2cd5c0380e
* guix/utils.scm (%struct-flock, F_SETLKW, F_xxLCK): New variables.
(fcntl-flock): New procedure.
* tests/utils.scm ("fcntl-flock"): New test.
563 lines
19 KiB
Scheme
563 lines
19 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2012, 2013, 2014 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2013 Mark H Weaver <mhw@netris.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (guix utils)
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#:use-module (guix config)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-9)
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#:use-module (srfi srfi-26)
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#:use-module (srfi srfi-39)
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#:use-module (srfi srfi-60)
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#:use-module (rnrs bytevectors)
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#:use-module ((rnrs io ports) #:select (put-bytevector))
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#:use-module ((guix build utils) #:select (dump-port))
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#:use-module (ice-9 vlist)
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#:use-module (ice-9 format)
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#:autoload (ice-9 popen) (open-pipe*)
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#:autoload (ice-9 rdelim) (read-line)
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#:use-module (ice-9 regex)
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#:use-module (ice-9 match)
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#:use-module (ice-9 format)
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#:use-module (system foreign)
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#:export (bytevector->base16-string
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base16-string->bytevector
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%nixpkgs-directory
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nixpkgs-derivation
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nixpkgs-derivation*
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compile-time-value
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fcntl-flock
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memoize
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default-keyword-arguments
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substitute-keyword-arguments
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<location>
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location
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location?
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location-file
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location-line
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location-column
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source-properties->location
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gnu-triplet->nix-system
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%current-system
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%current-target-system
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version-compare
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version>?
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guile-version>?
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package-name->name+version
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string-tokenize*
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string-replace-substring
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file-extension
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file-sans-extension
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call-with-temporary-output-file
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with-atomic-file-output
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fold2
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filtered-port))
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;;;
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;;; Compile-time computations.
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;;;
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(define-syntax compile-time-value
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(syntax-rules ()
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"Evaluate the given expression at compile time. The expression must
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evaluate to a simple datum."
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((_ exp)
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(let-syntax ((v (lambda (s)
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(let ((val exp))
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(syntax-case s ()
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(_ #`'#,(datum->syntax s val)))))))
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v))))
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;;;
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;;; Base 16.
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;;;
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(define (bytevector->base16-string bv)
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"Return the hexadecimal representation of BV's contents."
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(define len
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(bytevector-length bv))
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(let-syntax ((base16-chars (lambda (s)
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(syntax-case s ()
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(_
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(let ((v (list->vector
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(unfold (cut > <> 255)
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(lambda (n)
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(format #f "~2,'0x" n))
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1+
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0))))
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v))))))
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(define chars base16-chars)
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(let loop ((i 0)
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(r '()))
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(if (= i len)
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(string-concatenate-reverse r)
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(loop (+ 1 i)
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(cons (vector-ref chars (bytevector-u8-ref bv i)) r))))))
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(define base16-string->bytevector
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(let ((chars->value (fold (lambda (i r)
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(vhash-consv (string-ref (number->string i 16)
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0)
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i r))
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vlist-null
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(iota 16))))
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(lambda (s)
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"Return the bytevector whose hexadecimal representation is string S."
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(define bv
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(make-bytevector (quotient (string-length s) 2) 0))
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(string-fold (lambda (chr i)
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(let ((j (quotient i 2))
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(v (and=> (vhash-assv chr chars->value) cdr)))
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(if v
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(if (zero? (logand i 1))
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(bytevector-u8-set! bv j
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(arithmetic-shift v 4))
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(let ((w (bytevector-u8-ref bv j)))
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(bytevector-u8-set! bv j (logior v w))))
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(error "invalid hexadecimal character" chr)))
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(+ i 1))
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0
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s)
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bv)))
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;;;
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;;; Filtering & pipes.
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;;;
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(define (filtered-port command input)
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"Return an input port where data drained from INPUT is filtered through
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COMMAND (a list). In addition, return a list of PIDs that the caller must
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wait. When INPUT is a file port, it must be unbuffered; otherwise, any
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buffered data is lost."
