;;; cpio-bin.el --- handle bin 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
;;
(require 'bindat)
(eval-when-compile (require 'cpio-generic)) ;For `with-writable-buffer'!
;;;;;;;;;;;;;;;;
;; Things to make the byte compiler happy.
(declare-function cpio-entry-name "cpio-mode.el" (attrs))
(declare-function cpio-ino "cpio-mode.el" (attrs))
(declare-function cpio-mode-value "cpio-mode.el" (attrs))
(declare-function cpio-uid "cpio-mode.el" (attrs))
(declare-function cpio-gid "cpio-mode.el" (attrs))
(declare-function cpio-nlink "cpio-mode.el" (attrs))
(declare-function cpio-mtime "cpio-mode.el" (attrs))
(declare-function cpio-entry-size "cpio-mode.el" (attrs))
(declare-function cpio-dev-maj "cpio-mode.el" (attrs))
(declare-function cpio-rdev-maj "cpio-mode.el" (attrs))
(declare-function cpio-entry-attrs-from-catalog-entry "cpio-mode.el" (entry))
(declare-function cpio-contents-start "cpio-mode.el" (entry-name))
(declare-function cpio-entry-attrs "cpio-mode.el" (entry-name))
(defvar *cpio-catalog*)
;; EO things for the byte compiler.
;;;;;;;;;;;;;;;;
;;
;; Vars
;;
(defconst *cpio-bin-header-length* (length (string-as-unibyte "\307q\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0 \0\0\0\0\0"))
"The length of a bin header.")
;; \307q\0\375c\9\244\201\350\3\350\3\1\0\0\0\377Z\320q\2\0\0\0\4\0a\0
;; \307q \0\375 c\9 \244\201 \350\3 \350\3 \1\0 \0\0 \377Z\320q \2\0 \0\0\4\0 a\0
(defconst *cpio-bin-magic-re* "\307q" ; 070707 \307q
"RE to match the magic number of a bin archive.")
(setq *cpio-bin-magic-re* "\307q")
(defconst *cpio-bin-dev-re* "\\w\\w"
"RE to match the c_dev field in a bin header.")
(setq *cpio-bin-dev-re* "\\w\\w")
(defconst *cpio-bin-ino-re* "\\w\\w"
"RE to match the c_ino field in a bin header.")
(setq *cpio-bin-ino-re* "\\w\\w")
(defconst *cpio-bin-mode-re* "\\w\\w"
"RE to match the c_mode field in a bin header.")
(setq *cpio-bin-mode-re* "\\w\\w")
(defconst *cpio-bin-uid-re* "\\w\\w"
"RE to match the c_uid field in a bin header.")
(setq *cpio-bin-uid-re* "\\w\\w")
(defconst *cpio-bin-gid-re* "\\w\\w"
"RE to match the c_gid field in a bin header.")
(setq *cpio-bin-gid-re* "\\w\\w")
(defconst *cpio-bin-nlink-re* "\\w\\w"
"RE to match the c_nlink field in a bin header.")
(setq *cpio-bin-nlink-re* "\\w\\w")
(defconst *cpio-bin-rdev-re* "\\w\\w"
"RE to match the c_rdev field in a bin header.")
(setq *cpio-bin-rdev-re* "\\w\\w")
(defconst *cpio-bin-mtime-re* "\\w\\w\\w\\w"
"RE to match the c_mtime field in a bin header.")
(setq *cpio-bin-mtime-re* "\\w\\w\\w\\w")
(defconst *cpio-bin-namesize-re* "\\w\\w"
"RE to match the c_rdev field in a bin header.")
(setq *cpio-bin-rdev-re* "\\w\\w")
(defconst *cpio-bin-filesize-re* "\\w\\w\\w\\w"
"RE to match the c_filesize field in a bin header.")
(setq *cpio-bin-filesize-re* "\\w\\w\\w\\w")
(defconst *cpio-bin-filename-re* ()
"RE to match a filename in a bin header.")
(setq *cpio-bin-filename-re* "[[:print:]]+")
(defconst *cpio-bin-header-re* ()
"RE to match bin header format cpio archives.")
