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home-manager/modules/services/emacs.nix
rcerc f3be3cda6a
services/emacs: add option to set emacsclient as the default editor (#2545)
* services/emacs: add `defaultEditor` option

Sets `emacsclient` as the default editor using the `EDITOR` environment variable.
2022-01-10 02:17:13 -05:00

183 lines
6.1 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.emacs;
emacsCfg = config.programs.emacs;
emacsBinPath = "${cfg.package}/bin";
emacsVersion = getVersion cfg.package;
clientWMClass =
if versionAtLeast emacsVersion "28" then "Emacsd" else "Emacs";
# Adapted from upstream emacs.desktop
clientDesktopItem = pkgs.writeTextDir "share/applications/emacsclient.desktop"
(generators.toINI { } {
"Desktop Entry" = {
Type = "Application";
Exec = "${emacsBinPath}/emacsclient ${
concatStringsSep " " cfg.client.arguments
} %F";
Terminal = false;
Name = "Emacs Client";
Icon = "emacs";
Comment = "Edit text";
GenericName = "Text Editor";
MimeType =
"text/english;text/plain;text/x-makefile;text/x-c++hdr;text/x-c++src;text/x-chdr;text/x-csrc;text/x-java;text/x-moc;text/x-pascal;text/x-tcl;text/x-tex;application/x-shellscript;text/x-c;text/x-c++;";
Categories = "Development;TextEditor;";
Keywords = "Text;Editor;";
StartupWMClass = clientWMClass;
};
});
# Match the default socket path for the Emacs version so emacsclient continues
# to work without wrapping it.
socketDir = "%t/emacs";
socketPath = "${socketDir}/server";
in {
meta.maintainers = [ maintainers.tadfisher ];
options.services.emacs = {
enable = mkEnableOption "the Emacs daemon";
package = mkOption {
type = types.package;
default = if emacsCfg.enable then emacsCfg.finalPackage else pkgs.emacs;
defaultText = literalExpression ''
if config.programs.emacs.enable then config.programs.emacs.finalPackage
else pkgs.emacs
'';
description = "The Emacs package to use.";
};
extraOptions = mkOption {
type = with types; listOf str;
default = [ ];
example = [ "-f" "exwm-enable" ];
description = ''
Extra command-line arguments to pass to <command>emacs</command>.
'';
};
client = {
enable = mkEnableOption "generation of Emacs client desktop file";
arguments = mkOption {
type = with types; listOf str;
default = [ "-c" ];
description = ''
Command-line arguments to pass to <command>emacsclient</command>.
'';
};
};
# Attrset for forward-compatibility; there may be a need to customize the
# socket path, though allowing for such is not easy to do as systemd socket
# units don't perform variable expansion for 'ListenStream'.
socketActivation = {
enable = mkEnableOption "systemd socket activation for the Emacs service";
};
defaultEditor = mkOption rec {
type = types.bool;
default = false;
example = !default;
description = ''
Whether to configure <command>emacsclient</command> as the default
editor using the <envar>EDITOR</envar> environment variable.
'';
};
};
config = mkIf cfg.enable (mkMerge [
{
assertions = [
(lib.hm.assertions.assertPlatform "services.emacs" pkgs
lib.platforms.linux)
];
systemd.user.services.emacs = {
Unit = {
Description = "Emacs text editor";
Documentation =
"info:emacs man:emacs(1) https://gnu.org/software/emacs/";
# Avoid killing the Emacs session, which may be full of
# unsaved buffers.
X-RestartIfChanged = false;
} // optionalAttrs (cfg.socketActivation.enable) {
# Emacs deletes its socket when shutting down, which systemd doesn't
# handle, resulting in a server without a socket.
# See https://github.com/nix-community/home-manager/issues/2018
RefuseManualStart = true;
};
Service = {
Type = "notify";
# We wrap ExecStart in a login shell so Emacs starts with the user's
# environment, most importantly $PATH and $NIX_PROFILES. It may be
# worth investigating a more targeted approach for user services to
# import the user environment.
ExecStart = ''
${pkgs.runtimeShell} -l -c "${emacsBinPath}/emacs --fg-daemon${
# In case the user sets 'server-directory' or 'server-name' in
# their Emacs config, we want to specify the socket path explicitly
# so launching 'emacs.service' manually doesn't break emacsclient
# when using socket activation.
optionalString cfg.socketActivation.enable
"=${escapeShellArg socketPath}"
} ${escapeShellArgs cfg.extraOptions}"'';
# Emacs will exit with status 15 after having received SIGTERM, which
# is the default "KillSignal" value systemd uses to stop services.
SuccessExitStatus = 15;
Restart = "on-failure";
} // optionalAttrs (cfg.socketActivation.enable) {
# Use read-only directory permissions to prevent emacs from
# deleting systemd's socket file before exiting.
ExecStartPost =
"${pkgs.coreutils}/bin/chmod --changes -w ${socketDir}";
ExecStopPost =
"${pkgs.coreutils}/bin/chmod --changes +w ${socketDir}";
};
} // optionalAttrs (!cfg.socketActivation.enable) {
Install = { WantedBy = [ "default.target" ]; };
};
home = {
packages = optional cfg.client.enable (hiPrio clientDesktopItem);
sessionVariables = mkIf cfg.defaultEditor {
EDITOR = getBin (pkgs.writeShellScript "editor" ''
exec ${
getBin cfg.package
}/bin/emacsclient "''${@:---create-frame}"'');
};
};
}
(mkIf cfg.socketActivation.enable {
systemd.user.sockets.emacs = {
Unit = {
Description = "Emacs text editor";
Documentation =
"info:emacs man:emacs(1) https://gnu.org/software/emacs/";
};
Socket = {
ListenStream = socketPath;
FileDescriptorName = "server";
SocketMode = "0600";
DirectoryMode = "0700";
};
Install = { WantedBy = [ "sockets.target" ]; };
};
})
]);
}