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tail: Handle truncation in follow mode

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Fabian Dellwing 2024-02-12 16:05:33 +01:00 • committed by Andrew Kaster
parent 5180e41918
commit e40aca2d77
1 changed files with 21 additions and 0 deletions
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21
Userland/Utilities/tail.cpp
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@ -64,6 +64,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
size_t wanted_line_count = DEFAULT_LINE_COUNT; size_t wanted_line_count = DEFAULT_LINE_COUNT;
bool start_from_end = true; bool start_from_end = true;
StringView file; StringView file;
size_t file_size;
Core::ArgsParser args_parser; Core::ArgsParser args_parser;
args_parser.set_general_help("Print the end ('tail') of a file."); args_parser.set_general_help("Print the end ('tail') of a file.");
@ -158,12 +159,32 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
TRY(tail_from_pos(*f, pos)); TRY(tail_from_pos(*f, pos));
if (follow) { if (follow) {
file_size = TRY(f->size());
TRY(f->seek(0, SeekMode::FromEndPosition)); TRY(f->seek(0, SeekMode::FromEndPosition));
Core::EventLoop event_loop; Core::EventLoop event_loop;
auto watcher = TRY(Core::FileWatcher::create()); auto watcher = TRY(Core::FileWatcher::create());
watcher->on_change = [&](Core::FileWatcherEvent const& event) { watcher->on_change = [&](Core::FileWatcherEvent const& event) {
if (event.type == Core::FileWatcherEvent::Type::ContentModified) { if (event.type == Core::FileWatcherEvent::Type::ContentModified) {
auto maybe_current_size = f->size();
if (maybe_current_size.is_error()) {
auto error = maybe_current_size.release_error();
warnln(error.string_literal());
event_loop.quit(error.code());
return;
}
auto current_size = maybe_current_size.value();
if (current_size < file_size) {
warnln("{}: file truncated", event.event_path);
auto maybe_seek_error = f->seek(0, SeekMode::SetPosition);
if (maybe_seek_error.is_error()) {
auto error = maybe_seek_error.release_error();
warnln(error.string_literal());
event_loop.quit(error.code());
return;
}
}
file_size = current_size;
auto buffer_or_error = f->read_until_eof(); auto buffer_or_error = f->read_until_eof();
if (buffer_or_error.is_error()) { if (buffer_or_error.is_error()) {
auto error = buffer_or_error.release_error(); auto error = buffer_or_error.release_error();