unofficial mirror of guix-patches@gnu.org 
 help / color / mirror / code / Atom feed
blob 43e85a5026a44d063f38012193d7613cf2e29c9b 29171 bytes (raw)
name: guix/git.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
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
 
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2017, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2021 Kyle Meyer <kyle@kyleam.com>
;;; Copyright © 2021 Marius Bakke <marius@gnu.org>
;;; Copyright © 2022 Maxime Devos <maximedevos@telenet.be>
;;;
;;; 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 git)
  #:use-module (git)
  #:use-module (git object)
  #:use-module (git submodule)
  #:use-module (guix i18n)
  #:use-module (guix base32)
  #:use-module (guix cache)
  #:use-module (gcrypt hash)
  #:use-module ((guix build utils)
                #:select (mkdir-p delete-file-recursively))
  #:use-module (guix store)
  #:use-module (guix utils)
  #:use-module (guix records)
  #:use-module (guix gexp)
  #:autoload   (guix git-download)
  (git-reference-url git-reference-commit git-reference-recursive?)
  #:use-module (guix sets)
  #:use-module ((guix diagnostics) #:select (leave warning))
  #:use-module (guix progress)
  #:autoload   (guix swh) (swh-download commit-id?)
  #:use-module (rnrs bytevectors)
  #:use-module (ice-9 format)
  #:use-module (ice-9 match)
  #:use-module (ice-9 ftw)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:export (%repository-cache-directory
            honor-system-x509-certificates!

            url-cache-directory
            with-repository
            with-git-error-handling
            false-if-git-not-found
            update-cached-checkout
            url+commit->name
            latest-repository-commit
            commit-difference
            commit-relation

            remote-refs

            git-checkout
            git-checkout?
            git-checkout-url
            git-checkout-branch
            git-checkout-commit
            git-checkout-recursive?

            git-reference->git-checkout))

(define %repository-cache-directory
  (make-parameter (string-append (cache-directory #:ensure? #f)
                                 "/checkouts")))

(define (honor-system-x509-certificates!)
  "Use the system's X.509 certificates for Git checkouts over HTTPS.  Honor
the 'SSL_CERT_FILE' and 'SSL_CERT_DIR' environment variables."
  ;; On distros such as CentOS 7, /etc/ssl/certs contains only a couple of
  ;; files (instead of all the certificates) among which "ca-bundle.crt".  On
  ;; other distros /etc/ssl/certs usually contains the whole set of
  ;; certificates along with "ca-certificates.crt".  Try to choose the right
  ;; one.
  (let ((file      (letrec-syntax ((choose
                                    (syntax-rules ()
                                      ((_ file rest ...)
                                       (let ((f file))
                                         (if (and f (file-exists? f))
                                             f
                                             (choose rest ...))))
                                      ((_)
                                       #f))))
                     (choose (getenv "SSL_CERT_FILE")
                             "/etc/ssl/certs/ca-certificates.crt"
                             "/etc/ssl/certs/ca-bundle.crt")))
        (directory (or (getenv "SSL_CERT_DIR") "/etc/ssl/certs")))
    (and (or file
             (and=> (stat directory #f)
                    (lambda (st)
                      (> (stat:nlink st) 2))))
         (begin
           (set-tls-certificate-locations! directory file)
           #t))))

(define %certificates-initialized?
  ;; Whether 'honor-system-x509-certificates!' has already been called.
  #f)

(define-syntax-rule (with-libgit2 thunk ...)
  (begin
    ;; XXX: The right thing to do would be to call (libgit2-shutdown) here,
    ;; but pointer finalizers used in guile-git may be called after shutdown,
    ;; resulting in a segfault. Hence, let's skip shutdown call for now.
    (libgit2-init!)
    (unless %certificates-initialized?
      (honor-system-x509-certificates!)
      (set! %certificates-initialized? #t))
    thunk ...))

(define* (url-cache-directory url
                              #:optional (cache-directory
                                          (%repository-cache-directory))
                              #:key recursive?)
  "Return the directory associated to URL in %repository-cache-directory."
  (string-append
   cache-directory "/"
   (bytevector->base32-string
    (sha256 (string->utf8 (if recursive?
                              (string-append "R:" url)
                              url))))))

(define (show-progress progress)
  "Display a progress bar as we fetch Git code.  PROGRESS is an
<indexer-progress> record from (git)."
  (define total
    (indexer-progress-total-objects progress))

  (define hundredth
    (match (quotient (indexer-progress-total-objects progress) 100)
      (0 1)
      (x x)))

  (define-values (done label)
    (if (< (indexer-progress-received-objects progress) total)
        (values (indexer-progress-received-objects progress)
                (G_ "receiving objects"))
        (values (indexer-progress-indexed-objects progress)
                (G_ "indexing objects"))))

  (define %
    (* 100. (/ done total)))

  (when (and (< % 100) (zero? (modulo done hundredth)))
    (erase-current-line (current-error-port))
    (let ((width (max (- (current-terminal-columns)
                         (string-length label) 7)
                      3)))
      (format (current-error-port) "~a ~3,d% ~a"
              label (inexact->exact (round %))
              (progress-bar % width)))
    (force-output (current-error-port)))

  (when (= % 100.)
    ;; We're done, erase the line.
    (erase-current-line (current-error-port))
    (force-output (current-error-port)))

  ;; Return true to indicate that we should go on.
  #t)

(define (make-default-fetch-options)
  "Return the default fetch options."
  (let ((auth-method (%make-auth-ssh-agent)))
    ;; The #:transfer-progress and #:proxy-url options appeared in Guile-Git
    ;; 0.4.0.  Omit them when using an older version.
    (catch 'wrong-number-of-args
      (lambda ()
        (make-fetch-options auth-method
                            ;; Guile-Git doesn't distinguish between these.
                            #:proxy-url (or (getenv "http_proxy")
                                            (getenv "https_proxy"))
                            #:transfer-progress
                            (and (isatty? (current-error-port))
                                 show-progress)))
      (lambda args
        (make-fetch-options auth-method)))))

(define GITERR_HTTP
  ;; Guile-Git <= 0.5.2 lacks this constant.
  (let ((errors (resolve-interface '(git errors))))
    (if (module-defined? errors 'GITERR_HTTP)
        (module-ref errors 'GITERR_HTTP)
        34)))

(define (clone* url directory)
  "Clone git repository at URL into DIRECTORY.  Upon failure,
make sure no empty directory is left behind."
  (with-throw-handler #t
    (lambda ()
      (mkdir-p directory)

      (clone url directory
             (make-clone-options
              #:fetch-options (make-default-fetch-options))))
    (lambda _
      (false-if-exception (rmdir directory)))))

(define (url+commit->name url sha1)
  "Return the string \"<REPO-NAME>-<SHA1:7>\" where REPO-NAME is the name of
the git repository, extracted from URL and SHA1:7 the seven first digits
of SHA1 string."
  (string-append
   (string-replace-substring
    (last (string-split url #\/)) ".git" "")
   "-" (string-take sha1 7)))

(define (resolve-reference repository ref)
  "Resolve the branch, commit or tag specified by REF, and return the
corresponding Git object."
  (let resolve ((ref ref))
    (match ref
      (('branch . branch)
       (let ((oid (reference-target
                   (branch-lookup repository branch BRANCH-REMOTE))))
         (object-lookup repository oid)))
      (('symref . symref)
       (let ((oid (reference-name->oid repository symref)))
         (object-lookup repository oid)))
      (('commit . commit)
       (let ((len (string-length commit)))
         ;; 'object-lookup-prefix' appeared in Guile-Git in Mar. 2018, so we
         ;; can't be sure it's available.  Furthermore, 'string->oid' used to
         ;; read out-of-bounds when passed a string shorter than 40 chars,
         ;; which is why we delay calls to it below.
         (if (< len 40)
             (object-lookup-prefix repository (string->oid commit) len)
             (object-lookup repository (string->oid commit)))))
      (('tag-or-commit . str)
       (cond ((and (string-contains str "-g")
                   (match (string-split str #\-)
                     ((version ... revision g+commit)
                      (if (and (> (string-length g+commit) 4)
                               (string-every char-set:digit revision)
                               (string-every char-set:hex-digit
                                             (string-drop g+commit 1)))
                          ;; Looks like a 'git describe' style ID, like
                          ;; v1.3.0-7-gaa34d4d28d.
                          (string-drop g+commit 1)
                          #f))
                     (_ #f)))
              => (lambda (commit) (resolve `(commit . ,commit))))
             ((or (> (string-length str) 40)
                  (not (string-every char-set:hex-digit str)))
              (resolve `(tag . ,str)))      ;definitely a tag
             (else
              (catch 'git-error
                (lambda ()
                  (resolve `(tag . ,str)))
                (lambda _
                  ;; There's no such tag, so it must be a commit ID.
                  (resolve `(commit . ,str)))))))
      (('tag    . tag)
       (let ((oid (reference-name->oid repository
                                       (string-append "refs/tags/" tag))))
         ;; OID may point to a "tag" object, but it can also point directly
         ;; to a "commit" object, as surprising as it may seem.  Return that
         ;; object, whatever that is.
         (object-lookup repository oid))))))

(define (switch-to-ref repository ref)
  "Switch to REPOSITORY's branch, commit or tag specified by REF.  Return the
OID (roughly the commit hash) corresponding to REF."
  (define obj
    (resolve-reference repository ref))

  (reset repository obj RESET_HARD)
  (object-id obj))

(define (call-with-repository directory proc)
  (let ((repository #f))
   (dynamic-wind
     (lambda ()
       (set! repository (repository-open directory)))
     (lambda ()
       (proc repository))
     (lambda ()
       (repository-close! repository)))))

(define-syntax-rule (with-repository directory repository exp ...)
  "Open the repository at DIRECTORY and bind REPOSITORY to it within the
dynamic extent of EXP."
  (call-with-repository directory
                        (lambda (repository) exp ...)))

(define (report-git-error error)
  "Report the given Guile-Git error."
  ;; Prior to Guile-Git commit b6b2760c2fd6dfaa5c0fedb43eeaff06166b3134,
  ;; errors would be represented by integers.
  (match error
    ((? integer? error)                           ;old Guile-Git
     (leave (G_ "Git error ~a~%") error))
    ((? git-error? error)                         ;new Guile-Git
     (leave (G_ "Git error: ~a~%") (git-error-message error)))))

(define-syntax-rule (with-git-error-handling body ...)
  (catch 'git-error
    (lambda ()
      body ...)
    (lambda (key err)
      (report-git-error err))))

(define* (update-submodules repository
                            #:key (log-port (current-error-port))
                            (fetch-options #f))
  "Update the submodules of REPOSITORY, a Git repository object."
  (for-each (lambda (name)
              (let ((submodule (submodule-lookup repository name)))
                (format log-port (G_ "updating submodule '~a'...~%")
                        name)
                (submodule-update submodule
                                  #:fetch-options fetch-options)

                ;; Recurse in SUBMODULE.
                (let ((directory (string-append
                                  (repository-working-directory repository)
                                  "/" (submodule-path submodule))))
                  (with-repository directory repository
                    (update-submodules repository
                                       #:fetch-options fetch-options
                                       #:log-port log-port)))))
            (repository-submodules repository)))

(define-syntax-rule (false-if-git-not-found exp)
  "Evaluate EXP, returning #false if a GIT_ENOTFOUND error is raised."
  (catch 'git-error
    (lambda ()
      exp)
    (lambda (key error . rest)
      (if (= GIT_ENOTFOUND (git-error-code error))
          #f
          (apply throw key error rest)))))

(define (reference-available? repository ref)
  "Return true if REF, a reference such as '(commit . \"cabba9e\"), is
definitely available in REPOSITORY, false otherwise."
  (match ref
    ((or ('commit . commit)
         ('tag-or-commit . (? commit-id? commit)))
     (let ((len (string-length commit))
           (oid (string->oid commit)))
       (false-if-git-not-found
        (->bool (if (< len 40)
                    (object-lookup-prefix repository oid len OBJ-COMMIT)
                    (commit-lookup repository oid))))))
    (_
     #f)))

(define (clone-from-swh url tag-or-commit output)
  "Attempt to clone TAG-OR-COMMIT (a string), which originates from URL, using
a copy archived at Software Heritage."
  (call-with-temporary-directory
   (lambda (bare)
     (and (swh-download url tag-or-commit bare
                        #:archive-type 'git-bare)
          (let ((repository (clone* bare output)))
            (remote-set-url! repository "origin" url)
            repository)))))

(define (clone/swh-fallback url ref cache-directory)
  "Like 'clone', but fallback to Software Heritage if the repository cannot be
found at URL."
  (define (inaccessible-url-error? err)
    (let ((class (git-error-class err))
          (code  (git-error-code err)))
      (or (= class GITERR_HTTP)                   ;404 or similar
          (= class GITERR_NET))))                 ;unknown host, etc.

