;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 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 serialization)
#:use-module (rnrs bytevectors)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module (srfi srfi-35)
#:use-module (ice-9 binary-ports)
#:use-module ((ice-9 rdelim) #:prefix rdelim:)
#:use-module (ice-9 match)
#:use-module (ice-9 ftw)
#:use-module (system foreign)
#:export (write-int read-int
write-long-long read-long-long
write-padding
write-bytevector write-string
read-string read-latin1-string read-maybe-utf8-string
write-string-list read-string-list
write-string-pairs read-string-pairs
write-store-path read-store-path
write-store-path-list read-store-path-list
(dump . dump-port*)
&nar-error
nar-error?
nar-error-port
nar-error-file
&nar-read-error
nar-read-error?
nar-read-error-token
write-file
write-file-tree
fold-archive
restore-file
dump-file))
;;; Comment:
;;;
;;; Serialization procedures used by the RPCs and the Nar format. This module
;;; is for internal consumption.
;;;
;;; Code:
;; Similar to serialize.cc in Nix.
(define-condition-type &nar-error &error ; XXX: inherit from &store-error ?
nar-error?
(file nar-error-file) ; file we were restoring, or #f
(port nar-error-port)) ; port from which we read
(define currently-restored-file
;; Name of the file being restored. Used internally for error reporting.
(make-parameter #f))
(define (get-bytevector-n* port count)
(let ((bv (get-bytevector-n port count)))
(when (or (eof-object? bv)
(< (bytevector-length bv) count))
(raise (condition (&nar-error
(file (currently-restored-file))
(port port)))))
bv))
(define (sub-bytevector bv len)
"Return a bytevector that aliases the first LEN bytes of BV."
(define max (bytevector-length bv))
(cond ((= len max) bv)
((< len max)
;; Yes, this is safe because the result of each conversion procedure
;; has its life cycle synchronized with that of its argument.
(pointer->bytevector (bytevector->pointer bv) len))
(else
(error "sub-bytevector called to get a super bytevector"))))
(define (write-int n p)
(let ((b (make-bytevector 8 0)))
(bytevector-u32-set! b 0 n (endianness little))
(put-bytevector p b)))
(define (read-int p)
(let ((b (get-bytevector-n* p 8)))
(bytevector-u32-ref b 0 (endianness little))))
(define (write-long-long n p)
(let ((b (make-bytevector 8 0)))
(bytevector-u64-set! b 0 n (endianness little))
(put-bytevector p b)))
(define (read-long-long p)
(let ((b (get-bytevector-n* p 8)))
(bytevector-u64-ref b 0 (endianness little))))
(define write-padding
(let ((zero (make-bytevector 8 0)))
(lambda (n p)
(let ((m (modulo n 8)))
(or (zero? m)
(put-bytevector p zero 0 (- 8 m)))))))
(define* (write-bytevector s p
#:optional (l (bytevector-length s)))
(let* ((m (modulo l 8))
(b (make-bytevector (+ 8 l (if (zero? m) 0 (- 8 m))))))
(bytevector-u32-set! b 0 l (endianness little))
(bytevector-copy! s 0 b 8 l)
(put-bytevector p b)))
(define (write-string s p)
(write-bytevector (string->utf8 s) p))
(define (read-byte-string p)
(let* ((len (read-int p))
(m (modulo len 8))
(pad (if (zero? m) 0 (- 8 m)))
(bv (get-bytevector-n* p (+ len pad))))
(sub-bytevector bv len)))
(define (read-string p)
(utf8->string (read-byte-string p)))
(define (read-latin1-string p)
"Read an ISO-8859-1 string from P."
;; Note: do not use 'get-string-n' to work around Guile bug
;; <http://bugs.gnu.org/19621>. See <http://bugs.gnu.org/19610> for
;; a discussion.
(let ((bv (read-byte-string p)))
;; XXX: Rewrite using (ice-9 iconv).
(list->string (map integer->char (bytevector->u8-list bv)))))
(define (read-maybe-utf8-string p)
"Read a serialized string from port P. Attempt to decode it as UTF-8 and
substitute invalid byte sequences with question marks. This is a
\"permissive\" UTF-8 decoder."
;; XXX: We rely on the port's decoding mechanism to do permissive decoding
;; and substitute invalid byte sequences with question marks, but this is
;; not very efficient. Eventually Guile may provide a lightweight
;; permissive UTF-8 decoder.
(let* ((bv (read-byte-string p))
(port (open-bytevector-input-port bv)))
(set-port-encoding! port "UTF-8")
(set-port-conversion-strategy! port 'substitute)
(rdelim:read-string port)))
(define (write-string-list l p)
(write-int (length l) p)
(for-each (cut write-string <> p) l))
(define (read-string-list p)
(let ((len (read-int p)))
(unfold (cut >= <> len)
(lambda (i)
(read-string p))
1+
0)))
(define (write-string-pairs l p)
(write-int (length l) p)
(for-each (match-lambda
((first . second)
(write-string first p)
(write-string second p)))
l))
(define (read-string-pairs p)
(let ((len (read-int p)))
(unfold (cut >= <> len)
(lambda (i)
(cons (read-string p) (read-string p)))
1+
0)))
(define (write-store-path f p)
(write-string f p)) ; TODO: assert path
(define (read-store-path p)
(read-string p)) ; TODO: assert path
(define write-store-path-list write-string-list)
(define read-store-path-list read-string-list)
(define-syntax write-literal-strings
(lambda (s)
"Write the given literal strings to PORT in an optimized fashion, without
any run-time allocations or computations."
