;;; GNU Guix --- Functional package management for GNU ;;; Copyright © 2013, 2014, 2015, 2017, 2018 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 search-paths) #:use-module (guix records) #:use-module (guix build utils) #:use-module (srfi srfi-1) #:use-module (srfi srfi-26) #:use-module (ice-9 match) #:export (<search-path-specification> search-path-specification search-path-specification? search-path-specification-variable search-path-specification-files search-path-specification-separator search-path-specification-file-type search-path-specification-file-pattern $PATH search-path-specification->sexp sexp->search-path-specification string-tokenize* evaluate-search-paths environment-variable-definition search-path-definition set-search-paths)) ;;; Commentary: ;;; ;;; This module defines "search path specifications", which allow packages to ;;; declare environment variables that they use to define search paths. For ;;; instance, GCC has the 'CPATH' variable, Guile has the 'GUILE_LOAD_PATH' ;;; variable, etc. ;;; ;;; Code: ;; The specification of a search path. (define-record-type* <search-path-specification> search-path-specification make-search-path-specification search-path-specification? (variable search-path-specification-variable) ;string (files search-path-specification-files) ;list of strings (separator search-path-specification-separator ;string | #f (default ":")) (file-type search-path-specification-file-type ;symbol (default 'directory)) (file-pattern search-path-specification-file-pattern ;#f | string (default #f))) (define $PATH ;; The 'PATH' variable. This variable is a bit special: it is not attached ;; to any package in particular. (search-path-specification (variable "PATH") (files '("bin" "sbin")))) (define (search-path-specification->sexp spec) "Return an sexp representing SPEC, a <search-path-specification>. The sexp corresponds to the arguments expected by `set-path-environment-variable'." ;; Note that this sexp format is used both by build systems and in ;; (guix profiles), so think twice before you change it. (match spec (($ <search-path-specification> variable files separator type pattern) `(,variable ,files ,separator ,type ,pattern)))) (define (sexp->search-path-specification sexp) "Convert SEXP, which is as returned by 'search-path-specification->sexp', to a <search-path-specification> object." (match sexp ((variable files separator type pattern) (search-path-specification (variable variable) (files files) (separator separator) (file-type type) (file-pattern pattern))))) (define-syntax-rule (with-null-error-port exp) "Evaluate EXP with the error port pointing to the bit bucket." (with-error-to-port (%make-void-port "w") (lambda () exp))) ;; XXX: This procedure used to be in (guix utils) but since we want to be able ;; to use (guix search-paths) on the build side, we want to avoid the ;; dependency on (guix utils), and so this procedure is back here for now. (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* (evaluate-search-paths search-paths directories #:optional (getenv (const #f))) "Evaluate SEARCH-PATHS, a list of search-path specifications, for DIRECTORIES, a list of directory names, and return a list of specification/value pairs. Use GETENV to determine the current settings and report only settings not already effective." (define (search-path-definition spec) (match spec (($ <search-path-specification> variable files #f type pattern) ;; Separator is #f so return the first match. (match (with-null-error-port (search-path-as-list files directories #:type type #:pattern pattern)) (() #f) ((head . _) (let ((value (getenv variable))) (if (and value (string=? value head)) #f ;VARIABLE already set appropriately (cons spec head)))))) (($ <search-path-specification> variable files separator type pattern) (let* ((values (or (and=> (getenv variable) (cut string-tokenize* <> separator)) '())) ;; XXX: Silence 'find-files' when it stumbles upon non-existent ;; directories (see ;; <http://lists.gnu.org/archive/html/guix-devel/2015-01/msg00269.html>.) (path (with-null-error-port (search-path-as-list files directories #:type type #:pattern pattern)))) (if (every (cut member <> values) path) #f ;VARIABLE is already set appropriately (cons spec (string-join path separator))))))) (filter-map search-path-definition search-paths)) (define* (environment-variable-definition variable value #:key (kind 'exact) (separator ":")) "Return a the definition of VARIABLE to VALUE in Bash syntax. KIND can be either 'exact (return the definition of VARIABLE=VALUE), 'prefix (return the definition where VALUE is added as a prefix to VARIABLE's current value), or 'suffix (return the definition where VALUE is added as a suffix to VARIABLE's current value.) In the case of 'prefix and 'suffix, SEPARATOR is used as the separator between VARIABLE's current value and its prefix/suffix." (match (if (not separator) 'exact kind) ('exact (format #f "export ~a=\"~a\"" variable value)) ('prefix (format #f "export ~a=\"~a${~a:+~a}$~a\"" variable value variable separator variable)) ('suffix (format #f "export ~a=\"$~a${~a:+~a}~a\"" variable variable variable separator value)))) (define* (search-path-definition search-path value #:key (kind 'exact)) "Similar to 'environment-variable-definition', but applied to a <search-path-specification>." (match search-path (($ <search-path-specification> variable _ separator) (environment-variable-definition variable value #:kind kind #:separator separator)))) (define* (set-search-paths search-paths directories #:key (setenv setenv)) "Set the search path environment variables specified by SEARCH-PATHS for the given directories." (for-each (match-lambda ((spec . value) (setenv (search-path-specification-variable spec) value))) (evaluate-search-paths search-paths directories))) ;;; search-paths.scm ends here