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Diffstat (limited to 'guix/cpio.scm')
| -rw-r--r-- | guix/cpio.scm | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/guix/cpio.scm b/guix/cpio.scm new file mode 100644 index 0000000000..f1c2130bfa --- /dev/null +++ b/guix/cpio.scm @@ -0,0 +1,240 @@ +;;; 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 |