(setq *cpio-bin-header-re* (concat "\\(" *cpio-bin-magic-re* "\\)"
"\\(" *cpio-bin-dev-re* "\\)"
"\\(" *cpio-bin-ino-re* "\\)"
"\\(" *cpio-bin-mode-re* "\\)"
"\\(" *cpio-bin-uid-re* "\\)"
"\\(" *cpio-bin-gid-re* "\\)"
"\\(" *cpio-bin-nlink-re* "\\)"
"\\(" *cpio-bin-rdev-re* "\\)"
"\\(" *cpio-bin-mtime-re* "\\)"
"\\(" *cpio-bin-namesize-re* "\\)"
"\\(" *cpio-bin-filesize-re* "\\)"
"\\(" *cpio-bin-filename-re* "\\)"
"\0"))
(defvar *cpio-bin-name-field-offset* (length "\307q\0\375z\r\244\201\350\350\0\0\0[\211\255\0\0\0\0")
"The offset of the name field in a cpio binary header.")
(defconst cpio-bin-index-spec
'(;; (:magic u16)
(:dev u16)
(:ino u16)
(:mode u16)
(:uid u16)
(:gid u16)
(:nlink u16)
(:rdev u16)
(:mtime u32)
(:namesize u16)
(:filesize u32)
(:filename strz (:namesize))))
(setq cpio-bin-index-spec
'((:magic u16r)
(:dev u16r)
(:ino u16r)
(:mode u16r)
(:uid u16r)
(:gid u16r)
(:nlink u16r)
(:rdev u16r)
(:mtime0 u16r)
(:mtime1 u16r)
(:namesize u16r)
(:filesize0 u16r)
(:filesize1 u16r)
(:filename strz (:namesize))))
(defconst *cpio-bin-magic* *cpio-bin-magic-re*
"The string that identifies an entry as a BIN style cpio(1) entry.")
(setq *cpio-bin-magic* *cpio-bin-magic-re*)
(defconst *cpio-bin-magic-int* #o070707
"An integer value of the cpio bin magic number.")
(defconst *cpio-bin-padding-modulus* 2
"The modulus to which some things are padded in a BIN cpio archive.")
(setq *cpio-bin-padding-modulus* 2)
(defconst *cpio-bin-padding-char* ?\0
"A character to be used for padding headers and entry contents
in a bin cpio archive.")
(setq *cpio-bin-padding-char* ?\0)
(defconst *cpio-bin-padding-str* "\0"
"A single character string of the character
to be used for padding headers and entry contents
in a bin cpio archive.")
(setq *cpio-bin-padding-str* "\0")
(defconst *cpio-bin-trailer* (string-as-unibyte "\307q\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0 \0\0\0\0\0TRAILER!!!\0\0")
"The TRAILER string of a cpio binary archive.")
(defcustom *cpio-bin-blocksize* 512
"The default blocksize for a cpio binary archive."
:type 'integer
:group 'cpio)
;;
;; Library
;;
(defun cpio-bin-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-bin-header-at-point")
(found nil))
(save-match-data
(cond ((looking-at *cpio-bin-header-re*)
(string-as-unibyte (match-string-no-properties 0)))
(t
(forward-char (length *cpio-bin-magic-re*))
(while (and (re-search-backward *cpio-bin-magic-re* (point-min) t)
(not (setq found (looking-at *cpio-bin-header-re*)))))
(if found
(string-as-unibyte (match-string-no-properties 0))))))))
(defun cpio-bin-parse-header (header-string)
"Return the internal entry header structure encoded in HEADER-STRING.
HEADER-STRING is a unibyte string.
The function does NOT get the contents of that entry."
(let ((fname "cpio-bin-parse-header")
(header-info)
(mtime)
(filesize)
(result)
(entry-name))
(setq header-info (bindat-unpack cpio-bin-index-spec
header-string))
(setq mtime (list (bindat-get-field header-info :mtime0)
(bindat-get-field header-info :mtime1)))
(setq filesize (+ (* 256 256 (bindat-get-field header-info :filesize0))
(bindat-get-field header-info :filesize1)))
(cond ((string-equal (setq entry-name (bindat-get-field header-info :filename))
"TRAILER!!!")
nil)
(t
(setq result
(vector (bindat-get-field header-info :ino)
(bindat-get-field header-info :mode)
(bindat-get-field header-info :uid)
(bindat-get-field header-info :gid)
(bindat-get-field header-info :nlink)
mtime
filesize
(bindat-get-field header-info :dev)
0 ;dev min
(bindat-get-field header-info :rdev)
0 ;rdev min
(bindat-get-field header-info :namesize)
0 ;checksum
entry-name))
(if (cpio-entry-name result)
result
nil)))))
(defun cpio-bin-header-size (header-string namesize)
"Determine the length of the header implied by the given HEADER-STRING."
