[PATCH v2 0/9] initramfs: kunit tests and cleanups

[David Disseldorp <ddiss@suse.de>]

This patchset adds basic kunit test coverage for initramfs unpacking
and cleans up some minor buffer handling issues / inefficiencies.

Changes since v2 (patch 2 only):
- fix !CONFIG_INITRAMFS_PRESERVE_MTIME kunit test checks
- add test MODULE_DESCRIPTION(), as suggested by Jeff Johnson
- add some missing headers, reported by kernel test robot

Changes since v1 (RFC):
- rebase atop v6.12-rc6 and filename field overrun fix from
  https://lore.kernel.org/r/20241030035509.20194-2-ddiss@suse.de
- add unit test coverage (new patches 1 and 2)
- add patch: fix hardlink hash leak without TRAILER
- rework patch: avoid static buffer for error message
  + drop unnecessary message propagation
- drop patch: cpio_buf reuse for built-in and bootloader initramfs
  + no good justification for the change

Feedback appreciated.

David Disseldorp (9):
      init: add initramfs_internal.h
      initramfs_test: kunit tests for initramfs unpacking
      vsprintf: add simple_strntoul
      initramfs: avoid memcpy for hex header fields
      initramfs: remove extra symlink path buffer
      initramfs: merge header_buf and name_buf
      initramfs: reuse name_len for dir mtime tracking
      initramfs: fix hardlink hash leak without TRAILER
      initramfs: avoid static buffer for error message

 include/linux/kstrtox.h   |   1 +
 init/.kunitconfig         |   3 +
 init/Kconfig              |   7 +
 init/Makefile             |   1 +
 init/initramfs.c          |  73 +++++----
 init/initramfs_internal.h |   8 +
 init/initramfs_test.c     | 403 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/vsprintf.c            |   7 +
 8 files changed, 471 insertions(+), 32 deletions(-)
 create mode 100644 init/.kunitconfig
 create mode 100644 init/initramfs_internal.h
 create mode 100644 init/initramfs_test.c