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(let loop ((input input)
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(pids '()))
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(if (file-port? input)
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(match (pipe)
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((in . out)
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(match (primitive-fork)
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(0
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(close-port in)
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(close-port (current-input-port))
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(dup2 (fileno input) 0)
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(close-port (current-output-port))
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(dup2 (fileno out) 1)
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(apply execl (car command) command))
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(child
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(close-port out)
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(values in (cons child pids))))))
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;; INPUT is not a file port, so fork just for the sake of tunneling it
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;; through a file port.
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(match (pipe)
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((in . out)
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(match (primitive-fork)
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(0
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(dynamic-wind
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(const #t)
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(lambda ()
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(close-port in)
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(dump-port input out))
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(lambda ()
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(false-if-exception (close out))
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(primitive-exit 0))))
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(child
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(close-port out)
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(loop in (cons child pids)))))))))
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;;;
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;;; Nixpkgs.
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;;;
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(define %nixpkgs-directory
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(make-parameter
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;; Capture the build-time value of $NIXPKGS.
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(or %nixpkgs
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(and=> (getenv "NIXPKGS")
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(lambda (val)
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;; Bail out when passed an empty string, otherwise
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;; `nix-instantiate' will sit there and attempt to read
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;; from its standard input.
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(if (string=? val "")
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#f
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val))))))
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(define* (nixpkgs-derivation attribute #:optional (system (%current-system)))
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"Return the derivation path of ATTRIBUTE in Nixpkgs."
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(let* ((p (open-pipe* OPEN_READ (or (getenv "NIX_INSTANTIATE")
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%nix-instantiate)
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"-A" attribute (%nixpkgs-directory)
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"--argstr" "system" system))
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(l (read-line p))
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(s (close-pipe p)))
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(and (zero? (status:exit-val s))
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(not (eof-object? l))
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l)))
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(define-syntax-rule (nixpkgs-derivation* attribute)
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"Evaluate the given Nixpkgs derivation at compile-time."
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(compile-time-value (nixpkgs-derivation attribute)))
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;;;
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;;; Advisory file locking.
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;;;
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(define %struct-flock
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;; 'struct flock' from <fcntl.h>.
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(list short ; l_type
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short ; l_whence
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size_t ; l_start
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size_t ; l_len
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int)) ; l_pid
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(define F_SETLKW
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;; On Linux-based systems, this is usually 7, but not always
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;; (exceptions include SPARC.) On GNU/Hurd, it's 9.
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(compile-time-value
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(cond ((string-contains %host-type "sparc") 9) ; sparc-*-linux-gnu
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((string-contains %host-type "linux") 7) ; *-linux-gnu
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(else 9)))) ; *-gnu*
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(define F_xxLCK
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;; The F_RDLCK, F_WRLCK, and F_UNLCK constants.
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(compile-time-value
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(cond ((string-contains %host-type "sparc") #(1 2 3)) ; sparc-*-linux-gnu
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((string-contains %host-type "hppa") #(1 2 3)) ; hppa-*-linux-gnu
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((string-contains %host-type "linux") #(0 1 2)) ; *-linux-gnu
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(else #(1 2 3))))) ; *-gnu*
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(define fcntl-flock
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(let* ((ptr (dynamic-func "fcntl" (dynamic-link)))
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(proc (pointer->procedure int ptr `(,int ,int *))))
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(lambda (fd-or-port operation)
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"Perform locking OPERATION on the file beneath FD-OR-PORT. OPERATION
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must be a symbol, one of 'read-lock, 'write-lock, or 'unlock."
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(define (operation->int op)
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(case op
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((read-lock) (vector-ref F_xxLCK 0))
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((write-lock) (vector-ref F_xxLCK 1))
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((unlock) (vector-ref F_xxLCK 2))
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(else (error "invalid fcntl-flock operation" op))))
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(define fd
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(if (port? fd-or-port)
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(fileno fd-or-port)
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fd-or-port))
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;; XXX: 'fcntl' is a vararg function, but here we happily use the
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;; standard ABI; crossing fingers.
