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