(define (padding len)
(let ((m (modulo len 8)))
(if (zero? m)
0
(- 8 m))))
(syntax-case s ()
((_ port strings ...)
(let* ((bytes (map string->utf8 (syntax->datum #'(strings ...))))
(len (fold (lambda (bv size)
(+ size 8 (bytevector-length bv)
(padding (bytevector-length bv))))
0
bytes))
(bv (make-bytevector len))
(zeros (make-bytevector 8 0)))
(fold (lambda (str offset)
(let ((len (bytevector-length str)))
(bytevector-u32-set! bv offset len (endianness little))
(bytevector-copy! str 0 bv (+ 8 offset) len)
(bytevector-copy! zeros 0 bv (+ 8 offset len)
(padding len))
(+ offset 8 len (padding len))))
0
bytes)
#`(put-bytevector port #,bv))))))
(define-condition-type &nar-read-error &nar-error
nar-read-error?
(token nar-read-error-token)) ; faulty token, or #f
(define (dump in out size)
"Copy SIZE bytes from IN to OUT."
(define buf-size 65536)
(define buf (make-bytevector buf-size))
(let loop ((left size))
(if (<= left 0)
0
(let ((read (get-bytevector-n! in buf 0 (min left buf-size))))
(if (eof-object? read)
left
(begin
(put-bytevector out buf 0 read)
(loop (- left read))))))))
(define (write-contents-from-port input output size)
"Write SIZE bytes from port INPUT to port OUTPUT."
(write-string "contents" output)
(write-long-long size output)
;; Use 'sendfile' when both OUTPUT and INPUT are file ports.
(if (and (file-port? output) (file-port? input))
(sendfile output input size 0)
(dump input output size))
(write-padding size output))
(define (read-file-type port)
"Read the file type tag from PORT, and return either 'regular or
'executable."
(match (read-string port)
("contents"
'regular)
("executable"
(match (list (read-string port) (read-string port))
(("" "contents") 'executable)
(x (raise
(condition (&message
(message "unexpected executable file marker"))
(&nar-read-error (port port)
(file #f)
(token x)))))))
(x
(raise
(condition (&message (message "unsupported nar file type"))
(&nar-read-error (port port) (file #f) (token x)))))))
(define %archive-version-1
;; Magic cookie for Nix archives.
"nix-archive-1")
(define* (write-file file port
#:key (select? (const #t)))
"Write the contents of FILE to PORT in Nar format, recursing into
sub-directories of FILE as needed. For each directory entry, call (SELECT?
FILE STAT), where FILE is the entry's absolute file name and STAT is the
result of 'lstat'; exclude entries for which SELECT? does not return true."
(write-file-tree file port
#:file-type+size
(lambda (file)
(let* ((stat (lstat file))
(size (stat:size stat)))
(case (stat:type stat)
((directory)
(values 'directory size))
((regular)
(values (if (zero? (logand (stat:mode stat)
#o100))
'regular
'executable)
size))
(else
(values (stat:type stat) size))))) ;bah!
#:file-port (cut open-file <> "r0b")
#:symlink-target readlink
#:directory-entries
(lambda (directory)
;; 'scandir' defaults to 'string-locale<?' to sort files,
;; but this happens to be case-insensitive (at least in
;; 'en_US' locale on libc 2.18.) Conversely, we want
;; files to be sorted in a case-sensitive fashion.
(define basenames
(scandir directory (negate (cut member <> '("." "..")))
string<?))
(filter-map (lambda (base)
(let ((file (string-append directory
"/" base)))
(and (select? file (lstat file))
base)))
basenames))
;; The 'scandir' call above gives us filtered and sorted
;; entries, so no post-processing is needed.
#:postprocess-entries identity))
(define (filter/sort-directory-entries lst)
"Remove dot and dot-dot entries from LST, and sort it in lexicographical
order."
(delete-duplicates
(sort (remove (cute member <> '("." "..")) lst)
string<?)
string=?))
(define* (write-file-tree file port
#:key
file-type+size
file-port
symlink-target
directory-entries
(postprocess-entries filter/sort-directory-entries))
"Write the contents of FILE to PORT in Nar format, recursing into
sub-directories of FILE as needed.
This procedure does not make any file-system I/O calls. Instead, it calls the
user-provided FILE-TYPE+SIZE, FILE-PORT, SYMLINK-TARGET, and DIRECTORY-ENTRIES
procedures, which roughly correspond to 'lstat', 'readlink', and 'scandir'.
POSTPROCESS-ENTRIES ensures that directory entries are valid; leave it as-is
unless you know that DIRECTORY-ENTRIES provide filtered and sorted entries, in
which case you can use 'identity'."
(define p port)
(write-string %archive-version-1 p)
(let dump ((f file))
(define-values (type size)
(file-type+size f))
(write-literal-strings p "(")
(case type
((regular executable)
(write-literal-strings p "type" "regular")
(when (eq? 'executable type)
(write-literal-strings p "executable" ""))
(let ((input (file-port f)))
(dynamic-wind
(const #t)
(lambda ()
(write-contents-from-port input p size))
(lambda ()
(close-port input)))))
((directory)
(write-literal-strings p "type" "directory")
(let ((entries (postprocess-entries (directory-entries f))))
(for-each (lambda (e)
(let* ((f (string-append f "/" e)))
(write-literal-strings p "entry" "(" "name")
(write-string e p)
(write-literal-strings p "node")
(dump f)
(write-literal-strings p ")")))
entries)))
((symlink)
(write-literal-strings p "type" "symlink" "target")
(write-string (symlink-target f) p))
(else
(raise (condition (&message (message "unsupported file type"))
(&nar-error (file f) (port port))))))
(write-literal-strings p ")")))
(define port-conversion-strategy
(fluid->parameter %default-port-conversion-strategy))
(define (fold-archive proc seed port file)
"Read a file (possibly a directory structure) in Nar format from PORT. Call
PROC on each file or directory read from PORT using:
(PROC FILE TYPE CONTENTS RESULT)
using SEED as the first RESULT. TYPE is a symbol like 'regular, and CONTENTS
depends on TYPE."
(parameterize ((currently-restored-file file)
;; Error out if we can convert file names to the current
;; locale. (XXX: We'd prefer UTF-8 encoding for file names
;; regardless of the locale, but that's what Guile gives us
;; so far.)
(port-conversion-strategy 'error))
(let ((signature (read-string port)))
(unless (equal? signature %archive-version-1)
(raise
(condition (&message (message "invalid nar signature"))
(&nar-read-error (port port)
(token signature)
(file #f))))))
(let read ((file file)
(result seed))
(define (read-eof-marker)
(match (read-string port)
(")" #t)
(x (raise
(condition
(&message (message "invalid nar end-of-file marker"))
(&nar-read-error (port port) (file file) (token x)))))))
(currently-restored-file file)
(match (list (read-string port) (read-string port) (read-string port))
(("(" "type" "regular")
(let* ((type (read-file-type port))
(size (read-long-long port))
;; The caller must read exactly SIZE bytes from PORT.
(result (proc file type `(,port . ,size) result)))
(let ((m (modulo size 8)))
(unless (zero? m)
(get-bytevector-n* port (- 8 m))))
(read-eof-marker)
result))
(("(" "type" "symlink")
(match (list (read-string port) (read-string port))
(("target" target)
(let ((result (proc file 'symlink target result)))
(read-eof-marker)
result))
(x (raise
(condition
(&message (message "invalid symlink tokens"))
(&nar-read-error (port port) (file file) (token x)))))))
(("(" "type" "directory")
(let ((dir file))
(let loop ((prefix (read-string port))
(result (proc file 'directory #f result)))
(match prefix
("entry"
(match (list (read-string port)
(read-string port) (read-string port)
(read-string port))
(("(" "name" file "node")
(let ((result (read (string-append dir "/" file) result)))
(match (read-string port)
(")" #f)
(x
(raise
(condition
(&message
(message "unexpected directory entry termination"))
(&nar-read-error (port port)
(file file)
(token x))))))
(loop (read-string port) result)))))
(")" ;done with DIR
(proc file 'directory-complete #f result))
(x
(raise
(condition
(&message (message "unexpected directory inter-entry marker"))
(&nar-read-error (port port) (file file) (token x)))))))))
(x
(raise
(condition
(&message (message "unsupported nar entry type"))
(&nar-read-error (port port) (file file) (token x)))))))))
(define (dump-file file input size type)
"Dump SIZE bytes from INPUT to FILE.
This procedure is suitable for use as the #:dump-file argument to
'restore-file'."
(call-with-output-file file
(lambda (output)
(dump input output size))))
(define* (restore-file port file
#:key (dump-file dump-file))
"Read a file (possibly a directory structure) in Nar format from PORT.
Restore it as FILE with canonical permissions and timestamps. To write a
regular or executable file, call:
(DUMP-FILE FILE INPUT SIZE TYPE)
The default is to dump SIZE bytes from INPUT to FILE, but callers can provide
a custom procedure, for instance to deduplicate FILE on the fly."
(fold-archive (lambda (file type content result)
(match type
('directory
(mkdir file))
('directory-complete
(chmod file #o555)
(utime file 1 1 0 0))
('symlink
(symlink content file)
(utime file 1 1 0 0 AT_SYMLINK_NOFOLLOW))
((or 'regular 'executable)
(match content
((input . size)
(dump-file file input size type)
(chmod file (if (eq? type 'executable)
#o555
#o444))
(utime file 1 1 0 0))))))
#t
port
file))
;;; Local Variables:
;;; eval: (put 'call-with-binary-input-file 'scheme-indent-function 1)
;;; End:
;;; serialization.scm ends here
