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|
{ config, lib, pkgs, ... }:
let
# cups calls its backends as user `lp` (which is good!),
# but cups-pdf wants to be called as `root`, so it can change ownership of files.
# We add a suid wrapper and a wrapper script to trick cups into calling the suid wrapper.
# Note that a symlink to the suid wrapper alone wouldn't suffice, cups would complain
# > File "/nix/store/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-cups-progs/lib/cups/backend/cups-pdf" has insecure permissions (0104554/uid=0/gid=20)
# wrapper script that redirects calls to the suid wrapper
cups-pdf-wrapper = pkgs.writeTextFile {
name = "${pkgs.cups-pdf-to-pdf.name}-wrapper.sh";
executable = true;
destination = "/lib/cups/backend/cups-pdf";
checkPhase = ''
${pkgs.stdenv.shellDryRun} "$target"
${lib.getExe pkgs.shellcheck} "$target"
'';
text = ''
#! ${pkgs.runtimeShell}
exec "${config.security.wrapperDir}/cups-pdf" "$@"
'';
};
# wrapped cups-pdf package that uses the suid wrapper
cups-pdf-wrapped = pkgs.buildEnv {
name = "${pkgs.cups-pdf-to-pdf.name}-wrapped";
# using the wrapper as first path ensures it is used
paths = [ cups-pdf-wrapper pkgs.cups-pdf-to-pdf ];
ignoreCollisions = true;
};
instanceSettings = name: {
freeformType = with lib.types; nullOr (oneOf [ int str path package ]);
# override defaults:
# inject instance name into paths,
# also avoid conflicts between user names and special dirs
options.Out = lib.mkOption {
type = with lib.types; nullOr singleLineStr;
default = "/var/spool/cups-pdf-${name}/users/\${USER}";
defaultText = "/var/spool/cups-pdf-{instance-name}/users/\${USER}";
example = "\${HOME}/cups-pdf";
description = lib.mdDoc ''
output directory;
`''${HOME}` will be expanded to the user's home directory,
`''${USER}` will be expanded to the user name.
'';
};
options.AnonDirName = lib.mkOption {
type = with lib.types; nullOr singleLineStr;
default = "/var/spool/cups-pdf-${name}/anonymous";
defaultText = "/var/spool/cups-pdf-{instance-name}/anonymous";
example = "/var/lib/cups-pdf";
description = lib.mdDoc "path for anonymously created PDF files";
};
options.Spool = lib.mkOption {
type = with lib.types; nullOr singleLineStr;
default = "/var/spool/cups-pdf-${name}/spool";
defaultText = "/var/spool/cups-pdf-{instance-name}/spool";
example = "/var/lib/cups-pdf";
description = lib.mdDoc "spool directory";
};
options.Anonuser = lib.mkOption {
type = lib.types.singleLineStr;
default = "root";
description = lib.mdDoc ''
User for anonymous PDF creation.
An empty string disables this feature.
'';
};
options.GhostScript = lib.mkOption {
type = with lib.types; nullOr path;
default = lib.getExe pkgs.ghostscript;
defaultText = lib.literalExpression "lib.getExe pkgs.ghostscript";
example = lib.literalExpression ''''${pkgs.ghostscript}/bin/ps2pdf'';
description = lib.mdDoc "location of GhostScript binary";
};
};
instanceConfig = { name, config, ... }: {
options = {
enable = (lib.mkEnableOption (lib.mdDoc "this cups-pdf instance")) // { default = true; };
installPrinter = (lib.mkEnableOption (lib.mdDoc ''
a CUPS printer queue for this instance.
The queue will be named after the instance and will use the {file}`CUPS-PDF_opt.ppd` ppd file.
If this is disabled, you need to add the queue yourself to use the instance
'')) // { default = true; };
confFileText = lib.mkOption {
type = lib.types.lines;
description = lib.mdDoc ''
This will contain the contents of {file}`cups-pdf.conf` for this instance, derived from {option}`settings`.
You can use this option to append text to the file.
'';
};
settings = lib.mkOption {
type = lib.types.submodule (instanceSettings name);
default = {};
example = {
Out = "\${HOME}/cups-pdf";
UserUMask = "0033";
};
description = lib.mdDoc ''
Settings for a cups-pdf instance, see the descriptions in the template config file in the cups-pdf package.
The key value pairs declared here will be translated into proper key value pairs for {file}`cups-pdf.conf`.
Setting a value to `null` disables the option and removes it from the file.
'';
};
};
config.confFileText = lib.pipe config.settings [
(lib.filterAttrs (key: value: value != null))
(lib.mapAttrs (key: builtins.toString))
(lib.mapAttrsToList (key: value: "${key} ${value}\n"))
lib.concatStrings
];
};
cupsPdfCfg = config.services.printing.cups-pdf;
copyConfigFileCmds = lib.pipe cupsPdfCfg.instances [
(lib.filterAttrs (name: lib.getAttr "enable"))
(lib.mapAttrs (name: lib.getAttr "confFileText"))
(lib.mapAttrs (name: pkgs.writeText "cups-pdf-${name}.conf"))
(lib.mapAttrsToList (name: confFile: "ln --symbolic --no-target-directory ${confFile} /var/lib/cups/cups-pdf-${name}.conf\n"))
lib.concatStrings
];
printerSettings = lib.pipe cupsPdfCfg.instances [
(lib.filterAttrs (name: lib.getAttr "enable"))
(lib.filterAttrs (name: lib.getAttr "installPrinter"))
(lib.mapAttrsToList (name: instance: (lib.mapAttrs (key: lib.mkDefault) {
inherit name;
model = "CUPS-PDF_opt.ppd";
deviceUri = "cups-pdf:/${name}";
description = "virtual printer for cups-pdf instance ${name}";
location = instance.settings.Out;
})))
];
in
{
options.services.printing.cups-pdf = {
enable = lib.mkEnableOption (lib.mdDoc ''
the cups-pdf virtual pdf printer backend.
By default, this will install a single printer `pdf`.
but this can be changed/extended with {option}`services.printing.cups-pdf.instances`
'');
instances = lib.mkOption {
type = lib.types.attrsOf (lib.types.submodule instanceConfig);
default.pdf = {};
example.pdf.settings = {
Out = "\${HOME}/cups-pdf";
UserUMask = "0033";
};
description = lib.mdDoc ''
Permits to raise one or more cups-pdf instances.
Each instance is named by an attribute name, and the attribute's values control the instance' configuration.
'';
};
};
config = lib.mkIf cupsPdfCfg.enable {
services.printing.enable = true;
services.printing.drivers = [ cups-pdf-wrapped ];
hardware.printers.ensurePrinters = printerSettings;
# the cups module will install the default config file,
# but we don't need it and it would confuse cups-pdf
systemd.services.cups.preStart = lib.mkAfter ''
rm -f /var/lib/cups/cups-pdf.conf
${copyConfigFileCmds}
'';
security.wrappers.cups-pdf = {
group = "lp";
owner = "root";
permissions = "+r,ug+x";
setuid = true;
source = "${pkgs.cups-pdf-to-pdf}/lib/cups/backend/cups-pdf";
};
};
meta.maintainers = [ lib.maintainers.yarny ];
}
|
