#!@BASH@ # -*- mode: scheme; coding: utf-8; -*- # XXX: We have to go through Bash because there's no command-line switch to # augment %load-compiled-path, and because of the silly 127-byte limit for # the shebang line in Linux. # Use `load-compiled' because `load' (and `-l') doesn't otherwise load our # .go file (see <http://bugs.gnu.org/12519>). main="(@ (gnu build-support ld-wrapper) ld-wrapper)" exec @GUILE@ -c "(load-compiled \"@SELF@.go\") (apply $main (cdr (command-line)))" "$@" !# ;;; GNU Guix --- Functional package management for GNU ;;; Copyright © 2012, 2013, 2014, 2015 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 (gnu build-support ld-wrapper) #:use-module (srfi srfi-1) #:use-module (ice-9 match) #:export (ld-wrapper)) ;;; Commentary: ;;; ;;; This is a wrapper for the linker. Its purpose is to inspect the -L and ;;; -l switches passed to the linker, add corresponding -rpath arguments, and ;;; invoke the actual linker with this new set of arguments. ;;; ;;; The alternatives to this hack would be: ;;; ;;; 1. Using $LD_RUN_PATH. However, that would tend to include more than ;;; needed in the RPATH; for instance, given a package with `libfoo' as ;;; an input, all its binaries would have libfoo in their RPATH, ;;; regardless of whether they actually NEED it. ;;; ;;; 2. Use a GCC "lib" spec string such as `%{L*:-rpath %*}', which adds a ;;; `-rpath LIBDIR' argument for each occurrence of `-L LIBDIR'. ;;; However, this doesn't work when $LIBRARY_PATH is used, because the ;;; additional `-L' switches are not matched by the above rule, because ;;; the rule only matches explicit user-provided switches. See ;;; <http://gcc.gnu.org/ml/gcc-help/2012-09/msg00110.html> for details. ;;; ;;; As a bonus, this wrapper checks for "impurities"--i.e., references to ;;; libraries outside the store. ;;; ;;; Code: (define %real-ld ;; Name of the linker that we wrap. "@LD@") (define %store-directory ;; File name of the store. (or (getenv "NIX_STORE") "/gnu/store")) (define %temporary-directory ;; Temporary directory. (or (getenv "TMPDIR") "/tmp")) (define %build-directory ;; Top build directory when run from a builder. (getenv "NIX_BUILD_TOP")) (define %allow-impurities? ;; Whether to allow references to libraries outside the store. (getenv "GUIX_LD_WRAPPER_ALLOW_IMPURITIES")) (define %debug? ;; Whether to emit debugging output. (getenv "GUIX_LD_WRAPPER_DEBUG")) (define %disable-rpath? ;; Whether to disable automatic '-rpath' addition. (getenv "GUIX_LD_WRAPPER_DISABLE_RPATH")) (define (readlink* file) ;; Call 'readlink' until the result is not a symlink. (define %max-symlink-depth 50) (let loop ((file file) (depth 0)) (define (absolute target) (if (absolute-file-name? target) target (string-append (dirname file) "/" target))) (if (>= depth %max-symlink-depth) file (call-with-values (lambda () (catch 'system-error (lambda () (values #t (readlink file))) (lambda args (let ((errno (system-error-errno args))) (if (or (= errno EINVAL) (= errno ENOENT)) (values #f file) (apply throw args)))))) (lambda (success? target) (if success? (loop (absolute target) (+ depth 1)) file)))))) (define (pure-file-name? file) ;; Return #t when FILE is the name of a file either within the store ;; (possibly via a symlink) or within the build directory. (let ((file (readlink* file))) (or (not (string-prefix? "/" file)) (string-prefix? %store-directory file) (string-prefix? %temporary-directory file) (and %build-directory (string-prefix? %build-directory file))))) (define (store-file-name? file) ;; Return #t when FILE is a store file, possibly indirectly. (string-prefix? %store-directory (readlink* file))) (define (shared-library? file) ;; Return #t when FILE denotes a shared library. (or (string-suffix? ".so" file) (let ((index (string-contains file ".so."))) ;; Since we cannot use regexps during bootstrap, roll our own. (and index (string-every (char-set-union (char-set #\.) char-set:digit) (string-drop file (+ index 3))))))) (define (library-search-path args) ;; Return the library search path as a list of directory names. The GNU ld ;; manual notes that "[a]ll `-L' options apply to all `-l' options, ;; regardless of the order in which the options appear", so we must compute ;; the search path independently of the -l options. (let loop ((args args) (path '())) (match args (() (reverse path)) (("-L" directory . rest) (loop rest (cons directory path))) ((argument . rest) (if (string-prefix? "-L" argument) ;augment the search path (loop rest (cons (string-drop argument 2) path)) (loop rest path)))))) (define (library-files-linked args library-path) ;; Return the absolute file names of shared libraries explicitly linked ;; against via `-l' or with an absolute file name in ARGS, looking them up ;; in LIBRARY-PATH. (define files+args (fold (lambda (argument result) (match result ((library-files ((and flag (or "-dynamic-linker" "-plugin")) . rest)) ;; When passed '-dynamic-linker ld.so', ignore 'ld.so'; when ;; passed '-plugin liblto_plugin.so', ignore ;; 'liblto_plugin.so'. See <http://bugs.gnu.org/20102>. (list library-files (cons* argument flag rest))) ((library-files previous-args) (cond ((string-prefix? "-l" argument) ;add library (let* ((lib (string-append "lib" (string-drop argument 2) ".so")) (full (search-path library-path lib))) (list (if full (cons full library-files) library-files) (cons argument previous-args)))) ((and (string-prefix? %store-directory argument) (shared-library? argument)) ;add library (list (cons argument library-files) (cons argument previous-args))) (else (list library-files (cons argument previous-args))))))) (list '() '()) args)) (match files+args ((files arguments) (reverse files)))) (define (rpath-arguments library-files) ;; Return the `-rpath' argument list for each of LIBRARY-FILES, a list of ;; absolute file names. (fold-right (lambda (file args) ;; Add '-rpath' if and only if FILE is in the store; we don't ;; want to add '-rpath' for files under %BUILD-DIRECTORY or ;; %TEMPORARY-DIRECTORY because that could leak to installed ;; files. (cond ((and (not %disable-rpath?) (store-file-name? file)) (cons* "-rpath" (dirname file) args)) ((or %allow-impurities? (pure-file-name? file)) args) (else (begin (format (current-error-port) "ld-wrapper: error: attempt to use \ impure library ~s~%" file) (exit 1))))) '() library-files)) (define (ld-wrapper . args) ;; Invoke the real `ld' with ARGS, augmented with `-rpath' switches. (let* ((path (library-search-path args)) (libs (library-files-linked args path)) (args (append args (rpath-arguments libs)))) (when %debug? (format (current-error-port) "ld-wrapper: library search path: ~s~%" path) (format (current-error-port) "ld-wrapper: libraries linked: ~s~%" libs) (format (current-error-port) "ld-wrapper: invoking `~a' with ~s~%" %real-ld args)) (apply execl %real-ld (basename %real-ld) args))) ;;; ld-wrapper.scm ends here