @@
 #include "common/messages.h"
 #include "common/utils.h"
 
+/*
+ * Parse a string to u64.
+ *
+ * Return 0 if there is a valid numeric string and result would be stored in
+ * @result.
+ * Return -EINVAL if the string is not valid (no numeric string at all, or
+ * has any tailing characters, or a negative value).
+ * Return -ERANGE if the value is too large for u64.
+ */
 int parse_u64(const char *str, u64 *result)
 {
 	char *endptr;
 	u64 val;
 
+	/*
+	 * Although strtoull accepts a negative number and converts it u64, we
+	 * don't really want to utilize this as the helper is meant for u64 only.
+	 */
+	if (str[0] == '-')
+		return -EINVAL;
 	val = strtoull(str, &endptr, 10);
 	if (*endptr)
-		return 1;
+		return -EINVAL;
+	if (val == ULLONG_MAX && errno == ERANGE)
+		return -ERANGE;
 
 	*result = val;
 	return 0;

common/string-utils.c

@@ -20,6 +20,7 @@
 #include <limits.h>
 #include "common/string-utils.h"
 #include "common/messages.h"
+#include "common/parse-utils.h"
 
 int string_is_numerical(const char *str)
 {
@@ -50,25 +51,18 @@ int string_has_prefix(const char *str, const char *prefix)
 u64 arg_strtou64(const char *str)
 {
 	u64 value;
-	char *ptr_parse_end = NULL;
+	int ret;
 
-	value = strtoull(str, &ptr_parse_end, 0);
-	if (ptr_parse_end && *ptr_parse_end != '\0') {
-		error("%s is not a valid numeric value", str);
-		exit(1);
-	}
-
-	/*
-	 * if we pass a negative number to strtoull, it will return an
-	 * unexpected number to us, so let's do the check ourselves.
-	 */
-	if (str[0] == '-') {
-		error("%s: negative value is invalid", str);
-		exit(1);
-	}
-	if (value == ULLONG_MAX) {
+	ret = parse_u64(str, &value);
+	if (ret == -ERANGE) {
 		error("%s is too large", str);
 		exit(1);
+	} else if (ret == -EINVAL) {
+		if (str[0] == '-')
+			error("%s: negative value is invalid", str);
+		else
+			error("%s is not a valid numeric value", str);
+		exit(1);
 	}
 	return value;
 }

common/string-utils.h

@@ -17,6 +17,8 @@
 #ifndef __BTRFS_STRING_UTILS_H__
 #define __BTRFS_STRING_UTILS_H__
 
+#include "kerncompat.h"
+
 int string_is_numerical(const char *str);
 int string_has_prefix(const char *str, const char *prefix);
 u64 arg_strtou64(const char *str);