Fixing gpg signing in magit

Nov 25, 2019 22:06 · 363 words · 2 minutes read freebsd emacs

Today in the evening, when I wanted to sign my commits in magit, I came across this error:

    hint: Waiting for your editor to close the file...
    Waiting for Emacs...
    error: gpg failed to sign the data
    fatal: failed to write commit object

This log message was not really helpful so I went ahead and tried to sign something in my terminal: echo "test" | gpg --clearsign. I got a more useful log:

    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA256

    test
    gpg: signing failed: Invalid IPC response
    gpg: [stdin]: clear-sign failed: Invalid IPC response

I went ahead and read the gpg-agent’s man agent and I realized that I had not stuck this fella in my init(in my case .profile) scripts:

GPG_TTY=$(tty)
export GPG_TTY

This fixed the error I was seeing at my terminal but then I couldn’t still sign things from magit. Running pkg info pinentry showed that I was using the tty version of the program (pinentry):

Options        :
        FLTK           : off
        GNOME3         : off
        GTK2           : off
        NCURSES        : off
        QT5            : off
        TTY            : on

The downloaded binary you get by using a pkg install defaults to using the tty version of pinentry so this means that any time gpg is run, it expects pinentry(the program used to input the password) to be run from the terminal. This is why adding `GPG_TTY=$(tty)` above fixed the gpg error in the terminal. However, when you run emacs from a GUI, it has no access to the terminal hence the weird bug.

To make pinentry work in GNU/ Emacs, I had to remove the installed pinentry binary and compile it(from the ports collection) to use gtk. This way, when signing commits in git, I’ll get a floating dialog box from which I’ll input my password. This is not my ideal way of doing things, since I know that I can put the darn password within GNU/ Emacs. However, for now it suits my needs just fine :)

[Update - 2019-12-04]

Alternatively, to force pinentry to use gtk, you could stick this in ~/.gnupg/gpg-agent.conf:

# Keyboard control
no-grab

# PIN entry program
pinentry-program /usr/local/bin/pinentry-gtk-2

Be sure to restart the gpg-agent by running gpgconf --kill gpg-agent: