;;; cpio-crc.el --- handle crc cpio entry header formats -*- coding: utf-8 -*-
;; COPYRIGHT
;;
;; Copyright © 2019-2020 Free Software Foundation, Inc.
;; All rights reserved.
;;
;; This program 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.
;;
;; This program 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 this program. If not, see .
;;
;; Author: Douglas Lewan
;; Maintainer: Douglas Lewan
;; Created: 2015 Jan 03
;; Version: 0.17
;; Keywords: files
;;; Commentary:
;;; Documentation:
;;; Code:
;;
;; Dependencies
;;
;; (eval-when-compile
;; (condition-case err
;; (require 'cpio-generic)
;; (error
;; (if (file-exists-p (concat default-directory "cpio-generic.elc"))
;; (load (concat default-directory "cpio-generic.elc"))
;; (load (concat default-directory "cpio-generic.el")))))
;; (condition-case err
;; (require 'cpio-newc)
;; (error
;; (if (file-exists-p (concat default-directory "cpio-newc.elc"))
;; (load (concat default-directory "cpio-newc.elc"))
;; (load (concat default-directory "cpio-newc.el"))))))
(require 'cpio-newc)
(eval-when-compile (require 'cpio-generic)) ;For `with-writable-buffer'!
;;;;;;;;;;;;;;;;
;; Things to make the byte compiler happy.
(declare-function cg-pad-right "cpio-generic.el")
(declare-function cg-round-up "cpio-generic.el")
(declare-function cpio-contents "cpio-mode.el" (entry-name &optional archive-buffer))
(declare-function cpio-entry-exists-p "cpio-mode.el" (entry-name))
(declare-function cpio-entry-name "cpio-mode.el" (attrs))
(declare-function cpio-entry-size "cpio-mode.el" (attrs))
(declare-function cpio-newc-parse-chksum "cpio-newc.el")
(declare-function cpio-newc-parse-dev-maj "cpio-newc.el")
(declare-function cpio-newc-parse-dev-min "cpio-newc.el")
(declare-function cpio-newc-parse-filesize "cpio-newc.el")
(declare-function cpio-newc-parse-gid "cpio-newc.el")
(declare-function cpio-newc-parse-ino "cpio-newc.el")
(declare-function cpio-newc-parse-mode "cpio-newc.el")
(declare-function cpio-newc-parse-mtime "cpio-newc.el")
(declare-function cpio-newc-parse-name "cpio-newc.el")
(declare-function cpio-newc-parse-namesize "cpio-newc.el")
(declare-function cpio-newc-parse-nlink "cpio-newc.el")
(declare-function cpio-newc-parse-rdev-maj "cpio-newc.el")
(declare-function cpio-newc-parse-rdev-min "cpio-newc.el")
(declare-function cpio-newc-parse-uid "cpio-newc.el")
(declare-function cpio-special-file "cpio-modes.el")
(declare-function cpio-validate-catalog-entry "cpio-mode.el" (catalog-entry))
;; EO things for the byte compiler.
;;;;;;;;;;;;;;;;
;;
;; Vars
;;
(defconst *cpio-crc-header-length* (length "07070100000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000B00000000")
"The length of a crc header.")
;; MAINTENANCE The following must remain in synch with *cpio-newc-header-re*.
(defconst *cpio-crc-magic-re* "070702"
"RE to match the magic number of a newc archive.")
(setq *cpio-crc-magic-re* "070702")
(defconst *cpio-crc-ino-re* *cpio-newc-ino-re*)
(defconst *cpio-crc-mode-re* *cpio-newc-mode-re*)
(defconst *cpio-crc-uid-re* *cpio-newc-uid-re*)
(defconst *cpio-crc-gid-re* *cpio-newc-gid-re*)
(defconst *cpio-crc-nlink-re* *cpio-newc-nlink-re*)
(defconst *cpio-crc-mtime-re* *cpio-newc-mtime-re*)
(defconst *cpio-crc-filesize-re* *cpio-newc-filesize-re*)
(defconst *cpio-crc-dev-maj-re* *cpio-newc-dev-maj-re*)
(defconst *cpio-crc-dev-min-re* *cpio-newc-dev-min-re*)
(defconst *cpio-crc-rdev-maj-re* *cpio-newc-rdev-maj-re*)
(defconst *cpio-crc-rdev-min-re* *cpio-newc-rdev-min-re*)
(defconst *cpio-crc-rdev-min-re* *cpio-newc-rdev-min-re*)
(defconst *cpio-crc-namesize-re* *cpio-newc-namesize-re*)
(defconst *cpio-crc-chksum-re* *cpio-newc-chksum-re*)
(defconst *cpio-crc-filename-re* *cpio-newc-filename-re*)
(defconst *cpio-crc-header-re* ()
"RE to match crc header format cpio archives.")
(setq *cpio-crc-header-re* (concat "\\(" *cpio-crc-magic-re* "\\)"
"\\(" *cpio-crc-ino-re* "\\)"
"\\(" *cpio-crc-mode-re* "\\)"
"\\(" *cpio-crc-uid-re* "\\)"
"\\(" *cpio-crc-gid-re* "\\)"
"\\(" *cpio-crc-nlink-re* "\\)"
"\\(" *cpio-crc-mtime-re* "\\)"
"\\(" *cpio-crc-filesize-re* "\\)"
"\\(" *cpio-crc-dev-maj-re* "\\)"
"\\(" *cpio-crc-dev-min-re* "\\)"
"\\(" *cpio-crc-rdev-maj-re* "\\)"
"\\(" *cpio-crc-rdev-min-re* "\\)"
"\\(" *cpio-crc-namesize-re* "\\)"
"\\(" *cpio-crc-chksum-re* "\\)"
"\\(" *cpio-crc-filename-re* "\\)"
"\0"))
(defconst *cpio-crc-magic-re-idx* *cpio-newc-magic-re-idx*)
(defconst *cpio-crc-ino-re-idx* *cpio-newc-ino-re-idx*)
(defconst *cpio-crc-mode-re-idx* *cpio-newc-mode-re-idx*)
(defconst *cpio-crc-uid-re-idx* *cpio-newc-uid-re-idx*)
(defconst *cpio-crc-gid-re-idx* *cpio-newc-gid-re-idx*)
(defconst *cpio-crc-nlink-re-idx* *cpio-newc-nlink-re-idx*)
(defconst *cpio-crc-mtime-re-idx* *cpio-newc-mtime-re-idx*)
(defconst *cpio-crc-filesize-re-idx* *cpio-newc-filesize-re-idx*)
(defconst *cpio-crc-dev-maj-re-idx* *cpio-newc-dev-maj-re-idx*)
(defconst *cpio-crc-dev-min-re-idx* *cpio-newc-dev-min-re-idx*)
(defconst *cpio-crc-rdev-maj-re-idx* *cpio-newc-rdev-maj-re-idx*)
(defconst *cpio-crc-rdev-min-re-idx* *cpio-newc-rdev-min-re-idx*)
(defconst *cpio-crc-namesize-re-idx* *cpio-newc-namesize-re-idx*)
(defconst *cpio-crc-chksum-re-idx* *cpio-newc-chksum-re-idx*)
(defconst *cpio-crc-filename-re-idx* *cpio-newc-filename-re-idx*)
;;
;; EO newc header variables.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defconst *cpio-crc-field-width* *cpio-newc-field-width*)
(defconst *cpio-crc-padding-modulus* *cpio-newc-padding-modulus*)
(defconst *cpio-crc-padding-char* *cpio-newc-padding-char*)
(defconst *cpio-crc-padding-str* *cpio-newc-padding-str*)
(defconst *cpio-crc-magic-field-offset* *cpio-newc-magic-field-offset*)
(defconst *cpio-crc-ino-field-offset* *cpio-newc-ino-field-offset*)
(defconst *cpio-crc-mode-field-offset* *cpio-newc-mode-field-offset*)
(defconst *cpio-crc-uid-field-offset* *cpio-newc-uid-field-offset*)
(defconst *cpio-crc-gid-field-offset* *cpio-newc-gid-field-offset*)
(defconst *cpio-crc-nlink-field-offset* *cpio-newc-nlink-field-offset*)
(defconst *cpio-crc-mtime-field-offset* *cpio-newc-mtime-field-offset*)
(defconst *cpio-crc-filesize-field-offset* *cpio-newc-filesize-field-offset*)
(defconst *cpio-crc-dev-maj-field-offset* *cpio-newc-dev-maj-field-offset*)
(defconst *cpio-crc-dev-min-field-offset* *cpio-newc-dev-min-field-offset*)
(defconst *cpio-crc-rdev-maj-field-offset* *cpio-newc-rdev-maj-field-offset*)
(defconst *cpio-crc-rdev-min-field-offset* *cpio-newc-rdev-min-field-offset*)
(defconst *cpio-crc-namesize-field-offset* *cpio-newc-namesize-field-offset*)
(defconst *cpio-crc-chksum-field-offset* *cpio-newc-chksum-field-offset*)
(defconst *cpio-crc-name-field-offset* *cpio-newc-name-field-offset*)
(defconst *cpio-crc-trailer* "07070200000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000B00000000TRAILER!!!\0\0\0\0"
"The TRAILER string for a newc archive.")
