feat: add optional variadic args to all commands (#8)

Allow callers to pass additional systemctl flags (e.g. --no-block,
--force) via variadic string args on every exported function.

This is backward-compatible: existing callers without extra args
continue to work unchanged.

Introduces a prepareArgs helper to centralize argument construction,
replacing the duplicated args/UserMode pattern across all functions.

Closes #2

systemctl.go

@@ -12,8 +12,10 @@ import (
 // files, and recreate the entire dependency tree. While the daemon is being
 // reloaded, all sockets systemd listens on behalf of user configuration will
 // stay accessible.
-func DaemonReload(ctx context.Context, opts Options) error {
-	return daemonReload(ctx, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func DaemonReload(ctx context.Context, opts Options, args ...string) error {
+	return daemonReload(ctx, opts, args...)
 }
 
 // Reenables one or more units.
@@ -21,8 +23,10 @@ func DaemonReload(ctx context.Context, opts Options) error {
 // This removes all symlinks to the unit files backing the specified units from
 // the unit configuration directory, then recreates the symlink to the unit again,
 // atomically. Can be used to change the symlink target.
-func Reenable(ctx context.Context, unit string, opts Options) error {
-	return reenable(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Reenable(ctx context.Context, unit string, opts Options, args ...string) error {
+	return reenable(ctx, unit, opts, args...)
 }
 
 // Disables one or more units.
@@ -30,8 +34,10 @@ func Reenable(ctx context.Context, unit string, opts Options) error {
 // This removes all symlinks to the unit files backing the specified units from
 // the unit configuration directory, and hence undoes any changes made by
 // enable or link.
-func Disable(ctx context.Context, unit string, opts Options) error {
-	return disable(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Disable(ctx context.Context, unit string, opts Options, args ...string) error {
+	return disable(ctx, unit, opts, args...)
 }
 
 // Enable one or more units or unit instances.
@@ -40,17 +46,20 @@ func Disable(ctx context.Context, unit string, opts Options) error {
 // the indicated unit files. After the symlinks have been created, the system
 // manager configuration is reloaded (in a way equivalent to daemon-reload),
 // in order to ensure the changes are taken into account immediately.
-func Enable(ctx context.Context, unit string, opts Options) error {
-	return enable(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Enable(ctx context.Context, unit string, opts Options, args ...string) error {
+	return enable(ctx, unit, opts, args...)
 }
 
 // Check whether any of the specified units are active (i.e. running).
 //
 // Returns true if the unit is active, false if inactive or failed.
 // Also returns false in an error case.
-func IsActive(ctx context.Context, unit string, opts Options) (bool, error) {
-	result, err := isActive(ctx, unit, opts)
-	return result, err
+//
+// Any additional arguments are passed directly to the systemctl command.
+func IsActive(ctx context.Context, unit string, opts Options, args ...string) (bool, error) {
+	return isActive(ctx, unit, opts, args...)
 }
 
 // Checks whether any of the specified unit files are enabled (as with enable).
@@ -62,15 +71,17 @@ func IsActive(ctx context.Context, unit string, opts Options) (bool, error) {
 //
 // See https://www.freedesktop.org/software/systemd/man/systemctl.html#is-enabled%20UNIT%E2%80%A6
 // for more information
-func IsEnabled(ctx context.Context, unit string, opts Options) (bool, error) {
-	result, err := isEnabled(ctx, unit, opts)
-	return result, err
+//
+// Any additional arguments are passed directly to the systemctl command.
+func IsEnabled(ctx context.Context, unit string, opts Options, args ...string) (bool, error) {
+	return isEnabled(ctx, unit, opts, args...)
 }
 
 // Check whether any of the specified units are in a "failed" state.
-func IsFailed(ctx context.Context, unit string, opts Options) (bool, error) {
-	result, err := isFailed(ctx, unit, opts)
-	return result, err
+//
+// Any additional arguments are passed directly to the systemctl command.
+func IsFailed(ctx context.Context, unit string, opts Options, args ...string) (bool, error) {
+	return isFailed(ctx, unit, opts, args...)
 }
 
 // Mask one or more units, as specified on the command line. This will link
@@ -79,26 +90,33 @@ func IsFailed(ctx context.Context, unit string, opts Options) (bool, error) {
 // Notably, Mask may return ErrDoesNotExist if a unit doesn't exist, but it will
 // continue masking anyway. Calling Mask on a non-existing masked unit does not
 // return an error. Similarly, see Unmask.
-func Mask(ctx context.Context, unit string, opts Options) error {
-	return mask(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Mask(ctx context.Context, unit string, opts Options, args ...string) error {
+	return mask(ctx, unit, opts, args...)
 }
 
 // Stop and then start one or more units specified on the command line.
 // If the units are not running yet, they will be started.
-func Restart(ctx context.Context, unit string, opts Options) error {
-	return restart(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Restart(ctx context.Context, unit string, opts Options, args ...string) error {
+	return restart(ctx, unit, opts, args...)
 }
 
 // Show a selected property of a unit. Accepted properties are predefined in the
 // properties subpackage to guarantee properties are valid and assist code-completion.
-func Show(ctx context.Context, unit string, property properties.Property, opts Options) (string, error) {
-	str, err := show(ctx, unit, property, opts)
-	return str, err
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Show(ctx context.Context, unit string, property properties.Property, opts Options, args ...string) (string, error) {
+	return show(ctx, unit, property, opts, args...)
 }
 
 // Start (activate) a given unit
-func Start(ctx context.Context, unit string, opts Options) error {
-	return start(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Start(ctx context.Context, unit string, opts Options, args ...string) error {
+	return start(ctx, unit, opts, args...)
 }
 
 // Get back the status string which would be returned by running
@@ -106,14 +124,17 @@ func Start(ctx context.Context, unit string, opts Options) error {
 //
 // Generally, it makes more sense to programmatically retrieve the properties
 // using Show, but this command is provided for the sake of completeness
-func Status(ctx context.Context, unit string, opts Options) (string, error) {
-	stat, err := status(ctx, unit, opts)
-	return stat, err
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Status(ctx context.Context, unit string, opts Options, args ...string) (string, error) {
+	return status(ctx, unit, opts, args...)
 }
 
 // Stop (deactivate) a given unit
-func Stop(ctx context.Context, unit string, opts Options) error {
-	return stop(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Stop(ctx context.Context, unit string, opts Options, args ...string) error {
+	return stop(ctx, unit, opts, args...)
 }
 
 // Unmask one or more unit files, as specified on the command line.
@@ -123,6 +144,8 @@ func Stop(ctx context.Context, unit string, opts Options) error {
 // doesn't exist, but only if it's not already masked.
 // If the unit doesn't exist but it's masked anyway, no error will be
 // returned. Gross, I know. Take it up with Poettering.
-func Unmask(ctx context.Context, unit string, opts Options) error {
-	return unmask(ctx, unit, opts)
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Unmask(ctx context.Context, unit string, opts Options, args ...string) error {
+	return unmask(ctx, unit, opts, args...)
 }