  (catch 'git-error
    (lambda ()
      (clone* url cache-directory))
    (lambda (key err)
      (match ref
        (((or 'commit 'tag-or-commit) . commit)
         (if (inaccessible-url-error? err)
             (or (clone-from-swh url commit cache-directory)
                 (begin
                   (warning (G_ "revision ~a of ~a \
could not be fetched from Software Heritage~%")
                            commit url)
                   (throw key err)))
             (throw key err)))
        (_ (throw key err))))))

(define cached-checkout-expiration
  ;; Return the expiration time procedure for a cached checkout.
  ;; TODO: Honor $GUIX_GIT_CACHE_EXPIRATION.

  ;; Use the mtime rather than the atime to cope with file systems mounted
  ;; with 'noatime'.
  (file-expiration-time (* 90 24 3600) stat:mtime))

(define %checkout-cache-cleanup-period
  ;; Period for the removal of expired cached checkouts.
  (* 5 24 3600))

(define (delete-checkout directory)
  "Delete DIRECTORY recursively, in an atomic fashion."
  (let ((trashed (string-append directory ".trashed")))
    (rename-file directory trashed)
    (delete-file-recursively trashed)))

(define* (update-cached-checkout url
                                 #:key
                                 (ref '())
                                 recursive?
                                 (check-out? #t)
                                 starting-commit
                                 (log-port (%make-void-port "w"))
                                 (cache-directory
                                  (url-cache-directory
                                   url (%repository-cache-directory)
                                   #:recursive? recursive?)))
  "Update the cached checkout of URL to REF in CACHE-DIRECTORY.  Return three
values: the cache directory name, and the SHA1 commit (a string) corresponding
to REF, and the relation of the new commit relative to STARTING-COMMIT (if
provided) as returned by 'commit-relation'.

REF is pair whose key is [branch | commit | tag | tag-or-commit ] and value
the associated data: [<branch name> | <sha1> | <tag name> | <string>].
If REF is the empty list, the remote HEAD is used.

When RECURSIVE? is true, check out submodules as well, if any.

When CHECK-OUT? is true, reset the cached working tree to REF; otherwise leave
it unchanged."
  (define (cache-entries directory)
    (filter-map (match-lambda
                  ((or "." "..")
                   #f)
                  (file
                   (string-append directory "/" file)))
                (or (scandir directory) '())))

  (define canonical-ref
    ;; We used to require callers to specify "origin/" for each branch, which
    ;; made little sense since the cache should be transparent to them.  So
    ;; here we append "origin/" if it's missing and otherwise keep it.
    (match ref
      (() '(symref . "refs/remotes/origin/HEAD"))
      (('branch . branch)
       `(branch . ,(if (string-prefix? "origin/" branch)
                       branch
                       (string-append "origin/" branch))))
      (_ ref)))

  (with-libgit2
   (let* ((cache-exists? (openable-repository? cache-directory))
          (repository    (if cache-exists?
                             (repository-open cache-directory)
                             (clone/swh-fallback url ref cache-directory))))
     ;; Only fetch remote if it has not been cloned just before.
     (when (and cache-exists?
                (not (reference-available? repository ref)))
       (remote-fetch (remote-lookup repository "origin")
                     #:fetch-options (make-default-fetch-options)))
     (when recursive?
       (update-submodules repository #:log-port log-port
                          #:fetch-options (make-default-fetch-options)))

     ;; Note: call 'commit-relation' from here because it's more efficient
     ;; than letting users re-open the checkout later on.
     (let* ((oid      (if check-out?
                          (switch-to-ref repository canonical-ref)
                          (object-id
                           (resolve-reference repository canonical-ref))))
            (new      (and starting-commit
                           (commit-lookup repository oid)))
            (old      (and starting-commit
                           (false-if-git-not-found
                            (commit-lookup repository
                                           (string->oid starting-commit)))))
            (relation (and starting-commit
                           (if old
                               (commit-relation old new)
                               'unrelated))))