(defcustom *cpio-crc-blocksize* *cpio-newc-blocksize*
"The default block size for this cpio archive.
Taken from cpio-2.12/src/global.c."
:type 'integer
:group 'cpio)
;;
;; Library
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Functions for working with a cpio newc header
;;
(defun cpio-newc-header-at-point (&optional where)
"Return the header string at or following point WHERE.
If WHERE is not given, then use point.
CAVEATS:
1. This searches for the magic number at the begining of the header;
if WHERE is inside the magic number, then the search will fail.
This works best if you are (looking-at) a header.
2. This returns the pure header;
it does not provide the filename itself."
(unless where (setq where (point)))
(let ((fname "cpio-newc-header-at-point")
(found nil))
(save-match-data
(cond ((looking-at *cpio-newc-header-re*)
(match-string-no-properties 0))
(t
(forward-char (length *cpio-newc-magic-re*))
(while (and (re-search-backward *cpio-newc-magic-re* (point-min) t)
(not (setq found (looking-at *cpio-newc-header-re*)))))
(if found
(match-string-no-properties 0)))))))
;; OBSOLETE (setq cpio-header-at-point-func 'cpio-newc-header-at-point)
;;;;;;;;;;;;;;;;
;;
;; Parsing a header
;;
(defalias 'cpio-crc-header-size 'cpio-newc-header-size)
(defalias 'cpio-crc-parse-magic 'cpio-newc-parse-magic)
(defalias 'cpio-crc-parse-ino 'cpio-newc-parse-ino)
(defalias 'cpio-crc-parse-mode 'cpio-newc-parse-mode)
(defalias 'cpio-crc-parse-uid 'cpio-newc-parse-uid)
(defalias 'cpio-crc-parse-gid 'cpio-newc-parse-gid)
(defalias 'cpio-crc-parse-nlink 'cpio-newc-parse-nlink)
(defalias 'cpio-crc-parse-mtime 'cpio-newc-parse-mtime)
(defalias 'cpio-crc-parse-filesize 'cpio-newc-parse-filesize)
(defalias 'cpio-crc-parse-dev-maj 'cpio-newc-parse-dev-maj)
(defalias 'cpio-crc-parse-dev-min 'cpio-newc-parse-dev-min)
(defalias 'cpio-crc-parse-rdev-maj 'cpio-newc-parse-rdev-maj)
(defalias 'cpio-crc-parse-rdev-min 'cpio-newc-parse-rdev-min)
(defalias 'cpio-crc-parse-namesize 'cpio-newc-parse-namesize)
(defalias 'cpio-crc-parse-chksum 'cpio-newc-parse-chksum)
(defalias 'cpio-crc-parse-name 'cpio-newc-parse-name)
(defalias 'cpio-crc-parse-chksum 'cpio-newc-parse-chksum)
(defalias 'cpio-crc-parse-contents 'cpio-newc-parse-contents)
(defun cpio-crc-parse-header (header-string)
"Return the internal entry header structure encoded in HEADER-STR.
The optional argument WHERE should be a buffer location
at the beginning of a known cpio newc header.
If WHERE is not given, then take point and hope.
This function does NOT get the contents."
(let ((fname "cpio-newc-parse-header")
(namesize)
(filesize)
(result))
;; There's an arguable level of redundancy here,
;; but the caller likely grabbed HEADER-STR
;; from the buffer and we're using the string proper.
;; This call establishes the match-data
;; that the subsequent calls will use.
(save-match-data
(string-match *cpio-newc-header-re* header-string)
(setq result
(vector (cpio-newc-parse-ino header-string)
(cpio-newc-parse-mode header-string)
(cpio-newc-parse-uid header-string)
(cpio-newc-parse-gid header-string)
(cpio-newc-parse-nlink header-string)
(cpio-newc-parse-mtime header-string)
(setq filesize (cpio-newc-parse-filesize header-string))
(cpio-newc-parse-dev-maj header-string)
(cpio-newc-parse-dev-min header-string)
(cpio-newc-parse-rdev-maj header-string)
(cpio-newc-parse-rdev-min header-string)
(setq namesize (cpio-newc-parse-namesize header-string))
(cpio-newc-parse-chksum header-string)
(cpio-newc-parse-name header-string namesize))))
(if (cpio-entry-name result)
result
nil)))
(defun cpio-crc-make-header-string (attrs &optional contents)
"Make a header string for a CRC archive based on ATTRS.
This function does NOT include the contents."
(let ((fname "cpio-crc-make-header-string")
(name (cpio-entry-name attrs))
(header-string))
(setq header-string (concat (cpio-crc-make-magic attrs)
(cpio-crc-make-ino attrs)
(cpio-crc-make-mode attrs)
(cpio-crc-make-uid attrs)
(cpio-crc-make-gid attrs)
(cpio-crc-make-nlink attrs)
(cpio-crc-make-mtime attrs)
(cpio-crc-make-filesize attrs)
(cpio-crc-make-dev-maj attrs)
(cpio-crc-make-dev-min attrs)
(cpio-crc-make-rdev-maj attrs)
(cpio-crc-make-rdev-min attrs)
(format "%08X" (1+ (length name)))
(format "%08X"
(if (cpio-special-file attrs) ;See cpio-modes.el
0
(cpio-crc-make-chksum (if contents
contents
name))))
name
"\0"))
(setq header-string (cg-pad-right header-string (cg-round-up (length header-string) *cpio-crc-padding-modulus*) "\0"))
;; Check (at least during development).
(if (string-match-p *cpio-crc-header-re* header-string)
header-string
(error "%s(): I built a bad header: [[%s]]" fname header-string))))
(defun cpio-crc-make-magic (attrs)
"Return the magic string for a CRC archive."
*cpio-crc-magic-re*)
(defalias 'cpio-crc-make-ino 'cpio-newc-make-ino)
(defalias 'cpio-crc-make-mode 'cpio-newc-make-mode)
(defalias 'cpio-crc-make-uid 'cpio-newc-make-uid)
(defalias 'cpio-crc-make-gid 'cpio-newc-make-gid)
(defalias 'cpio-crc-make-nlink 'cpio-newc-make-nlink)
(defalias 'cpio-crc-make-mtime 'cpio-newc-make-mtime)
(defalias 'cpio-crc-make-filesize 'cpio-newc-make-filesize)
(defalias 'cpio-crc-make-dev-maj 'cpio-newc-make-dev-maj)
(defalias 'cpio-crc-make-dev-min 'cpio-newc-make-dev-min)
(defalias 'cpio-crc-make-rdev-maj 'cpio-newc-make-rdev-maj)
(defalias 'cpio-crc-make-rdev-min 'cpio-newc-make-rdev-min)
(defun cpio-crc-make-chksum (entry-name-or-contents)
"Return a string value for the newc cpio entry from the file attributes ATTRS."
(let ((fname "cpio-crc-make-chksum")
(result 0)
(contents (if (cpio-entry-exists-p entry-name-or-contents)
(cpio-contents entry-name-or-contents)
entry-name-or-contents)))
;; According to the info this is only populated for crc archives.
;; It has always been 00000000 for my concrete newc examples.
;; And, indeed, it's only set in crc archives.
;; See copyout.c->writeout-defered-file() and nowhere else.
(mapc (lambda (c)
(setq result (+ result c)))
contents)
result))
;; Filename is not one of ATTRS. ∴ It doesn't get a constructor here.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Functions for whole entries
;;
(defun cpio-crc-parse-header-at-point ()
"Parse the crc cpio header that begins at point.
If there is no header there, then signal an error."
