Fix #49: Skip tmpfs directories at bootclean

We can safely skip tmpfs, nothing to clean from previous boot there.
In fact, if we clean it we may spoil things for udev, which saves
pre-boot files in /run/udev.

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

plugins/bootmisc.c

@@ -22,6 +22,7 @@
  */
 
 #include <ftw.h>
+#include <mntent.h>
 #include <string.h>
 #include <lite/lite.h>
 
@@ -31,6 +32,28 @@
 #include "../plugin.h"
 #include "../utmp-api.h"
 
+static int is_tmpfs(char *dir)
+{
+	int tmpfs = 0;
+	FILE *fp;
+	struct mntent *mnt;
+
+	fp = setmntent("/proc/mounts", "r");
+	if (!fp)
+		return 0;	/* Dunno, maybe not */
+
+	while ((mnt = getmntent(fp))) {
+		if (!strcmp(dir, mnt->mnt_dir))
+			break;
+	}
+
+	if (mnt && !strcmp("tmpfs", mnt->mnt_type))
+		tmpfs = 1;
+	endmntent(fp);
+
+	return tmpfs;
+}
+
 static void create(char *path, mode_t mode, uid_t uid, gid_t gid)
 {
 	if (touch(path) || chmod(path, mode) || chown(path, uid, gid))
@@ -48,6 +71,7 @@ static int do_clean(const char *fpath, const struct stat *UNUSED(sb), int UNUSED
 	return 0;
 }
 
+/* We can safely skip tmpfs, nothing to clean from previous boot there */
 static void bootclean(void)
 {
 	char *dir[] = {
@@ -57,8 +81,12 @@ static void bootclean(void)
 		NULL
 	};
 
-	for (int i = 0; dir[i]; i++)
+	for (int i = 0; dir[i]; i++) {
+		if (is_tmpfs(dir[i]))
+			continue;
+
 		nftw(dir[i], do_clean, 20, FTW_DEPTH);
+	}
 }
 
 /*