diff -up Linux-PAM-1.3.1/libpam/include/pam_cc_compat.h.inline Linux-PAM-1.3.1/libpam/include/pam_cc_compat.h
--- Linux-PAM-1.3.1/libpam/include/pam_cc_compat.h.inline	2022-05-26 10:44:31.702623614 +0200
+++ Linux-PAM-1.3.1/libpam/include/pam_cc_compat.h	2022-05-26 10:44:31.703623621 +0200
@@ -44,4 +44,17 @@
 # define DIAG_POP_IGNORE_CAST_ALIGN	/* empty */
 #endif
 
+/*
+ * Evaluates to
+ * 1, if the given two types are known to be the same
+ * 0, otherwise.
+ */
+#if PAM_GNUC_PREREQ(3, 0)
+# define PAM_IS_SAME_TYPE(x_, y_)					\
+	__builtin_types_compatible_p(__typeof__(x_), __typeof__(y_))
+#else
+/* Cannot tell whether these types are the same.  */
+# define PAM_IS_SAME_TYPE(x_, y_)	0
+#endif
+
 #endif /* PAM_CC_COMPAT_H */
diff -up Linux-PAM-1.3.1/libpam/include/pam_inline.h.inline Linux-PAM-1.3.1/libpam/include/pam_inline.h
--- Linux-PAM-1.3.1/libpam/include/pam_inline.h.inline	2022-05-26 10:44:31.703623621 +0200
+++ Linux-PAM-1.3.1/libpam/include/pam_inline.h	2022-05-26 10:44:31.703623621 +0200
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2020 Dmitry V. Levin <ldv@altlinux.org>
+ *
+ * Handy inline functions and macros providing some convenient functionality
+ * to libpam and its modules.
+ */
+
+#ifndef PAM_INLINE_H
+#define PAM_INLINE_H
+
+#include "pam_cc_compat.h"
+#include <string.h>
+
+/*
+ * Evaluates to
+ * - a syntax error if the argument is 0,
+ * 0, otherwise.
+ */
+#define PAM_FAIL_BUILD_ON_ZERO(e_)	(sizeof(int[-1 + 2 * !!(e_)]) * 0)
+
+/*
+ * Evaluates to
+ * 1, if the given type is known to be a non-array type
+ * 0, otherwise.
+ */
+#define PAM_IS_NOT_ARRAY(a_)		PAM_IS_SAME_TYPE((a_), &(a_)[0])
+
+/*
+ * Evaluates to
+ * - a syntax error if the argument is not an array,
+ * 0, otherwise.
+ */
+#define PAM_MUST_BE_ARRAY(a_)		PAM_FAIL_BUILD_ON_ZERO(!PAM_IS_NOT_ARRAY(a_))
+
+/* Evaluates to the number of elements in the specified array.  */
+#define PAM_ARRAY_SIZE(a_)		(sizeof(a_) / sizeof((a_)[0]) + PAM_MUST_BE_ARRAY(a_))
+
+/*
+ * Returns NULL if STR does not start with PREFIX,
+ * or a pointer to the first char in STR after PREFIX.
+ * The length of PREFIX is specified by PREFIX_LEN.
+ */
+static inline const char *
+pam_str_skip_prefix_len(const char *str, const char *prefix, size_t prefix_len)
+{
+	return strncmp(str, prefix, prefix_len) ? NULL : str + prefix_len;
+}
+
+#define pam_str_skip_prefix(str_, prefix_)	\
+	pam_str_skip_prefix_len((str_), (prefix_), sizeof(prefix_) - 1 + PAM_MUST_BE_ARRAY(prefix_))
+
+/*
+ * Returns NULL if STR does not start with PREFIX
+ * (ignoring the case of the characters),
+ * or a pointer to the first char in STR after PREFIX.
+ * The length of PREFIX is specified by PREFIX_LEN.
+ */
+static inline const char *
+pam_str_skip_icase_prefix_len(const char *str, const char *prefix, size_t prefix_len)
+{
+	return strncasecmp(str, prefix, prefix_len) ? NULL : str + prefix_len;
+}
+
+#define pam_str_skip_icase_prefix(str_, prefix_)	\
+	pam_str_skip_icase_prefix_len((str_), (prefix_), sizeof(prefix_) - 1 + PAM_MUST_BE_ARRAY(prefix_))
+
+#endif /* PAM_INLINE_H */
diff -up Linux-PAM-1.3.1/libpam/Makefile.am.inline Linux-PAM-1.3.1/libpam/Makefile.am
--- Linux-PAM-1.3.1/libpam/Makefile.am.inline	2022-05-26 10:44:31.702623614 +0200
+++ Linux-PAM-1.3.1/libpam/Makefile.am	2022-05-26 10:45:21.146977780 +0200
@@ -18,7 +18,8 @@ include_HEADERS = include/security/_pam_
 	include/security/pam_ext.h include/security/pam_modutil.h
 
 noinst_HEADERS = pam_prelude.h pam_private.h pam_tokens.h \
-		pam_modutil_private.h include/pam_cc_compat.h
+		pam_modutil_private.h include/pam_cc_compat.h \
+		include/pam_inline.h
 
 libpam_la_LDFLAGS = -no-undefined -version-info 84:2:84
 libpam_la_LIBADD = @LIBAUDIT@ $(LIBPRELUDE_LIBS) @LIBDL@