summaryrefslogtreecommitdiff
path: root/guix/build/utils.scm
blob: dd5a91f52f818f92f4eaf132ad521f3832569220 (about) (plain)
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
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2013 Andreas Enge <andreas@enge.fr>
;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
;;; Copyright © 2015, 2018, 2021 Mark H Weaver <mhw@netris.org>
;;; Copyright © 2018 Arun Isaac <arunisaac@systemreboot.net>
;;; Copyright © 2018, 2019 Ricardo Wurmus <rekado@elephly.net>
;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
;;; Copyright © 2020, 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
;;; Copyright © 2021 Brendan Tildesley <mail@brendan.scot>
;;;
;;; 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 utils)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:use-module (srfi srfi-60)
  #:use-module (ice-9 ftw)
  #:use-module (ice-9 match)
  #:use-module (ice-9 regex)
  #:use-module (ice-9 rdelim)
  #:use-module (ice-9 format)
  #:use-module (ice-9 threads)
  #:use-module (rnrs bytevectors)
  #:use-module (rnrs io ports)
  #:re-export (alist-cons
               alist-delete

               ;; Note: Re-export 'delete' to allow for proper syntax matching
               ;; in 'modify-phases' forms.  See
               ;; <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=26805#16>.
               delete)
  #:export (%store-directory
            store-file-name?
            strip-store-file-name
            package-name->name+version
            parallel-job-count

            compressor
            tarball?
            %xz-parallel-args

            directory-exists?
            executable-file?
            symbolic-link?
            call-with-temporary-output-file
            call-with-ascii-input-file
            elf-file?
            ar-file?
            gzip-file?
            reset-gzip-timestamp
            with-directory-excursion
            mkdir-p
            install-file
            make-file-writable
            copy-recursively
            delete-file-recursively
            file-name-predicate
            find-files
            false-if-file-not-found

            search-path-as-list
            set-path-environment-variable
            search-path-as-string->list
            list->search-path-as-string
            which
            search-input-file
            search-input-directory
            search-error?
            search-error-path
            search-error-file

            every*
            alist-cons-before
            alist-cons-after
            alist-replace
            modify-phases

            with-atomic-file-replacement
            substitute
            substitute*
            dump-port
            set-file-time
            patch-shebang
            patch-makefile-SHELL
            patch-/usr/bin/file
            fold-port-matches
            remove-store-references
            wrapped-program?
            wrap-program
            wrap-script

            wrap-error?
            wrap-error-program
            wrap-error-type

            invoke
            invoke-error?
            invoke-error-program
            invoke-error-arguments
            invoke-error-exit-status
            invoke-error-term-signal
            invoke-error-stop-signal
            report-invoke-error

            invoke/quiet

            make-desktop-entry-file

            locale-category->string))


;;;
;;; Guile 2.0 compatibility later.
;;;

;; The bootstrap Guile is Guile 2.0, so provide a compatibility layer.
(cond-expand
  ((and guile-2 (not guile-2.2))
   (define (setvbuf port mode . rest)
     (apply (@ (guile) setvbuf) port
            (match mode
              ('line _IOLBF)
              ('block _IOFBF)
              ('none _IONBF)
              (_ mode))                           ;an _IO* integer
            rest))

   (module-replace! (current-module) '(setvbuf)))
  (else #f))


;;;
;;; Compression helpers.
;;;

(define (compressor file-name)
  "Return the name of the compressor package/binary used to compress or
decompress FILE-NAME, based on its file extension, else false."
  (cond ((string-suffix? "gz"  file-name)  "gzip")
        ((string-suffix? "Z"   file-name)  "gzip")
        ((string-suffix? "bz2" file-name)  "bzip2")
        ((string-suffix? "lz"  file-name)  "lzip")
        ((string-suffix? "zip" file-name)  "unzip")
        ((string-suffix? "xz"  file-name)  "xz")
        (else #f)))                ;no compression used/unknown file extension

(define (tarball? file-name)
  "True when FILE-NAME has a tar file extension."
  (string-match "\\.(tar(\\..*)?|tgz|tbz)$" file-name))

(define (%xz-parallel-args)
  "The xz arguments required to enable bit-reproducible, multi-threaded
compression."
  (list "--memlimit=50%"
        (format #f "--threads=~a" (max 2 (parallel-job-count)))))


;;;
;;; Directories.
;;;

(define (%store-directory)
  "Return the directory name of the store."
  (or (getenv "NIX_STORE_DIR")          ;outside of builder
      (getenv "NIX_STORE")              ;inside builder, set by the daemon
      "/gnu/store"))

(define (store-file-name? file)
  "Return true if FILE is in the store."
  (string-prefix? (%store-directory) file))

(define (strip-store-file-name file)
  "Strip the '/gnu/store' and hash from FILE, a store file name.  The result
is typically a \"PACKAGE-VERSION\" string."
  (string-drop file
               (+ 34 (string-length (%store-directory)))))

(define (package-name->name+version name)
  "Given NAME, a package name like \"foo-0.9.1b\", return two values:
\"foo\" and \"0.9.1b\".  When the version part is unavailable, NAME and
#f are returned.  The first hyphen followed by a digit is considered to
introduce the version part."
  ;; See also `DrvName' in Nix.

  (define number?
    (cut char-set-contains? char-set:digit <>))

  (let loop ((chars   (string->list name))
             (prefix '()))
    (match chars
      (()
       (values name #f))
      ((#\- (? number? n) rest ...)
       (values (list->string (reverse prefix))
               (list->string (cons n rest))))
      ((head tail ...)
       (loop tail (cons head prefix))))))

(define parallel-job-count
  ;; Number of processes to be passed next to GNU Make's `-j' argument.
  (make-parameter
   (match (getenv "NIX_BUILD_CORES")              ;set by the daemon
     (#f  1)
     ("0" (current-processor-count))
     (x   (or (string->number x) 1)))))

(define (directory-exists? dir)
  "Return #t if DIR exists and is a directory."
  (let ((s (stat dir #f)))
    (and s
         (eq? 'directory (stat:type s)))))

(define (executable-file? file)
  "Return #t if FILE exists and is executable."
  (let ((s (stat file #f)))
    (and s
         (not (zero? (logand (stat:mode s) #o100))))))

(define (symbolic-link? file)
  "Return #t if FILE is a symbolic link (aka. \"symlink\".)"
  (eq? (stat:type (lstat file)) 'symlink))

(define (call-with-temporary-output-file proc)
  "Call PROC with a name of a temporary file and open output port to that
file; close the file and delete it when leaving the dynamic extent of this
call."
  (let* ((directory (or (getenv "TMPDIR") "/tmp"))
         (template  (string-append directory "/guix-file.XXXXXX"))
         (out       (mkstemp! template)))
    (dynamic-wind
      (lambda ()
        #t)
      (lambda ()
        (proc template out))
      (lambda ()
        (false-if-exception (close out))
        (false-if-exception (delete-file template))))))