       ;; Reclaim file descriptors and memory mappings associated with
       ;; REPOSITORY as soon as possible.
       (repository-close! repository)

       ;; Update CACHE-DIRECTORY's mtime to so the cache logic sees it.
       (match (gettimeofday)
         ((seconds . microseconds)
          (let ((nanoseconds (* 1000 microseconds)))
            (utime cache-directory
                   seconds seconds
                   nanoseconds nanoseconds))))

       ;; When CACHE-DIRECTORY is a sub-directory of the default cache
       ;; directory, remove expired checkouts that are next to it.
       (let ((parent (dirname cache-directory)))
         (when (string=? parent (%repository-cache-directory))
           (maybe-remove-expired-cache-entries parent cache-entries
                                               #:entry-expiration
                                               cached-checkout-expiration
                                               #:delete-entry delete-checkout
                                               #:cleanup-period
                                               %checkout-cache-cleanup-period)))

       (values cache-directory (oid->string oid) relation)))))

(define* (latest-repository-commit store url
                                   #:key
                                   recursive?
                                   (log-port (%make-void-port "w"))
                                   (cache-directory
                                    (%repository-cache-directory))
                                   (ref '()))
  "Return two values: the content of the git repository at URL copied into a
store directory and the sha1 of the top level commit in this directory.  The
reference to be checkout, once the repository is fetched, is specified by REF.
REF is pair whose key is [branch | commit | tag] and value the associated
data, respectively [<branch name> | <sha1> | <tag name>].  If REF is the empty
list, the remote HEAD is used.

When RECURSIVE? is true, check out submodules as well, if any.

Git repositories are kept in the cache directory specified by
%repository-cache-directory parameter.

Log progress and checkout info to LOG-PORT."
  (define (dot-git? file stat)
    (and (string=? (basename file) ".git")
         (or (eq? 'directory (stat:type stat))

             ;; Submodule checkouts end up with a '.git' regular file that
             ;; contains metadata about where their actual '.git' directory
             ;; lives.
             (and recursive?
                  (eq? 'regular (stat:type stat))))))

  (format log-port "updating checkout of '~a'...~%" url)
  (let*-values
      (((checkout commit _)
        (update-cached-checkout url
                                #:recursive? recursive?
                                #:ref ref
                                #:cache-directory
                                (url-cache-directory url cache-directory
                                                     #:recursive?
                                                     recursive?)
                                #:log-port log-port))
       ((name)
        (url+commit->name url commit)))
    (format log-port "retrieved commit ~a~%" commit)
    (values (add-to-store store name #t "sha256" checkout
                          #:select? (negate dot-git?))
            commit)))

(define (print-git-error port key args default-printer)
  (match args
    (((? git-error? error) . _)
     (format port (G_ "Git error: ~a~%")
             (git-error-message error)))))

(set-exception-printer! 'git-error print-git-error)

\f
;;;
;;; Commit difference.
;;;

(define* (commit-closure commit #:optional (visited (setq)))
  "Return the closure of COMMIT as a set.  Skip commits contained in VISITED,
a set, and adjoin VISITED to the result."
  (let loop ((commits (list commit))
             (visited visited))
    (match commits
      (()
       visited)
      ((head . tail)
       (if (set-contains? visited head)
           (loop tail visited)
           (loop (append (commit-parents head) tail)
                 (set-insert head visited)))))))

(define* (commit-difference new old #:optional (excluded '()))
  "Return the list of commits between NEW and OLD, where OLD is assumed to be
an ancestor of NEW.  Exclude all the commits listed in EXCLUDED along with
their ancestors.

