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/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Disseldorp <[email protected]>
Reviewed-by: Martin Wilck <[email protected]>
Acked-by: Christian Brauner <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions