guix-devel/guix/utils.scm

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;;; Guix --- Nix package management from Guile. -*- coding: utf-8 -*-
;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of Guix.
;;;
;;; 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.
;;;
;;; 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 Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (guix utils)
#:use-module (guix config)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-39)
#:use-module (srfi srfi-60)
#:use-module (rnrs bytevectors)
#:use-module ((rnrs io ports) #:select (put-bytevector))
#:use-module (ice-9 vlist)
#:use-module (ice-9 format)
#:autoload (ice-9 popen) (open-pipe*)
#:autoload (ice-9 rdelim) (read-line)
#:use-module (ice-9 regex)
#:use-module (ice-9 match)
#:use-module (ice-9 format)
#:autoload (system foreign) (pointer->procedure)
#:export (bytevector->base16-string
base16-string->bytevector
sha256
%nixpkgs-directory
nixpkgs-derivation
nixpkgs-derivation*
define-record-type*
compile-time-value
memoize
default-keyword-arguments
substitute-keyword-arguments
location
location?
location-file
location-line
location-column
source-properties->location
gnu-triplet->nix-system
%current-system
package-name->name+version))
;;;
;;; Compile-time computations.
;;;
(define-syntax compile-time-value
(syntax-rules ()
"Evaluate the given expression at compile time. The expression must
evaluate to a simple datum."
((_ exp)
(let-syntax ((v (lambda (s)
(let ((val exp))
(syntax-case s ()
(_ #`'#,(datum->syntax s val)))))))
v))))
;;;
;;; Base 16.
;;;
(define (bytevector->base16-string bv)
"Return the hexadecimal representation of BV's contents."
(define len
(bytevector-length bv))
(let-syntax ((base16-chars (lambda (s)
(syntax-case s ()
(_
(let ((v (list->vector
(unfold (cut > <> 255)
(lambda (n)
(format #f "~2,'0x" n))
1+
0))))
v))))))
(define chars base16-chars)
(let loop ((i 0)
(r '()))
(if (= i len)
(string-concatenate-reverse r)
(loop (+ 1 i)
(cons (vector-ref chars (bytevector-u8-ref bv i)) r))))))
(define base16-string->bytevector
(let ((chars->value (fold (lambda (i r)
(vhash-consv (string-ref (number->string i 16)
0)
i r))
vlist-null
(iota 16))))
(lambda (s)
"Return the bytevector whose hexadecimal representation is string S."
(define bv
(make-bytevector (quotient (string-length s) 2) 0))
(string-fold (lambda (chr i)
(let ((j (quotient i 2))
(v (and=> (vhash-assv chr chars->value) cdr)))
(if v
(if (zero? (logand i 1))
(bytevector-u8-set! bv j
(arithmetic-shift v 4))
(let ((w (bytevector-u8-ref bv j)))
(bytevector-u8-set! bv j (logior v w))))
(error "invalid hexadecimal character" chr)))
(+ i 1))
0
s)
bv)))
;;;
;;; Hash.
;;;
(define sha256
(let ((hash (pointer->procedure void
(dynamic-func "gcry_md_hash_buffer"
(dynamic-link %libgcrypt))
`(,int * * ,size_t)))
(sha256 8)) ; GCRY_MD_SHA256, as of 1.5.0
(lambda (bv)
"Return the SHA256 of BV as a bytevector."
(let ((digest (make-bytevector (/ 256 8))))
(hash sha256 (bytevector->pointer digest)
(bytevector->pointer bv) (bytevector-length bv))
digest))))
;;;
;;; Nixpkgs.
;;;
(define %nixpkgs-directory
(make-parameter
;; Capture the build-time value of $NIXPKGS.
(or %nixpkgs (getenv "NIXPKGS"))))
(define* (nixpkgs-derivation attribute #:optional (system (%current-system)))
"Return the derivation path of ATTRIBUTE in Nixpkgs."
(let* ((p (open-pipe* OPEN_READ (or (getenv "NIX_INSTANTIATE")
%nix-instantiate)
"-A" attribute (%nixpkgs-directory)
"--argstr" "system" system))
(l (read-line p))
(s (close-pipe p)))
(and (zero? (status:exit-val s))
(not (eof-object? l))
l)))
(define-syntax-rule (nixpkgs-derivation* attribute)
"Evaluate the given Nixpkgs derivation at compile-time."
(compile-time-value (nixpkgs-derivation attribute)))
;;;
;;; Miscellaneous.
;;;
(define-syntax define-record-type*
(lambda (s)
"Define the given record type such that an additional \"syntactic
constructor\" is defined, which allows instances to be constructed with named
field initializers, à la SRFI-35, as well as default values."
(define (make-syntactic-constructor type name ctor fields defaults)
"Make the syntactic constructor NAME for TYPE, that calls CTOR, and
expects all of FIELDS to be initialized. DEFAULTS is the list of
FIELD/DEFAULT-VALUE tuples."
(with-syntax ((type type)
(name name)
(ctor ctor)
(expected fields)
(defaults defaults))
#`(define-syntax name
(lambda (s)
(define (record-inheritance orig-record field+value)
;; Produce code that returns a record identical to
;; ORIG-RECORD, except that values for the FIELD+VALUE alist
;; prevail.
(define (field-inherited-value f)
(and=> (find (lambda (x)
(eq? f (car (syntax->datum x))))
field+value)
car))
#`(make-struct type 0
#,@(map (lambda (field index)
(or (field-inherited-value field)
#`(struct-ref #,orig-record
#,index)))
'expected
(iota (length 'expected)))))
(syntax-case s (inherit #,@fields)
((_ (inherit orig-record) (field value) (... ...))
