wic: Warn if an ext filesystem affected by the Y2038 problem is used

We are getting closer and closer to the year 2038 where the 32 bit
time_t overflow will happen. While products (= embedded systems) with an
expected life time of 15 years are still save the situation may change
if your system has to survive the next 20 years.

ext2 and ext3 filesystems are always affected by the time overflow, so
let's warn the user if these filesystems are still being used.

If ext4 is affected depends on the inode size chosen during filesystem
creation. At least 256 bytes are necessary to be safe. As ext4 is
used very often (and partitions may be created small first and extended
later) this might be an issue for many users.

Some filesystems created during CI runs were already affected by the Y2038
problem. By using `--mkfs-extraopts "-T default"` we tell mke2fs not to
auto-detect the usage type based on the filesystem size. mke2fs will use
the default values for tuning parameters instead. The inode size is one
of these parameters.

(From OE-Core rev: eecbe625558406680121d2a7e84917fea45ea9dc)

Signed-off-by: Florian Bezdeka <florian.bezdeka@siemens.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/canned-wks/common.wks.inc

@@ -1,3 +1,3 @@
 # This file is included into 3 canned wks files from this directory
 part /boot --source bootimg-pcbios --ondisk sda --label boot --active --align 1024
-part / --source rootfs --use-uuid --fstype=ext4 --label platform --align 1024
+part / --source rootfs --use-uuid --fstype=ext4 --mkfs-extraopts "-T default" --label platform --align 1024

scripts/lib/wic/canned-wks/directdisk-gpt.wks

@@ -4,7 +4,7 @@
 
 
 part /boot --source bootimg-pcbios --ondisk sda --label boot --active --align 1024
-part / --source rootfs --ondisk sda --fstype=ext4 --label platform --align 1024 --use-uuid
+part / --source rootfs --ondisk sda --fstype=ext4 --mkfs-extraopts "-T default" --label platform --align 1024 --use-uuid
 
 bootloader  --ptable gpt --timeout=0  --append="rootwait rootfstype=ext4 video=vesafb vga=0x318 console=tty0 console=ttyS0,115200n8"
 

scripts/lib/wic/canned-wks/mkefidisk.wks

@@ -4,7 +4,7 @@
 
 part /boot --source bootimg-efi --sourceparams="loader=grub-efi" --ondisk sda --label msdos --active --align 1024
 
-part / --source rootfs --ondisk sda --fstype=ext4 --label platform --align 1024 --use-uuid
+part / --source rootfs --ondisk sda --fstype=ext4 --mkfs-extraopts "-T default"  --label platform --align 1024 --use-uuid
 
 part swap --ondisk sda --size 44 --label swap1 --fstype=swap
 

scripts/lib/wic/misc.py

@@ -26,6 +26,7 @@ logger = logging.getLogger('wic')
 
 # executable -> recipe pairs for exec_native_cmd
 NATIVE_RECIPES = {"bmaptool": "bmap-tools",
+                  "dumpe2fs": "e2fsprogs",
                   "grub-mkimage": "grub-efi",
                   "isohybrid": "syslinux",
                   "mcopy": "mtools",

scripts/lib/wic/partition.py

@@ -298,6 +298,8 @@ class Partition():
         mkfs_cmd = "fsck.%s -pvfD %s" % (self.fstype, rootfs)
         exec_native_cmd(mkfs_cmd, native_sysroot, pseudo=pseudo)
 
+        self.check_for_Y2038_problem(rootfs, native_sysroot)
+
     def prepare_rootfs_btrfs(self, rootfs, cr_workdir, oe_builddir, rootfs_dir,
                              native_sysroot, pseudo):
         """
@@ -388,6 +390,8 @@ class Partition():
             (self.fstype, extraopts, label_str, self.fsuuid, rootfs)
         exec_native_cmd(mkfs_cmd, native_sysroot)
 
+        self.check_for_Y2038_problem(rootfs, native_sysroot)
+
     def prepare_empty_partition_btrfs(self, rootfs, oe_builddir,
                                       native_sysroot):
         """
@@ -449,3 +453,37 @@ class Partition():
 
         mkswap_cmd = "mkswap %s -U %s %s" % (label_str, self.fsuuid, path)
         exec_native_cmd(mkswap_cmd, native_sysroot)
+
+    def check_for_Y2038_problem(self, rootfs, native_sysroot):
+        """
+        Check if the filesystem is affected by the Y2038 problem
+        (Y2038 problem = 32 bit time_t overflow in January 2038)
+        """
+        def get_err_str(part):
+            err = "The {} filesystem {} has no Y2038 support."
+            if part.mountpoint:
+                args = [part.fstype, "mounted at %s" % part.mountpoint]
+            elif part.label:
+                args = [part.fstype, "labeled '%s'" % part.label]
+            elif part.part_name:
+                args = [part.fstype, "in partition '%s'" % part.part_name]
+            else:
+                args = [part.fstype, "in partition %s" % part.num]
+            return err.format(*args)
+
+        # ext2 and ext3 are always affected by the Y2038 problem
+        if self.fstype in ["ext2", "ext3"]:
+            logger.warn(get_err_str(self))
+            return
+
+        ret, out = exec_native_cmd("dumpe2fs %s" % rootfs, native_sysroot)
+
+        # if ext4 is affected by the Y2038 problem depends on the inode size
+        for line in out.splitlines():
+            if line.startswith("Inode size:"):
+                size = int(line.split(":")[1].strip())
+                if size < 256:
+                    logger.warn("%s Inodes (of size %d) are too small." %
+                                (get_err_str(self), size))
+                break
+