unofficial mirror of guix-patches@gnu.org 
 help / color / mirror / code / Atom feed
blob 4a31c3cfaf3519b30d539b779cc1dcf8a50f8c78 13878 bytes (raw)
name: guix/build/gremlin.scm 	 # note: path name is non-authoritative(*)

  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
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
 
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015, 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 build gremlin)
  #:use-module (guix elf)
  #:use-module ((guix build utils) #:select (store-file-name?))
  #:use-module (ice-9 match)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (system foreign)
  #:use-module (rnrs bytevectors)
  #:use-module (rnrs io ports)
  #:export (elf-error?
            elf-error-elf
            invalid-segment-size?
            invalid-segment-size-segment

            elf-dynamic-info
            elf-dynamic-info?
            elf-dynamic-info-soname
            elf-dynamic-info-needed
            elf-dynamic-info-rpath
            elf-dynamic-info-runpath
            expand-origin

            validate-needed-in-runpath
            strip-runpath))

;;; Commentary:
;;;
;;; A gremlin is sort-of like an elf, you know, and this module provides tools
;;; to deal with dynamic-link information from ELF files.
;;;
;;; Code:

(define-condition-type &elf-error &error
  elf-error?
  (elf elf-error-elf))

(define-condition-type &invalid-segment-size &elf-error
  invalid-segment-size?
  (segment invalid-segment-size-segment))


(define (dynamic-link-segment elf)
  "Return the 'PT_DYNAMIC' segment of ELF--i.e., the segment that contains
dynamic linking information."
  (let ((size (bytevector-length (elf-bytes elf))))
    (find (lambda (segment)
            (unless (<= (+ (elf-segment-offset segment)
                           (elf-segment-filesz segment))
                        size)
              ;; This happens on separate debug output files created by
              ;; 'strip --only-keep-debug' (Binutils 2.25.)
              (raise (condition (&invalid-segment-size
                                 (elf elf)
                                 (segment segment)))))

            (= (elf-segment-type segment) PT_DYNAMIC))
          (elf-segments elf))))

(define (word-reader size byte-order)
  "Return a procedure to read a word of SIZE bytes according to BYTE-ORDER."
  (case size
    ((8)
     (lambda (bv index)
       (bytevector-u64-ref bv index byte-order)))
    ((4)
     (lambda (bv index)
       (bytevector-u32-ref bv index byte-order)))))


;; Dynamic entry:
;;
;; typedef struct
;; {
;;   Elf64_Sxword       d_tag;   /* Dynamic entry type */
;;   union
;;     {
;;       Elf64_Xword d_val;      /* Integer value */
;;       Elf64_Addr d_ptr;       /* Address value */
;;     } d_un;
;; } Elf64_Dyn;

(define-record-type <dynamic-entry>
  (dynamic-entry type value offset)
  dynamic-entry?
  (type   dynamic-entry-type)                     ;DT_*
  (value  dynamic-entry-value)                    ;string | number | ...
  (offset dynamic-entry-offset))                  ;integer

(define (raw-dynamic-entries elf segment)
  "Return as a list of <dynamic-entry> for the dynamic entries found in
SEGMENT, the 'PT_DYNAMIC' segment of ELF."
  (define start
    (elf-segment-offset segment))
  (define bytes
    (elf-bytes elf))
  (define word-size
    (elf-word-size elf))
  (define byte-order
    (elf-byte-order elf))
  (define read-word
    (word-reader word-size byte-order))

  (let loop ((offset 0)
             (result '()))
    (if (>= offset (elf-segment-memsz segment))
        (reverse result)
        (let ((type  (read-word bytes (+ start offset)))
              (value (read-word bytes (+ start offset word-size))))
          (if (= type DT_NULL)                    ;finished?
              (reverse result)
              (loop (+ offset (* 2 word-size))
                    (cons (dynamic-entry type value
                                         (+ start offset word-size))
                          result)))))))

(define (vma->offset elf vma)
  "Convert VMA, a virtual memory address, to an offset within ELF.

Do that by looking at the loadable program segment (PT_LOAD) of ELF that
contains VMA and by taking into account that segment's virtual address and
offset."
  ;; See 'offset_from_vma' in Binutils.
  (define loads
    (filter (lambda (segment)
              (= (elf-segment-type segment) PT_LOAD))
            (elf-segments elf)))

  (let ((load (find (lambda (segment)
                      (let ((vaddr (elf-segment-vaddr segment)))
                        (and (>= vma vaddr)
                             (< vma (+ (elf-segment-memsz segment)
                                       vaddr)))))
                    loads)))
    (+ (- vma (elf-segment-vaddr load))
       (elf-segment-offset load))))

(define (dynamic-entries elf segment)
  "Return all the dynamic entries found in SEGMENT, the 'PT_DYNAMIC' segment
of ELF, as a list of <dynamic-entry>.  The value of each entry may be a string
or an integer depending on the entry type (for instance, the value of
DT_NEEDED entries is a string.)  Likewise the offset is the offset within the
string table if the type is a string."
  (define entries
    (raw-dynamic-entries elf segment))

  (define string-table-offset
    (any (lambda (entry)
           (and (= (dynamic-entry-type entry) DT_STRTAB)
                (dynamic-entry-value entry)))
         entries))

  (define (interpret-dynamic-entry entry)
    (let ((type  (dynamic-entry-type entry))
          (value (dynamic-entry-value entry)))
      (cond ((memv type (list DT_NEEDED DT_SONAME DT_RPATH DT_RUNPATH))
             (if string-table-offset
                 (let* ((offset (vma->offset elf (+ string-table-offset value)))
                        (value  (pointer->string
                                 (bytevector->pointer (elf-bytes elf) offset))))
                   (dynamic-entry type value offset))
                 (dynamic-entry type value (dynamic-entry-offset entry))))
            (else
             (dynamic-entry type value (dynamic-entry-offset entry))))))

  (map interpret-dynamic-entry entries))

\f
;;;
;;; High-level interface.
;;;

(define-record-type <elf-dynamic-info>
  (%elf-dynamic-info soname needed rpath runpath)
  elf-dynamic-info?
  (soname    elf-dynamic-info-soname)
  (needed    elf-dynamic-info-needed)
  (rpath     elf-dynamic-info-rpath)
  (runpath   elf-dynamic-info-runpath))

(define search-path->list
  (let ((not-colon (char-set-complement (char-set #\:))))
    (lambda (str)
      "Split STR on ':' characters."
      (string-tokenize str not-colon))))

(define (elf-dynamic-info elf)
  "Return dynamic-link information for ELF as an <elf-dynamic-info> object, or
#f if ELF lacks dynamic-link information."
  (define (matching-entry type)
    (lambda (entry)
      (= type (dynamic-entry-type entry))))

  (match (dynamic-link-segment elf)
    (#f #f)
    ((? elf-segment? dynamic)
     (let ((entries (dynamic-entries elf dynamic)))
       (%elf-dynamic-info (or (and=> (find (matching-entry DT_SONAME)
                                           entries)
                                     dynamic-entry-value)
                              #f)
                          (filter-map (lambda (entry)
                                        (and (= (dynamic-entry-type entry)
                                                DT_NEEDED)
                                             (dynamic-entry-value entry)))
                                      entries)
                          (or (and=> (find (matching-entry DT_RPATH)
                                           entries)
                                     (compose search-path->list
                                              dynamic-entry-value))
                              '())
                          (or (and=> (find (matching-entry DT_RUNPATH)
                                           entries)
                                     (compose search-path->list
                                              dynamic-entry-value))
                              '()))))))

(define %libc-libraries
  ;; List of libraries as of glibc 2.21 (there are more but those are
  ;; typically mean to be LD_PRELOADed and thus do not appear as NEEDED.)
  '("libanl.so"
    "libcrypt.so"
    "libc.so"
    "libdl.so"
    "libm.so"
    "libnsl.so"                                   ;NEEDED by nscd
    "libpthread.so"
    "libresolv.so"
    "librt.so"
    "libutil.so"))

(define (libc-library? lib)
  "Return #t if LIB is one of the libraries shipped with the GNU C Library."
  (find (lambda (libc-lib)
          (string-prefix? libc-lib lib))
        %libc-libraries))

(define (expand-variable str variable value)
  "Replace occurrences of '$VARIABLE' or '${VARIABLE}' in STR with VALUE."
  (define variables
    (list (string-append "$" variable)
          (string-append "${" variable "}")))

  (let loop ((thing variables)
             (str   str))
    (match thing
      (()
       str)
      ((head tail ...)
       (let ((index (string-contains str head))
             (len   (string-length head)))
         (loop (if index variables tail)
               (if index
                   (string-replace str value
                                   index (+ index len))
                   str)))))))

(define (expand-origin str directory)
  "Replace occurrences of '$ORIGIN' in STR with DIRECTORY."
  (expand-variable str "ORIGIN" directory))

(define* (validate-needed-in-runpath file
                                     #:key (always-found? libc-library?))
  "Return #t if all the libraries listed as FILE's 'DT_NEEDED' entries are
present in its RUNPATH, or if FILE lacks dynamic-link information.  Return #f
otherwise.  Libraries whose name matches ALWAYS-FOUND? are considered to be
always available."
  (guard (c ((invalid-segment-size? c)
             (let ((segment (invalid-segment-size-segment c)))
               (format (current-error-port)
                       "~a: error: offset + size of segment ~a (type ~a) \
exceeds total size~%"
                       file
                       (elf-segment-index segment)
                       (elf-segment-type segment))
               #f)))

    (let* ((elf     (call-with-input-file file
                      (compose parse-elf get-bytevector-all)))
           (expand  (cute expand-origin <> (dirname file)))
           (dyninfo (elf-dynamic-info elf)))
      (when dyninfo
        ;; XXX: In theory we should also expand $PLATFORM and $LIB, but these
        ;; appear to be really unused.
        (let* ((expanded  (map expand (elf-dynamic-info-runpath dyninfo)))
               (runpath   (filter store-file-name? expanded))
               (bogus     (remove store-file-name? expanded))
               (needed    (remove always-found?
                                  (elf-dynamic-info-needed dyninfo)))
               (not-found (remove (cut search-path runpath <>)
                                  needed)))
          (unless (null? bogus)
            (format (current-error-port)
                    "~a: warning: RUNPATH contains bogus entries: ~s~%"
                    file bogus))

          (for-each (lambda (lib)
                      (format (current-error-port)
                              "~a: error: depends on '~a', which cannot \
be found in RUNPATH ~s~%"
                              file lib runpath))
                    not-found)
          ;; (when (null? not-found)
          ;;   (format (current-error-port) "~a is OK~%" file))
          (null? not-found))))))

(define (strip-runpath file)
  "Remove from the DT_RUNPATH of FILE any entries that are not necessary
according to DT_NEEDED."
  (define (minimal-runpath needed runpath)
    (filter (lambda (directory)
              (and (string-prefix? "/" directory)
                   (any (lambda (lib)
                          (file-exists? (string-append directory "/" lib)))
                        needed)))
            runpath))

  (define port
    (open-file file "r+b"))

  (catch #t
    (lambda ()
      (let* ((elf      (parse-elf (get-bytevector-all port)))
             (entries  (dynamic-entries elf (dynamic-link-segment elf)))
             (needed   (filter-map (lambda (entry)
                                     (and (= (dynamic-entry-type entry)
                                             DT_NEEDED)
                                          (dynamic-entry-value entry)))
                                   entries))
             (runpath  (find (lambda (entry)
                               (= DT_RUNPATH (dynamic-entry-type entry)))
                             entries))
             (old      (search-path->list
                        (dynamic-entry-value runpath)))
             (new      (minimal-runpath needed old)))
        (unless (equal? old new)
          (format (current-error-port)
                  "~a: stripping RUNPATH to ~s (removed ~s)~%"
                  file new
                  (lset-difference string=? old new))
          (seek port (dynamic-entry-offset runpath) SEEK_SET)
          (put-bytevector port (string->utf8 (string-join new ":")))
          (put-u8 port 0))
        (close-port port)
        new))
    (lambda (key . args)
      (false-if-exception (close-port port))
      (apply throw key args))))

;;; gremlin.scm ends here

debug log:

solving 4a31c3cfaf ...
found 4a31c3cfaf in https://yhetil.org/guix-patches/20210420194429.GB29387@dm9.info/
found e8ea66dfb3 in https://git.savannah.gnu.org/cgit/guix.git
preparing index
index prepared:
100644 e8ea66dfb3f0f28f8db26983b193eaf31f7d4978	guix/build/gremlin.scm

applying [1/1] https://yhetil.org/guix-patches/20210420194429.GB29387@dm9.info/
diff --git a/guix/build/gremlin.scm b/guix/build/gremlin.scm
index e8ea66dfb3..4a31c3cfaf 100644

Checking patch guix/build/gremlin.scm...
Applied patch guix/build/gremlin.scm cleanly.

index at:
100644 4a31c3cfaf3519b30d539b779cc1dcf8a50f8c78	guix/build/gremlin.scm

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/guix.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).