Re: [PATCH] profiles: Generate database file for manpages

[Ludovic Courtès]

Hi Maxim,

Maxim Cournoyer <address@hidden> skribis:

> I've managed to finalize a profile hooks which takes care of generating
> the manpages database file. This file is used by apropos or man -k to
> provide results.

Awesome!  I’ve been willing to have this for some time.

> I've tested and found it to be working for the regular user profile. To
> try it, apply the patch and use a guix command that causes a new profile
> generation.
>
> For example: guix package -r git -i git
> Then: "apropos git" should return plenty of results.

For some reason I have to use “man -K” (capital):

--8<---------------cut here---------------start------------->8---
~$ apropos guile
guile: nothing appropriate.
~$ man -k guile
guile: nothing appropriate.
~$ man -K guile
--Man-- next: skribilo(1) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]
--Man-- next: guile(1) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]
--Man-- next: guix-pull(1) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]
--Man-- next: guix-package(1) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]
--Man-- next: gv(3guile) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]
~$ env | grep MANPATH
MANPATH=/home/ludo/.guix-profile/share/man:/run/current-system/profile/share/man:/home/ludo/.guix-profile/share/man:/run/current-system/profile/share/man:/home/ludo/.opam/system/man
--8<---------------cut here---------------end--------------->8---

Any idea why?

> It requires extra processing time to do the work since the complete
> database (on my system, there are thousands or manpages being indexed)
> is recreated everytime a new profile is generated.

On my laptop (with an SSD), I found it to be reasonable:

--8<---------------cut here---------------start------------->8---
$ time guix build 
/gnu/store/rkri628apz2a2i2jvav11ylv2736fvv3-manual-database.drv --check
@ build-started /gnu/store/rkri628apz2a2i2jvav11ylv2736fvv3-manual-database.drv 
- x86_64-linux 
/var/log/guix/drvs/rk//ri628apz2a2i2jvav11ylv2736fvv3-manual-database.drv.bz2
/gnu/store/g7qxdk1cn7fwkamkaisi4428k6ijg0w2-manual-database

real    0m2.647s
user    0m0.116s
sys     0m0.004s
$ guix package -I |wc -l
229
--8<---------------cut here---------------end--------------->8---

> For now it doesn't work for guix environments (yet), but this should be
> easy to fix (it seems the $GUIX_ENVIRONMENT/share/man should be merged
> with $HOME/.guix-profile/share/man, but I need to look at it more
> carefully).

It seems to work but only with capital -K:

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix environment --ad-hoc guile man-db --pure -- man -K guile
man: can't execute cat: No such file or directory
man: command exited with status 255: sed -e '/^[[:space:]]*$/{ N; 
/^[[:space:]]*\n[[:space:]]*$/D; }' | (cd <fd 3> && LESS=-ix8RmPm Manual page 
guile(1) ?ltline %lt?L/%L.:byte %bB?s/%s..?e (END):?pB %pB\%.. (press h for 
help or q to quit)$PM Manual page guile(1) ?ltline %lt?L/%L.:byte %bB?s/%s..?e 
(END):?pB %pB\%.. (press h for help or q to quit)$ MAN_PN=guile(1) cat)
--8<---------------cut here---------------end--------------->8---

(And we should hard-code the file name of ‘cat’ in ‘man’…)

> From dbbe6894919164cd34572a28bfbbf6d4d681e35b Mon Sep 17 00:00:00 2001
> From: Maxim Cournoyer <address@hidden>
> Date: Tue, 28 Mar 2017 09:25:21 -0700
> Subject: [PATCH] profiles: Generate database file for manpages
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
>
> The mandb database file (index.db) is used by the "apropos" (whatis) or
> "man -k" commands. This change introduces a profile hook to generate
> such database file.
>
> Co-authored by Ludovic Courtès
>
> * guix/profiles.scm (manual-database): New procedure.
> (%default-profile-hooks): Add it.

I made some simplifications to the patch.  WDYT?

Thanks,
Ludo’.

diff --git a/guix/profiles.scm b/guix/profiles.scm
index 795c9447f..f565f358b 100644
--- a/guix/profiles.scm
+++ b/guix/profiles.scm
@@ -7,6 +7,7 @@
 ;;; Copyright © 2016 Ricardo Wurmus <address@hidden>
 ;;; Copyright © 2016 Chris Marusich <address@hidden>
 ;;; Copyright © 2017 Huang Ying <address@hidden>
+;;; Copyright © 2017 Maxim Cournoyer <address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -946,10 +947,73 @@ files for the fonts of the @var{manifest} entries."
                     #:local-build? #t
                     #:substitutable? #f))
 
+(define (manual-database manifest)
+  (define man-db                                  ;lazy reference
+    (module-ref (resolve-interface '(gnu packages man)) 'man-db))
+
+  (define build
+    #~(begin
+        (use-modules (guix build utils)
+                     (srfi srfi-1))
+
+        (define entries
+          (filter-map (lambda (directory)
+                        (let ((man (string-append directory "/share/man")))
+                          (and (directory-exists? man)
+                               man)))
+                      '#$(manifest-inputs manifest)))
+
+        (define manpages-collection-dir
+          (string-append (getenv "PWD") "/manpages-collection"))
+
+        (define man-directory
+          (string-append #$output "/share/man"))
+
+        (define (populate-manpages-collection-dir entries)
+          (let ((manpages (append-map find-files entries)))
+            (for-each (lambda (manpage)
+                        (let* ((dest-file (string-append
+                                           manpages-collection-dir "/"
+                                           (strip-store-file-name manpage))))
+                          (mkdir-p (dirname dest-file))
+                          (catch 'system-error
+                            (lambda ()
+                              (symlink manpage dest-file))
+                            (lambda args
+                              ;; Different packages may contain the same
+                              ;; manpage.  Simply ignore the symlink error.
+                              #t))))
+                      manpages)))
+
+        (mkdir-p manpages-collection-dir)
+        (populate-manpages-collection-dir entries)
+
+        ;; Create a mandb config file which contains a custom made
+        ;; manpath. The associated catpath is the location where the database
+        ;; gets generated.
+        (copy-file #+(file-append man-db "/etc/man_db.conf")
+                   "man_db.conf")
+
+        (substitute* "man_db.conf"
+          (("MANDB_MAP\\>.*$")
+           (string-append "MANDB_MAP " manpages-collection-dir " "
+                          man-directory "\n")))
+
+        (mkdir-p man-directory)
+        (setenv "MANPATH" (string-join entries ":"))
+        (zero? (system* #+(file-append man-db "/bin/mandb")
+                        "--quiet" "--create"
+                        "-C" "man_db.conf"))))
+
+  (gexp->derivation "manual-database" build
+                    #:modules '((guix build utils))
+                    #:local-build? #t))
+
 (define %default-profile-hooks
   ;; This is the list of derivation-returning procedures that are called by
   ;; default when making a non-empty profile.
   (list info-dir-file
+        manual-database
         fonts-dir-file
         ghc-package-cache-file
         ca-certificate-bundle