How to work around a error in an eclass file located in a Gentoo overlay?

Two possible ways. The first is easier but untested:

Easy way: Install a supported version and upgrade to an unsupported one

The error in this case occurs during a clean installation of an unsupported version of MySQL. It occurs when running the command emerge --config which is run after a clean installation as opposed to an upgrade. Therefore the easiest workaround is probably to first install an older, supported version of MySQL from the main repository; then upgrade it to the later, unsupported version from the overlay. So:

$ emerge --ask --verbose dev-db/mysql 

Verify it asks to install a supported version. Let it run, then complete the installation as instructed:

$ emerge --config =dev-db/mysql-SUPPORTED.VERSION 

Now unmask the later, unsupported version from the overlay repository, and upgrade to it:

$ emerge --ask --verbose dev-db/mysql 

Verify the version it offers, and again let it run. That should work, though I haven't tested it; instead I did it the hard way.

Hard way: Override the eclass and deal with the errors

The developer manual says, ‘If an ebuild defines a function that is exported, this gets priority over any eclass version. This can be used to override eclass-defined defaults’. So copy mysql-5.7.12.ebuild from the ‘mysql’ overlay to your local overlay (priority +1000 in my case) and modify it there, appending the override:

pkg_config() { # test override of mysql-multilib-r1_pkg_config die "ebuild override works!"; } 

Verify that Portage will run the ebuild:

$ equery which dev-db/mysql /usr/local/portage/dev-db/mysql/mysql-5.7.12.ebuild 

Then test it:

$ emerge --ask --unmerge dev-db/mysql $ rm --recursive /var/lib/mysql/* # clean away any remnants $ emerge --ask --verbose dev-db/mysql ⋮ # waiting while it compiles … $ emerge --config =dev-db/mysql-5.7.12 

Sure enough, it dies with the message ‘ebuild override works!’.

Now if you edit the ebuild file to do something more useful than dying, then redo the last command above, you'll see that it still dies with the same message. The Portage cache remains a problem. But since this is an ebuild file, not an eclass, and since it's in your own local overlay, you can easily work around the cache by using proper ebuild revisions:

$ pwd /usr/local/portage/dev-db/mysql $ cp mysql-5.7.12.ebuild mysql-5.7.12-r1.ebuild 

And in the revision file mysql-5.7.12-r1.ebuild, edit pkg_config to implement the real fix:

pkg_config() { # modified from mysql-multilib-r1.eclass # of http://gpo.zugaina.org/Overlays/mysql einfo "Overriding mysql-multilib-r1_pkg_config from this ebuild" ⋮ # initialize_options="--initialize-insecure '--init-file=${sqltmp}'" # fix: initialize_options="--initialize-insecure --init-file=${sqltmp} " ⋮ } 

Then re-test it:

$ rm --recursive /var/lib/mysql/* # clean away any remnants $ emerge --ask --verbose dev-db/mysql ⋮ # waiting while it recompiles … $ emerge --config =dev-db/mysql-5.7.12-r1 

Here it turns out that pkg_config still has errors:

[ERROR] Failed to open the bootstrap file /var/tmp/portage/ … tmp.PD6hqOe8kA [ERROR] 1105 Bootstrap file error, return code (0). Nearest query: … 

Probably it's file permissions. Anyway, it works if you re-run the failed command as root:

$ /usr/sbin/mysqld --basedir=/usr \ --loose-skip-grant-tables --loose-skip-host-cache --loose-skip-name-resolve \ --loose-skip-networking --loose-skip-slave-start --loose-skip-ssl \ --loose-skip-log-bin --loose-skip-relay-log --loose-skip-slow-query-log \ --loose-skip-external-locking --loose-skip-log-slave-updates \ --user=mysql --datadir=/var/lib/mysql --tmpdir=/tmp/ --initialize-insecure \ --init-file=/var/tmp/portage/dev-db/mysql-5.7.12-r1/temp/tmp.PD6hqOe8kA 

Then carry on, manually interpreting and executing the Python code:

$ chown -R mysql:mysql /var/lib/mysql $ chmod 0750 /var/lib/mysql $ /usr/sbin/mysqld --loose-skip-grant-tables --loose-skip-host-cache --loose-skip-name-resolve \ --loose-skip-networking --loose-skip-slave-start --loose-skip-ssl \ --loose-skip-log-bin --loose-skip-relay-log --loose-skip-slow-query-log \ --loose-skip-external-locking --loose-skip-log-slave-updates \ --user=mysql --log-warnings=0 --basedir=/usr --datadir=/var/lib/mysql \ --max_allowed_packet=8M --net_buffer_length=16K \ --default-storage-engine=MyISAM \ --socket=/var/run/mysqld/mysqld99.sock \ --pid-file=/var/run/mysqld/mysqld99.pid \ --tmpdir=/tmp/ & 

Verify that socket file (above) is created. Then:

$ /usr/bin/mysql --socket=/var/run/mysqld/mysqld99.sock -hlocalhost -e \ "UPDATE mysql.user SET Password = PASSWORD('your-password-here') WHERE USER='root'; FLUSH PRIVILEGES" 

Here it fails with:

ERROR 1054 (42S22) at line 1: Unknown column 'Password' in 'field list' 

I found the fix on Stack Overflow:

$ /usr/bin/mysql --socket=/var/run/mysqld/mysqld99.sock -hlocalhost -e \ "UPDATE mysql.user SET authentication_string = PASSWORD('your-password-here') WHERE USER='root'; FLUSH PRIVILEGES" 

Finally, terminate mysqld:

$ kill $(< /var/run/mysqld/mysqld99.pid ) # from the --pid-file above 

That's it. Now you can add MySQL to a runlevel, or start and stop it manually:

$ /etc/init.d/mysql start $ /etc/init.d/mysql stop 

I'm not entirely sure what you're doing here, but an important point should be made:

If you're not re-emerging mysql before running --config, the config you use will be read, not out of any of your eclasses in your overlay, but from the files in /var/db/pkg/*/*/environment.bz2

Installing a package does some really cute tricks, for instance, if you write an ebuild and export a variable in src_compile ... that variable will likely still be accessible during pkg_config

If you have a poke around in that environment.bz2 file, you'll see all the inlined mysql eclass functions.

Hence, as you stated in your other answer, upgrading appears to fix it.

But it fixes it by replacing the installed copies of the eclass code :)