Fix build with glibc 2.43 sntp/crypto.c includes sntp/config.h, then sntp/crypto.h which includes ntp_stdlib.h which in turn includes l_stdlib.h that contains #ifndef HAVE_MEMCHR extern void *memchr(const void *s, int c, size_t n); #endif and breaks the build with glibc 2.43: ./../include/l_stdlib.h:225:14: error: expected identifier or '(' before '_Generic' 225 | extern void *memchr(const void *s, int c, size_t n); sntp/config.h does not contain any information about memchr() while the top-level config.h does but this top-level config.h is not included because sntp/Makefile lacks -I$(top_builddir) so sntp/config.h gets included which does not define HAVE_MEMCHR although glibc does provide memchr() but sntp/configure lacks a check for memchr(). This was not a problem with previous glibc versions but due to recent C23 changes in glibc the ntp build is now broken. To fix the problem we add a configure check for memchr() to sntp/configure so HAVE_MEMCHR gets defined in sntp/config.h. Upstream: https://bugs.ntp.org/show_bug.cgi?id=4015 Signed-off-by: Bernd Kuhls diff -uNr ntp-4.2.8p18/sntp/m4/ntp_libntp.m4 ntp-4.2.8p18/sntp/m4/ntp_libntp.m4 --- ntp-4.2.8p18/sntp/m4/ntp_libntp.m4 2024-05-07 13:21:13.000000000 +0200 +++ ntp-4.2.8p18/sntp/m4/ntp_libntp.m4 2026-02-19 21:50:37.291724180 +0100 @@ -77,7 +77,7 @@ ;; esac -AC_CHECK_FUNCS([getclock stime timegm strlcpy strlcat]) +AC_CHECK_FUNCS([getclock memchr stime timegm strlcpy strlcat]) # Bug 2713 LDADD_LIBUTIL=