(let ((fname "cpio-bin-header-size")
;; CAUTION: The following assumes that (string-to-number) doesn't care about leading zeroes.
;; The namesize in the header includes the terminating NULL at the end of the name.
(local-namesize (1- namesize))
(total -1))
(if (= 0 (mod (setq total (+ 1 *cpio-bin-name-field-offset* local-namesize))
*cpio-bin-padding-modulus*))
(setq total (1+ total)))
(cg-round-up total *cpio-bin-padding-modulus*)))
;;;;;;;;;;;;;;;;
;;
;; Header construction
;;
(defun cpio-bin-make-header-string (attrs &optional contents)
"Make a BIN style padded cpio header for the given ATTRibuteS.
This function does NOT include the contents."
(let ((fname "cpio-bin-make-header-string")
(name (cpio-entry-name attrs))
(header-string)
(padding)
(mtime (cpio-bin-make-mtime attrs))
(filesize (cpio-bin-make-filesize attrs)))
(setq header-string
(bindat-pack cpio-bin-index-spec
(list
(cons :magic (cpio-bin-make-magic attrs))
(cons :dev (cpio-bin-make-dev-maj attrs))
(cons :ino (cpio-bin-make-ino attrs))
(cons :mode (cpio-bin-make-mode attrs))
(cons :uid (cpio-bin-make-uid attrs))
(cons :gid (cpio-bin-make-gid attrs))
(cons :nlink (cpio-bin-make-nlink attrs))
(cons :rdev (cpio-bin-make-rdev-maj attrs))
(cons :mtime0 (car mtime))
(cons :mtime1 (cdr mtime))
(cons :namesize (1+ (length name)))
(cons :filesize0 (car filesize))
(cons :filesize1 (cdr filesize))
(cons :filename (concat name "\0")))))
(setq header-string (cg-pad-right header-string (cg-round-up (length header-string)
*cpio-bin-padding-modulus*)
"\0"))))
(defun cpio-bin-make-magic (attrs)
"Return the BIN magic header string"
(let ((fname "cpio-bin-make-magic"))
*cpio-bin-magic-int*))
(defun cpio-bin-make-ino (attrs)
"Return a string value for the inode from the file attributes ATTRS."
(let ((fname "cpio-bin-make-ino"))
(cpio-ino attrs)))
(defun cpio-bin-make-mode (attrs)
"Return a string value for the mode from the file attributes ATTRS."
(let ((fname "cpio-bin-make-mode"))
(cpio-mode-value attrs)))
(defun cpio-bin-make-uid (attrs)
"Return an integer string value for the UID from the file attributes ATTRS."
(let ((fname "cpio-bin-make-uid"))
(cpio-uid attrs)))
(defun cpio-bin-make-gid (attrs)
"Return an integer string value for the GID from the file attributes ATTRS."
(let ((fname "cpio-bin-make-gid"))
(cpio-gid attrs)))
(defun cpio-bin-make-nlink (attrs)
"Return an integer string value for the number of links from the file attributes ATTRS."
(let ((fname "cpio-bin-make-nlink"))
(cpio-nlink attrs)))
(defun cpio-bin-make-mtime (attrs)
"Return a string value for the mod time from the file attributes ATTRS."
(let* ((fname "cpio-bin-make-mtime")
(mod-time (cpio-mtime attrs))
(high-time (car mod-time))
(low-time (cadr mod-time)))
(cons high-time low-time)))
(defun cpio-bin-make-filesize (attrs)
"Return an 8 digit hex string for the filesize attribute among the given ATTRs."
(let ((fname "cpio-bin-make-filesize")
(filesize (cpio-entry-size attrs)))
(cons (lsh (logand #xFFFF0000 filesize) 8)
(logand #xFFFF filesize))))
(defun cpio-bin-make-dev-maj (attrs)
"Return a string value for the major device from the file attributes ATTRS."
