AUTOTOOLS: More robust detection of inotify.

We checked only header file "sys/inotify" for detection whether inotify
works. Some platforms do not have built in inotify, but contain library,
which provides inotify-compatible interface.

This patch adds more robust detection of inotify in configuration time and
appends linker flags to Makefile if inotify is provided by library.

4 files changed, 39 insertions, 5 deletions

diff --git a/Makefile.am b/Makefile.am
index b6d2fd0d..d21c5a71 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -630,6 +630,7 @@ sssd_SOURCES = \
     src/util/nscd.c
 sssd_LDADD = \
     $(SSSD_LIBS) \
+    $(INOTIFY_LIBS) \
     $(LIBNL_LIBS) \
     $(KEYUTILS_LIBS) \
     $(SSSD_INTERNAL_LTLIBS)
diff --git a/configure.ac b/configure.ac
index cdf46d4c..ebce2025 100644
--- a/configure.ac
+++ b/configure.ac
@@ -153,6 +153,7 @@ m4_include([src/external/libnl.m4])
 m4_include([src/external/systemd.m4])
 m4_include([src/external/pac_responder.m4])
 m4_include([src/external/signal.m4])
+m4_include([src/external/inotify.m4])
 m4_include([src/external/libndr_nbt.m4])
 
 WITH_UNICODE_LIB
@@ -251,7 +252,7 @@ if test x$cryptolib = xlibcrypto; then
     AM_CHECK_LIBCRYPTO
 fi
 
-AC_CHECK_HEADERS([sys/inotify.h])
+AM_CHECK_INOTIFY
 
 AC_CHECK_HEADERS([sasl/sasl.h],,AC_MSG_ERROR([Could not find SASL headers]))
 
diff --git a/src/external/inotify.m4 b/src/external/inotify.m4
new file mode 100644
index 00000000..9572f6d2
--- /dev/null
+++ b/src/external/inotify.m4
@@ -0,0 +1,32 @@
+dnl A macro to check if inotify works
+AC_DEFUN([AM_CHECK_INOTIFY],
+[
+    AC_CHECK_HEADERS([sys/inotify.h])
+
+    AC_MSG_CHECKING([whether sys/inotify.h actually works])
+    AC_LINK_IFELSE(
+        [AC_LANG_SOURCE([
+#ifdef HAVE_SYS_INOTITY_H
+#include <sys/inotify.h>,
+#endif
+int main () {
+    return (-1 == inotify_init());
+}])],
+        [AC_MSG_RESULT([yes]); inotify_works=yes],
+        [AC_MSG_RESULT([no])]
+    )
+
+    SSS_AC_EXPAND_LIB_DIR()
+    AS_IF([test x"$inotify_works" != xyes],
+          [AC_CHECK_LIB([inotify],
+                        [inotify_init],
+                        [INOTIFY_LIBS="$sss_extra_libdir -linotify"
+                         inotify_works=yes],
+                        [inotify_works=no],
+                        [$sss_extra_libdir])]
+    )
+
+    AS_IF([test x"$inotify_works" = xyes],
+          [AC_DEFINE_UNQUOTED([HAVE_INOTIFY], [1], [Inotify works])])
+    AC_SUBST(INOTIFY_LIBS)
+])
diff --git a/src/monitor/monitor.c b/src/monitor/monitor.c
index 495f31e3..d8bbfbcb 100644
--- a/src/monitor/monitor.c
+++ b/src/monitor/monitor.c
@@ -1642,7 +1642,7 @@ errno_t monitor_config_file_fallback(TALLOC_CTX *mem_ctx,
                                      monitor_reconf_fn fn,
                                      bool ignore_missing);
 
-#ifdef HAVE_SYS_INOTIFY_H
+#ifdef HAVE_INOTIFY
 static void process_config_file(struct tevent_context *ev,
                                 struct tevent_timer *te,
                                 struct timeval t, void *ptr);
@@ -1867,7 +1867,7 @@ static void rewatch_config_file(struct tevent_context *ev,
     talloc_free(rw_ctx);
     file_ctx->needs_update = 0;
 }
-#endif
+#endif /* HAVE_INOTIFY */
 
 static void poll_config_file(struct tevent_context *ev,
                                     struct tevent_timer *te,
@@ -1917,7 +1917,7 @@ static void poll_config_file(struct tevent_context *ev,
 static int try_inotify(struct config_file_ctx *file_ctx, const char *filename,
                        monitor_reconf_fn fn)
 {
-#ifdef HAVE_SYS_INOTIFY_H
+#ifdef HAVE_INOTIFY
     int err, fd_args, ret;
     struct tevent_fd *tfd;
     struct config_file_callback *cb;
@@ -1986,7 +1986,7 @@ static int try_inotify(struct config_file_ctx *file_ctx, const char *filename,
     return EOK;
 #else
     return EINVAL;
-#endif
+#endif /* HAVE_INOTIFY */
 }
 
 static int monitor_config_file(TALLOC_CTX *mem_ctx,