btrfs-progs: reset errno before strtoull()

strtoull may return the boundary values, if the callers could expect
that and verify it then the errno must be reset before the call.

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

common/parse-utils.c

@@ -158,6 +158,7 @@ u64 parse_size_from_string(const char *s)
 		error("size value '%s' is less equal than 0", s);
 		exit(1);
 	}
+	errno = 0;
 	ret = strtoull(s, &endptr, 10);
 	if (endptr == s) {
 		error("size value '%s' is invalid", s);

common/sysfs-utils.c

@@ -108,6 +108,7 @@ int sysfs_read_file_u64(const char *name, u64 *value)
 	if (ret < 0)
 		goto out;
 	/* Raw value in any numeric format should work, followed by a newline. */
+	errno = 0;
 	*value = strtoull(str, NULL, 0);
 out:
 	close(fd);
@@ -127,6 +128,7 @@ int sysfs_read_fsid_file_u64(int fd, const char *name, u64 *value)
 	if (ret < 0)
 		goto out;
 	/* Raw value in any numeric format should work, followed by a newline. */
+	errno = 0;
 	*value = strtoull(str, NULL, 0);
 out:
 	close(fd);