(let ((fname "cpio-bin-make-dev-maj"))
(cpio-dev-maj attrs)))
(defun cpio-bin-make-dev-min (attrs)
"Return a string value for the minor device from the file attributes ATTRS."
(let ((fname "cpio-bin-make-dev-min"))
0))
(defun cpio-bin-make-rdev-maj (attrs)
"Return a string value for the major rdev from the file attributes ATTRS."
(let ((fname "cpio-bin-make-rdev-maj"))
(cpio-rdev-maj attrs)))
(defun cpio-bin-make-rdev-min (attrs)
"Return a string value for the minor rdev from the file attributes ATTRS."
(let ((fname "cpio-bin-make-rdev-min"))
0))
(defun cpio-bin-make-chksum (attrs)
"Return a string value for the bin cpio entry from the file attributes ATTRS."
(let ((fname "cpio-bin-make-chksum"))
0))
;; Filename is not one of ATTRS. ∴ It doesn't get a constructor here.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Functions for whole entries
;;
(defun cpio-bin-parse-header-at-point ()
"Parse the bin cpio header that begins at point.
If there is no header there, then signal an error."
(let ((fname "cpio-bin-parse-header-at-point"))
(unless (looking-at-p *cpio-bin-header-re*)
(error "%s(): point is not looking at a bin header." fname))
(cpio-bin-parse-header (string-as-unibyte (match-string-no-properties 0)))))
(defun cpio-bin-goto-next-header ()
"Move the point to the beginning of the next bin 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-bin-goto-next-header")
(header-start)
(header-string))
(cond ((re-search-forward *cpio-bin-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-bin-build-catalog ()
"Build an internal structure reflecting the contents of the bin 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-bin-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-bin-goto-next-header))
(setq header-start (car header-info))
(setq that-header-string (cdr header-info))
parsed-header)
(cond ((setq parsed-header (cpio-bin-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 arithmétic 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-bin-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)))
(nreverse catalog)))
(defun cpio-bin-start-of-trailer ()
"Return the character position of the (ostensible) start of the trailer
for the current cpio archive."
(let ((fname "cpio-bin-start-of-trailer")
(end-of-contents 0))
(mapc (lambda (ce)
(let ((attrs (cpio-entry-attrs-from-catalog-entry ce)))
(setq end-of-contents (+ (cpio-entry-size attrs) (cpio-contents-start ce)))))
*cpio-catalog*)
end-of-contents))
(defun cpio-bin-end-of-archive ()
"Calculate the location of the end of the current archive
once the TRAILER is written and padded."
(let ((fname "cpio-bin-end-of-archive")
(end-of-contents (cpio-bin-start-of-trailer)))
(cg-round-up (+ end-of-contents (length *cpio-bin-trailer*)) 512)))
(defun cpio-bin-adjust-trailer ()
"Replace thed current trailer in the current cpio bin archive."
(let* ((fname "cpio-bin-adjust-trailer"))
(cpio-bin-delete-trailer)
(cpio-bin-insert-trailer)))
(defun cpio-bin-insert-trailer ()
"Insert a bin trailer into a cpio archive."
(let* ((fname "cpio-bin-insert-trailer")
(base-trailer *cpio-bin-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-bin-blocksize*))
(setq len (1+ (- len (point))))
(insert (make-string len ?\0)))))
(defun cpio-bin-delete-trailer ()
"Delete the trailer in the current cpio bin archive."
(let ((fname "cpio-bin-delete-trailer"))
(unless (eq major-mode 'cpio-mode)
(error "%s(): Called outside of a cpio archive buffer." fname))
;; First, get to the end of the last entry in the archive.
(goto-char (point-min))
(mapc (lambda (e)
(let* ((ename (car e)) ;Isn't there a generic function for this?
(attrs (cpio-entry-attrs ename))
;; Fencepost issue here.
(entry-end (+ (cpio-contents-start ename)
(cpio-entry-size attrs))))
(goto-char entry-end)
(skip-chars-forward "\0")))
*cpio-catalog*)
;; Next, delete what's left...
(with-writable-buffer
(delete-region (point) (point-max)))))
(defun cpio-bin-make-chcksum-for-file (filename)
"Return the checksum for FILENAME."
(let ((fname "cpio-newc-make-chcksum-for-file"))
0))
;;
;; Commands
;;
(provide 'cpio-bin)
;;; cpio-bin.el ends here.