[FFe] libevent 2.1.12-stable-5 FTBFS on kinetic

[Benjamin Drung]

libevent 2.1.12-stable-5 fails to build from source on kinetic:

   dh_makeshlibs -a
dpkg-gensymbols: error: some symbols or patterns disappeared in the symbols file: see diff output below
dpkg-gensymbols: warning: debian/libevent-2.1-7/DEBIAN/symbols doesn't match completely debian/libevent-2.1-7.symbols
--- debian/libevent-2.1-7.symbols (libevent-2.1-7_2.1.12-stable-5_amd64)
+++ dpkg-gensymbolsM1jjt2 2022-09-27 08:36:16.746026078 +0000
@@ -617,7 +617,7 @@
  evutil_parse_sockaddr_port@Base 2.1.8-stable
  evutil_read_file_@Base 2.1.8-stable
  evutil_rtrim_lws_@Base 2.1.8-stable
- evutil_secure_rng_add_bytes@Base 2.1.8-stable
+#MISSING: 2.1.12-stable-5# evutil_secure_rng_add_bytes@Base 2.1.8-stable
  evutil_secure_rng_get_bytes@Base 2.1.8-stable
  evutil_secure_rng_global_setup_locks_@Base 2.1.8-stable
  evutil_secure_rng_init@Base 2.1.8-stable
dpkg-gensymbols: error: some symbols or patterns disappeared in the symbols file: see diff output below
dpkg-gensymbols: warning: debian/libevent-core-2.1-7/DEBIAN/symbols doesn't match completely debian/libevent-core-2.1-7.symbols
--- debian/libevent-core-2.1-7.symbols (libevent-core-2.1-7_2.1.12-stable-5_amd64)
+++ dpkg-gensymbolseal7TI 2022-09-27 08:36:16.902023091 +0000
@@ -394,7 +394,7 @@
  evutil_parse_sockaddr_port@Base 2.1.8-stable
  evutil_read_file_@Base 2.1.8-stable
  evutil_rtrim_lws_@Base 2.1.8-stable
- evutil_secure_rng_add_bytes@Base 2.1.8-stable
+#MISSING: 2.1.12-stable-5# evutil_secure_rng_add_bytes@Base 2.1.8-stable
  evutil_secure_rng_get_bytes@Base 2.1.8-stable
  evutil_secure_rng_global_setup_locks_@Base 2.1.8-stable
  evutil_secure_rng_init@Base 2.1.8-stable
dh_makeshlibs: error: failing due to earlier errors

[Benjamin Drung (bdrung)]

This is the condition for evutil_secure_rng_add_bytes:

#if !defined(EVENT__HAVE_ARC4RANDOM) || defined(EVENT__HAVE_ARC4RANDOM_ADDRANDOM)

The Debian unstable build says:

checking for arc4random... no
checking for arc4random_buf... no
checking for arc4random_addrandom... no

The kinetic build says:

checking for arc4random... yes
checking for arc4random_buf... yes
checking for arc4random_addrandom... no

[Benjamin Drung (bdrung)]

arc4random and arc4random_buf are defined in /usr/include/stdlib.h shipped by libc6-dev 2.36-0ubuntu2.

[Benjamin Drung (bdrung)]

Attached a patch to add evutil_secure_rng_add_bytes back.

[Simon Chopin (schopin)]

This patch wouldn't work as intended, as we'd mix arc4random functions from the vendored sources and from glibc, each set having their own internal static data. Sounds like a recipe for disaster :)

[Benjamin Drung (bdrung)]

Instead of patching libevent to use its own arc4random functions, I prefer to do a library transition to drop evutil_secure_rng_add_bytes. "reverse-depends -b libevent-dev" shows 79 packages.

[Benjamin Drung (bdrung)]

Reason for proposing the library transition is that this would avoid the possibility to mix glibc's and libevent's arc4random implementation.

[Graham Inggs (ginggs)]

I understand there's a test rebuild ongoing. Please change this bug's status back to New when you are ready.

[Benjamin Drung (bdrung)]

The rebuild is done in https://launchpad.net/~bdrung/+archive/ubuntu/ppa/+packages

Except for ARM builds of qt6-webengine and qtwebengine-opensource-src the results are there. There are a few build failures, but all build failures are existing build failures:

* libcamera on ppc64el: bug #1955767
* libreswan: bug #1991910
* ladvd: bug #1991909
* tgl on s390x: bug #1991912

[Benjamin Drung (bdrung)]

Attached the debdiff for libevent.

[Utkarsh Gupta (utkarsh)]

telegram-cli also fails on s390x, btw. :(

[Benjamin Drung (bdrung)]

Transition tracker: https://people.canonical.com/~ubuntu-archive/transitions/html/libevent-2.1-7a.html

[Graham Inggs (ginggs)]

Let's go ahead, FFe granted.

[Benjamin Drung (bdrung)]

Uploaded no-change rebuild packages:
./library-transition --lp 1990941 libevent-2.1-7 libevent-2.1-7a

[Launchpad Janitor (janitor)]

This bug was fixed in the package libevent - 2.1.12-stable-5ubuntu1

---------------
libevent (2.1.12-stable-5ubuntu1) kinetic; urgency=medium

  * Bump soname for libevent and libevent-core to 2.1-7a for dropping
    evutil_secure_rng_add_bytes (LP: #1990941)

 -- Benjamin Drung <email address hidden> Wed, 05 Oct 2022 19:13:56 +0200