1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
|
#!/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
|