guix-kreyren/guix/serialization.scm
Ludovic Courtès 01e5d63c87
serialization: 'read-byte-string' makes a single read(2) call.
On "guix build libreoffice -nd", this reduces the number of read(2)
system calls from 10,434 to 8092.

* guix/serialization.scm (sub-bytevector): New procedure.
(read-byte-string): Make a single 'get-bytevector-n*' call and use
'sub-bytevector'.
2020-01-24 23:56:43 +01:00

485 lines
18 KiB
Scheme
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 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 (guix combinators)
#: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
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))
;;; 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 (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-list p)
(let ((len (read-int p)))
(unfold (cut >= <> len)
(lambda (i)
(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-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-string "(" p)
(case type
((regular executable)
(write-string "type" p)
(write-string "regular" p)
(when (eq? 'executable type)
(write-string "executable" p)
(write-string "" p))
(let ((input (file-port f)))
(dynamic-wind
(const #t)
(lambda ()
(write-contents-from-port input p size))
(lambda ()
(close-port input)))))
((directory)
(write-string "type" p)
(write-string "directory" p)
(let ((entries (postprocess-entries (directory-entries f))))
(for-each (lambda (e)
(let* ((f (string-append f "/" e)))
(write-string "entry" p)
(write-string "(" p)
(write-string "name" p)
(write-string e p)
(write-string "node" p)
(dump f)
(write-string ")" p)))
entries)))
((symlink)
(write-string "type" p)
(write-string "symlink" p)
(write-string "target" p)
(write-string (symlink-target f) p))
(else
(raise (condition (&message (message "unsupported file type"))
(&nar-error (file f) (port port))))))
(write-string ")" 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)))))
(")" result) ;done with DIR
(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 (restore-file port file)
"Read a file (possibly a directory structure) in Nar format from PORT.
Restore it as FILE."
(fold-archive (lambda (file type content result)
(match type
('directory
(mkdir file))
('symlink
(symlink content file))
((or 'regular 'executable)
(match content
((input . size)
(call-with-output-file file
(lambda (output)
(dump input output size)
(when (eq? type 'executable)
(chmod output #o755)))))))))
#t
port
file))
;;; Local Variables:
;;; eval: (put 'call-with-binary-input-file 'scheme-indent-function 1)
;;; End:
;;; serialization.scm ends here