cpio: Fix device number calculation.

“dev_t in glibc is a 64-bit quantity, with 32-bit major and minor
 numbers.”  — glibc's <bits/sysmacros.h>

The "tests/cpio.scm" was failing because (guix cpio) treated it as a
16-bit quantity instead, leading to header mismatches with the GNU cpio
reference output.

* guix/cpio.scm (device-number, device->major+minor): Use all the bits.
This commit is contained in:
Tobias Geerinckx-Rice 2021-07-04 04:26:01 +02:00
parent 7cde70c7f8
commit f7e1478202
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1 changed files with 11 additions and 5 deletions

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@ -1,5 +1,6 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2021 Tobias Geerinckx-Rice <me@tobias.gr>
;;;
;;; This file is part of GNU Guix.
;;;
@ -153,15 +154,20 @@ denotes, similar to 'stat:type'."
(else
(error "unsupported file type" mode)))))
(define (device-number major minor) ;see <sys/sysmacros.h>
(define (device-number major minor) ; see glibc's <sys/sysmacros.h>
"Return the device number for the device with MAJOR and MINOR, for use as
the last argument of `mknod'."
(+ (* major 256) minor))
(logior (ash (logand #x00000fff major) 8)
(ash (logand #xfffff000 major) 32)
(logand #x000000ff minor)
(ash (logand #xffffff00 minor) 12)))
(define (device->major+minor device)
(define (device->major+minor device) ; see glibc's <sys/sysmacros.h>
"Return two values: the major and minor device numbers that make up DEVICE."
(values (ash device -8)
(logand device #xff)))
(values (logior (ash (logand #x00000000000fff00 device) -8)
(ash (logand #xfffff00000000000 device) -32))
(logior (logand #x00000000000000ff device)
(ash (logand #x00000ffffff00000 device) -12))))
(define* (file->cpio-header file #:optional (file-name file)
#:key (stat lstat))