Essentially, this computes the set difference between the closure of NEW and
that of OLD."
  (let loop ((commits (list new))
             (result '())
             (visited (fold commit-closure
                            (setq)
                            (cons old excluded))))
    (match commits
      (()
       (reverse result))
      ((head . tail)
       (if (set-contains? visited head)
           (loop tail result visited)
           (loop (append (commit-parents head) tail)
                 (cons head result)
                 (set-insert head visited)))))))

(define (commit-relation old new)
  "Return a symbol denoting the relation between OLD and NEW, two commit
objects: 'ancestor (meaning that OLD is an ancestor of NEW), 'descendant, or
'unrelated, or 'self (OLD and NEW are the same commit)."
  (if (eq? old new)
      'self
      (let ((newest (commit-closure new)))
        (if (set-contains? newest old)
            'ancestor
            (let* ((seen   (list->setq (commit-parents new)))
                   (oldest (commit-closure old seen)))
              (if (set-contains? oldest new)
                  'descendant
                  'unrelated))))))
\f
;;
;;; Remote operations.
;;;

(define* (remote-refs url #:key tags?)
  "Return the list of references advertised at Git repository URL.  If TAGS?
is true, limit to only refs/tags."
  (define (ref? ref)
    ;; Like `git ls-remote --refs', only show actual references.
    (and (string-prefix? "refs/" ref)
         (not (string-suffix? "^{}" ref))))

  (define (tag? ref)
    (string-prefix? "refs/tags/" ref))

  (define (include? ref)
    (and (ref? ref)
         (or (not tags?) (tag? ref))))

  (define (remote-head->ref remote)
    (let ((name (remote-head-name remote)))
      (and (include? name)
           name)))

  (with-libgit2
   (call-with-temporary-directory
    (lambda (cache-directory)
      (let* ((repository (repository-init cache-directory))
             ;; Create an in-memory remote so we don't touch disk.
             (remote (remote-create-anonymous repository url)))
        (remote-connect remote)

        (let* ((remote-heads (remote-ls remote))
               (refs (filter-map remote-head->ref remote-heads)))
          ;; Wait until we're finished with the repository before closing it.
          (remote-disconnect remote)
          (repository-close! repository)
          refs))))))

\f
;;;
;;; Checkouts.
;;;

;; Representation of the "latest" checkout of a branch or a specific commit.
(define-record-type* <git-checkout>
  git-checkout make-git-checkout
  git-checkout?
  (url     git-checkout-url)
  (branch  git-checkout-branch (default #f))
  (commit  git-checkout-commit (default #f))      ;#f | tag | commit
  (recursive? git-checkout-recursive? (default #f)))

(define (git-reference->git-checkout reference)
  "Convert the <git-reference> REFERENCE to an equivalent <git-checkout>."
  (git-checkout
   (url (git-reference-url reference))
   (commit (git-reference-commit reference))
   (recursive? (git-reference-recursive? reference))))

(define* (latest-repository-commit* url #:key ref recursive? log-port)
  ;; Monadic variant of 'latest-repository-commit'.
  (lambda (store)
    ;; The caller--e.g., (guix scripts build)--may not handle 'git-error' so
    ;; translate it into '&message' conditions that we know will be properly
    ;; handled.
    (catch 'git-error
      (lambda ()
        (values (latest-repository-commit store url
                                          #:ref ref
                                          #:recursive? recursive?
                                          #:log-port log-port)
                store))
      (lambda (key error . _)
        (raise (condition
                (&message
                 (message
                  (match ref
                    (('commit . commit)
                     (format #f (G_ "cannot fetch commit ~a from ~a: ~a")
                             commit url (git-error-message error)))
                    (('branch . branch)
                     (format #f (G_ "cannot fetch branch '~a' from ~a: ~a")
                             branch url (git-error-message error)))
                    (_
                     (format #f (G_ "Git failure while fetching ~a: ~a")
                             url (git-error-message error))))))))))))

(define-gexp-compiler (git-checkout-compiler (checkout <git-checkout>)
                                             system target)
  ;; "Compile" CHECKOUT by updating the local checkout and adding it to the
  ;; store.
  (match checkout
    (($ <git-checkout> url branch commit recursive?)
     (latest-repository-commit* url
                                #:ref (cond (commit
                                             `(tag-or-commit . ,commit))
                                            (branch
                                             `(branch . ,branch))
                                            (else '()))
                                #:recursive? recursive?
                                #:log-port (current-error-port)))))

;; Local Variables:
;; eval: (put 'with-repository 'scheme-indent-function 2)
;; End:

debug log:

solving 43e85a5026 ...
found 43e85a5026 in https://git.savannah.gnu.org/cgit/guix.git

(*) 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).