148 lines
3.5 KiB
Go
148 lines
3.5 KiB
Go
// Copyright (c) 2026 Storm Dragon
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// SPDX-License-Identifier: GPL-3.0-or-later
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package spellcheck
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import (
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"sort"
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"strings"
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"syscall"
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"time"
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)
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func Exceptions_path(home string) string {
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return filepath.Join(home, ".local/share/stormux/fenrirscreenreader/spelling/exceptions.json")
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}
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func load_exceptions(path string) (map[string]string, error) {
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words := make(map[string]string)
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file, err := os.Open(path)
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if errors.Is(err, os.ErrNotExist) {
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return words, nil
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}
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if err != nil {
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return nil, err
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}
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defer file.Close()
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data, err := io.ReadAll(io.LimitReader(file, (1<<20)+1))
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if err != nil {
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return nil, err
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}
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if len(data) > 1<<20 {
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return nil, fmt.Errorf("exceptions file exceeds 1 MiB")
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}
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var entries []string
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if err := json.Unmarshal(data, &entries); err != nil {
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return nil, err
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}
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for _, word := range entries {
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if !valid_word(word) {
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return nil, fmt.Errorf("invalid exceptions file")
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}
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words[strings.ToLower(word)] = word
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}
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return words, nil
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}
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func exception_list(words map[string]string) []string {
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entries := make([]string, 0, len(words))
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for _, word := range words {
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entries = append(entries, word)
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}
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sort.Slice(entries, func(i, j int) bool { return strings.ToLower(entries[i]) < strings.ToLower(entries[j]) })
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return entries
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}
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// Each edit reloads the latest list while holding a stable, per-file lock.
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// Atomic replacement alone cannot protect against another reader's stale copy.
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func update_exceptions(ctx context.Context, path string, operation Operation, word string) (map[string]string, error) {
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if err := os.MkdirAll(filepath.Dir(path), 0700); err != nil {
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return nil, err
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}
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lock, err := os.OpenFile(path+".lock", os.O_CREATE|os.O_RDWR|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0600)
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if err != nil {
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return nil, err
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}
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defer lock.Close()
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info, err := lock.Stat()
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if err != nil {
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return nil, err
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}
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if !info.Mode().IsRegular() || info.Mode().Perm()&0077 != 0 || info.Sys().(*syscall.Stat_t).Uid != uint32(os.Geteuid()) {
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return nil, fmt.Errorf("exceptions lock must be private and owned by the current account")
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}
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waitCtx, cancel := context.WithTimeout(ctx, 2*time.Second)
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defer cancel()
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for {
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if err := waitCtx.Err(); err != nil {
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return nil, err
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}
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err = syscall.Flock(int(lock.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
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if err == nil {
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break
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}
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if !errors.Is(err, syscall.EWOULDBLOCK) {
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return nil, err
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}
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timer := time.NewTimer(10 * time.Millisecond)
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select {
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case <-waitCtx.Done():
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timer.Stop()
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return nil, waitCtx.Err()
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case <-timer.C:
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}
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}
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words, err := load_exceptions(path)
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if err != nil {
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return nil, err
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}
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key := strings.ToLower(word)
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if operation == Add {
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words[key] = word
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} else {
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delete(words, key)
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}
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if err := save_exceptions(path, words); err != nil {
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return nil, err
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}
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return words, nil
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}
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func save_exceptions(path string, words map[string]string) error {
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data, err := json.MarshalIndent(exception_list(words), "", " ")
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if err != nil {
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return err
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}
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if len(data) > 1<<20 {
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return fmt.Errorf("exceptions file exceeds 1 MiB")
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}
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dir := filepath.Dir(path)
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if err := os.MkdirAll(dir, 0700); err != nil {
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return err
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}
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file, err := os.CreateTemp(dir, ".exceptions-*.json")
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if err != nil {
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return err
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}
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defer os.Remove(file.Name())
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if _, err := file.Write(append(data, '\n')); err != nil {
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file.Close()
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return err
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}
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if err := file.Sync(); err != nil {
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file.Close()
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return err
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}
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if err := file.Close(); err != nil {
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return err
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}
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return os.Rename(file.Name(), path)
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}
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