(define (call-with-ascii-input-file file proc)
  "Open FILE as an ASCII or binary file, and pass the resulting port to
PROC.  FILE is closed when PROC's dynamic extent is left.  Return the
return values of applying PROC to the port."
  (let ((port (with-fluids ((%default-port-encoding #f))
                ;; Use "b" so that `open-file' ignores `coding:' cookies.
                (open-file file "rb"))))
    (dynamic-wind
      (lambda ()
        #t)
      (lambda ()
        (proc port))
      (lambda ()
        (close-input-port port)))))

(define (file-header-match header)
  "Return a procedure that returns true when its argument is a file starting
with the bytes in HEADER, a bytevector."
  (define len
    (bytevector-length header))

  (lambda (file)
    "Return true if FILE starts with the right magic bytes."
    (define (get-header)
      (call-with-input-file file
        (lambda (port)
          (get-bytevector-n port len))
        #:binary #t #:guess-encoding #f))

    (catch 'system-error
      (lambda ()
        (equal? (get-header) header))
      (lambda args
        (if (= EISDIR (system-error-errno args))
            #f                                    ;FILE is a directory
            (apply throw args))))))

(define %elf-magic-bytes
  ;; Magic bytes of ELF files.  See <elf.h>.
  (u8-list->bytevector (map char->integer (string->list "\x7FELF"))))

(define elf-file?
  (file-header-match %elf-magic-bytes))

(define %ar-magic-bytes
  ;; Magic bytes of archives created by 'ar'.  See <ar.h>.
  (u8-list->bytevector (map char->integer (string->list "!<arch>\n"))))

(define ar-file?
  (file-header-match %ar-magic-bytes))

(define %gzip-magic-bytes
  ;; Magic bytes of gzip file.  Beware, it's a small header so there could be
  ;; false positives.
  #vu8(#x1f #x8b))

(define gzip-file?
  (file-header-match %gzip-magic-bytes))

(define* (reset-gzip-timestamp file #:key (keep-mtime? #t))
  "If FILE is a gzip file, reset its embedded timestamp (as with 'gzip
--no-name') and return true.  Otherwise return #f.  When KEEP-MTIME? is true,
preserve FILE's modification time."
  (let ((stat (stat file))
        (port (open file O_RDWR)))
    (dynamic-wind
      (const #t)
      (lambda ()
        (and (= 4 (seek port 4 SEEK_SET))
             (put-bytevector port #vu8(0 0 0 0))))
      (lambda ()
        (close-port port)
        (set-file-time file stat)))))

(define-syntax-rule (with-directory-excursion dir body ...)
  "Run BODY with DIR as the process's current directory."
  (let ((init (getcwd)))
   (dynamic-wind
     (lambda ()
       (chdir dir))
     (lambda ()
       body ...)
     (lambda ()
       (chdir init)))))

(define (mkdir-p dir)
  "Create directory DIR and all its ancestors."
  (define absolute?
    (string-prefix? "/" dir))

  (define not-slash
    (char-set-complement (char-set #\/)))

  (let loop ((components (string-tokenize dir not-slash))
             (root       (if absolute?
                             ""
                             ".")))
    (match components
      ((head tail ...)
       (let ((path (string-append root "/" head)))
         (catch 'system-error
           (lambda ()
             (mkdir path)
             (loop tail path))
           (lambda args
             (if (= EEXIST (system-error-errno args))
                 (loop tail path)
                 (apply throw args))))))
      (() #t))))

(define (install-file file directory)
  "Create DIRECTORY if it does not exist and copy FILE in there under the same
name."
  (mkdir-p directory)
  (copy-file file (string-append directory "/" (basename file))))

(define (make-file-writable file)
  "Make FILE writable for its owner."
  (let ((stat (lstat file)))                      ;XXX: symlinks
    (chmod file (logior #o600 (stat:perms stat)))))

(define* (copy-recursively source destination
                           #:key
                           (log (current-output-port))
                           (follow-symlinks? #f)
                           (copy-file copy-file)
                           keep-mtime? keep-permissions?)
  "Copy SOURCE directory to DESTINATION.  Follow symlinks if FOLLOW-SYMLINKS?
is true; otherwise, just preserve them.  Call COPY-FILE to copy regular files.
When KEEP-MTIME? is true, keep the modification time of the files in SOURCE on
those of DESTINATION.  When KEEP-PERMISSIONS? is true, preserve file
permissions.  Write verbose output to the LOG port."
  (define strip-source
    (let ((len (string-length source)))
      (lambda (file)
        (substring file len))))

  (file-system-fold (const #t)                    ; enter?
                    (lambda (file stat result)    ; leaf
                      (let ((dest (string-append destination
                                                 (strip-source file))))
                        (format log "`~a' -> `~a'~%" file dest)
                        (case (stat:type stat)
                          ((symlink)
                           (let ((target (readlink file)))
                             (symlink target dest)))
                          (else
                           (copy-file file dest)
                           (when keep-permissions?
                             (chmod dest (stat:perms stat)))))
                        (when keep-mtime?
                          (set-file-time dest stat))))
                    (lambda (dir stat result)     ; down
                      (let ((target (string-append destination
                                                   (strip-source dir))))
                        (mkdir-p target)))
                    (lambda (dir stat result)     ; up
                      (let ((target (string-append destination
                                                   (strip-source dir))))
                        (when keep-mtime?
                          (set-file-time target stat))
                        (when keep-permissions?
                          (chmod target (stat:perms stat)))))
                    (const #t)                    ; skip
                    (lambda (file stat errno result)
                      (format (current-error-port) "i/o error: ~a: ~a~%"
                              file (strerror errno))
                      #f)
                    #t
                    source

                    (if follow-symlinks?
                        stat
                        lstat)))

(define-syntax-rule (warn-on-error expr file)
  (catch 'system-error
    (lambda ()
      expr)
    (lambda args
      (format (current-error-port)
              "warning: failed to delete ~a: ~a~%"
              file (strerror
                    (system-error-errno args))))))

(define* (delete-file-recursively dir
                                  #:key follow-mounts?)
  "Delete DIR recursively, like `rm -rf', without following symlinks.  Don't
follow mount points either, unless FOLLOW-MOUNTS? is true.  Report but ignore
errors."
  (let ((dev (stat:dev (lstat dir))))
    (file-system-fold (lambda (dir stat result)    ; enter?
                        (or follow-mounts?
                            (= dev (stat:dev stat))))
                      (lambda (file stat result)   ; leaf
                        (warn-on-error (delete-file file) file))
                      (const #t)                   ; down
                      (lambda (dir stat result)    ; up
                        (warn-on-error (rmdir dir) dir))
                      (const #t)                   ; skip
                      (lambda (file stat errno result)
                        (format (current-error-port)
                                "warning: failed to delete ~a: ~a~%"
                                file (strerror errno)))
                      #t
                      dir

                      ;; Don't follow symlinks.
                      lstat)))

(define (file-name-predicate regexp)
  "Return a predicate that returns true when passed a file name whose base
name matches REGEXP."
  (let ((file-rx (if (regexp? regexp)
                     regexp
                     (make-regexp regexp))))
    (lambda (file stat)
      (regexp-exec file-rx (basename file)))))

(define* (find-files dir #:optional (pred (const #t))
                     #:key (stat lstat)
                     directories?
                     fail-on-error?)
  "Return the lexicographically sorted list of files under DIR for which PRED
returns true.  PRED is passed two arguments: the absolute file name, and its
stat buffer; the default predicate always returns true.  PRED can also be a
regular expression, in which case it is equivalent to (file-name-predicate
PRED).  STAT is used to obtain file information; using 'lstat' means that
symlinks are not followed.  If DIRECTORIES? is true, then directories will
also be included.  If FAIL-ON-ERROR? is true, raise an exception upon error."
  (let ((pred (if (procedure? pred)
                  pred
                  (file-name-predicate pred))))
    ;; Sort the result to get deterministic results.
    (sort (file-system-fold (const #t)
                            (lambda (file stat result) ; leaf
                              (if (pred file stat)
                                  (cons file result)
                                  result))
                            (lambda (dir stat result) ; down
                              (if (and directories?
                                       (pred dir stat))
                                  (cons dir result)
                                  result))
                            (lambda (dir stat result) ; up
                              result)
                            (lambda (file stat result) ; skip
                              result)
                            (lambda (file stat errno result)
                              (format (current-error-port) "find-files: ~a: ~a~%"
                                      file (strerror errno))
                              (when fail-on-error?
                                (error "find-files failed"))
                              result)
                            '()
                            dir
                            stat)
          string<?)))

(define-syntax-rule (false-if-file-not-found exp)
  "Evaluate EXP but return #f if it raises to 'system-error with ENOENT."
  (catch 'system-error
    (lambda () exp)
    (lambda args
      (if (= ENOENT (system-error-errno args))
          #f
          (apply throw args)))))


;;;
;;; Search paths.
;;;

(define* (search-path-as-list files input-dirs
                              #:key (type 'directory) pattern)
  "Return the list of directories among FILES of the given TYPE (a symbol as
returned by 'stat:type') that exist in INPUT-DIRS.  Example:

  (search-path-as-list '(\"share/emacs/site-lisp\" \"share/emacs/24.1\")
                       (list \"/package1\" \"/package2\" \"/package3\"))
  => (\"/package1/share/emacs/site-lisp\"
      \"/package3/share/emacs/site-lisp\")

When PATTERN is true, it is a regular expression denoting file names to look
for under the directories designated by FILES.  For example:

  (search-path-as-list '(\"xml\") (list docbook-xml docbook-xsl)
                       #:type 'regular
                       #:pattern \"^catalog\\\\.xml$\")
  => (\"/…/xml/dtd/docbook/catalog.xml\"
      \"/…/xml/xsl/docbook-xsl-1.78.1/catalog.xml\")
"
  (append-map (lambda (input)
                (append-map (lambda (file)
                              (let ((file (string-append input "/" file)))
                                (if pattern
                                    (find-files file (lambda (file stat)
                                                       (and stat
                                                            (eq? type (stat:type stat))
                                                            ((file-name-predicate pattern) file stat)))
                                                #:stat stat
                                                #:directories? #t)
                                    (let ((stat (stat file #f)))
                                      (if (and stat (eq? type (stat:type stat)))
                                          (list file)
                                          '())))))
                            files))
              (delete-duplicates input-dirs)))

(define (list->search-path-as-string lst separator)
  (if separator
      (string-join lst separator)
      (match lst
        ((head rest ...) head)
        (() ""))))

(define* (search-path-as-string->list path #:optional (separator #\:))
  (if separator
      (string-tokenize path
                       (char-set-complement (char-set separator)))
      (list path)))

(define* (set-path-environment-variable env-var files input-dirs
                                        #:key
                                        (separator ":")
                                        (type 'directory)
                                        pattern)
  "Look for each of FILES of the given TYPE (a symbol as returned by
'stat:type') in INPUT-DIRS.  Set ENV-VAR to a SEPARATOR-separated path
accordingly.  Example:

  (set-path-environment-variable \"PKG_CONFIG\"
                                 '(\"lib/pkgconfig\")
                                 (list package1 package2))

When PATTERN is not #f, it must be a regular expression (really a string)
denoting file names to look for under the directories designated by FILES:

  (set-path-environment-variable \"XML_CATALOG_FILES\"
                                 '(\"xml\")
                                 (list docbook-xml docbook-xsl)
                                 #:type 'regular
                                 #:pattern \"^catalog\\\\.xml$\")
"
  (let* ((path  (search-path-as-list files input-dirs
                                     #:type type
                                     #:pattern pattern))
         (value (list->search-path-as-string path separator)))
    (if (string-null? value)
        (begin
          ;; Never set ENV-VAR to an empty string because often, the empty
          ;; string is equivalent to ".".  This is the case for
          ;; GUILE_LOAD_PATH in Guile 2.0, for instance.
          (unsetenv env-var)
          (format #t "environment variable `~a' unset~%" env-var))
        (begin
          (setenv env-var value)
          (format #t "environment variable `~a' set to `~a'~%"
                  env-var value)))))

(define (which program)
  "Return the complete file name for PROGRAM as found in $PATH, or #f if
PROGRAM could not be found."
  (search-path (search-path-as-string->list (getenv "PATH"))
               program))

(define-condition-type &search-error &error
  search-error?
  (path         search-error-path)
  (file         search-error-file))

(define (search-input-file inputs file)
  "Find a file named FILE among the INPUTS and return its absolute file name.

FILE must be a string like \"bin/sh\". If FILE is not found, an exception is
raised."
  (match inputs
    (((_ . directories) ...)
     ;; Accept both "bin/sh" and "/bin/sh" as FILE argument.
     (let ((file (string-trim file #\/)))
       (or (search-path directories file)
           (raise
            (condition (&search-error (path directories) (file file)))))))))

(define (search-input-directory inputs directory)
  "Find a sub-directory named DIRECTORY among the INPUTS and return its
absolute file name.