#`(letrec* ((field value) (... ...))
#,(record-inheritance #'orig-record
#'((field value) (... ...)))))
((_ (field value) (... ...))
(let ((fields (map syntax->datum #'(field (... ...))))
(dflt (map (match-lambda
((f v)
(list (syntax->datum f) v)))
#'defaults)))
(define (field-value f)
(or (and=> (find (lambda (x)
(eq? f (car (syntax->datum x))))
#'((field value) (... ...)))
car)
(car (assoc-ref dflt (syntax->datum f)))))
(let-syntax ((error*
(syntax-rules ()
((_ fmt args (... ...))
(syntax-violation 'name
(format #f fmt args
(... ...))
s)))))
(let ((fields (append fields (map car dflt))))
(cond ((lset= eq? fields 'expected)
#`(letrec* ((field value) (... ...))
(ctor #,@(map field-value 'expected))))
((pair? (lset-difference eq? fields 'expected))
(error* "extraneous field initializers ~a"
(lset-difference eq? fields 'expected)))
(else
(error* "missing field initializers ~a"
(lset-difference eq? 'expected
fields)))))))))))))
(define (field-default-value s)
(syntax-case s (default)
((field (default val) _ ...)
(list #'field #'val))
((field _ options ...)
(field-default-value #'(field options ...)))
(_ #f)))
(syntax-case s ()
((_ type syntactic-ctor ctor pred
(field get options ...) ...)
#`(begin
(define-record-type type
(ctor field ...)
pred
(field get) ...)
#,(make-syntactic-constructor #'type #'syntactic-ctor #'ctor
#'(field ...)
(filter-map field-default-value
#'((field options ...)
...))))))))
(define (memoize proc)
"Return a memoizing version of PROC."
(let ((cache (make-hash-table)))
(lambda args
(let ((results (hash-ref cache args)))
(if results
(apply values results)
(let ((results (call-with-values (lambda ()
(apply proc args))
list)))
(hash-set! cache args results)
(apply values results)))))))
(define (default-keyword-arguments args defaults)
"Return ARGS augmented with any keyword/value from DEFAULTS for
keywords not already present in ARGS."
(let loop ((defaults defaults)
(args args))
(match defaults
((kw value rest ...)
(loop rest
(if (assoc-ref kw args)
args
(cons* kw value args))))
(()
args))))
(define-syntax substitute-keyword-arguments
(syntax-rules ()
"Return a new list of arguments where the value for keyword arg KW is
replaced by EXP. EXP is evaluated in a context where VAR is boud to the
previous value of the keyword argument."
((_ original-args ((kw var) exp) ...)
(let loop ((args original-args)
(before '()))
(match args
((kw var rest (... ...))
(loop rest (cons* exp kw before)))
...
((x rest (... ...))
(loop rest (cons x before)))
(()
(reverse before)))))))
(define (gnu-triplet->nix-system triplet)
"Return the Nix system type corresponding to TRIPLET, a GNU triplet as
returned by `config.guess'."
(let ((triplet (cond ((string-match "^i[345]86-(.*)$" triplet)
=>
(lambda (m)
(string-append "i686-" (match:substring m 1))))
(else triplet))))
(cond ((string-match "^([^-]+)-([^-]+-)?linux-gnu.*" triplet)
=>
(lambda (m)
;; Nix omits `-gnu' for GNU/Linux.
(string-append (match:substring m 1) "-linux")))
((string-match "^([^-]+)-([^-]+-)?([[:alpha:]]+)([0-9]+\\.?)*$" triplet)
=>
(lambda (m)
;; Nix strip the version number from names such as `gnu0.3',
;; `darwin10.2.0', etc., and always strips the vendor part.
(string-append (match:substring m 1) "-"
(match:substring m 3))))
(else triplet))))
(define %current-system
;; System type as expected by Nix, usually ARCHITECTURE-KERNEL.
(make-parameter (gnu-triplet->nix-system %host-type)))
(define (package-name->name+version name)
"Given NAME, a package name like \"foo-0.9.1b\", return two values:
\"foo\" and \"0.9.1b\". When the version part is unavailable, NAME and
#f are returned. The first hyphen followed by a digit is considered to
introduce the version part."
;; See also `DrvName' in Nix.
(define number?
(cut char-set-contains? char-set:digit <>))
(let loop ((chars (string->list name))
(prefix '()))
(match chars
(()
(values name #f))
((#\- (? number? n) rest ...)
(values (list->string (reverse prefix))
(list->string (cons n rest))))
((head tail ...)
(loop tail (cons head prefix))))))
;;;
;;; Source location.
;;;
;; A source location.
(define-record-type <location>
(make-location file line column)
location?
(file location-file) ; file name
(line location-line) ; 1-indexed line
(column location-column)) ; 0-indexed column
(define location
(memoize
(lambda (file line column)
"Return the <location> object for the given FILE, LINE, and COLUMN."
(and line column file
(make-location file line column)))))
(define (source-properties->location loc)
"Return a location object based on the info in LOC, an alist as returned
by Guile's `source-properties', `frame-source', `current-source-location',
etc."
(let ((file (assq-ref loc 'filename))
(line (assq-ref loc 'line))
(col (assq-ref loc 'column)))
;; In accordance with the GCS, start line and column numbers at 1.
(location file (and line (+ line 1)) (and col (+ col 1)))))