guix/status.scm

   1 ;;; GNU Guix --- Functional package management for GNU
   2 ;;; Copyright © 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
   3 ;;; Copyright © 2018, 2019 Ricardo Wurmus <rekado@elephly.net>
   4 ;;;
   5 ;;; This file is part of GNU Guix.
   6 ;;;
   7 ;;; GNU Guix is free software; you can redistribute it and/or modify it
   8 ;;; under the terms of the GNU General Public License as published by
   9 ;;; the Free Software Foundation; either version 3 of the License, or (at
  10 ;;; your option) any later version.
  11 ;;;
  12 ;;; GNU Guix is distributed in the hope that it will be useful, but
  13 ;;; WITHOUT ANY WARRANTY; without even the implied warranty of
  14 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 ;;; GNU General Public License for more details.
  16 ;;;
  17 ;;; You should have received a copy of the GNU General Public License
  18 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
  19
  20 (define-module (guix status)
  21   #:use-module (guix records)
  22   #:use-module (guix i18n)
  23   #:use-module (guix colors)
  24   #:use-module (guix progress)
  25   #:autoload   (guix build syscalls) (terminal-columns)
  26   #:autoload   (guix build download) (nar-uri-abbreviation)
  27   #:use-module (guix store)
  28   #:use-module (guix derivations)
  29   #:use-module (guix memoization)
  30   #:use-module (srfi srfi-1)
  31   #:use-module (srfi srfi-9)
  32   #:use-module (srfi srfi-9 gnu)
  33   #:use-module (srfi srfi-19)
  34   #:use-module (srfi srfi-26)
  35   #:use-module (ice-9 regex)
  36   #:use-module (ice-9 match)
  37   #:use-module (ice-9 format)
  38   #:use-module (ice-9 binary-ports)
  39   #:autoload   (ice-9 rdelim) (read-string)
  40   #:use-module (rnrs bytevectors)
  41   #:use-module ((system foreign)
  42                 #:select (bytevector->pointer pointer->bytevector))
  43   #:export (build-event-output-port
  44             compute-status
  45
  46             build-status
  47             build-status?
  48             build-status-building
  49             build-status-downloading
  50             build-status-builds-completed
  51             build-status-downloads-completed
  52
  53             build?
  54             build
  55             build-derivation
  56             build-system
  57             build-log-file
  58             build-phase
  59             build-completion
  60
  61             download?
  62             download
  63             download-item
  64             download-uri
  65             download-size
  66             download-start
  67             download-end
  68             download-transferred
  69
  70             build-status-updater
  71             print-build-event
  72             print-build-event/quiet
  73             print-build-status
  74
  75             with-status-report
  76             with-status-verbosity))
  77
  78 ;;; Commentary:
  79 ;;;
  80 ;;; This module provides facilities to track the status of ongoing builds and
  81 ;;; downloads in a given session, as well as tools to report about the current
  82 ;;; status to user interfaces.  It does so by analyzing the output of
  83 ;;; 'current-build-output-port'.  The build status is maintained in a
  84 ;;; <build-status> record.
  85 ;;;
  86 ;;; Code:
  87
  88 \f
  89 ;;;
  90 ;;; Build status tracking.
  91 ;;;
  92
  93 ;; Builds and substitutions performed by the daemon.
  94 (define-record-type* <build-status> build-status make-build-status
  95   build-status?
  96   (building     build-status-building             ;list of <build>
  97                 (default '()))
  98   (downloading  build-status-downloading          ;list of <download>
  99                 (default '()))
 100   (builds-completed build-status-builds-completed ;list of <build>
 101                     (default '()))
 102   (downloads-completed build-status-downloads-completed ;list of <download>
 103                        (default '())))
 104
 105 ;; On-going or completed build.
 106 (define-immutable-record-type <build>
 107   (%build derivation id system log-file phase completion)
 108   build?
 109   (derivation  build-derivation)                ;string (.drv file name)
 110   (id          build-id)                        ;#f | integer
 111   (system      build-system)                    ;string
 112   (log-file    build-log-file)                  ;#f | string
 113   (phase       build-phase                      ;#f | symbol
 114                set-build-phase)
 115   (completion  build-completion                 ;#f | integer (percentage)
 116                set-build-completion))
 117
 118 (define* (build derivation system #:key id log-file phase completion)
 119   "Return a new build."
 120   (%build derivation id system log-file phase completion))
 121
 122 ;; On-going or completed downloads.  Downloads can be stem from substitutes
 123 ;; and from "builtin:download" fixed-output derivations.
 124 (define-record-type <download>
 125   (%download item uri size start end transferred)
 126   download?
 127   (item         download-item)            ;store item
 128   (uri          download-uri)             ;string | #f
 129   (size         download-size)            ;integer | #f
 130   (start        download-start)           ;<time>
 131   (end          download-end)             ;#f | <time>
 132   (transferred  download-transferred))    ;integer
 133
 134 (define* (download item uri
 135                    #:key size
 136                    (start (current-time time-monotonic)) end
 137                    (transferred 0))
 138   "Return a new download."
 139   (%download item uri size start end transferred))
 140
 141 (define (matching-build drv)
 142   "Return a predicate that matches builds of DRV."
 143   (lambda (build)
 144     (string=? drv (build-derivation build))))
 145
 146 (define (matching-download item)
 147   "Return a predicate that matches downloads of ITEM."
 148   (lambda (download)
 149     (string=? item (download-item download))))
 150
 151 (define %phase-start-rx
 152   ;; Match the "starting phase" message emitted by 'gnu-build-system'.
 153   (make-regexp "^starting phase [`']([^']+)'"))
 154
 155 (define %percentage-line-rx
 156   ;; Things like CMake write lines like "[ 10%] gcc -c …".  This regexp
 157   ;; matches them.
 158   (make-regexp "^[[:space:]]*\\[ *([0-9]+)%\\]"))
 159
 160 (define %fraction-line-rx
 161   ;; The 'compiled-modules' derivations and Ninja produce reports like
 162   ;; "[ 1/32]" at the beginning of each line, while GHC prints "[ 6 of 45]".
 163   ;; This regexp matches these.
 164   (make-regexp "^[[:space:]]*\\[ *([0-9]+) *(/|of) *([0-9]+)\\]"))
 165
 166 (define (update-build status id line)
 167   "Update STATUS based on LINE, a build output line for ID that might contain
 168 a completion indication."
 169   (define (find-build)
 170     (find (lambda (build)
 171             (and (build-id build)
 172                  (= (build-id build) id)))
 173           (build-status-building status)))
 174
 175   (define (update %)
 176     (let ((build (find-build)))
 177       (build-status
 178        (inherit status)
 179        (building (cons (set-build-completion build %)
 180                        (delq build (build-status-building status)))))))
 181
 182   (cond ((string-any #\nul line)
 183          ;; Don't try to match a regexp here.
 184          status)
 185         ((regexp-exec %percentage-line-rx line)
 186          =>
 187          (lambda (match)
 188            (let ((% (string->number (match:substring match 1))))
 189              (update %))))
 190         ((regexp-exec %fraction-line-rx line)
 191          =>
 192          (lambda (match)
 193            (let ((done  (string->number (match:substring match 1)))
 194                  (total (string->number (match:substring match 3))))
 195              (update (* 100. (/ done total))))))
 196         ((regexp-exec %phase-start-rx line)
 197          =>
 198          (lambda (match)
 199            (let ((phase (match:substring match 1))
 200                  (build (find-build)))
 201              (if build
 202                  (build-status
 203                   (inherit status)
 204                   (building
 205                    (cons (set-build-phase (set-build-completion build #f)
 206                                           (string->symbol phase))
 207                          (delq build (build-status-building status)))))
 208                  status))))
 209         (else
 210          status)))
 211
 212 (define* (compute-status event status
 213                          #:key
 214                          (current-time current-time)
 215                          (derivation-path->output-path
 216                           derivation-path->output-path))
 217   "Given EVENT, a tuple like (build-started \"/gnu/store/...-foo.drv\" ...),
 218 compute a new status based on STATUS."
 219   (match event
 220     (('build-started drv "-" system log-file . rest)
 221      (let ((build (build drv system
 222                          #:id (match rest
 223                                 ((pid . _) (string->number pid))
 224                                 (_ #f))
 225                          #:log-file (if (string-null? log-file)
 226                                         #f
 227                                         log-file))))
 228        (build-status
 229         (inherit status)
 230         (building (cons build (build-status-building status))))))
 231     (((or 'build-succeeded 'build-failed) drv _ ...)
 232      (let ((build (find (matching-build drv)
 233                         (build-status-building status))))
 234        ;; If BUILD is #f, this may be because DRV corresponds to a
 235        ;; fixed-output derivation that is listed as a download.
 236        (if build
 237            (build-status
 238             (inherit status)
 239             (building (delq build (build-status-building status)))
 240             (builds-completed
 241              (cons build (build-status-builds-completed status))))
 242            status)))
 243
 244     ;; Note: Ignore 'substituter-started' and 'substituter-succeeded' because
 245     ;; they're not as informative as 'download-started' and
 246     ;; 'download-succeeded'.
 247
 248     (('download-started item uri (= string->number size))
 249      ;; This is presumably a fixed-output derivation so move it from
 250      ;; 'building' to 'downloading'.  XXX: This doesn't work in 'check' mode
 251      ;; because ITEM is different from DRV's output.
 252      (build-status
 253       (inherit status)
 254       (building (remove (lambda (build)
 255                           (let ((drv (build-derivation build)))
 256                             (equal? (false-if-exception
 257                                      (derivation-path->output-path drv))
 258                                     item)))
 259                         (build-status-building status)))
 260       (downloading (cons (download item uri #:size size
 261                                    #:start (current-time time-monotonic))
 262                          (build-status-downloading status)))))
 263     (('download-succeeded item uri (= string->number size))
 264      (let ((current (find (matching-download item)
 265                           (build-status-downloading status))))
 266        (build-status
 267         (inherit status)
 268         (downloading (delq current (build-status-downloading status)))
 269         (downloads-completed
 270          (cons (download item uri
 271                          #:size size
 272                          #:start (download-start current)
 273                          #:transferred size
 274                          #:end (current-time time-monotonic))
 275                (build-status-downloads-completed status))))))
 276     (('substituter-succeeded item _ ...)
 277      (match (find (matching-download item)
 278                   (build-status-downloading status))
 279        (#f
 280         ;; Presumably we already got a 'download-succeeded' event for ITEM,
 281         ;; everything is fine.
 282         status)
 283        (current
 284         ;; Maybe the build process didn't emit a 'download-succeeded' event
 285         ;; for ITEM, so remove CURRENT from the queue now.
 286         (build-status
 287          (inherit status)
 288          (downloading (delq current (build-status-downloading status)))
 289          (downloads-completed
 290           (cons (download item (download-uri current)
 291                           #:size (download-size current)
 292                           #:start (download-start current)
 293                           #:transferred (download-size current)
 294                           #:end (current-time time-monotonic))
 295                 (build-status-downloads-completed status)))))))
 296     (('download-progress item uri
 297                          (= string->number size)
 298                          (= string->number transferred))
 299      (let ((downloads (remove (matching-download item)
 300                               (build-status-downloading status)))
 301            (current   (find (matching-download item)
 302                             (build-status-downloading status))))
 303        (build-status
 304         (inherit status)
 305         (downloading (cons (download item uri
 306                                      #:size size
 307                                      #:start
 308                                      (or (and current
 309                                               (download-start current))
 310                                          (current-time time-monotonic))
 311                                      #:transferred transferred)
 312                            downloads)))))
 313     (('build-log (? integer? pid) line)
 314      (update-build status pid line))
 315     (_
 316      status)))
 317
 318 (define (simultaneous-jobs status)
 319   "Return the number of on-going builds and downloads for STATUS."
 320   (+ (length (build-status-building status))
 321      (length (build-status-downloading status))))
 322
 323 \f
 324 ;;;
 325 ;;; Rendering.
 326 ;;;
 327
 328 (define (extended-build-trace-supported?)
 329   "Return true if the currently used store is known to support \"extended
 330 build traces\" such as \"@ download-progress\" traces."
 331   ;; Support for extended build traces was added in protocol version #x162.
 332   (and (current-store-protocol-version)
 333        (>= (current-store-protocol-version) #x162)))
 334
 335 (define (multiplexed-output-supported?)
 336   "Return true if the daemon supports \"multiplexed output\"--i.e., \"@
 337 build-log\" traces."
 338   (and (current-store-protocol-version)
 339        (>= (current-store-protocol-version) #x163)))
 340
 341 (define spin!
 342   (let ((steps (circular-list "\\" "|" "/" "-")))
 343     (lambda (phase port)
 344       "Display a spinner on PORT.  If PHASE is true, display it as a hint of
 345 the current build phase."
 346       (when (isatty?* port)
 347         (match steps
 348           ((first . rest)
 349            (set! steps rest)
 350            (display "\r\x1b[K" port)
 351            (display first port)
 352            (when phase
 353              (display " " port)
 354              ;; TRANSLATORS: The word "phase" here denotes a "build phase";
 355              ;; "~a" is a placeholder for the untranslated name of the current
 356              ;; build phase--e.g., 'configure' or 'build'.
 357              (format port (G_ "'~a' phase") phase))
 358            (force-output port)))))))
 359
 360 (define colorize-log-line
 361   ;; Take a string and return a possibly colorized string according to the
 362   ;; rules below.
 363   (color-rules
 364    ("^(phase)(.*)(succeeded after)(.*)(seconds)(.*)"
 365     GREEN    BOLD GREEN          RESET  GREEN  BLUE)
 366    ("^(phase)(.*)(failed after)(.*)(seconds)(.*)"
 367     RED BLUE RED BLUE RED BLUE)
 368    ("^(.*)(error|fail|failed|\\<FAIL|FAILED)([[:blank:]]*)(:)(.*)"
 369     RESET  RED                           BOLD         BOLD BOLD)
 370    ("^(.*)(warning)([[:blank:]]*)(:)(.*)"
 371     RESET  MAGENTA   BOLD        BOLD BOLD)))
 372
 373 (define (hook-message hook-type)
 374   "Return a human-readable string for the profile hook type HOOK-TYPE."
 375   (match hook-type
 376     ('info-dir
 377      (G_ "building directory of Info manuals..."))
 378     ('ghc-package-cache
 379      (G_ "building GHC package cache..."))
 380     ('ca-certificate-bundle
 381      (G_ "building CA certificate bundle..."))
 382     ('glib-schemas
 383      (G_ "generating GLib schema cache..."))
 384     ('gtk-icon-themes
 385      (G_ "creating GTK+ icon theme cache..."))
 386     ('gtk-im-modules
 387      (G_ "building cache files for GTK+ input methods..."))
 388     ('xdg-desktop-database
 389      (G_ "building XDG desktop file cache..."))
 390     ('xdg-mime-database
 391      (G_ "building XDG MIME database..."))
 392     ('fonts-dir
 393      (G_ "building fonts directory..."))
 394     ('texlive-configuration
 395      (G_ "building TeX Live configuration..."))
 396     ('manual-database
 397      (G_ "building database for manual pages..."))
 398     ('package-cache                    ;package cache generated by 'guix pull'
 399      (G_ "building package cache..."))
 400     (_ #f)))
 401
 402 (define* (print-build-event event old-status status
 403                             #:optional (port (current-error-port))
 404                             #:key
 405                             (colorize? (color-output? port))
 406                             (print-urls? #t)
 407                             (print-log? #t))
 408   "Print information about EVENT and STATUS to PORT.  When COLORIZE? is true,
 409 produce colorful output.  When PRINT-LOG? is true, display the build log in
 410 addition to build events.  When PRINT-URLS? is true, display the URL of
 411 substitutes being downloaded."
 412   (define info
 413     (if colorize?
 414         (cute colorize-string <> (color BOLD))
 415         identity))
 416
 417   (define success
 418     (if colorize?
 419         (cute colorize-string <> (color GREEN BOLD))
 420         identity))
 421
 422   (define failure
 423     (if colorize?
 424         (cute colorize-string <> (color RED BOLD))
 425         identity))
 426
 427   (define tty?
 428     (isatty?* port))
 429
 430   (define (report-build-progress phase %)
 431     (let ((% (min (max % 0) 100)))                ;sanitize
 432       (erase-current-line port)
 433       (let* ((prefix (format #f "~3d% ~@['~a' ~]"
 434                             (inexact->exact (round %))
 435                             (case phase
 436                               ((build) #f)        ;not useful to display it
 437                               (else phase))))
 438              (length (string-length prefix)))
 439         (display prefix port)
 440         (display (progress-bar % (- (current-terminal-columns) length))
 441                  port))
 442       (force-output port)))
 443
 444   (define print-log-line
 445     (if print-log?
 446         (if colorize?
 447             (lambda (id line)
 448               (display (colorize-log-line line) port))
 449             (lambda (id line)
 450               (display line port)))
 451         (lambda (id line)
 452           (match (build-status-building status)
 453             ((build)                              ;single job
 454              (match (build-completion build)
 455                ((? number? %)
 456                 (report-build-progress (build-phase build) %))
 457                (_
 458                 (spin! (build-phase build) port))))
 459             (_
 460              (spin! #f port))))))
 461
 462   (define erase-current-line*
 463     (if (and (not print-log?) (isatty?* port))
 464         (lambda ()
 465           (erase-current-line port)
 466           (force-output port))
 467         (const #t)))
 468
 469   (match event
 470     (('build-started drv . _)
 471      (erase-current-line*)
 472      (let ((properties (derivation-properties
 473                         (read-derivation-from-file drv))))
 474        (match (assq-ref properties 'type)
 475          ('graft
 476            (let ((count (match (assq-ref properties 'graft)
 477                           (#f  0)
 478                           (lst (or (assq-ref lst 'count) 0)))))
 479              (format port (info (N_ "applying ~a graft for ~a ..."
 480                                     "applying ~a grafts for ~a ..."
 481                                     count))
 482                      count drv)))
 483          ('profile
 484           (let ((count (match (assq-ref properties 'profile)
 485                          (#f  0)
 486                          (lst (or (assq-ref lst 'count) 0)))))
 487             (format port (info (N_ "building profile with ~a package..."
 488                                    "building profile with ~a packages..."
 489                                    count))
 490                     count)))
 491          ('profile-hook
 492           (let ((hook-type (assq-ref properties 'hook)))
 493             (or (and=> (hook-message hook-type)
 494                        (lambda (msg)
 495                          (format port (info msg))))
 496                 (format port (info (G_ "running profile hook of type '~a'..."))
 497                         hook-type))))
 498          (_
 499           (format port (info (G_ "building ~a...")) drv))))
 500      (newline port))
 501     (('build-succeeded drv . _)
 502      (erase-current-line*)                      ;erase spinner or progress bar
 503      (when (or print-log? (not (extended-build-trace-supported?)))
 504        (format port (success (G_ "successfully built ~a")) drv)
 505        (newline port))
 506      (match (build-status-building status)
 507        (() #t)
 508        (ongoing                                   ;when max-jobs > 1
 509         (format port
 510                 (N_ "The following build is still in progress:~%~{  ~a~%~}~%"
 511                     "The following builds are still in progress:~%~{  ~a~%~}~%"
 512                     (length ongoing))
 513                 (map build-derivation ongoing)))))
 514     (('build-failed drv . _)
 515      (erase-current-line*)                      ;erase spinner or progress bar
 516      (format port (failure (G_ "build of ~a failed")) drv)
 517      (newline port)
 518      (match (derivation-log-file drv)
 519        (#f
 520         (format port (failure (G_ "Could not find build log for '~a'."))
 521                 drv))
 522        (log
 523         (format port (info (G_ "View build log at '~a'.")) log)))
 524      (newline port))
 525     (('substituter-started item _ ...)
 526      (erase-current-line*)
 527      (when (or print-log? (not (extended-build-trace-supported?)))
 528        (format port (info (G_ "substituting ~a...")) item)
 529        (newline port)))
 530     (('download-started item uri _ ...)
 531      (when print-urls?
 532        (erase-current-line*)
 533        (format port (info (G_ "downloading from ~a ...")) uri)
 534        (newline port)))
 535     (('download-progress item uri
 536                          (= string->number size)
 537                          (= string->number transferred))
 538      ;; Print a progress bar, but only if there's only one on-going
 539      ;; job--otherwise the output would be intermingled.
 540      (when (= 1 (simultaneous-jobs status))
 541        (match (find (matching-download item)
 542                     (build-status-downloading status))
 543          (#f #f)                                  ;shouldn't happen!
 544          (download
 545           ;; XXX: It would be nice to memoize the abbreviation.
 546           (let ((uri (if (string-contains uri "/nar/")
 547                          (nar-uri-abbreviation uri)
 548                          (basename uri))))
 549             (display-download-progress uri size
 550                                        #:tty? tty?
 551                                        #:start-time
 552                                        (download-start download)
 553                                        #:transferred transferred))))))
 554     (('substituter-succeeded item _ ...)
 555      (when (extended-build-trace-supported?)
 556        ;; If there are no jobs running, we already reported download completion
 557        ;; so there's nothing left to do.
 558        (unless (zero? (simultaneous-jobs status))
 559          (format port (success (G_ "substitution of ~a complete")) item))
 560
 561        (when (and print-urls? (zero? (simultaneous-jobs status)))
 562          ;; Leave a blank line after the "downloading ..." line and the
 563          ;; progress bar (that's three lines in total).
 564          (newline port))))
 565     (('substituter-failed item _ ...)
 566      (format port (failure (G_ "substitution of ~a failed")) item)
 567      (newline port))
 568     (('hash-mismatch item algo expected actual _ ...)
 569      ;; TRANSLATORS: The final string looks like "sha256 hash mismatch for
 570      ;; /gnu/store/…-sth:", where "sha256" is the hash algorithm.
 571      (format port (failure (G_ "~a hash mismatch for ~a:")) algo item)
 572      (newline port)
 573      (format port (info (G_ "\
 574   expected hash: ~a
 575   actual hash:   ~a~%"))
 576              expected actual))
 577     (('build-remote drv host _ ...)
 578      (format port (info (G_ "offloading build of ~a to '~a'")) drv host)
 579      (newline port))
 580     (('build-log pid line)
 581      (if (multiplexed-output-supported?)
 582          (if (not pid)
 583              (begin
 584                ;; LINE comes from the daemon, not from builders.  Let it
 585                ;; through.
 586                (display line port)
 587                (force-output port))
 588              (print-log-line pid line))
 589          (cond ((string-prefix? "substitute: " line)
 590                 ;; The daemon prefixes early messages coming with 'guix
 591                 ;; substitute' with "substitute:".  These are useful ("updating
 592                 ;; substitutes from URL"), so let them through.
 593                 (display line port)
 594                 (force-output port))
 595                ((string-prefix? "waiting for locks" line)
 596                 ;; This is when a derivation is already being built and we're just
 597                 ;; waiting for the build to complete.
 598                 (display (info (string-trim-right line)) port)
 599                 (newline))
 600                (else
 601                 (print-log-line pid line)))))
 602     (_
 603      event)))
 604
 605 (define* (print-build-event/quiet event old-status status
 606                                   #:optional
 607                                   (port (current-error-port))
 608                                   #:key
 609                                   (colorize? (color-output? port)))
 610   (print-build-event event old-status status port
 611                      #:colorize? colorize?
 612                      #:print-urls? #f
 613                      #:print-log? #f))
 614
 615 (define* (print-build-event/quiet-with-urls event old-status status
 616                                             #:optional
 617                                             (port (current-error-port))
 618                                             #:key
 619                                             (colorize? (color-output? port)))
 620   (print-build-event event old-status status port
 621                      #:colorize? colorize?
 622                      #:print-urls? #t             ;show download URLs
 623                      #:print-log? #f))
 624
 625 (define* (build-status-updater #:optional (on-change (const #t)))
 626   "Return a procedure that can be passed to 'build-event-output-port'.  That
 627 procedure computes the new build status upon each event and calls ON-CHANGE:
 628
 629   (ON-CHANGE event status new-status)
 630
 631 ON-CHANGE can display the build status, build events, etc."
 632   (lambda (event status)
 633     (let ((new (compute-status event status)))
 634       (on-change event status new)
 635       new)))
 636
 637 \f
 638 ;;;
 639 ;;; Build port.
 640 ;;;
 641
 642 (define (maybe-utf8->string bv)
 643   "Attempt to decode BV as UTF-8 string and return it.  Gracefully handle the
 644 case where BV does not contain only valid UTF-8."
 645   (catch 'decoding-error
 646     (lambda ()
 647       (utf8->string bv))
 648     (lambda _
 649       ;; This is the sledgehammer but it's the only safe way we have to
 650       ;; properly handle this.  It's expensive but it's rarely needed.
 651       (let ((port (open-bytevector-input-port bv)))
 652         (set-port-encoding! port "UTF-8")
 653         (set-port-conversion-strategy! port 'substitute)
 654         (let ((str (read-string port)))
 655           (close-port port)
 656           str)))))
 657
 658 (define (bytevector-index bv number offset count)
 659   "Search for NUMBER in BV starting from OFFSET and reading up to COUNT bytes;
 660 return the offset where NUMBER first occurs or #f if it could not be found."
 661   (let loop ((offset offset)
 662              (count count))
 663     (cond ((zero? count) #f)
 664           ((= (bytevector-u8-ref bv offset) number) offset)
 665           (else (loop (+ 1 offset) (- count 1))))))
 666
 667 (define (split-lines str)
 668   "Split STR into lines in a way that preserves newline characters."
 669   (let loop ((str str)
 670              (result '()))
 671     (if (string-null? str)
 672         (reverse result)
 673         (match (string-index str #\newline)
 674           (#f
 675            (loop "" (cons str result)))
 676           (index
 677            (loop (string-drop str (+ index 1))
 678                  (cons (string-take str (+ index 1)) result)))))))
 679
 680 (define* (build-event-output-port proc #:optional (seed (build-status)))
 681   "Return an output port for use as 'current-build-output-port' that calls
 682 PROC with its current state value, initialized with SEED, on every build
 683 event.  Build events passed to PROC are tuples corresponding to the \"build
 684 traces\" produced by the daemon:
 685
 686   (build-started \"/gnu/store/...-foo.drv\" ...)
 687   (substituter-started \"/gnu/store/...-foo\" ...)
 688
 689 and so on.
 690
 691 The second return value is a thunk to retrieve the current state."
 692   (define %fragments
 693     ;; Line fragments received so far.
 694     '())
 695
 696   (define %state
 697     ;; Current state for PROC.
 698     seed)
 699
 700   ;; When true, this represents the current state while reading a
 701   ;; "@ build-log" trace: the current builder PID, the previously-read
 702   ;; bytevectors, and the number of bytes that remain to be read.
 703   (define %build-output-pid #f)
 704   (define %build-output '())
 705   (define %build-output-left #f)
 706
 707   (define (process-line line)
 708     (cond ((string-prefix? "@ " line)
 709            ;; Note: Drop the trailing \n, and use 'string-split' to preserve
 710            ;; spaces (the log file part of 'build-started' events can be the
 711            ;; empty string.)
 712            (match (string-split (string-drop (string-drop-right line 1) 2)
 713                                 #\space)
 714              (("build-log" (= string->number pid) (= string->number len))
 715               (set! %build-output-pid pid)
 716               (set! %build-output '())
 717               (set! %build-output-left len))
 718              (((= string->symbol event-name) args ...)
 719               (set! %state
 720                 (proc (cons event-name args)
 721                       %state)))))
 722           (else
 723            (set! %state (proc (list 'build-log #f line)
 724                               %state)))))
 725
 726   (define (process-build-output pid output)
 727     ;; Transform OUTPUT in 'build-log' events or download events as generated
 728     ;; by extended build traces.
 729     (define (line->event line)
 730       (match (and (string-prefix? "@ " line)
 731                   (string-tokenize (string-drop line 2)))
 732         ((type . args)
 733          (if (or (string-prefix? "download-" type)
 734                  (string=? "build-remote" type))
 735              (cons (string->symbol type) args)
 736              `(build-log ,pid ,line)))
 737         (_
 738          `(build-log ,pid ,line))))
 739
 740     (let* ((lines  (split-lines output))
 741            (events (map line->event lines)))
 742       (set! %state (fold proc %state events))))
 743
 744   (define (bytevector-range bv offset count)
 745     (let ((ptr (bytevector->pointer bv offset)))
 746       (pointer->bytevector ptr count)))
 747
 748   (define (write! bv offset count)
 749     (if %build-output-pid
 750         (let ((keep (min count %build-output-left)))
 751           (set! %build-output
 752             (let ((bv* (make-bytevector keep)))
 753               (bytevector-copy! bv offset bv* 0 keep)
 754               (cons bv* %build-output)))
 755           (set! %build-output-left
 756             (- %build-output-left keep))
 757
 758           (when (zero? %build-output-left)
 759             (process-build-output %build-output-pid
 760                                   (string-concatenate-reverse
 761                                    (map maybe-utf8->string %build-output))) ;XXX
 762             (set! %build-output '())
 763             (set! %build-output-pid #f))
 764           keep)
 765         (match (bytevector-index bv (char->integer #\newline)
 766                                  offset count)
 767           ((? integer? cr)
 768            (let* ((tail (maybe-utf8->string
 769                          (bytevector-range bv offset (- cr -1 offset))))
 770                   (line (string-concatenate-reverse
 771                          (cons tail %fragments))))
 772              (process-line line)
 773              (set! %fragments '())
 774              (- cr -1 offset)))
 775           (#f
 776            (unless (zero? count)
 777              (let ((str (maybe-utf8->string
 778                          (bytevector-range bv offset count))))
 779                (set! %fragments (cons str %fragments))))
 780            count))))
 781
 782   (define port
 783     (make-custom-binary-output-port "filtering-input-port"
 784                                     write!
 785                                     #f #f
 786                                     #f))
 787
 788   ;; The build port actually receives Unicode strings.
 789   (set-port-encoding! port "UTF-8")
 790   (setvbuf port 'line)
 791   (values port (lambda () %state)))
 792
 793 (define (call-with-status-report on-event thunk)
 794   (parameterize ((current-terminal-columns (terminal-columns))
 795                  (current-build-output-port
 796                   (build-event-output-port (build-status-updater on-event))))
 797     (thunk)))
 798
 799 (define-syntax-rule (with-status-report on-event exp ...)
 800   "Set up build status reporting to the user using the ON-EVENT procedure;
 801 evaluate EXP... in that context."
 802   (call-with-status-report on-event (lambda () exp ...)))
 803
 804 (define (logger-for-level level)
 805   "Return the logging procedure that corresponds to LEVEL."
 806   (cond ((<= level 0) (const #t))
 807         ((= level 1)  print-build-event/quiet)
 808         ((= level 2)  print-build-event/quiet-with-urls)
 809         (else         print-build-event)))
 810
 811 (define (call-with-status-verbosity level thunk)
 812   (call-with-status-report (logger-for-level level) thunk))
 813
 814 (define-syntax-rule (with-status-verbosity level exp ...)
 815   "Set up build status reporting to the user at the given LEVEL: 0 means
 816 silent, 1 means quiet, 2 means verbose.  Evaluate EXP... in that context."
 817   (call-with-status-verbosity level (lambda () exp ...)))