DIRECTORY must be a string like \"xml/dtd/docbook\".  If DIRECTORY is not
found, an exception is raised."
  (match inputs
    (((_ . directories) ...)
     (or (any (lambda (parent)
                (let ((directory (string-append parent "/" directory)))
                  (and (directory-exists? directory)
                       directory)))
              directories)
         (raise (condition
                 (&search-error (path directories) (file directory))))))))


;;;
;;; Phases.
;;;
;;; In (guix build gnu-build-system), there are separate phases (configure,
;;; build, test, install).  They are represented as a list of name/procedure
;;; pairs.  The following procedures make it easy to change the list of
;;; phases.
;;;

(define (every* pred lst)
  "This is like 'every', but process all the elements of LST instead of
stopping as soon as PRED returns false.  This is useful when PRED has side
effects, such as displaying warnings or error messages."
  (let loop ((lst    lst)
             (result #t))
    (match lst
      (()
       result)
      ((head . tail)
       (loop tail (and (pred head) result))))))

(define* (alist-cons-before reference key value alist
                            #:optional (key=? equal?))
  "Insert the KEY/VALUE pair before the first occurrence of a pair whose key
is REFERENCE in ALIST.  Use KEY=? to compare keys."
  (let-values (((before after)
                (break (match-lambda
                        ((k . _)
                         (key=? k reference)))
                       alist)))
    (append before (alist-cons key value after))))

(define* (alist-cons-after reference key value alist
                           #:optional (key=? equal?))
  "Insert the KEY/VALUE pair after the first occurrence of a pair whose key
is REFERENCE in ALIST.  Use KEY=? to compare keys."
  (let-values (((before after)
                (break (match-lambda
                        ((k . _)
                         (key=? k reference)))
                       alist)))
    (match after
      ((reference after ...)
       (append before (cons* reference `(,key . ,value) after)))
      (()
       (append before `((,key . ,value)))))))

(define* (alist-replace key value alist #:optional (key=? equal?))
  "Replace the first pair in ALIST whose car is KEY with the KEY/VALUE pair.
An error is raised when no such pair exists."
  (let-values (((before after)
                (break (match-lambda
                        ((k . _)
                         (key=? k key)))
                       alist)))
    (match after
      ((_ after ...)
       (append before (alist-cons key value after))))))

(define-syntax-rule (modify-phases phases mod-spec ...)
  "Modify PHASES sequentially as per each MOD-SPEC, which may have one of the
following forms:

  (delete <old-phase-name>)
  (replace <old-phase-name> <new-phase>)
  (add-before <old-phase-name> <new-phase-name> <new-phase>)
  (add-after <old-phase-name> <new-phase-name> <new-phase>)

Where every <*-phase-name> is an expression evaluating to a symbol, and
<new-phase> an expression evaluating to a procedure."
  (let* ((phases* phases)
         (phases* (%modify-phases phases* mod-spec))
         ...)
    phases*))

(define-syntax %modify-phases
  (syntax-rules (delete replace add-before add-after)
    ((_ phases (delete old-phase-name))
     (alist-delete old-phase-name phases))
    ((_ phases (replace old-phase-name new-phase))
     (alist-replace old-phase-name new-phase phases))
    ((_ phases (add-before old-phase-name new-phase-name new-phase))
     (alist-cons-before old-phase-name new-phase-name new-phase phases))
    ((_ phases (add-after old-phase-name new-phase-name new-phase))
     (alist-cons-after old-phase-name new-phase-name new-phase phases))))


;;;
;;; Program invocation.
;;;

(define-condition-type &invoke-error &error
  invoke-error?
  (program      invoke-error-program)
  (arguments    invoke-error-arguments)
  (exit-status  invoke-error-exit-status)
  (term-signal  invoke-error-term-signal)
  (stop-signal  invoke-error-stop-signal))

(define (invoke program . args)
  "Invoke PROGRAM with the given ARGS.  Raise an exception
if the exit code is non-zero; otherwise return #t."
  (let ((code (apply system* program args)))
    (unless (zero? code)
      (raise (condition (&invoke-error
                         (program program)
                         (arguments args)
                         (exit-status (status:exit-val code))
                         (term-signal (status:term-sig code))
                         (stop-signal (status:stop-sig code))))))
    #t))

(define* (report-invoke-error c #:optional (port (current-error-port)))
  "Report to PORT about C, an '&invoke-error' condition, in a human-friendly
way."
  (format port "command~{ ~s~} failed with ~:[signal~;status~] ~a~%"
          (cons (invoke-error-program c)
                (invoke-error-arguments c))
          (invoke-error-exit-status c)
          (or (invoke-error-exit-status c)
              (invoke-error-term-signal c)
              (invoke-error-stop-signal c))))

(define (open-pipe-with-stderr program . args)
  "Run PROGRAM with ARGS in an input pipe, but, unlike 'open-pipe*', redirect
both its standard output and standard error to the pipe.  Return two value:
the pipe to read PROGRAM's data from, and the PID of the child process running
PROGRAM."
  ;; 'open-pipe*' doesn't attempt to capture stderr in any way, which is why
  ;; we need to roll our own.
  (match (pipe)
    ((input .  output)
     (match (primitive-fork)
       (0
        (dynamic-wind
          (const #t)
          (lambda ()
            (close-port input)
            (dup2 (fileno output) 1)
            (dup2 (fileno output) 2)
            (apply execlp program program args))
          (lambda ()
            (primitive-exit 127))))
       (pid
        (close-port output)
        (values input pid))))))

(define (invoke/quiet program . args)
  "Invoke PROGRAM with ARGS and capture PROGRAM's standard output and standard
error.  If PROGRAM succeeds, print nothing and return the unspecified value;
otherwise, raise a '&message' error condition that includes the status code
and the output of PROGRAM."
  (let-values (((pipe pid)
                (apply open-pipe-with-stderr program args)))
    (let loop ((lines '()))
      (match (read-line pipe)
        ((? eof-object?)
         (close-port pipe)
         (match (waitpid pid)
           ((_ . status)
            (unless (zero? status)
              (let-syntax ((G_ (syntax-rules ()   ;for xgettext
                                 ((_ str) str))))
                (raise (condition
                        (&message
                         (message (format #f (G_ "'~a~{ ~a~}' exited \
with status ~a; output follows:~%~%~{  ~a~%~}")
                                          program args
                                          (or (status:exit-val status)
                                              status)
                                          (reverse lines)))))))))))
        (line
         (loop (cons line lines)))))))


;;;
;;; Text substitution (aka. sed).
;;;

(define (with-atomic-file-replacement file proc)
  "Call PROC with two arguments: an input port for FILE, and an output
port for the file that is going to replace FILE.  Upon success, FILE is
atomically replaced by what has been written to the output port, and
PROC's result is returned."
  (let* ((template (string-append file ".XXXXXX"))
         (out      (mkstemp! template))
         (mode     (stat:mode (stat file))))
    (with-throw-handler #t
      (lambda ()
        (call-with-input-file file
          (lambda (in)
            (let ((result (proc in out)))
              (close out)
              (chmod template mode)
              (rename-file template file)
              result))))
      (lambda (key . args)
        (false-if-exception (delete-file template))))))

