[gnome-continuous-yocto/gnomeostree-3.28-rocko: 7019/8267] wic: copy rootfs directory before changing fstab

[Emmanuele Bassi <ebassi src gnome org>]

commit c4f9d8151fb680570d89bdbc9f969c8d9760091c
Author: Ed Bartosh <ed bartosh linux intel com>
Date:   Tue Jul 25 14:26:36 2017 +0300

    wic: copy rootfs directory before changing fstab
    
    wic updates /etc/fstab on root partition if there are
    valid mount points in .wks
    
    When wic runs from bitbake this can cause incorrect results
    or even breakage of other tasks working with the same rootfs
    directory in parallel with do_image_wic.
    
    Implemented copying rootfs directory to a temporary location
    using copyhardlinktree before updating fstab to avoid conflicts with
    other tasks working with the same rootfs directory.
    
    (From OE-Core rev: 92e1c7d47e695eb4ce1a863cd0f6c49dca1c2339)
    
    Signed-off-by: Ed Bartosh <ed bartosh linux intel com>
    Signed-off-by: Richard Purdie <richard purdie linuxfoundation org>

 scripts/lib/wic/plugins/imager/direct.py |   24 +++++++++++++++---------
 1 files changed, 15 insertions(+), 9 deletions(-)
---
diff --git a/scripts/lib/wic/plugins/imager/direct.py b/scripts/lib/wic/plugins/imager/direct.py
index f20d843..4f441c1 100644
--- a/scripts/lib/wic/plugins/imager/direct.py
+++ b/scripts/lib/wic/plugins/imager/direct.py
@@ -32,6 +32,8 @@ import uuid
 
 from time import strftime
 
+from oe.path import copyhardlinktree
+
 from wic import WicError
 from wic.filemap import sparse_copy
 from wic.ksparser import KickStart, KickStartError
@@ -115,12 +117,18 @@ class DirectPlugin(ImagerPlugin):
             fstab_lines = fstab.readlines()
 
         if self._update_fstab(fstab_lines, self.parts):
-            shutil.copyfile(fstab_path, fstab_path + ".orig")
+            # copy rootfs dir to workdir to update fstab
+            # as rootfs can be used by other tasks and can't be modified
+            new_rootfs = os.path.realpath(os.path.join(self.workdir, "rootfs_copy"))
+            copyhardlinktree(image_rootfs, new_rootfs)
+            fstab_path = os.path.join(new_rootfs, 'etc/fstab')
+
+            os.unlink(fstab_path)
 
             with open(fstab_path, "w") as fstab:
                 fstab.writelines(fstab_lines)
 
-            return fstab_path
+            return new_rootfs
 
     def _update_fstab(self, fstab_lines, parts):
         """Assume partition order same as in wks"""
@@ -156,7 +164,10 @@ class DirectPlugin(ImagerPlugin):
         filesystems from the artifacts directly and combine them into
         a partitioned image.
         """
-        fstab_path = self._write_fstab(self.rootfs_dir.get("ROOTFS_DIR"))
+        new_rootfs = self._write_fstab(self.rootfs_dir.get("ROOTFS_DIR"))
+        if new_rootfs:
+            # rootfs was copied to update fstab
+            self.rootfs_dir['ROOTFS_DIR'] = new_rootfs
 
         for part in self.parts:
             # get rootfs size from bitbake variable if it's not set in .ks file
@@ -172,12 +183,7 @@ class DirectPlugin(ImagerPlugin):
                     if rsize_bb:
                         part.size = int(round(float(rsize_bb)))
 
-        try:
-            self._image.prepare(self)
-        finally:
-            if fstab_path:
-                shutil.move(fstab_path + ".orig", fstab_path)
-
+        self._image.prepare(self)
         self._image.layout_partitions()
         self._image.create()