wic: Optimise fstab modification for ext2/3/4 and msdos partitions

The fix for [Yocto #13994] required the rootfs directory to be copied
(using hardlinks if possible) when modifying the fstab file under wic.

We can optimise this copy away for filesystems where we have the tools
to modify the contents of the partition image after it is created. For
ext2/3/4 filesystems we have the debugfs tool and for msdos/vfat
filesystems we have the mcopy tool. So for any of these filesystems we
skip the modification of the fstab file in the rootfs directory (and
skip the associated copy unless it is otherwise necessary) and update
the contents of fstab directly in the partition image.

(From OE-Core rev: 1988d07b65ad38bdf8fac8615f11fb6536a75806)

Signed-off-by: Paul Barker <pbarker@konsulko.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 5fb8ae0e9159597d7eaa9307a3a8543800bf9405)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/scripts/lib/wic/plugins/source/rootfs.py b/scripts/lib/wic/plugins/source/rootfs.py
index f19ec3312b..c8c1c0f58f 100644
--- a/scripts/lib/wic/plugins/source/rootfs.py
+++ b/scripts/lib/wic/plugins/source/rootfs.py
@@ -77,6 +77,7 @@ class RootfsPlugin(SourcePlugin):
                                "it is not a valid path, exiting" % part.rootfs_dir)
 
         part.rootfs_dir = cls.__get_rootfs_dir(rootfs_dir)
+        part.has_fstab = os.path.exists(os.path.join(part.rootfs_dir, "etc/fstab"))
         pseudo_dir = os.path.join(part.rootfs_dir, "../pseudo")
         if not os.path.lexists(pseudo_dir):
             logger.warn("%s folder does not exist. "
@@ -86,7 +87,7 @@ class RootfsPlugin(SourcePlugin):
         new_rootfs = None
         new_pseudo = None
         # Handle excluded paths.
-        if part.exclude_path or part.include_path or part.change_directory or part.updated_fstab_path:
+        if part.exclude_path or part.include_path or part.change_directory or part.update_fstab_in_rootfs:
             # We need a new rootfs directory we can safely modify without
             # interfering with other tasks. Copy to workdir.
             new_rootfs = os.path.realpath(os.path.join(cr_workdir, "rootfs%d" % part.lineno))
@@ -159,8 +160,10 @@ class RootfsPlugin(SourcePlugin):
                     rm_cmd = "rm -rf %s" % (full_path)
                     exec_native_cmd(rm_cmd, native_sysroot, pseudo)
 
-            has_fstab = os.path.exists(os.path.join(new_rootfs, "etc/fstab"))
-            if part.updated_fstab_path and has_fstab:
+            # Update part.has_fstab here as fstab may have been added or
+            # removed by the above modifications.
+            part.has_fstab = os.path.exists(os.path.join(new_rootfs, "etc/fstab"))
+            if part.update_fstab_in_rootfs and part.has_fstab:
                 fstab_path = os.path.join(new_rootfs, "etc/fstab")
                 # Assume that fstab should always be owned by root with fixed permissions
                 install_cmd = "install -m 0644 %s %s" % (part.updated_fstab_path, fstab_path)