(define (unused-private-use-code-point s)
  "Find a code point within a Unicode Private Use Area that is not
present in S, and return the corresponding character object.  If one
cannot be found, return false."
  (define (scan lo hi)
    (and (<= lo hi)
         (let ((c (integer->char lo)))
           (if (string-index s c)
               (scan (+ lo 1) hi)
               c))))
  (or (scan   #xE000   #xF8FF)
      (scan  #xF0000  #xFFFFD)
      (scan #x100000 #x10FFFD)))

(define (replace-char c1 c2 s)
  "Return a string which is equal to S except with all instances of C1
replaced by C2.  If C1 and C2 are equal, return S."
  (if (char=? c1 c2)
      s
      (string-map (lambda (c)
                    (if (char=? c c1)
                        c2
                        c))
                  s)))

(define (substitute file pattern+procs)
  "PATTERN+PROCS is a list of regexp/two-argument-procedure pairs.  For each
line of FILE, and for each PATTERN that it matches, call the corresponding
PROC as (PROC LINE MATCHES); PROC must return the line that will be written as
a substitution of the original line.  Be careful about using '$' to match the
end of a line; by itself it won't match the terminating newline of a line."
  (let ((rx+proc  (map (match-lambda
                        (((? regexp? pattern) . proc)
                         (cons pattern proc))
                        ((pattern . proc)
                         (cons (make-regexp pattern regexp/extended)
                               proc)))
                       pattern+procs)))
    (with-atomic-file-replacement file
      (lambda (in out)
        (let loop ((line (read-line in 'concat)))
          (if (eof-object? line)
              #t
              ;; Work around the fact that Guile's regexp-exec does not handle
              ;; NUL characters (a limitation of the underlying GNU libc's
              ;; regexec) by temporarily replacing them by an unused private
              ;; Unicode code point.
              ;; TODO: Use SRFI-115 instead, once available in Guile.
              (let* ((nul* (or (and (string-index line #\nul)
                                    (unused-private-use-code-point line))
                               #\nul))
                     (line* (replace-char #\nul nul* line))
                     (line1* (fold (lambda (r+p line)
                                     (match r+p
                                       ((regexp . proc)
                                        (match (list-matches regexp line)
                                          ((and m+ (_ _ ...))
                                           (proc line m+))
                                          (_ line)))))
                                   line*
                                   rx+proc))
                     (line1 (replace-char nul* #\nul line1*)))
                (display line1 out)
                (loop (read-line in 'concat)))))))))


(define-syntax let-matches
  ;; Helper macro for `substitute*'.
  (syntax-rules (_)
    ((let-matches index match (_ vars ...) body ...)
     (let-matches (+ 1 index) match (vars ...)
                  body ...))
    ((let-matches index match (var vars ...) body ...)
     (let ((var (match:substring match index)))
       (let-matches (+ 1 index) match (vars ...)
                    body ...)))
    ((let-matches index match () body ...)
     (begin body ...))))

(define-syntax substitute*
  (syntax-rules ()
    "Substitute REGEXP in FILE by the string returned by BODY.  BODY is
evaluated with each MATCH-VAR bound to the corresponding positional regexp
sub-expression.  For example:

  (substitute* file
     ((\"hello\")
      \"good morning\\n\")
     ((\"foo([a-z]+)bar(.*)$\" all letters end)
      (string-append \"baz\" letters end)))

Here, anytime a line of FILE contains \"hello\", it is replaced by \"good
morning\".  Anytime a line of FILE matches the second regexp, ALL is bound to
the complete match, LETTERS is bound to the first sub-expression, and END is
bound to the last one.

When one of the MATCH-VAR is `_', no variable is bound to the corresponding
match substring.

Alternatively, FILE may be a list of file names, in which case they are
all subject to the substitutions.

Be careful about using '$' to match the end of a line; by itself it won't
match the terminating newline of a line."
    ((substitute* file ((regexp match-var ...) body ...) ...)
     (let ()
       (define (substitute-one-file file-name)
         (substitute
          file-name
          (list (cons regexp
                      (lambda (l m+)
                        ;; Iterate over matches M+ and return the
                        ;; modified line based on L.
                        (let loop ((m* m+)  ; matches
                                   (o  0)   ; offset in L
                                   (r  '())) ; result
                          (match m*
                            (()
                             (let ((r (cons (substring l o) r)))
                               (string-concatenate-reverse r)))
                            ((m . rest)
                             (let-matches 0 m (match-var ...)
                               (loop rest
                                     (match:end m)
                                     (cons*
                                      (begin body ...)
                                      (substring l o (match:start m))
                                      r))))))))
                ...)))

       (match file
         ((files (... ...))
          (for-each substitute-one-file files))
         ((? string? f)
          (substitute-one-file f)))))))


;;;
;;; Patching shebangs---e.g., /bin/sh -> /gnu/store/xyz...-bash/bin/sh.
;;;

(define* (dump-port in out
                    #:optional len
                    #:key (buffer-size 16384)
                    (progress (lambda (t k) (k))))
  "Read LEN bytes from IN or as much data as possible if LEN is #f, and write
it to OUT, using chunks of BUFFER-SIZE bytes.  Call PROGRESS at the beginning
and after each successful transfer of BUFFER-SIZE bytes or less, passing it
the total number of bytes transferred and the continuation of the transfer as
a thunk."
  (define buffer
    (make-bytevector buffer-size))

  (define (loop total bytes)
    (or (eof-object? bytes)
        (and len (= total len))
        (let ((total (+ total bytes)))
          (put-bytevector out buffer 0 bytes)
          (progress total
                    (lambda ()
                      (loop total
                            (get-bytevector-n! in buffer 0
                                               (if len
                                                   (min (- len total) buffer-size)
                                                   buffer-size))))))))

  ;; Make sure PROGRESS is called when we start so that it can measure
  ;; throughput.
  (progress 0
            (lambda ()
              (loop 0 (get-bytevector-n! in buffer 0
                                         (if len
                                             (min len buffer-size)
                                             buffer-size))))))

(define AT_SYMLINK_NOFOLLOW
  ;; Guile 2.0 did not define this constant, hence this hack.
  (let ((variable (module-variable the-root-module 'AT_SYMLINK_NOFOLLOW)))
    (if variable
        (variable-ref variable)
        256)))                                    ;for GNU/Linux

(define (set-file-time file stat)
  "Set the atime/mtime of FILE to that specified by STAT."
  (utime file
         (stat:atime stat)
         (stat:mtime stat)
         (stat:atimensec stat)
         (stat:mtimensec stat)
         AT_SYMLINK_NOFOLLOW))