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(let ((err (proc fd
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F_SETLKW ; lock & wait
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(make-c-struct %struct-flock
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(list (operation->int operation)
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SEEK_SET
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0 0 ; whole file
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0)))))
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(or (zero? err)
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;; Presumably we got EAGAIN or so.
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(throw 'flock-error fd))))))
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;;;
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;;; Miscellaneous.
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;;;
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(define (memoize proc)
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"Return a memoizing version of PROC."
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(let ((cache (make-hash-table)))
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(lambda args
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(let ((results (hash-ref cache args)))
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(if results
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(apply values results)
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(let ((results (call-with-values (lambda ()
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(apply proc args))
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list)))
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(hash-set! cache args results)
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(apply values results)))))))
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(define (default-keyword-arguments args defaults)
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"Return ARGS augmented with any keyword/value from DEFAULTS for
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keywords not already present in ARGS."
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(let loop ((defaults defaults)
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(args args))
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(match defaults
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((kw value rest ...)
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(loop rest
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(if (assoc-ref kw args)
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args
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(cons* kw value args))))
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(()
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args))))
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(define-syntax substitute-keyword-arguments
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(syntax-rules ()
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"Return a new list of arguments where the value for keyword arg KW is
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replaced by EXP. EXP is evaluated in a context where VAR is boud to the
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previous value of the keyword argument."
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((_ original-args ((kw var) exp) ...)
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(let loop ((args original-args)
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(before '()))
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(match args
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((kw var rest (... ...))
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(loop rest (cons* exp kw before)))
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...
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((x rest (... ...))
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(loop rest (cons x before)))
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(()
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(reverse before)))))))
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(define (gnu-triplet->nix-system triplet)
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"Return the Nix system type corresponding to TRIPLET, a GNU triplet as
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returned by `config.guess'."
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(let ((triplet (cond ((string-match "^i[345]86-(.*)$" triplet)
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=>
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(lambda (m)
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(string-append "i686-" (match:substring m 1))))
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(else triplet))))
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(cond ((string-match "^([^-]+)-([^-]+-)?linux-gnu.*" triplet)
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=>
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(lambda (m)
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;; Nix omits `-gnu' for GNU/Linux.
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(string-append (match:substring m 1) "-linux")))
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((string-match "^([^-]+)-([^-]+-)?([[:alpha:]]+)([0-9]+\\.?)*$" triplet)
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=>
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(lambda (m)
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;; Nix strip the version number from names such as `gnu0.3',
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;; `darwin10.2.0', etc., and always strips the vendor part.
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(string-append (match:substring m 1) "-"
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(match:substring m 3))))
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(else triplet))))
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(define %current-system
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;; System type as expected by Nix, usually ARCHITECTURE-KERNEL.
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;; By default, this is equal to (gnu-triplet->nix-system %host-type).
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(make-parameter %system))
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(define %current-target-system
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;; Either #f or a GNU triplet representing the target system we are
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;; cross-building to.
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(make-parameter #f))
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(define version-compare
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(let ((strverscmp
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(let ((sym (or (dynamic-func "strverscmp" (dynamic-link))
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(error "could not find `strverscmp' (from GNU libc)"))))
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(pointer->procedure int sym (list '* '*)))))
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(lambda (a b)
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"Return '> when A denotes a newer version than B,
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'< when A denotes a older version than B,
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or '= when they denote equal versions."
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(let ((result (strverscmp (string->pointer a) (string->pointer b))))
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(cond ((positive? result) '>)
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((negative? result) '<)
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(else '=))))))
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(define (version>? a b)
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"Return #t when A denotes a newer version than B."
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(eq? '> (version-compare a b)))
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(define (guile-version>? str)
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"Return #t if the running Guile version is greater than STR."
