guix-devel/guix/utils.scm

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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 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 ((guix build utils) #:select (dump-port))
#: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*
compile-time-value
memoize
default-keyword-arguments
substitute-keyword-arguments
<location>
location
location?
location-file
location-line
location-column
source-properties->location
gnu-triplet->nix-system
%current-system
version-compare
version>?
package-name->name+version
string-tokenize*
file-extension
call-with-temporary-output-file
fold2
filtered-port))
;;;
;;; 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))))
;;;
;;; Filtering & pipes.
;;;
(define (filtered-port command input)
"Return an input port where data drained from INPUT is filtered through
COMMAND (a list). In addition, return a list of PIDs that the caller must
wait."
(let loop ((input input)
(pids '()))
(if (file-port? input)
(match (pipe)
((in . out)
(match (primitive-fork)
(0
(close-port in)
(close-port (current-input-port))
(dup2 (fileno input) 0)
(close-port (current-output-port))
(dup2 (fileno out) 1)
(apply execl (car command) command))
(child
(close-port out)
(values in (cons child pids))))))
;; INPUT is not a file port, so fork just for the sake of tunneling it
;; through a file port.
(match (pipe)
((in . out)
(match (primitive-fork)
(0
(dynamic-wind
(const #t)
(lambda ()
(close-port in)
(dump-port input out))
(lambda ()
(false-if-exception (close out))
(primitive-exit 0))))
(child
(close-port out)
(loop in (cons child pids)))))))))
;;;
;;; Nixpkgs.
;;;
(define %nixpkgs-directory
(make-parameter
;; Capture the build-time value of $NIXPKGS.
(or %nixpkgs
(and=> (getenv "NIXPKGS")
(lambda (val)
;; Bail out when passed an empty string, otherwise
;; `nix-instantiate' will sit there and attempt to read
;; from its standard input.
(if (string=? val "")
#f
val))))))
(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 (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.
;; By default, this is equal to (gnu-triplet->nix-system %host-type).
(make-parameter %system))
(define version-compare
(let ((strverscmp
(let ((sym (or (dynamic-func "strverscmp" (dynamic-link))
(error "could not find `strverscmp' (from GNU libc)"))))
(pointer->procedure int sym (list '* '*)))))
(lambda (a b)
"Return '> when A denotes a newer version than B,
'< when A denotes a older version than B,
or '= when they denote equal versions."
(let ((result (strverscmp (string->pointer a) (string->pointer b))))
(cond ((positive? result) '>)
((negative? result) '<)
(else '=))))))
(define (version>? a b)
"Return #t when A denotes a newer version than B."
(eq? '> (version-compare a b)))
(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))))))
(define (file-extension file)
"Return the extension of FILE or #f if there is none."
(let ((dot (string-rindex file #\.)))
(and dot (substring file (+ 1 dot) (string-length file)))))
(define (string-tokenize* string separator)
"Return the list of substrings of STRING separated by SEPARATOR. This is
like `string-tokenize', but SEPARATOR is a string."
(define (index string what)
(let loop ((string string)
(offset 0))
(cond ((string-null? string)
#f)
((string-prefix? what string)
offset)
(else
(loop (string-drop string 1) (+ 1 offset))))))
(define len
(string-length separator))
(let loop ((string string)
(result '()))
(cond ((index string separator)
=>
(lambda (offset)
(loop (string-drop string (+ offset len))
(cons (substring string 0 offset)
result))))
(else
(reverse (cons string result))))))
(define (call-with-temporary-output-file proc)
"Call PROC with a name of a temporary file and open output port to that
file; close the file and delete it when leaving the dynamic extent of this
call."
(let* ((template (string-copy "guix-file.XXXXXX"))
(out (mkstemp! template)))
(dynamic-wind
(lambda ()
#t)
(lambda ()
(proc template out))
(lambda ()
(false-if-exception (close out))
(false-if-exception (delete-file template))))))
(define fold2
(case-lambda
((proc seed1 seed2 lst)
"Like `fold', but with a single list and two seeds."
(let loop ((result1 seed1)
(result2 seed2)
(lst lst))
(if (null? lst)
(values result1 result2)
(call-with-values
(lambda () (proc (car lst) result1 result2))
(lambda (result1 result2)
(loop result1 result2 (cdr lst)))))))
((proc seed1 seed2 lst1 lst2)
"Like `fold', but with a two lists and two seeds."
(let loop ((result1 seed1)
(result2 seed2)
(lst1 lst1)
(lst2 lst2))
(if (or (null? lst1) (null? lst2))
(values result1 result2)
(call-with-values
(lambda () (proc (car lst1) (car lst2) result1 result2))
(lambda (result1 result2)
(fold2 proc result1 result2 (cdr lst1) (cdr lst2)))))))))
;;;
;;; 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. Note
;; that unlike LINE and `port-column', COL is actually 1-indexed here...
(location file (and line (+ line 1)) col)))