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1 | ;;; GNU Guix --- Functional package management for GNU |
2 | ;;; Copyright © 2015 Ludovic Courtès <ludo@gnu.org> | |
3 | ;;; | |
4 | ;;; This file is part of GNU Guix. | |
5 | ;;; | |
6 | ;;; GNU Guix is free software; you can redistribute it and/or modify it | |
7 | ;;; under the terms of the GNU General Public License as published by | |
8 | ;;; the Free Software Foundation; either version 3 of the License, or (at | |
9 | ;;; your option) any later version. | |
10 | ;;; | |
11 | ;;; GNU Guix is distributed in the hope that it will be useful, but | |
12 | ;;; WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | ;;; GNU General Public License for more details. | |
15 | ;;; | |
16 | ;;; You should have received a copy of the GNU General Public License | |
17 | ;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. | |
18 | ||
19 | (define-module (guix cpio) | |
20 | #:use-module ((guix build utils) #:select (dump-port)) | |
21 | #:use-module (srfi srfi-9) | |
22 | #:use-module (srfi srfi-11) | |
23 | #:use-module (rnrs bytevectors) | |
24 | #:use-module (rnrs io ports) | |
25 | #:use-module (ice-9 match) | |
26 | #:export (cpio-header? | |
27 | make-cpio-header | |
28 | file->cpio-header | |
29 | write-cpio-header | |
30 | read-cpio-header | |
31 | ||
32 | write-cpio-archive)) | |
33 | ||
34 | ;;; Commentary: | |
35 | ;;; | |
36 | ;;; This module implements the cpio "new ASCII" format, bit-for-bit identical | |
37 | ;;; to GNU cpio with the '-H newc' option. | |
38 | ;;; | |
39 | ;;; Code: | |
40 | ||
41 | ;; Values for 'mode', OR'd together. | |
42 | ||
43 | (define C_IRUSR #o000400) | |
44 | (define C_IWUSR #o000200) | |
45 | (define C_IXUSR #o000100) | |
46 | (define C_IRGRP #o000040) | |
47 | (define C_IWGRP #o000020) | |
48 | (define C_IXGRP #o000010) | |
49 | (define C_IROTH #o000004) | |
50 | (define C_IWOTH #o000002) | |
51 | (define C_IXOTH #o000001) | |
52 | ||
53 | (define C_ISUID #o004000) | |
54 | (define C_ISGID #o002000) | |
55 | (define C_ISVTX #o001000) | |
56 | ||
57 | (define C_FMT #o170000) ;bit mask | |
58 | (define C_ISBLK #o060000) | |
59 | (define C_ISCHR #o020000) | |
60 | (define C_ISDIR #o040000) | |
61 | (define C_ISFIFO #o010000) | |
62 | (define C_ISSOCK #o0140000) | |
63 | (define C_ISLNK #o0120000) | |
64 | (define C_ISCTG #o0110000) | |
65 | (define C_ISREG #o0100000) | |
66 | ||
67 | ||
68 | (define MAGIC | |
69 | ;; The "new" portable format with ASCII header, as produced by GNU cpio with | |
70 | ;; '-H newc'. | |
71 | (string->number "070701" 16)) | |
72 | ||
73 | (define (read-header-field size port) | |
74 | (string->number (get-string-n port size) 16)) | |
75 | ||
76 | (define (write-header-field value size port) | |
77 | (put-bytevector port | |
78 | (string->utf8 | |
79 | (string-pad (string-upcase (number->string value 16)) | |
80 | size #\0)))) | |
81 | ||
82 | (define-syntax define-pack | |
83 | (syntax-rules () | |
84 | ((_ type ctor pred write read (field-names field-sizes field-getters) ...) | |
85 | (begin | |
86 | (define-record-type type | |
87 | (ctor field-names ...) | |
88 | pred | |
89 | (field-names field-getters) ...) | |
90 | ||
91 | (define (read port) | |
92 | (set-port-encoding! port "ISO-8859-1") | |
93 | (ctor (read-header-field field-sizes port) | |
94 | ...)) | |
95 | ||
96 | (define (write obj port) | |
97 | (let* ((size (+ field-sizes ...))) | |
98 | (match obj | |
99 | (($ type field-names ...) | |
100 | (write-header-field field-names field-sizes port) | |
101 | ...)))))))) | |
102 | ||
103 | ;; cpio header in "new ASCII" format, without checksum. | |
104 | (define-pack <cpio-header> | |
105 | %make-cpio-header cpio-header? | |
106 | write-cpio-header read-cpio-header | |
107 | (magic 6 cpio-header-magic) | |
108 | (ino 8 cpio-header-inode) | |
109 | (mode 8 cpio-header-mode) | |
110 | (uid 8 cpio-header-uid) | |
111 | (gid 8 cpio-header-gid) | |
112 | (nlink 8 cpio-header-nlink) | |
113 | (mtime 8 cpio-header-mtime) | |
114 | (file-size 8 cpio-header-file-size) | |
115 | (dev-maj 8 cpio-header-device-major) | |
116 | (dev-min 8 cpio-header-device-minor) | |
117 | (rdev-maj 8 cpio-header-rdevice-major) | |
118 | (rdev-min 8 cpio-header-rdevice-minor) | |
119 | (name-size 8 cpio-header-name-size) | |
120 | (checksum 8 cpio-header-checksum)) ;0 for "newc" format | |
121 | ||
122 | (define* (make-cpio-header #:key | |
123 | (inode 0) | |
124 | (mode (logior C_ISREG C_IRUSR)) | |