(define (get-char* p)
  ;; We call it `get-char', but that's really a binary version
  ;; thereof.  (The real `get-char' cannot be used here because our
  ;; bootstrap Guile is hacked to always use UTF-8.)
  (match (get-u8 p)
    ((? integer? x) (integer->char x))
    (x x)))

(define patch-shebang
  (let ((shebang-rx (make-regexp "^[[:blank:]]*(/[[:graph:]]+)[[:blank:]]*([[:graph:]]*)(.*)$")))
    (lambda* (file
              #:optional
              (path (search-path-as-string->list (getenv "PATH")))
              #:key (keep-mtime? #t))
      "Replace the #! interpreter file name in FILE by a valid one found in
PATH, when FILE actually starts with a shebang.  Return #t when FILE was
patched, #f otherwise.  When KEEP-MTIME? is true, the atime/mtime of
FILE are kept unchanged."
      (define (patch p interpreter rest-of-line)
        (let* ((template (string-append file ".XXXXXX"))
               (out      (mkstemp! template))
               (st       (stat file))
               (mode     (stat:mode st)))
          (with-throw-handler #t
            (lambda ()
              (format out "#!~a~a~%"
                      interpreter rest-of-line)
              (dump-port p out)
              (close out)
              (chmod template mode)
              (rename-file template file)
              (when keep-mtime?
                (set-file-time file st))
              #t)
            (lambda (key . args)
              (format (current-error-port)
                      "patch-shebang: ~a: error: ~a ~s~%"
                      file key args)
              (false-if-exception (delete-file template))
              #f))))

      (call-with-ascii-input-file file
        (lambda (p)
          (and (eq? #\# (get-char* p))
               (eq? #\! (get-char* p))
               (let ((line (false-if-exception (read-line p))))
                 (and=> (and line (regexp-exec shebang-rx line))
                        (lambda (m)
                          (let* ((interp (match:substring m 1))
                                 (arg1 (match:substring m 2))
                                 (rest (match:substring m 3))
                                 (has-env (string-suffix? "/env" interp))
                                 (cmd (if has-env arg1 (basename interp)))
                                 (bin (search-path path cmd)))
                            (if bin
                                (if (string=? bin interp)
                                    #f            ; nothing to do
                                    (if has-env
                                        (begin
                                          (format (current-error-port)
                                                  "patch-shebang: ~a: changing `~a' to `~a'~%"
                                                  file (string-append interp " " arg1) bin)
                                          (patch p bin rest))
                                      (begin 
                                        (format (current-error-port)
                                                "patch-shebang: ~a: changing `~a' to `~a'~%"
                                                file interp bin)
                                        (patch p bin
                                               (if (string-null? arg1)
                                                   ""
                                                   (string-append " " arg1 rest))))))
                                (begin
                                  (format (current-error-port)
                                          "patch-shebang: ~a: warning: no binary for interpreter `~a' found in $PATH~%"
                                          file (basename cmd))
                                  #f))))))))))))

(define* (patch-makefile-SHELL file #:key (keep-mtime? #t))
  "Patch the `SHELL' variable in FILE, which is supposedly a makefile.
When KEEP-MTIME? is true, the atime/mtime of FILE are kept unchanged."

  ;; For instance, Gettext-generated po/Makefile.in.in do not honor $SHELL.

  ;; XXX: Unlike with `patch-shebang', FILE is always touched.

  (define (find-shell name)
    (let ((shell (which name)))
      (unless shell
        (format (current-error-port)
                "patch-makefile-SHELL: warning: no binary for shell `~a' found in $PATH~%"
                name))
      shell))

  (let ((st (stat file)))
    ;; Consider FILE is using an 8-bit encoding to avoid errors.
    (with-fluids ((%default-port-encoding #f))
      (substitute* file
        (("^ *SHELL[[:blank:]]*:?=[[:blank:]]*([[:graph:]]*/)([[:graph:]]+)(.*)$"
          _ dir shell args)
         (let* ((old (string-append dir shell))
                (new (or (find-shell shell) old)))
           (unless (string=? new old)
             (format (current-error-port)
                     "patch-makefile-SHELL: ~a: changing `SHELL' from `~a' to `~a'~%"
                     file old new))
           (string-append "SHELL = " new args)))))

   (when keep-mtime?
     (set-file-time file st))))

(define* (patch-/usr/bin/file file
                              #:key
                              (file-command (which "file"))
                              (keep-mtime? #t))
  "Patch occurrences of \"/usr/bin/file\" in FILE, replacing them with
FILE-COMMAND.  When KEEP-MTIME? is true, keep FILE's modification time
unchanged."
  (if (not file-command)
      (format (current-error-port)
              "patch-/usr/bin/file: warning: \
no replacement 'file' command, doing nothing~%")
      (let ((st (stat file)))
        ;; Consider FILE is using an 8-bit encoding to avoid errors.
        (with-fluids ((%default-port-encoding #f))
          (substitute* file
            (("/usr/bin/file")
             (begin
               (format (current-error-port)
                       "patch-/usr/bin/file: ~a: changing `~a' to `~a'~%"
                       file "/usr/bin/file" file-command)
               file-command))))

        (when keep-mtime?
          (set-file-time file st)))))

(define* (fold-port-matches proc init pattern port
                            #:optional (unmatched (lambda (_ r) r)))
  "Read from PORT character-by-character; for each match against
PATTERN, call (PROC MATCH RESULT), where RESULT is seeded with INIT.
PATTERN is a list of SRFI-14 char-sets.  Call (UNMATCHED CHAR RESULT)
for each unmatched character."
  (define initial-pattern
    ;; The poor developer's regexp.
    (if (string? pattern)
        (map char-set (string->list pattern))
        pattern))

  ;; Note: we're not really striving for performance here...
  (let loop ((chars   '())
             (pattern initial-pattern)
             (matched '())
             (result  init))
    (cond ((null? chars)
           (loop (list (get-char* port))
                 pattern
                 matched
                 result))
          ((null? pattern)
           (loop chars
                 initial-pattern
                 '()
                 (proc (list->string (reverse matched)) result)))
          ((eof-object? (car chars))
           (fold-right unmatched result matched))
          ((char-set-contains? (car pattern) (car chars))
           (loop (cdr chars)
                 (cdr pattern)
                 (cons (car chars) matched)
                 result))
          ((null? matched)                        ; common case
           (loop (cdr chars)
                 pattern
                 matched
                 (unmatched (car chars) result)))
          (else
           (let ((matched (reverse matched)))
             (loop (append (cdr matched) chars)
                   initial-pattern
                   '()
                   (unmatched (car matched) result)))))))

(define* (remove-store-references file
                                  #:optional (store (%store-directory)))
  "Remove from FILE occurrences of file names in STORE; return #t when
store paths were encountered in FILE, #f otherwise.  This procedure is
known as `nuke-refs' in Nixpkgs."
  (define pattern
    (let ((nix-base32-chars
           '(#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9
             #\a #\b #\c #\d #\f #\g #\h #\i #\j #\k #\l #\m #\n
             #\p #\q #\r #\s #\v #\w #\x #\y #\z)))
      `(,@(map char-set (string->list store))
        ,(char-set #\/)
        ,@(make-list 32 (list->char-set nix-base32-chars))
        ,(char-set #\-))))

  (with-fluids ((%default-port-encoding #f))
    (with-atomic-file-replacement file
      (lambda (in out)
        ;; We cannot use `regexp-exec' here because it cannot deal with
        ;; strings containing NUL characters.
        (format #t "removing store references from `~a'...~%" file)
        (setvbuf in 'block 65536)
        (setvbuf out 'block 65536)
        (fold-port-matches (lambda (match result)
                             (put-bytevector out (string->utf8 store))
                             (put-u8 out (char->integer #\/))
                             (put-bytevector out
                                             (string->utf8
                                              "eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-"))
                             #t)
                           #f
                           pattern
                           in
                           (lambda (char result)
                             (put-u8 out (char->integer char))
                             result))))))

(define-condition-type &wrap-error &error
  wrap-error?
  (program    wrap-error-program)
  (type       wrap-error-type))

(define (wrapped-program? prog)
  "Return #t if PROG is a program that was moved and wrapped by 'wrap-program'."
  (and (file-exists? prog)
       (let ((base (basename prog)))
         (and (string-prefix? "." base)
              (string-suffix? "-real" base)))))

(define* (wrap-program prog #:key (sh (which "bash")) #:rest vars)
  "Make a wrapper for PROG.  VARS should look like this:

  '(VARIABLE DELIMITER POSITION LIST-OF-DIRECTORIES)

where DELIMITER is optional.  ':' will be used if DELIMITER is not given.

For example, this command:

  (wrap-program \"foo\"
                '(\"PATH\" \":\" = (\"/gnu/.../bar/bin\"))
                '(\"CERT_PATH\" suffix (\"/gnu/.../baz/certs\"
                                        \"/qux/certs\")))

will copy 'foo' to '.foo-real' and create the file 'foo' with the following
contents:

  #!location/of/bin/bash
  export PATH=\"/gnu/.../bar/bin\"
  export CERT_PATH=\"$CERT_PATH${CERT_PATH:+:}/gnu/.../baz/certs:/qux/certs\"
  exec -a $0 location/of/.foo-real \"$@\"

This is useful for scripts that expect particular programs to be in $PATH, for
programs that expect particular shared libraries to be in $LD_LIBRARY_PATH, or
modules in $GUILE_LOAD_PATH, etc.

If PROG has previously been wrapped by 'wrap-program', the wrapper is extended
with definitions for VARS. If it is not, SH will be used as interpreter."
  (define vars/filtered
    (match vars
      ((#:sh _ . vars) vars)
      (vars vars)))

  (define wrapped-file
    (string-append (dirname prog) "/." (basename prog) "-real"))

  (define already-wrapped?
    (file-exists? wrapped-file))

  (define (last-line port)
    ;; Return the last line read from PORT and leave PORT's cursor right
    ;; before it.
    (let loop ((previous-line-offset 0)
               (previous-line "")
               (position (seek port 0 SEEK_CUR)))
      (match (read-line port 'concat)
        ((? eof-object?)
         (seek port previous-line-offset SEEK_SET)
         previous-line)
        ((? string? line)
         (loop position line (+ (string-length line) position))))))

  (define (export-variable lst)
    ;; Return a string that exports an environment variable.
    (match lst
      ((var sep '= rest)
       (format #f "export ~a=\"~a\""
               var (string-join rest sep)))
      ((var sep 'prefix rest)
       (format #f "export ~a=\"~a${~a:+~a}$~a\""
               var (string-join rest sep) var sep var))
      ((var sep 'suffix rest)
       (format #f "export ~a=\"$~a${~a+~a}~a\""
               var var var sep (string-join rest sep)))
      ((var '= rest)
       (format #f "export ~a=\"~a\""
               var (string-join rest ":")))
      ((var 'prefix rest)
       (format #f "export ~a=\"~a${~a:+:}$~a\""
               var (string-join rest ":") var var))
      ((var 'suffix rest)
       (format #f "export ~a=\"$~a${~a:+:}~a\""
               var var var (string-join rest ":")))))

  (when (wrapped-program? prog)
    (error (string-append prog " is a wrapper. Refusing to wrap.")))

  (if already-wrapped?

      ;; PROG is already a wrapper: add the new "export VAR=VALUE" lines just
      ;; before the last line.
      (let* ((port (open-file prog "r+"))
             (last (last-line port)))
        (for-each (lambda (var)
                    (display (export-variable var) port)
                    (newline port))
                  vars/filtered)
        (display last port)
        (close-port port))

      ;; PROG is not wrapped yet: create a shell script that sets VARS.
      (let ((prog-tmp (string-append wrapped-file "-tmp")))
        (link prog wrapped-file)

        (call-with-output-file prog-tmp
          (lambda (port)
            (format port
                    "#!~a~%~a~%exec -a \"$0\" \"~a\" \"$@\"~%"
                    sh
                    (string-join (map export-variable vars/filtered) "\n")
                    (canonicalize-path wrapped-file))))

        (chmod prog-tmp #o755)
        (rename-file prog-tmp prog))))

(define wrap-script
  (let ((interpreter-regex
         (make-regexp
          (string-append "^#! ?(/[^ ]+/bin/("
                         (string-join '("python[^ ]*"
                                        "Rscript"
                                        "perl"
                                        "ruby"
                                        "bash"
                                        "sh") "|")
                         "))( ?.*)")))
        (coding-line-regex
         (make-regexp
          ".*#.*coding[=:][[:space:]]*([-a-zA-Z_0-9.]+)")))
    (lambda* (prog #:key (guile (which "guile")) #:rest vars)
      "Wrap the script PROG such that VARS are set first.  The format of VARS
is the same as in the WRAP-PROGRAM procedure.  This procedure differs from
WRAP-PROGRAM in that it does not create a separate shell script.  Instead,
PROG is modified directly by prepending a Guile script, which is interpreted
as a comment in the script's language.

Special encoding comments as supported by Python are recreated on the second
line.

