Hi,

Christopher Baines <mail@cbaines.net> skribis:

> This test seems to fail, maybe because of high inode numbers, maybe
> something to with btrfs.

Uh.

> scheme@(guix-user)> (file->cpio-header "guix/guix.scm")
> $1 = #<<cpio-header> magic: 460545 ino: 5031515288 mode: 33188 uid: 1003 gid: 998 nlink: 1 mtime: 1671460627 file-size: 1452 dev-maj: 0 dev-min: 24 rdev-maj: 0 rdev-min: 0 name-size: 14 checksum: 0>

[...]

>         (let ((port (open-bytevector-input-port (get-bv))))
>           (equal? (peek "A" header)
>                   (peek "B" (read-cpio-header port))))))
>
> ;;; ("A" #<<cpio-header> magic: 460545 ino: 5031515288 mode: 33188 uid: 1003 gid: 998 nlink: 1 mtime: 1671460627 file-size: 1452 dev-maj: 0 dev-min: 24 rdev-maj: 0 rdev-min: 0 name-size: 14 checksum: 0>)
>
> ;;; ("B" #<<cpio-header> magic: 460545 ino: 736547992 mode: 33188 uid: 1003 gid: 998 nlink: 1 mtime: 1671460627 file-size: 1452 dev-maj: 0 dev-min: 24 rdev-maj: 0 rdev-min: 0 name-size: 14 checksum: 0>)
> $3 = #f

(guix cpio) defines cpio headers like this:

--8<---------------cut here---------------start------------->8---
(define-pack <cpio-header>
  %make-cpio-header cpio-header?
  write-cpio-header read-cpio-header
  (magic     6  cpio-header-magic)
  (ino       8  cpio-header-inode)
  (mode      8  cpio-header-mode)
  (uid       8  cpio-header-uid)
  (gid       8  cpio-header-gid)
  (nlink     8  cpio-header-nlink)
  (mtime     8  cpio-header-mtime)
  (file-size 8  cpio-header-file-size)
  (dev-maj   8  cpio-header-device-major)
  (dev-min   8  cpio-header-device-minor)
  (rdev-maj  8  cpio-header-rdevice-major)
  (rdev-min  8  cpio-header-rdevice-minor)
  (name-size 8  cpio-header-name-size)
  (checksum  8  cpio-header-checksum))            ;0 for "newc" format
--8<---------------cut here---------------end--------------->8---

The ‘ino’ value is stored as an 8-digit hexadecimal number—i.e., on 32
bits.  And, guess what:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> 5031515288  ;the inode number above
$15 = 5031515288
scheme@(guile-user)> (expt 2 32)
$16 = 4294967296
scheme@(guile-user)> (- $16 $15)
$17 = -736547992
--8<---------------cut here---------------end--------------->8---

Noways, libc + kernel typically use a 64-bit ‘ino_t’, so fundamentally
the cpio format is “wrong”.  But what can we do?

At least we can skip this test when that is the case (patch below).
WDYT?

Thanks,
Ludo’.