From: Karel Zak <kzak@redhat.com>
Date: Thu, 7 Aug 2025 11:15:32 +0000 (+0200)
Subject: libmount: ifdef for fanotify support on older systems
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=489ebfe7046136ca02b6df7ec5b75f3daa2980fb;p=thirdparty%2Futil-linux.git

libmount: ifdef for fanotify support on older systems

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/configure.ac b/configure.ac
index f076f60f1..6836f0564 100644
--- a/configure.ac
+++ b/configure.ac
@@ -550,6 +550,8 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 [AC_DEFINE([HAVE_TM_GMTOFF], [1], [Does struct tm have a field tm_gmtoff?])
 ])
 
+AC_CHECK_TYPES([struct fanotify_event_info_header], [], [], [[#include <linux/fanotify.h>]])
+
 AC_CHECK_TYPES([struct mount_attr], [], [], [[#include <linux/mount.h>]])
 AC_CHECK_TYPES([enum fsconfig_command], [], [], [[#include <linux/mount.h>]])
 
diff --git a/libmount/src/monitor_fanotify.c b/libmount/src/monitor_fanotify.c
index 7e6903beb..e9e6e64f6 100644
--- a/libmount/src/monitor_fanotify.c
+++ b/libmount/src/monitor_fanotify.c
@@ -14,6 +14,14 @@
 #include "mountP.h"
 #include "monitor.h"
 
+/*
+ * The fanotify info header is suppported since kernel v5.1 (commit 5e469c830fdb5).
+ *
+ * We do not provide fallback for so old systems. There is fallback only for
+ * missing "struct fanotify_event_info_mnt" (since v6.15, commit 0f46d81f2bce9).
+ */
+#ifdef HAVE_STRUCT_FANOTIFY_EVENT_INFO_HEADER
+
 #include "strutils.h"
 #include "pathnames.h"
 
@@ -319,3 +327,16 @@ err:
 	DBG(MONITOR, ul_debugobj(mn, "failed to allocate fanotify monitor [rc=%d]", rc));
 	return rc;
 }
+
+
+#else /* !HAVE_STRUCT_FANOTIFY_EVENT_INFO_HEADER */
+
+int mnt_monitor_enable_fanotify(
+		struct libmnt_monitor *mn __attribute__((__unused__)),
+		int enable __attribute__((__unused__)),
+		int ns __attribute__((__unused__)))
+{
+	errno = ENOTSUP;
+	return -errno;
+}
+#endif
diff --git a/libmount/src/version.c b/libmount/src/version.c
index 3b61618b5..19326d280 100644
--- a/libmount/src/version.c
+++ b/libmount/src/version.c
@@ -49,6 +49,9 @@ static const char *lib_features[] = {
 #if defined(HAVE_STATX) && defined(HAVE_STRUCT_STATX) && defined(AT_STATX_DONT_SYNC)
 	"statx",
 #endif
+#ifdef HAVE_STRUCT_FANOTIFY_EVENT_INFO_HEADER
+	"fanotify",
+#endif
 #if !defined(NDEBUG)
 	"assert",	/* libc assert.h stuff */
 #endif
diff --git a/meson.build b/meson.build
index 68c040442..e3038240a 100644
--- a/meson.build
+++ b/meson.build
@@ -99,11 +99,13 @@ login_lastlogin = get_option('login-lastlogin')
 conf.set('USE_LOGIN_LASTLOG', login_lastlogin ? 1 : false)
 summary('login-lastlogin', login_lastlogin ? 'enabled' : 'disabled', section : 'components')
 
+have = cc.has_type('struct fanotify_event_info_header', prefix : '#include <linux/fanotify.h>')
+conf.set('HAVE_STRUCT_FANOTIFY_EVENT_INFO_HEADER', have ? 1 : false)
+
 have_mountfd_api = cc.has_type('struct mount_attr', prefix : '#include <linux/mount.h>')
 conf.set('HAVE_STRUCT_MOUNT_ATTR', have_mountfd_api ? 1 : false)
 conf.set('HAVE_MOUNTFD_API', have_mountfd_api ? 1 : false)
 
-
 have_struct_statx = cc.has_type('struct statx', prefix : '#include <sys/stat.h>')
 conf.set('HAVE_STRUCT_STATX', have_struct_statx ? 1 : false)
 have = cc.has_member('struct statx', 'stx_mnt_id',