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[scarthgap,2.8,1/4] fetch2: don't try to preserve all attributes when unpacking files

Message ID 9580f15aae08ae6e3693ebb898b6fd5238f5a7f8.1773966318.git.yoann.congal@smile.fr
State New
Headers show
Series [scarthgap,2.8,1/4] fetch2: don't try to preserve all attributes when unpacking files | expand

Commit Message

Yoann Congal March 20, 2026, 12:26 a.m. UTC 
From: Ross Burton <ross.burton@arm.com>

When copying files as part of the unpack we currently use cp -p, which
is a shortcut for --preserve=mode,ownership,timestamps.

We do want to preserve timestamps, because some fetchers set these
explicitly.

We don't care about ownership. If the files are owned by us then they
ill remain owned by us, and if they're not then the attempt to change
ownership will be silently ignored.  In a shared DL_DIR where files have
group ownership this group access isn't relevant in the single-user build
tree.

We do want to preserve executable bits in the mode, but cp always does
this.  The difference between --preserve=mode and no --preserve is that
the mode isn't preserved exactly (no sticky bits, no suid, umask is
applied) but this also isn't a relevant difference in a build tree.

Also expand the arguments to be clearer about what options are being
passed.

The impetus for this is that coreutils 9.4 includes a change in gnulib[1]
and will now try to preserve permission-based xattrs if asked to preserve
the mode.  This can result in cp failing when copying a file from a
NFSv4 server with ACLs stored in xattrs to a non-NFS directory where
those xattrs cannot be written:

cp: preserving permissions for ‘./jquery-3.7.1.js’: Operation not supported

The error comes from the kernel refusing to write a system.nfs4_acl
xattr to a file on ext4.

This situation doesn't appear on all systems with coreutils 9.4, at the
time of writing it fails on Ubuntu 24.04 onwards but not Fedora 40. This
is because /etc/xattr.conf is used to determine which xattrs describe
permissions, and Fedora 40 has removed the NFSv4 attributes[2].

Also, use long-form options to make the cp command clearer.

[1] https://github.com/coreutils/gnulib/commit/eb6a8a4dfb
[2] https://src.fedoraproject.org/rpms/attr/blob/rawhide/f/0003-attr-2.4.48-xattr-conf-nfs4-acls.patch

[ YOCTO #15596 ]

(cherry picked from commit 2f35dac0c821ab231459922ed98e1b2cc599ca9a)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Alexander Feilke <Alexander.Feilke@ew.tq-group.com>
Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
---
 lib/bb/fetch2/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/lib/bb/fetch2/__init__.py b/lib/bb/fetch2/__init__.py
index 7b75d5d83..224408de0 100644
--- a/lib/bb/fetch2/__init__.py
+++ b/lib/bb/fetch2/__init__.py
@@ -1606,7 +1606,7 @@  class FetchMethod(object):
                     if urlpath.find("/") != -1:
                         destdir = urlpath.rsplit("/", 1)[0] + '/'
                         bb.utils.mkdirhier("%s/%s" % (unpackdir, destdir))
-                cmd = 'cp -fpPRH "%s" "%s"' % (file, destdir)
+                cmd = 'cp --force --preserve=timestamps --no-dereference --recursive -H "%s" "%s"' % (file, destdir)
         else:
             urldata.unpack_tracer.unpack("archive-extract", unpackdir)