125 | (uid 0) (gid 0) | |
126 | (nlink 1) (mtime 0) (size 0) | |
127 | (dev 0) (rdev 0) (name-size 0)) | |
128 | "Return a new cpio file header." | |
129 | (let-values (((major minor) (device->major+minor dev)) | |
130 | ((rmajor rminor) (device->major+minor rdev))) | |
131 | (%make-cpio-header MAGIC | |
132 | inode mode uid gid | |
133 | nlink mtime | |
134 | (if (= C_ISDIR (logand mode C_FMT)) | |
135 | 0 | |
136 | size) | |
137 | major minor rmajor rminor | |
138 | (+ name-size 1) ;include trailing zero | |
139 | 0))) ;checksum | |
140 | ||
141 | (define (mode->type mode) | |
142 | "Given the number MODE, return a symbol representing the kind of file MODE | |
143 | denotes, similar to 'stat:type'." | |
144 | (let ((fmt (logand mode C_FMT))) | |
145 | (cond ((= C_ISREG fmt) 'regular) | |
146 | ((= C_ISDIR fmt) 'directory) | |
147 | ((= C_ISLNK fmt) 'symlink) | |
148 | (else | |
149 | (error "unsupported file type" mode))))) | |
150 | ||
151 | (define (device-number major minor) ;see <sys/sysmacros.h> | |
152 | "Return the device number for the device with MAJOR and MINOR, for use as | |
153 | the last argument of `mknod'." | |
154 | (+ (* major 256) minor)) | |
155 | ||
156 | (define (device->major+minor device) | |
157 | "Return two values: the major and minor device numbers that make up DEVICE." | |
158 | (values (ash device -8) | |
159 | (logand device #xff))) | |
160 | ||
161 | (define* (file->cpio-header file #:optional (file-name file) | |
162 | #:key (stat lstat)) | |
163 | "Return a cpio header corresponding to the info returned by STAT for FILE, | |
164 | using FILE-NAME as its file name." | |
165 | (let ((st (stat file))) | |
166 | (make-cpio-header #:inode (stat:ino st) | |
167 | #:mode (stat:mode st) | |
168 | #:uid (stat:uid st) | |
169 | #:gid (stat:gid st) | |
170 | #:nlink (stat:nlink st) | |
171 | #:mtime (stat:mtime st) | |
172 | #:size (stat:size st) | |
173 | #:dev (stat:dev st) | |
174 | #:rdev (stat:rdev st) | |
175 | #:name-size (string-length file-name)))) | |
176 | ||
177 | (define %trailer | |
178 | "TRAILER!!!") | |
179 | ||
180 | (define %last-header | |
181 | ;; The header that marks the end of the archive. | |
182 | (make-cpio-header #:mode 0 | |
183 | #:name-size (string-length %trailer))) | |
184 | ||
185 | (define* (write-cpio-archive files port | |
186 | #:key (file->header file->cpio-header)) | |
187 | "Write to PORT a cpio archive in \"new ASCII\" format containing all of FILES. | |
188 | ||
189 | The archive written to PORT is intended to be bit-identical to what GNU cpio | |
190 | produces with the '-H newc' option." | |
191 | (define (write-padding offset port) | |
192 | (let ((padding (modulo (- 4 (modulo offset 4)) 4))) | |
193 | (put-bytevector port (make-bytevector padding)))) | |
194 | ||
195 | (define (pad-block port) | |
196 | ;; Write padding to PORT such that we finish with a 512-byte block. | |
197 | ;; XXX: We rely on PORT's internal state, assuming it's a file port. | |
198 | (let* ((offset (seek port 0 SEEK_CUR)) | |
199 | (padding (modulo (- 512 (modulo offset 512)) 512))) | |
200 | (put-bytevector port (make-bytevector padding)))) | |
201 | ||
202 | (define (dump-file file) | |
203 | (let* ((header (file->header file)) | |
204 | (size (cpio-header-file-size header))) | |
205 | (write-cpio-header header port) | |
206 | (put-bytevector port (string->utf8 file)) | |
207 | (put-u8 port 0) | |
208 | ||
209 | ;; We're padding the header + following file name + trailing zero, and | |
210 | ;; the header is 110 byte long. | |
211 | (write-padding (+ 110 1 (string-length file)) port) | |
212 | ||
213 | (case (mode->type (cpio-header-mode header)) | |
214 | ((regular) | |
215 | (call-with-input-file file | |
216 | (lambda (input) | |
217 | (dump-port input port)))) | |
218 | ((symlink) | |
219 | (let ((target (readlink file))) | |
220 | (put-string port target))) | |
221 | ((directory) | |
222 | #t) | |
223 | (else | |
224 | (error "file type not supported"))) | |
225 | ||
226 | ;; Pad the file content. | |
227 | (write-padding size port))) | |
228 | ||
229 | (set-port-encoding! port "ISO-8859-1") | |
230 | ||
231 | (for-each dump-file files) | |
232 | ||
233 | (write-cpio-header %last-header port) | |
234 | (put-bytevector port (string->utf8 %trailer)) | |
235 | (write-padding (string-length %trailer) port) | |
236 | ||
237 | ;; Pad so the last block is 512-byte long. | |
238 | (pad-block port)) | |
239 | ||
240 | ;;; cpio.scm ends here |