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;; Note: Using (version>? (version) "2.0.5") or similar doesn't work,
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;; because the result of (version) can have a prefix, like "2.0.5-deb1".
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(version>? (string-append (major-version) "."
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(minor-version) "."
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(micro-version))
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str))
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(define (package-name->name+version name)
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"Given NAME, a package name like \"foo-0.9.1b\", return two values:
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\"foo\" and \"0.9.1b\". When the version part is unavailable, NAME and
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#f are returned. The first hyphen followed by a digit is considered to
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introduce the version part."
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;; See also `DrvName' in Nix.
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(define number?
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(cut char-set-contains? char-set:digit <>))
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(let loop ((chars (string->list name))
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(prefix '()))
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(match chars
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(()
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(values name #f))
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((#\- (? number? n) rest ...)
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(values (list->string (reverse prefix))
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(list->string (cons n rest))))
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((head tail ...)
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(loop tail (cons head prefix))))))
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(define (file-extension file)
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"Return the extension of FILE or #f if there is none."
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(let ((dot (string-rindex file #\.)))
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(and dot (substring file (+ 1 dot) (string-length file)))))
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(define (file-sans-extension file)
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"Return the substring of FILE without its extension, if any."
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(let ((dot (string-rindex file #\.)))
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(if dot
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(substring file 0 dot)
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file)))
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(define (string-tokenize* string separator)
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"Return the list of substrings of STRING separated by SEPARATOR. This is
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like `string-tokenize', but SEPARATOR is a string."
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(define (index string what)
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(let loop ((string string)
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(offset 0))
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(cond ((string-null? string)
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#f)
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((string-prefix? what string)
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offset)
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(else
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(loop (string-drop string 1) (+ 1 offset))))))
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(define len
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(string-length separator))
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(let loop ((string string)
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(result '()))
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(cond ((index string separator)
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=>
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(lambda (offset)
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(loop (string-drop string (+ offset len))
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(cons (substring string 0 offset)
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result))))
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(else
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(reverse (cons string result))))))
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(define* (string-replace-substring str substr replacement
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#:optional
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(start 0)
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(end (string-length str)))
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"Replace all occurrences of SUBSTR in the START--END range of STR by
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REPLACEMENT."
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(match (string-length substr)
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(0
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(error "string-replace-substring: empty substring"))
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(substr-length
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(let loop ((start start)
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(pieces (list (substring str 0 start))))
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(match (string-contains str substr start end)
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(#f
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(string-concatenate-reverse
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(cons (substring str start) pieces)))
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(index
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(loop (+ index substr-length)
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(cons* replacement
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(substring str start index)
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pieces))))))))
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(define (call-with-temporary-output-file proc)
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"Call PROC with a name of a temporary file and open output port to that
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file; close the file and delete it when leaving the dynamic extent of this
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call."
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(let* ((template (string-copy "guix-file.XXXXXX"))
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(out (mkstemp! template)))
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(dynamic-wind
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(lambda ()
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#t)
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(lambda ()
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(proc template out))
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(lambda ()
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(false-if-exception (close out))
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(false-if-exception (delete-file template))))))
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(define (with-atomic-file-output file proc)
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"Call PROC with an output port for the file that is going to replace FILE.
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Upon success, FILE is atomically replaced by what has been written to the
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output port, and PROC's result is returned."
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(let* ((template (string-append file ".XXXXXX"))
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(out (mkstemp! template)))
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(with-throw-handler #t
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(lambda ()
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(let ((result (proc out)))
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(close out)
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(rename-file template file)
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result))
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(lambda (key . args)
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(false-if-exception (delete-file template))))))
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(define fold2
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(case-lambda
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((proc seed1 seed2 lst)
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"Like `fold', but with a single list and two seeds."
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(let loop ((result1 seed1)
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(result2 seed2)
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(lst lst))
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(if (null? lst)
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(values result1 result2)
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(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)))
|