(let ((fname "cpio-crc-parse-header-at-point"))
(unless (looking-at-p *cpio-crc-header-re*)
(error "%s(): point is not looking at a crc header." fname))
(cpio-crc-parse-header (match-string-no-properties 0))))
(defun cpio-crc-goto-next-header ()
"Move the point to the beginning of the next crc cpio header.
If point is looking-at such a header, then that is the next one
and there is no movement.
\(Thus, a caller may have to make sure that point has moved.\)
This returns the a marker for point where the header is found, if one is found.
It returns NIL otherwise.
This sets match-data for the entire header and each field."
(let ((fname "cpio-crc-goto-next-header")
(header-start)
(header-string))
(cond ((re-search-forward *cpio-crc-header-re* (point-max) t)
(setq header-start (goto-char (match-beginning 0)))
(setq header-string (match-string-no-properties 0))
(cons (point-marker) header-string))
(t nil))))
(defun cpio-crc-build-catalog ()
"Build an internal structure reflecting the contents of the crc cpio archive in the current buffer.
See the variable *cpio-catalog* for more information.
CAVEAT: This respects neither narrowing nor the point."
(let ((fname "cpio-crc-build-catalog")
(header-start) ;A marker.
(header-end)
(that-header-string)
(header-info ())
(parsed-header t)
(filesize) ;A marker.
(contents-start)
(contents-end) ;NOT NEEDED?
(those-contents) ;
(catalog ()))
(widen)
(goto-char (point-min))
(while (and (setq header-info (cpio-crc-goto-next-header))
(setq header-start (car header-info))
(setq that-header-string (cdr header-info))
parsed-header)
(cond ((setq parsed-header (cpio-crc-parse-header-at-point))
(setq filesize (cpio-entry-size parsed-header))
(forward-char (length that-header-string))
(setq header-end (point))
;; A little bit of arithmetic gymnastics here
;; because cpio, being written in C, starts counting at 0, but
;; emacs' points start at 1.
(goto-char (1+ (cg-round-up (1- header-end) *cpio-crc-padding-modulus*)))
(setq contents-start (point-marker))
(set-marker-insertion-type contents-start *cg-insert-after*)
;; It feels like I really want a function for getting the contents.
;; But it's not obvious what is simpler or appropriately more general
;; than this one-liner.
;; Indeed. (setq those-contents (buffer-substring-no-properties contents-start contents-end))
(push (cons (cpio-entry-name parsed-header)
(vector
parsed-header
header-start
contents-start
'cpio-mode-entry-unmodified))
catalog)
(setq contents-end (+ contents-start filesize -1))
(goto-char contents-end))
(t t)))
(mapc (lambda (ce)
(cpio-validate-catalog-entry (cdr ce)))
catalog)
(nreverse catalog)))
(defalias 'cpio-crc-start-of-trailer 'cpio-newc-start-of-trailer)
(defalias 'cpio-crc-end-of-archive 'cpio-newc-end-of-archive)
(defun cpio-crc-adjust-trailer ()
"Replace thed current trailer in the current cpio crc archive."
(let ((fname "cpio-crc-adjust-trailer"))
(cpio-crc-delete-trailer)
(cpio-crc-insert-trailer)))
(defun cpio-crc-insert-trailer ()
"Insert a crc trailer into a cpio archive."
(let* ((fname "cpio-crc-insert-trailer")
(base-trailer *cpio-crc-trailer*)
(base-len (length base-trailer))
(len))
;; ...and insert the new trailer...
(with-writable-buffer
(insert base-trailer)
(goto-char (point-max))
;; ...with padding.
(setq len (cg-round-up (1- (point)) *cpio-crc-blocksize*))
(setq len (1+ (- len (point))))
(insert (make-string len ?\0)))))
(defalias 'cpio-crc-delete-trailer 'cpio-newc-delete-trailer)
(defun cpio-crc-make-chksum-for-file (filename)
"Return the checksum for FILENAME."
(let ((fname "cpio-newc-make-chksum-for-file"))
(with-temp-buffer
(insert-file-contents filename)
(cpio-crc-make-chksum (buffer-substring-no-properties (point-min) (point-max))))))
;;
;; Commands
;;
(provide 'cpio-crc)
;;; cpio-crc.el ends here.