initramfs: refactor do_header() cpio magic checks
authorDavid Disseldorp <ddiss@suse.de>
Tue, 10 May 2022 01:29:19 +0000 (18:29 -0700)
committerakpm <akpm@linux-foundation.org>
Tue, 10 May 2022 01:29:19 +0000 (18:29 -0700)
commitda028e4c4b0279eb49f80220d8f7cc62b4a57ccb
tree06cf79a0ecbd9692d475802a9db3fe245c48a28a
parent7055197705709c59b8ab77e6a5c7d46d61edd96e
initramfs: refactor do_header() cpio magic checks

Patch series "initramfs: "crc" cpio format and INITRAMFS_PRESERVE_MTIME", v7.

This patchset does some minor initramfs refactoring and allows cpio entry
mtime preservation to be disabled via a new Kconfig
INITRAMFS_PRESERVE_MTIME option.

Patches 4/6 to 6/6 implement support for creation and extraction of "crc"
cpio archives, which carry file data checksums.  Basic tests for this
functionality can be found at https://github.com/rapido-linux/rapido/pull/163

This patch (of 6):

do_header() is called for each cpio entry and fails if the first six bytes
don't match "newc" magic.  The magic check includes a special case error
message if POSIX.1 ASCII (cpio -H odc) magic is detected.  This special
case POSIX.1 check can be nested under the "newc" mismatch code path to
avoid calling memcmp() twice in a non-error case.

Link: https://lkml.kernel.org/r/20220404093429.27570-1-ddiss@suse.de
Link: https://lkml.kernel.org/r/20220404093429.27570-2-ddiss@suse.de
Signed-off-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
init/initramfs.c