Add (guix cpio).

* guix/cpio.scm, tests/cpio.scm: New files.
* Makefile.am (MODULES): Add guix/cpio.scm.
  (SCM_TESTS): Add tests/cpio.scm.

1 files changed, 240 insertions, 0 deletions

diff --git a/guix/cpio.scm b/guix/cpio.scm
new file mode 100644
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+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix cpio)
+  #:use-module ((guix build utils) #:select (dump-port))
+  #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-11)
+  #:use-module (rnrs bytevectors)
+  #:use-module (rnrs io ports)
+  #:use-module (ice-9 match)
+  #:export (cpio-header?
+            make-cpio-header
+            file->cpio-header
+            write-cpio-header
+            read-cpio-header
+
+            write-cpio-archive))
+
+;;; Commentary:
+;;;
+;;; This module implements the cpio "new ASCII" format, bit-for-bit identical
+;;; to GNU cpio with the '-H newc' option.
+;;;
+;;; Code:
+
+;; Values for 'mode', OR'd together.
+
+(define C_IRUSR #o000400)
+(define C_IWUSR #o000200)
+(define C_IXUSR #o000100)
+(define C_IRGRP #o000040)
+(define C_IWGRP #o000020)
+(define C_IXGRP #o000010)
+(define C_IROTH #o000004)
+(define C_IWOTH #o000002)
+(define C_IXOTH #o000001)
+
+(define C_ISUID #o004000)
+(define C_ISGID #o002000)
+(define C_ISVTX #o001000)
+
+(define C_FMT   #o170000)                         ;bit mask
+(define C_ISBLK #o060000)
+(define C_ISCHR #o020000)
+(define C_ISDIR #o040000)
+(define C_ISFIFO #o010000)
+(define C_ISSOCK #o0140000)
+(define C_ISLNK #o0120000)
+(define C_ISCTG #o0110000)
+(define C_ISREG #o0100000)
+
+
+(define MAGIC
+  ;; The "new" portable format with ASCII header, as produced by GNU cpio with
+  ;; '-H newc'.
+  (string->number "070701" 16))
+
+(define (read-header-field size port)
+  (string->number (get-string-n port size) 16))
+
+(define (write-header-field value size port)
+  (put-bytevector port
+                  (string->utf8
+                   (string-pad (string-upcase (number->string value 16))
+                               size #\0))))
+
+(define-syntax define-pack
+  (syntax-rules ()
+    ((_ type ctor pred write read (field-names field-sizes field-getters) ...)
+     (begin
+       (define-record-type type
+         (ctor field-names ...)
+         pred
+         (field-names field-getters) ...)
+
+       (define (read port)
+         (set-port-encoding! port "ISO-8859-1")
+         (ctor (read-header-field field-sizes port)
+               ...))
+
+       (define (write obj port)
+         (let* ((size (+ field-sizes ...)))
+           (match obj
+             (($ type field-names ...)
+              (write-header-field field-names field-sizes port)
+              ...))))))))
+
+;; cpio header in "new ASCII" format, without checksum.
+(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
+
+(define* (make-cpio-header #:key
+                           (inode 0)
+                           (mode (logior C_ISREG C_IRUSR))
+                           (uid 0) (gid 0)
+                           (nlink 1) (mtime 0) (size 0)
+                           (dev 0) (rdev 0) (name-size 0))
+  "Return a new cpio file header."
+  (let-values (((major minor)   (device->major+minor dev))
+               ((rmajor rminor) (device->major+minor rdev)))
+    (%make-cpio-header MAGIC
+                       inode mode uid gid
+                       nlink mtime
+                       (if (= C_ISDIR (logand mode C_FMT))
+                           0
+                           size)
+                       major minor rmajor rminor
+                       (+ name-size 1)              ;include trailing zero
+                       0)))                          ;checksum
+
+(define (mode->type mode)
+  "Given the number MODE, return a symbol representing the kind of file MODE
+denotes, similar to 'stat:type'."
+  (let ((fmt (logand mode C_FMT)))
+    (cond ((= C_ISREG fmt) 'regular)
+          ((= C_ISDIR fmt) 'directory)
+          ((= C_ISLNK fmt) 'symlink)
+          (else
+           (error "unsupported file type" mode)))))
+
+(define (device-number major minor)               ;see <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))
+
+(define (device->major+minor device)
+  "Return two values: the major and minor device numbers that make up DEVICE."
+  (values (ash device -8)
+          (logand device #xff)))
+
+(define* (file->cpio-header file #:optional (file-name file)
+                            #:key (stat lstat))
+  "Return a cpio header corresponding to the info returned by STAT for FILE,
+using FILE-NAME as its file name."
+  (let ((st (stat file)))
+    (make-cpio-header #:inode (stat:ino st)
+                      #:mode (stat:mode st)
+                      #:uid (stat:uid st)
+                      #:gid (stat:gid st)
+                      #:nlink (stat:nlink st)
+                      #:mtime (stat:mtime st)
+                      #:size (stat:size st)
+                      #:dev (stat:dev st)
+                      #:rdev (stat:rdev st)
+                      #:name-size (string-length file-name))))
+
+(define %trailer
+  "TRAILER!!!")
+
+(define %last-header
+  ;; The header that marks the end of the archive.
+  (make-cpio-header #:mode 0
+                    #:name-size (string-length %trailer)))
+
+(define* (write-cpio-archive files port
+                             #:key (file->header file->cpio-header))
+  "Write to PORT a cpio archive in \"new ASCII\" format containing all of FILES.
+
+The archive written to PORT is intended to be bit-identical to what GNU cpio
+produces with the '-H newc' option."
+  (define (write-padding offset port)
+    (let ((padding (modulo (- 4 (modulo offset 4)) 4)))
+      (put-bytevector port (make-bytevector padding))))
+
+  (define (pad-block port)
+    ;; Write padding to PORT such that we finish with a 512-byte block.
+    ;; XXX: We rely on PORT's internal state, assuming it's a file port.
+    (let* ((offset  (seek port 0 SEEK_CUR))
+           (padding (modulo (- 512 (modulo offset 512)) 512)))
+      (put-bytevector port (make-bytevector padding))))
+
+  (define (dump-file file)
+    (let* ((header (file->header file))
+           (size   (cpio-header-file-size header)))
+      (write-cpio-header header port)
+      (put-bytevector port (string->utf8 file))
+      (put-u8 port 0)
+
+      ;; We're padding the header + following file name + trailing zero, and
+      ;; the header is 110 byte long.
+      (write-padding (+ 110 1 (string-length file)) port)
+
+      (case (mode->type (cpio-header-mode header))
+        ((regular)
+         (call-with-input-file file
+           (lambda (input)
+             (dump-port input port))))
+        ((symlink)
+         (let ((target (readlink file)))
+           (put-string port target)))
+        ((directory)
+         #t)
+        (else
+         (error "file type not supported")))
+
+      ;; Pad the file content.
+      (write-padding size port)))
+
+  (set-port-encoding! port "ISO-8859-1")
+
+  (for-each dump-file files)
+
+  (write-cpio-header %last-header port)
+  (put-bytevector port (string->utf8 %trailer))
+  (write-padding (string-length %trailer) port)
+
+  ;; Pad so the last block is 512-byte long.
+  (pad-block port))
+
+;;; cpio.scm ends here