Only unmount non-protected filesystems at shutdown

This patch adds support for a more fine grained approach to what
filesystems are unmounted at shutdown/reboot.  This so we later
can add support for `mdadm --wait-clean --scan`, which relies on
/proc, /sys, and /dev being there before we call reboot().

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

Makefile.am

@@ -1,8 +1,8 @@
 ACLOCAL_AMFLAGS    = -I m4
 sbin_PROGRAMS      = finit initctl reboot
-finit_SOURCES      = finit.c api.c client.c conf.c exec.c getty.c helpers.c pid.c \
+finit_SOURCES      = finit.c api.c client.c conf.c exec.c getty.c helpers.c \
-		     sig.c svc.c service.c plugin.c tty.c cond.c cond-w.c sm.c    \
+		     mount.c pid.c sig.c svc.c service.c plugin.c tty.c	    \
-		     utmp-api.c utmp-api.h
+		     cond.c cond-w.c sm.c utmp-api.c utmp-api.h
 pkginclude_HEADERS = cond.h finit.h helpers.h inetd.h plugin.h svc.h
 if INETD
 finit_SOURCES     += inetd.c

mount.c

@@ -0,0 +1,110 @@
+/* Mount and unmount helpers
+ *
+ * Copyright (c) 2016  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <string.h>
+#include <mntent.h>
+#include <sys/mount.h>
+
+/*
+ * SysV init on Debian/Ubuntu skips these protected mount points
+ *
+ * It also skips anything below /proc, /sys and /run for good meausre so
+ * we do the same here.  What we want is a list of non-protected tmpfs
+ * and regular filesystems that can be safely unmounted before we do
+ * swapoff, and remount / as read-only, respectively.
+ */
+static int is_protected(char *dir)
+{
+	size_t i;
+	char *protected[] = {
+		"/sys", "/proc",
+		"/.dev", "/dev", "/dev/pts", "/dev/shm", "dev/.static/dev", "/dev/vcs",
+		"/run", "/var/run",
+		"/", NULL
+	};
+	char *any[] = {
+		"/proc/", "/sys/", "/run/", NULL
+	};
+
+	for (i = 0; protected[i]; i++) {
+		if (!strcmp(dir, protected[i]))
+			return 1;
+	}
+
+	for (i = 0; any[i]; i++) {
+		if (!strncmp(dir, any[i], strlen(any[i])))
+			return 1;
+	}
+
+	return 0;
+}
+
+static struct mntent *iterator(char *fstab)
+{
+	static FILE *fp = NULL;
+	static struct mntent *mnt;
+
+	if (!fp && fstab) {
+		fp = setmntent(fstab, "r");
+		if (!fp)
+			return NULL;
+	}
+
+	while ((mnt = getmntent(fp))) {
+		if (is_protected(mnt->mnt_dir))
+			continue;
+
+		return mnt;
+	}
+
+	endmntent(fp);
+	fp = NULL;
+
+	return NULL;
+}
+
+void unmount_tmpfs(void)
+{
+	struct mntent *mnt;
+
+	while ((mnt = iterator("/proc/mounts"))) {
+		if (!strcmp("tmpfs", mnt->mnt_fsname))
+			umount(mnt->mnt_dir);
+	}
+}
+
+void unmount_regular(void)
+{
+	struct mntent *mnt;
+
+	while ((mnt = iterator("/proc/mounts"))) {
+		umount(mnt->mnt_dir);
+	}
+}
+
+/**
+ * Local Variables:
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */

sig.c

@@ -86,6 +86,9 @@ static uev_t sighup_watcher,  sigint_watcher,  sigpwr_watcher;
 static uev_t sigchld_watcher, sigsegv_watcher;
 static uev_t sigstop_watcher, sigtstp_watcher, sigcont_watcher;
 
+void unmount_tmpfs(void);
+void unmount_regular(void);
+
 
 void do_shutdown(shutop_t op)
 {
@@ -141,17 +144,19 @@ void do_shutdown(shutop_t op)
 	}
 
 	/* Unmount any tmpfs before unmounting swap ... */
-	run("/bin/umount -r -a");
+	unmount_tmpfs();
 	run("/sbin/swapoff -e -a");
 
-	/* Now, unmount everything else ... err, just force it. */
+	/* ... unmount remaining regular file systems. */
-	run("/bin/umount -n -f -r -a");
+	unmount_regular();
 
 	/* We sit on / so we must remount it ro, try all the things! */
 	run("/bin/mount -n -o remount,ro -t dummytype dummydev /");
 	run("/bin/mount -n -o remount,ro dummydev /");
 	run("/bin/mount -n -o remount,ro /");
 
+	/* XXX: Call mdadm to mark RAID array(s) as clean before halting. */
+
 	_d("%s.", op == SHUT_REBOOT ? "Rebooting" : "Halting");
 	if (op == SHUT_REBOOT)
 		reboot(RB_AUTOBOOT);