https://github.com/libpwquality/libpwquality/commit/9084c1b032161cdb53d5f66132a91bdc207faecf

From: Noel Kuntze <noel.kuntze@thermi.consulting>
Date: Mon, 24 May 2021 14:15:34 +0200
Subject: [PATCH] pam_pwquality.c: Use pam_modutil_check_user_in_passwd instead
 of fgetpwent_r (not available on musl)

--- a/configure.ac
+++ b/configure.ac
@@ -97,6 +97,11 @@ if test "$enable_pam" != "no"; then
       test $fail = 1 &&
         AC_MSG_ERROR([You must install the PAM development package in order to compile libpwquality])
   fi
+  AC_CHECK_FUNC(
+    [pam_modutil_check_user_in_passwd],
+    [AC_DEFINE([HAVE_PAM_CHECK_USER_IN_PASSWD], [], [have pam_modutil_check_user_in_passwd])],
+    []
+  )  
 fi
 
 if test "$enable_pam" = "yes"; then
--- a/src/pam_pwquality.c
+++ b/src/pam_pwquality.c
@@ -98,6 +98,9 @@ static int
 check_local_user (pam_handle_t *pamh,
                   const char *user)
 {
+#ifdef HAVE_PAM_CHECK_USER_IN_PASSWD
+        return pam_modutil_check_user_in_passwd(pamh, user, NULL) == PAM_SUCCESS;
+#else
         struct passwd pw, *pwp;
         char buf[4096];
         int found = 0;
@@ -136,6 +139,7 @@ check_local_user (pam_handle_t *pamh,
         } else {
                 return found;
         }
+#endif
 }
 
 PAM_EXTERN int