Re: [v3] Erlang

[Leo Famulari <leo@famulari.name>]

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On Sun, Apr 03, 2016 at 11:26:48PM +0200, Ludovic Courtès wrote:
> Leo Famulari <leo@famulari.name> skribis:
> > All the .beam files have timestamps and build paths embedded [0]. This
> > is a known issue without a clear solution. The build paths don't seem so
> > bad to me, since my understanding is that they are set deterministically
> > by the Guix builder.

> A patch along the lines of the one of the page above should do the work
> for beam files, no?  We’d have to change DEB_BUILD_DATE to
> SOURCE_DATE_EPOCH, and remove regexp-matching from there.

There is a more generic patch applied to the actual Debian package [0],
and I've applied it to ours in the attached revision. It will allow us
to build Erlang packages without the timestamp. Unfortunately, it seems
to have no effect when building Erlang itself.

> > There are also some .script files that also embed timestamps in a human
> > readable string. Grepping for the string makes it easy to find the
> > source of this. We could patch the timestamp format string with the
> > value of SOURCE_DATE_EPOCH.

Debian's package exhibits this problem. The timestamps are generated in
the following places in the source code. I don't know how to approach
this problem.

lib/kernel/test/global_SUITE_data/global_trace.erl:    io:format("The trace was generated at ~p~n", [EndTime]),
lib/reltool/bin/reltool.escript:    lists:flatten(io_lib:format("%% ~s generated at ~w ~w\n~p.\n\n",
lib/reltool/src/reltool_server.erl:    IoList = io_lib:format("%% config generated at ~w ~w\n~p.\n\n",
lib/reltool/src/reltool_target.erl:    RelIoList = io_lib:format("%% rel generated at ~w ~w\n~p.\n\n",
lib/reltool/src/reltool_target.erl:    ScriptIoList = io_lib:format("%% script generated at ~w ~w\n~p.\n\n",
lib/reltool/src/reltool_target.erl:            AppIoList = io_lib:format("%% app generated at ~w ~w\n~p.\n\n",
lib/reltool/src/reltool_target.erl:            AppIoList = io_lib:format("%% app generated at ~w ~w\n~p.\n\n",
lib/runtime_tools/src/erts_alloc_config.erl:	"generated at ~w-~2..0w-~2..0w ~2..0w:~2..0w.~2..0w by "
lib/sasl/src/systools_make.erl:	    io:format(Fd, "%% script generated at ~w ~w\n~p.\n",
lib/wx/src/gen/gl.erl:%% The program object's information log is updated and the program is generated at the time

[0]
https://sources.debian.net/src/erlang/1:18.3-dfsg-1/debian/patches/reproducible-build.patch/

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From 180f142a3f67f80aa029fc34c38f21cd8988eefe Mon Sep 17 00:00:00 2001
Message-Id: <180f142a3f67f80aa029fc34c38f21cd8988eefe.1459741136.git.leo@famulari.name>
From: Steve Sprang <scs@stevesprang.com>
Date: Sat, 6 Feb 2016 12:40:53 -0800
Subject: [v3 1/1] gnu: Add erlang.

* gnu/packages/erlang.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.
* gnu/packages/patches/erlang-reproducible-build.patch: New file.
* gnu-system.am (dist_PATCH_DATA): Add it.

Co-authored by: Leo Famulari <leo@famulari.name>
---
 gnu-system.am                                      |   2 +
 gnu/packages/erlang.scm                            | 119 +++++++++++++++++++++
 .../patches/erlang-reproducible-build.patch        |  30 ++++++
 3 files changed, 151 insertions(+)
 create mode 100644 gnu/packages/erlang.scm
 create mode 100644 gnu/packages/patches/erlang-reproducible-build.patch

diff --git a/gnu-system.am b/gnu-system.am
index d45b3d1..498910f 100644
--- a/gnu-system.am
+++ b/gnu-system.am
@@ -102,6 +102,7 @@ GNU_SYSTEM_MODULES =				\
   gnu/packages/enchant.scm			\
   gnu/packages/engineering.scm			\
   gnu/packages/enlightenment.scm		\
+  gnu/packages/erlang.scm			\
   gnu/packages/fcitx.scm			\
   gnu/packages/feh.scm                          \
   gnu/packages/figlet.scm			\
@@ -459,6 +460,7 @@ dist_patch_DATA =						\
   gnu/packages/patches/emacs-exec-path.patch			\
   gnu/packages/patches/emacs-scheme-complete-scheme-r5rs-info.patch	\
   gnu/packages/patches/emacs-source-date-epoch.patch		\
+  gnu/packages/patches/erlang-reproducible-build.patch		\
   gnu/packages/patches/eudev-rules-directory.patch		\
   gnu/packages/patches/evilwm-lost-focus-bug.patch		\
   gnu/packages/patches/expat-CVE-2015-1283.patch		\
diff --git a/gnu/packages/erlang.scm b/gnu/packages/erlang.scm
new file mode 100644
index 0000000..b241961
--- /dev/null
+++ b/gnu/packages/erlang.scm
@@ -0,0 +1,119 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2016 Steve Sprang <scs@stevesprang.com>
+;;; Copyright © 2016 Leo Famulari <leo@famulari.name>
+;;;
+;;; 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 (gnu packages erlang)
+  #:use-module ((guix licenses) #:prefix license:)
+  #:use-module (guix build-system gnu)
+  #:use-module (guix download)
+  #:use-module (guix packages)
+  #:use-module (gnu packages)
+  #:use-module (gnu packages ncurses)
+  #:use-module (gnu packages perl)
+  #:use-module (gnu packages tls))
+
+(define-public erlang
+  (package
+    (name "erlang")
+    ;; When updating, remember to update the hash of erlang-manpages!
+    (version "18.3")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append
+                    "http://erlang.org/download/otp_src_"
+                    version
+                    ".tar.gz"))
+              (sha256
+               (base32
+                "1hy9slq9gjvwdb504dmvp6rax90isnky6chqkyq5v4ybl4lq3azx"))
+              (patches (map search-patch
+                            '("erlang-reproducible-build.patch")))))
+    (build-system gnu-build-system)
+    (native-inputs
+     `(("perl" ,perl)
+
+       ;; Erlang's documentation is distributed in a separate tarball.
+       ("erlang-manpages"
+        ,(origin
+           (method url-fetch)
+           (uri (string-append "http://erlang.org/download/otp_doc_man_"
+                               version ".tar.gz"))
+           (sha256
+            (base32
+             "1hpcr7a3dx2y9gnb53bvb4g6lyvbwigadl9s3f978s01x40f32wp"))))))
+    (inputs
+     `(("ncurses" ,ncurses)
+       ("openssl" ,openssl)))
+    (arguments
+     `(#:test-target "release_tests"
+       #:configure-flags
+       (list (string-append "--with-ssl=" (assoc-ref %build-inputs "openssl")))
+       #:phases
+       (modify-phases %standard-phases
+         (add-after 'unpack 'path-to-rm
+           (lambda _
+             (substitute* "erts/configure"
+               (("/bin/rm") (which "rm")))
+             (substitute* "lib/odbc/configure"
+               (("/bin/rm") (which "rm")))))
+         (add-after 'patch-source-shebangs 'patch-source-env
+           (lambda _
+             (let ((escripts
+                    (append
+                     (find-files "." "\\.escript")
+                     (find-files "lib/stdlib/test/escript_SUITE_data/")
+                     '("erts/lib_src/utils/make_atomics_api"
+                       "erts/preloaded/src/add_abstract_code"
+                       "lib/diameter/bin/diameterc"
+                       "lib/reltool/examples/display_args"
+                       "lib/reltool/examples/mnesia_core_dump_viewer"
+                       "lib/snmp/src/compile/snmpc.src"
+                       "make/verify_runtime_dependencies"
+                       "make/emd2exml.in"))))
+               (substitute* escripts
+                 (("/usr/bin/env") (which "env"))))))
+         (add-before 'configure 'set-erl-top
+           (lambda _
+             (setenv "ERL_TOP" (getcwd))))
+         (add-after 'install 'patch-erl
+           ;; This only works after install.
+           (lambda _
+             (substitute* (string-append (assoc-ref %outputs "out") "/bin/erl")
+               (("sed") (which "sed")))))
+         (add-after 'install 'install-doc
+           (lambda* (#:key inputs outputs #:allow-other-keys)
+             (let* ((out (assoc-ref outputs "out"))
+                    (manpages (assoc-ref inputs "erlang-manpages"))
+                    (share (string-append out "/share/")))
+             (mkdir-p share)
+             (with-directory-excursion share
+               (and
+                 (zero? (system* "tar" "xvf" manpages))
+                 ;; Delete superfluous files.
+                 (for-each delete-file '("COPYRIGHT"
+                                         "PR.template"
+                                         "README"))))))))))
+    (home-page "http://erlang.org/")
+    (synopsis "The Erlang programming language")
+    (description
+     "Erlang is a programming language used to build massively
+scalable soft real-time systems with requirements on high
+availability.  Some of its uses are in telecoms, banking, e-commerce,
+computer telephony and instant messaging.  Erlang's runtime system has
+built-in support for concurrency, distribution and fault tolerance.")
+    (license license:asl2.0)))
diff --git a/gnu/packages/patches/erlang-reproducible-build.patch b/gnu/packages/patches/erlang-reproducible-build.patch
new file mode 100644
index 0000000..7e874a5
--- /dev/null
+++ b/gnu/packages/patches/erlang-reproducible-build.patch
@@ -0,0 +1,30 @@
+Copied from Debian [0].
+
+[0]
+https://sources.debian.net/src/erlang/1:18.3-dfsg-1/debian/patches/reproducible-build.patch/
+
+---
+
+Author: Chris Lamb <lamby@debian.org>
+Description: Patch makes erlang compiler honor the SOURCE_DATE_EPOCH
+ environment variable and use its value in build results instead of the
+ current timestamp. The goal is to maintain reproducible builds. More info:
+ https://wiki.debian.org/ReproducibleBuilds
+Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=795834
+Last-modified: Mon, 17 Aug 2015 14:32:15 +0300
+
+--- a/lib/compiler/src/beam_asm.erl
++++ b/lib/compiler/src/beam_asm.erl
+@@ -226,7 +226,11 @@
+ build_attributes(Opts, SourceFile, Attr, MD5) ->
+     Misc = case member(slim, Opts) of
+ 	       false ->
+-		   {{Y,Mo,D},{H,Mi,S}} = erlang:universaltime(),
++                  {{Y,Mo,D},{H,Mi,S}} = case string:to_integer(os:getenv("SOURCE_DATE_EPOCH")) of
++                       {N,[]} ->calendar:gregorian_seconds_to_datetime(N +
++			    calendar:datetime_to_gregorian_seconds({{1970,1,1},{0,0,0}}));
++                       {_,_} -> erlang:universaltime()
++                  end,
+ 		   [{time,{Y,Mo,D,H,Mi,S}},{source,SourceFile}];
+ 	       true -> []
+ 	   end,
-- 
2.7.3