Note that this procedure can only be used once per file as Guile scripts are
not supported."
      (define update-env
        (match-lambda
          ((var sep '= rest)
           `(setenv ,var ,(string-join rest sep)))
          ((var sep 'prefix rest)
           `(let ((current (getenv ,var)))
              (setenv ,var (if current
                               (string-append ,(string-join rest sep)
                                              ,sep current)
                               ,(string-join rest sep)))))
          ((var sep 'suffix rest)
           `(let ((current (getenv ,var)))
              (setenv ,var (if current
                               (string-append current ,sep
                                              ,(string-join rest sep))
                               ,(string-join rest sep)))))
          ((var '= rest)
           `(setenv ,var ,(string-join rest ":")))
          ((var 'prefix rest)
           `(let ((current (getenv ,var)))
              (setenv ,var (if current
                               (string-append ,(string-join rest ":")
                                              ":" current)
                               ,(string-join rest ":")))))
          ((var 'suffix rest)
           `(let ((current (getenv ,var)))
              (setenv ,var (if current
                               (string-append current ":"
                                              ,(string-join rest ":"))
                               ,(string-join rest ":")))))))
      (let-values (((interpreter args coding-line)
                    (call-with-ascii-input-file prog
                      (lambda (p)
                        (let ((first-match
                               (false-if-exception
                                (regexp-exec interpreter-regex (read-line p)))))
                          (values (and first-match (match:substring first-match 1))
                                  (and first-match (match:substring first-match 3))
                                  (false-if-exception
                                   (and=> (regexp-exec coding-line-regex (read-line p))
                                          (lambda (m) (match:substring m 0))))))))))
        (if interpreter
            (let* ((header (format #f "\
#!~a --no-auto-compile
#!#; ~a
#\\-~s
#\\-~s
"
                                   guile
                                   (or coding-line "Guix wrapper")
                                   (cons 'begin (map update-env
                                                     (match vars
                                                       ((#:guile _ . vars) vars)
                                                       (_ vars))))
                                   `(let ((cl (command-line)))
                                      (apply execl ,interpreter
                                             (car cl)
                                             (append
                                              ',(string-tokenize args char-set:graphic)
                                              cl)))))
                   (template (string-append prog ".XXXXXX"))
                   (out      (mkstemp! template))
                   (st       (stat prog))
                   (mode     (stat:mode st)))
              (with-throw-handler #t
                (lambda ()
                  (call-with-ascii-input-file prog
                    (lambda (p)
                      (display header out)
                      (dump-port p out)
                      (close out)
                      (chmod template mode)
                      (rename-file template prog)
                      (set-file-time prog st))))
                (lambda (key . args)
                  (format (current-error-port)
                          "wrap-script: ~a: error: ~a ~s~%"
                          prog key args)
                  (false-if-exception (delete-file template))
                  (raise (condition
                          (&wrap-error (program prog)
                                       (type key))))
                  #f)))
            (raise (condition
                    (&wrap-error (program prog)
                                 (type 'no-interpreter-found)))))))))

(define* (make-desktop-entry-file destination #:key
                                  (type "Application") ; One of "Application", "Link" or "Directory".
                                  (version "1.1")
                                  name
                                  (generic-name name)
                                  (no-display #f)
                                  comment
                                  icon
                                  (hidden #f)
                                  only-show-in
                                  not-show-in
                                  (d-bus-activatable #f)
                                  try-exec
                                  exec
                                  path
                                  (terminal #f)
                                  actions
                                  mime-type
                                  (categories "Application")
                                  implements
                                  keywords
                                  (startup-notify #t)
                                  startup-w-m-class
                                  #:rest all-args)
  "Create a desktop entry file at DESTINATION.
You must specify NAME.

Values can be booleans, numbers, strings or list of strings.

Additionally, locales can be specified with an alist where the key is the
locale.  The #f key specifies the default.  Example:

  #:name '((#f \"I love Guix\") (\"fr\" \"J'aime Guix\"))

produces

  Name=I love Guix
  Name[fr]=J'aime Guix

For a complete description of the format, see the specifications at
https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html."
  (define (escape-semicolon s)
    (string-join (string-split s #\;) "\\;"))
  (define* (parse key value #:optional locale)
    (set! value (match value
                  (#t "true")
                  (#f "false")
                  ((?  number? n) n)
                  ((?  string? s) (escape-semicolon s))
                  ((?  list? value)
                   (catch 'wrong-type-arg
                     (lambda () (string-join (map escape-semicolon value) ";"))
                     (lambda args (error "List arguments can only contain strings: ~a" args))))
                  (_ (error "Value must be a boolean, number, string or list of strings"))))
    (format #t "~a=~a~%"
            (if locale
                (format #f "~a[~a]" key locale)
                key)
            value))

  (define key-error-message "This procedure only takes key arguments beside DESTINATION")

  (unless name
    (error "Missing NAME key argument"))
  (unless (member #:type all-args)
    (set! all-args (append (list #:type type) all-args)))
  (mkdir-p (dirname destination))

  (with-output-to-file destination
    (lambda ()
      (format #t "[Desktop Entry]~%")
      (let loop ((args all-args))
        (match args
          (() #t)
          ((_) (error key-error-message))
          ((key value . ...)
           (unless (keyword? key)
             (error key-error-message))
           (set! key
                 (string-join (map string-titlecase
                                   (string-split (symbol->string
                                                  (keyword->symbol key))
                                                 #\-))
                              ""))
           (match value
             (((_ . _) . _)
              (for-each (lambda (locale-subvalue)
                          (parse key
                                 (if (and (list? (cdr locale-subvalue))
                                          (= 1 (length (cdr locale-subvalue))))
                                     ;; Support both proper and improper lists for convenience.
                                     (cadr locale-subvalue)
                                     (cdr locale-subvalue))
                                 (car locale-subvalue)))
                        value))
             (_
              (parse key value)))
           (loop (cddr args))))))))


;;;
;;; Locales.
;;;

(define (locale-category->string category)
  "Return the name of locale category CATEGORY, one of the 'LC_' constants.
If CATEGORY is a bitwise or of several 'LC_' constants, an approximation is
returned."
  (letrec-syntax ((convert (syntax-rules ()
                             ((_)
                              (number->string category))
                             ((_ first rest ...)
                              (if (= first category)
                                  (symbol->string 'first)
                                  (convert rest ...))))))
    (convert LC_ADDRESS LC_ALL LC_COLLATE LC_CTYPE
             LC_IDENTIFICATION LC_MEASUREMENT LC_MESSAGES LC_MONETARY
             LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE
             LC_TIME)))

;;; Local Variables:
;;; eval: (put 'call-with-output-file/atomic 'scheme-indent-function 1)
;;; eval: (put 'call-with-ascii-input-file 'scheme-indent-function 1)
;;; eval: (put 'with-throw-handler 'scheme-indent-function 1)
;;; eval: (put 'let-matches 'scheme-indent-function 3)
;;; eval: (put 'with-atomic-file-replacement 'scheme-indent-function 1)
;;; End: