gnupg on Arch Linux broken since readline upgrade - can't find libreadline.so.6

Question

I've just upgraded readline to a new major release:

$ grep readline.*7 /var/log/pacman.log 
[2016-11-15 21:53] [ALPM] upgraded readline (6.3.008-4 -> 7.0-1)

Since this GNUPG is broken:

$ gpg 
gpg: error while loading shared libraries: libreadline.so.6: cannot open shared object file: No such file or directory

That also means I can't upgrade any packages. How do I safely fix my installation?

What I've tried so far to downgrade readline:

• The package is not in /var/cache/pacman/pkg
• Building from the previous PKGBUILD failed because it doesn't bootstrap itself - it relies on awk which is also missing libreadline.so.6.

Answer 1

This has been reported to Arch here.

The workaround is to run

mkinitcpio -P

after the upgrade has completed, but before rebooting.

If you've rebooted before re-running mkinitcpio, then you'll need to boot off e.g. a USB key and run the mkinitcpio from the chroot. The easiest is to use arch-chroot as in the Arch install instructions.

I haven't had a chance to test this method in this particular case, however have done so in the past.

Answer 2

Fixed by manually verifying and installing an older version:

1. Download the previous release from Arch Linux Archive
2. Copy the package and signature file to another machine and verifying the signature there
3. Unpack the package: sudo tar -xvpf readline-6.3.008-4-x86_64.pkg.tar.xz -C / --exclude .PKGINFO --exclude .INSTALL

Warning: Other packages may contain pre- or post-install scripts. This one did not, but consider yourself warned!

Answer 3

It seems libreadline.so.7 is backward compatible enough for most utilities to keep working after running:

sudo ln -s /usr/lib/libreadline.so.7 /usr/lib/libreadline.so.6

After that it warned me that /usr/bin/bash: Symbol rl_readline_state has different size in shared object, consider re-linking, but I was able to update pacman-key and upgrade libgcrypt so that new packages would validate, and then pacman -S bash to rebuild my shell using readline 7.0.

After you've put out pacman's Catch-22-style fires, simply clean up with:

sudo rm /usr/lib/libreadline.so.6

Answer 4

I solve this by editing /etc/pacman.conf and uncomenting or adding this line under [options]:

SigLevel = Never

Save and run pacman -Syyu, it updates the system and repairs it. Then comment that line again and update the database.

Answer 5

I did what @chbrown suggests:

sudo ln -s /usr/lib/libreadline.so.7 /usr/lib/libreadline.so.6

(also had linking warning)

Then I had a new error regarding ca-certificates-utils so I had to follow this: https://bugs.archlinux.org/task/53217#comment155971

pacman -Sy --force  ca-certificates-utils

And then I could:

pacman -Syu

And all the upgrades went well and the libreadline/libreadline linking error was fixed.

Answer 6

It sounds like you have gotten your system into a weird partially upgraded state, but partial upgrades are not supported. The solution is that:

A simple pacman -Syu to a properly synced mirror will fix the problem as long as pacman is not broken.

Your problem is that pacman seems to be broken. You may be lucky and can fix things by simply turning package signing off. If you are worried about security, you can manually download the packages you need on another machine, check their signatures, and then add them to the package cache on the broken machine.

If in fact pacman is broken, then you need to manually reinstall pacman. This basically requires you to download the pacman dependencies and manually extract them in the correct places. Which packages need to be reinstalled depends on the exact state of your system.