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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013 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 hash)
#:use-module (guix config)
#:use-module (rnrs bytevectors)
#:use-module (rnrs io ports)
#:use-module (system foreign)
#:use-module ((guix build utils) #:select (dump-port))
#:use-module (srfi srfi-11)
#:export (sha256
open-sha256-port
port-sha256))
;;; Commentary:
;;;
;;; Cryptographic hashes.
;;;
;;; Code:
;;;
;;; Hash.
;;;
(define-syntax GCRY_MD_SHA256
;; Value as of Libgcrypt 1.5.2.
(identifier-syntax 8))
(define sha256
(let ((hash (pointer->procedure void
(dynamic-func "gcry_md_hash_buffer"
(dynamic-link %libgcrypt))
`(,int * * ,size_t))))
(lambda (bv)
"Return the SHA256 of BV as a bytevector."
(let ((digest (make-bytevector (/ 256 8))))
(hash GCRY_MD_SHA256 (bytevector->pointer digest)
(bytevector->pointer bv) (bytevector-length bv))
digest))))
(define open-sha256-md
(let ((open (pointer->procedure int
(dynamic-func "gcry_md_open"
(dynamic-link %libgcrypt))
`(* ,int ,unsigned-int))))
(lambda ()
(let* ((md (bytevector->pointer (make-bytevector (sizeof '*))))
(err (open md GCRY_MD_SHA256 0)))
(if (zero? err)
(dereference-pointer md)
(throw 'gcrypt-error err))))))
(define md-write
(pointer->procedure void
(dynamic-func "gcry_md_write"
(dynamic-link %libgcrypt))
`(* * ,size_t)))
(define md-read
(pointer->procedure '*
(dynamic-func "gcry_md_read"
(dynamic-link %libgcrypt))
`(* ,int)))
(define md-close
(pointer->procedure void
(dynamic-func "gcry_md_close"
(dynamic-link %libgcrypt))
'(*)))
(define (open-sha256-port)
"Return two values: an output port, and a thunk. When the thunk is called,
it returns the SHA256 hash (a bytevector) of all the data written to the
output port."
(define sha256-md
(open-sha256-md))
(define digest #f)
(define (finalize!)
(let ((ptr (md-read sha256-md 0)))
(set! digest (bytevector-copy (pointer->bytevector ptr 32)))
(md-close sha256-md)))
(define (write! bv offset len)
(if (zero? len)
(begin
(finalize!)
0)
(let ((ptr (bytevector->pointer bv offset)))
(md-write sha256-md ptr len)
len)))
(define (close)
(unless digest
(finalize!)))
(values (make-custom-binary-output-port "sha256"
write! #f #f
close)
(lambda ()
(unless digest
(finalize!))
digest)))
(define (port-sha256 port)
"Return the SHA256 hash (a bytevector) of all the data drained from PORT."
(let-values (((out get)
(open-sha256-port)))
(dump-port port out)
(close-port out)
(get)))
;;; hash.scm ends here
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