Cthulhu is no longer a fork. Now it is a screen reader written in Golang.

internal/preferences/catalog_protocol.go

@@ -0,0 +1,124 @@
+// Copyright (c) 2026 Storm Dragon
+// Authors: Storm Dragon, Angus Kola
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package preferences
+
+import (
+	"bufio"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"sort"
+
+	"git.stormux.org/storm/cthulhu/internal/speech"
+)
+
+const initialMessageLimit = 512 * 1024
+
+type catalogPart struct {
+	Catalog        speech.Catalog
+	CatalogPending bool
+}
+
+// EncodeInitial keeps each protocol line bounded without removing voices or
+// languages. The helper assembles the catalog before constructing GTK controls.
+func EncodeInitial(encoder *json.Encoder, response Response) error {
+	encoded, err := json.Marshal(response)
+	if err != nil {
+		return err
+	}
+	if len(encoded)+1 <= initialMessageLimit {
+		return encoder.Encode(json.RawMessage(encoded))
+	}
+	catalog := response.Catalog
+	response.Catalog = nil
+	response.CatalogPending = true
+	encoded, err = json.Marshal(response)
+	if err != nil {
+		return err
+	}
+	if len(encoded)+1 > initialMessageLimit {
+		return fmt.Errorf("preferences settings exceed %d-byte protocol limit", initialMessageLimit)
+	}
+	if err := encoder.Encode(json.RawMessage(encoded)); err != nil {
+		return err
+	}
+	modules := make([]string, 0, len(catalog))
+	for module := range catalog {
+		modules = append(modules, module)
+	}
+	sort.Strings(modules)
+	for _, module := range modules {
+		voices := catalog[module]
+		for {
+			count := min(len(voices), 128)
+			for {
+				encoded, err = json.Marshal(catalogPart{
+					Catalog: speech.Catalog{module: voices[:count]}, CatalogPending: true,
+				})
+				if err != nil {
+					return err
+				}
+				if len(encoded)+1 <= initialMessageLimit {
+					break
+				}
+				if count <= 1 {
+					return fmt.Errorf("preferences voice in module %q exceeds %d-byte protocol limit", module, initialMessageLimit)
+				}
+				count /= 2
+			}
+			if err := encoder.Encode(json.RawMessage(encoded)); err != nil {
+				return err
+			}
+			voices = voices[count:]
+			if len(voices) == 0 {
+				break
+			}
+		}
+	}
+	return encoder.Encode(catalogPart{})
+}
+
+// read_responses owns catalog assembly for the lifetime of the helper pipe.
+// Only complete responses reach GTK, including after application selection.
+func read_responses(ctx context.Context, input io.Reader, updates chan<- Response, errorsIn chan<- error) {
+	scanner := bufio.NewScanner(input)
+	scanner.Buffer(make([]byte, 4096), 1024*1024)
+	var initial *Response
+	for scanner.Scan() {
+		var response Response
+		if err := json.Unmarshal(scanner.Bytes(), &response); err != nil {
+			errorsIn <- err
+			return
+		}
+		if initial != nil {
+			if initial.Catalog == nil {
+				initial.Catalog = make(speech.Catalog)
+			}
+			for module, voices := range response.Catalog {
+				initial.Catalog[module] = append(initial.Catalog[module], voices...)
+			}
+			if response.CatalogPending {
+				continue
+			}
+			response = *initial
+			response.CatalogPending = false
+			initial = nil
+		} else if response.CatalogPending {
+			initial = &response
+			continue
+		}
+		select {
+		case updates <- response:
+		case <-ctx.Done():
+			return
+		}
+	}
+	err := scanner.Err()
+	if err == nil && initial != nil {
+		err = io.ErrUnexpectedEOF
+	}
+	errorsIn <- err
+}