After commit c018f5fd29 Fenrir is being switched over to go. If you do not want to be part of the testing process, please switch to master.

internal/speech/drivers.go

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+// Fenrir console screen reader.
+// Copyright (c) 2026 Storm Dragon
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+// more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program. If not, see <https://www.gnu.org/licenses/gpl-3.0.html>.
+
+package speech
+
+import "fmt"
+
+// Driver binds a stable file/CLI ID to its implementation. Availability must
+// be a cheap dependency/hardware check, never connect, speak or start a service.
+// Connection failures are reported by Open and never select another driver.
+type Driver struct {
+	ID, Label string
+	Serial    bool
+	Hardware  bool
+	Check     func() error
+	Open      func(Options) (Transport, error)
+	Modules   func(Options) ([]string, error)
+	Catalog   func(Options) (Catalog, error)
+	Voices    func(Options) ([]Voice, error)
+}
+
+func (d Driver) Availability() error {
+	if d.Check != nil {
+		return d.Check()
+	}
+	return nil
+}
+
+var drivers = append([]Driver{{
+	ID: "speech-dispatcher", Label: "Speech Dispatcher",
+	Open: func(options Options) (Transport, error) {
+		if options.Socket == "" {
+			options.Socket = Default_socket()
+		}
+		return Open(options)
+	},
+	Modules: discover_modules,
+	Catalog: Discover,
+	Voices:  discover_voices,
+}}, hardware_drivers()...)
+
+func hardware_drivers() []Driver {
+	var result []Driver
+	for _, entry := range []struct{ id, label string }{
+		{"dectalk", "DECtalk"}, {"dectalk-usb", "DECtalk USB"},
+		{"litetalk", "LiteTalk"}, {"doubletalk", "DoubleTalk LT"}, {"tripletalk", "TripleTalk"},
+	} {
+		driver := Driver{ID: entry.id, Label: entry.label,
+			Serial:   entry.id != "dectalk-usb",
+			Hardware: true,
+			Open:     func(options Options) (Transport, error) { return open_hardware(entry.id, options) },
+		}
+		if entry.id == "dectalk-usb" {
+			driver.Check = usb_available
+		}
+		result = append(result, driver)
+	}
+	return result
+}
+
+// Drivers returns a copy; registering a completed implementation here supplies
+// settings validation, UI choices, discovery and startup from the same entry.
+func Drivers() []Driver { return append([]Driver(nil), drivers...) }
+
+func Find_driver(id string) (Driver, error) {
+	for _, driver := range drivers {
+		if driver.ID == id {
+			return driver, nil
+		}
+	}
+	return Driver{}, fmt.Errorf("unknown speech driver %q", id)
+}
+
+func Open_driver(id string, options Options) (Transport, error) {
+	driver, err := Find_driver(id)
+	if err != nil {
+		return nil, err
+	}
+	if err := Validate_driver_options(id, options); err != nil {
+		return nil, err
+	}
+	if err = driver.Availability(); err != nil {
+		return nil, fmt.Errorf("speech driver %s unavailable: %w", id, err)
+	}
+	return driver.Open(options)
+}
+
+// discover_modules uses a separate, bounded connection. It never changes the
+// active speaking client, cancels speech or starts a speech service.
+func discover_modules(options Options) ([]string, error) {
+	if options.Socket == "" {
+		options.Socket = Default_socket()
+	}
+	wire, err := connect(options.Socket)
+	if err != nil {
+		return nil, err
+	}
+	defer wire.conn.Close()
+	modules, err := wire.command("LIST OUTPUT_MODULES")
+	if err != nil {
+		return nil, err
+	}
+	seen := map[string]bool{}
+	for _, module := range modules {
+		if !valid_module(module) || module == "" || seen[module] {
+			return nil, fmt.Errorf("invalid Speech Dispatcher module list")
+		}
+		seen[module] = true
+	}
+	return modules, nil
+}
+
+func valid_module(module string) bool {
+	for _, char := range module {
+		if !(char >= 'a' && char <= 'z' || char >= 'A' && char <= 'Z' || char >= '0' && char <= '9' || char == '.' || char == '_' || char == '+' || char == '-') {
+			return false
+		}
+	}
+	return true
+}