[PATCH 1/1] wic: Content of the temporary updated fstab should be copied into the original not replacing it entirely.

[dani.barra25@gmail.com]

From: Daniel Andrade <dani.barra25@gmail.com>

Fixes [15947]
The current functionality to update fstab generates a new temporary fstab with the new partition configuration.
However, this file does not retain any metadata being it a completely new file.
Because of this, when the rootfs plugin under `poky/scripts/lib/wic/plugins/source/rootfs.py` copies the file, it overrides the original fstab metadata.
The patch removes implementation of msdos/ext code for fstab since it is not possible to append content without rewriting the file to preserve metadata.

The timestamp applied to fstab is not the same as every other file.
It seems like the `SOURCE_DATE_EPOCH` variable goes to the fallback timestamp SOURCE_DATE_EPOCH_FALLBACK.
Since that variable is used everywhere, it is not the same value as REPRODUCIBLE_TIMESTAMP_ROOTFS under poky/meta/conf/bitbake.conf that is applied in every other file.

Signed-off-by: Daniel Andrade <dani.barra25@gmail.com>
---
 meta/conf/bitbake.conf                   |  4 +++-
 scripts/lib/wic/partition.py             | 15 +--------------
 scripts/lib/wic/plugins/source/rootfs.py |  4 ++--
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/meta/conf/bitbake.conf b/meta/conf/bitbake.conf
index acf4e2d153..0581fc3564 100644
--- a/meta/conf/bitbake.conf
+++ b/meta/conf/bitbake.conf
@@ -684,8 +684,10 @@ export PYTHONHASHSEED = "0"
 export PERL_HASH_SEED = "0"
 export SOURCE_DATE_EPOCH ?= "${@get_source_date_epoch_value(d)}"
 # A SOURCE_DATE_EPOCH of '0' might be misinterpreted as no SDE
+# If these 2 are misaligned, when generating fstab later on wic, the timestamps will never match because
+# The repeatibility uses the REPRODUCIBLE_TIMESTAMP_ROOTFS while wic uses SOURCE_DATE_EPOCH (therefore its fallback)
 SOURCE_DATE_EPOCH_FALLBACK ??= "1302044400"
-REPRODUCIBLE_TIMESTAMP_ROOTFS ??= "1520598896"
+REPRODUCIBLE_TIMESTAMP_ROOTFS ??= "1302044400"
 
 ##################################################################
 # Settings used by bitbake-layers.
diff --git a/scripts/lib/wic/partition.py b/scripts/lib/wic/partition.py
index bf2c34d594..82d754835c 100644
--- a/scripts/lib/wic/partition.py
+++ b/scripts/lib/wic/partition.py
@@ -131,7 +131,7 @@ class Partition():
         partition command parameters.
         """
         self.updated_fstab_path = updated_fstab_path
-        if self.updated_fstab_path and not (self.fstype.startswith("ext") or self.fstype == "msdos"):
+        if self.updated_fstab_path:
             self.update_fstab_in_rootfs = True
 
         if not self.source:
@@ -295,15 +295,6 @@ class Partition():
             (self.fstype, extraopts, rootfs, label_str, self.fsuuid, rootfs_dir)
         exec_native_cmd(mkfs_cmd, native_sysroot, pseudo=pseudo)
 
-        if self.updated_fstab_path and self.has_fstab and not self.no_fstab_update:
-            debugfs_script_path = os.path.join(cr_workdir, "debugfs_script")
-            with open(debugfs_script_path, "w") as f:
-                f.write("cd etc\n")
-                f.write("rm fstab\n")
-                f.write("write %s fstab\n" % (self.updated_fstab_path))
-            debugfs_cmd = "debugfs -w -f %s %s" % (debugfs_script_path, rootfs)
-            exec_native_cmd(debugfs_cmd, native_sysroot)
-
         mkfs_cmd = "fsck.%s -pvfD %s" % (self.fstype, rootfs)
         exec_native_cmd(mkfs_cmd, native_sysroot, pseudo=pseudo)
 
@@ -400,10 +391,6 @@ class Partition():
         mcopy_cmd = "mcopy -i %s -s %s/* ::/" % (rootfs, rootfs_dir)
         exec_native_cmd(mcopy_cmd, native_sysroot)
 
-        if self.updated_fstab_path and self.has_fstab and not self.no_fstab_update:
-            mcopy_cmd = "mcopy -m -i %s %s ::/etc/fstab" % (rootfs, self.updated_fstab_path)
-            exec_native_cmd(mcopy_cmd, native_sysroot)
-
         chmod_cmd = "chmod 644 %s" % rootfs
         exec_cmd(chmod_cmd)
 
diff --git a/scripts/lib/wic/plugins/source/rootfs.py b/scripts/lib/wic/plugins/source/rootfs.py
index e29f3a4c2f..3848af2a91 100644
--- a/scripts/lib/wic/plugins/source/rootfs.py
+++ b/scripts/lib/wic/plugins/source/rootfs.py
@@ -223,8 +223,8 @@ class RootfsPlugin(SourcePlugin):
             part.has_fstab = os.path.exists(os.path.join(new_rootfs, "etc/fstab"))
             if part.update_fstab_in_rootfs and part.has_fstab and not part.no_fstab_update:
                 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 -p %s %s" % (part.updated_fstab_path, fstab_path)
+                # We dont want any metadata of the updated fstab, just the one that already existed
+                install_cmd = "cp --no-preserve=all %s %s" % (part.updated_fstab_path, fstab_path)
                 if new_pseudo:
                     pseudo = cls.__get_pseudo(native_sysroot, new_rootfs, new_pseudo)
                 else: