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diff --git a/distro/ld-wrapper.scm b/distro/ld-wrapper.scm
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+#!/bin/sh
+# -*- 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="(@ (distro ld-wrapper) ld-wrapper)"
+exec @GUILE@ -c "(load-compiled \"$0.go\") (apply $main (cdr (command-line)))" "$@"
+!#
+;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
+;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of Guix.
+;;;
+;;; 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.
+;;;
+;;; 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 Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (distro ld-wrapper)
+  #:use-module (srfi srfi-1)
+  #: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") "/nix/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 (pure-file-name? file)
+  ;; Return #t when FILE is the name of a file either within the store or
+  ;; within the build directory.
+  (or (not (string-prefix? "/" file))
+      (string-prefix? %store-directory file)
+      (string-prefix? %temporary-directory file)
+      (and %build-directory
+           (string-prefix? %build-directory file))))
+
+(define (switch-arguments switch args)
+  ;; Return the arguments passed for the occurrences of SWITCH--e.g.,
+  ;; "-L"--in ARGS.
+  (let ((prefix-len (string-length switch)))
+    (fold-right (lambda (arg path)
+                  (if (string-prefix? switch arg)
+                      (cons (substring arg prefix-len) path)
+                      path))
+                '()
+                args)))
+
+(define (library-path args)
+  ;; Return the library search path extracted from `-L' switches in ARGS.
+  ;; Note: allow references to out-of-store directories.  When this leads to
+  ;; actual impurities, this is caught later.
+  (switch-arguments "-L" args))
+
+(define (library-files-linked args)
+  ;; Return the file names of shared libraries explicitly linked against via
+  ;; `-l' in ARGS.
+  (map (lambda (lib)
+         (string-append "lib" lib ".so"))
+       (switch-arguments "-l" args)))
+
+(define (rpath-arguments lib-path library-files)
+  ;; Return the `-rpath' argument list for each of LIBRARY-FILES found in
+  ;; LIB-PATH.
+  (fold-right (lambda (file args)
+                (let ((absolute (search-path lib-path file)))
+                  (if absolute
+                      (if (or %allow-impurities?
+                              (pure-file-name? absolute))
+                          (cons* "-rpath" (dirname absolute)
+                                 args)
+                          (begin
+                            (format (current-error-port)
+                                    "ld-wrapper: error: attempt to use impure library ~s~%"
+                                    absolute)
+                            (exit 1)))
+                      args)))
+              '()
+              library-files))
+
+(define (ld-wrapper . args)
+  ;; Invoke the real `ld' with ARGS, augmented with `-rpath' switches.
+  (let* ((lib-path (library-path args))
+         (libs     (library-files-linked args))
+         (args     (append args (rpath-arguments lib-path libs))))
+    (if %debug?
+        (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