--- /dev/null
+/* Simple strspn.
+
+ Copyright (C) 2022 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <string.h>
+
+size_t strspn (const char *str, const char *accept)
+{
+ if (accept[0] == 0)
+ return 0;
+ if (accept[1] == 0)
+ {
+ const char *p;
+ for (p = str; *p == accept[0]; p++);
+ return p - str;
+ }
+
+ unsigned char table[256] = {0};
+ unsigned char *us;
+ for (us = (unsigned char*) accept; *us != 0; table[*us++] = 1);
+
+ for (us = (unsigned char*) str; table[*us] != 0; us++);
+ return us - (unsigned char *) str;
+}
+libc_hidden_builtin_def (strspn)