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tail: Collapse repeated error handling into statement expression

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Co-authored-by: Timothy Flynn <trflynn89@pm.me>
This commit is contained in:
Fabian Dellwing 2024-02-19 20:46:56 +01:00 committed by Andrew Kaster
parent e40aca2d77
commit 29ef508b4e
Notes: sideshowbarker 2024-07-17 09:37:30 +09:00 
Author: https://github.com/fdellwing
Commit: https://github.com/SerenityOS/serenity/commit/29ef508b4e
Pull-request: https://github.com/SerenityOS/serenity/pull/23168
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/gmta
1 changed files with 18 additions and 31 deletions
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49
Userland/Utilities/tail.cpp
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@ -11,6 +11,20 @@
#include <LibCore/FileWatcher.h> #include <LibCore/FileWatcher.h>
#include <LibCore/System.h> #include <LibCore/System.h>
#define TRY_OR_REPORT_ERROR(expression) \
({ \
/* Ignore -Wshadow to allow nesting the macro. */ \
AK_IGNORE_DIAGNOSTIC("-Wshadow", \
auto&& _temporary_result = (expression)); \
static_assert(!::AK::Detail::IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
if (_temporary_result.is_error()) [[unlikely]] { \
warnln("{}", _temporary_result.error().string_literal()); \
event_loop.quit(_temporary_result.error().code()); \
} \
_temporary_result.release_value(); \
})
#define DEFAULT_LINE_COUNT 10 #define DEFAULT_LINE_COUNT 10
static ErrorOr<void> tail_from_pos(Core::File& file, off_t startline) static ErrorOr<void> tail_from_pos(Core::File& file, off_t startline)
@ -166,42 +180,15 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
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(); auto current_size = TRY_OR_REPORT_ERROR(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) { if (current_size < file_size) {
warnln("{}: file truncated", event.event_path); warnln("{}: file truncated", event.event_path);
auto maybe_seek_error = f->seek(0, SeekMode::SetPosition); TRY_OR_REPORT_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; file_size = current_size;
auto buffer_or_error = f->read_until_eof(); auto bytes = TRY_OR_REPORT_ERROR(f->read_until_eof());
if (buffer_or_error.is_error()) {
auto error = buffer_or_error.release_error();
warnln(error.string_literal());
event_loop.quit(error.code());
return;
}
auto bytes = buffer_or_error.value().bytes();
out("{}", StringView { bytes }); out("{}", StringView { bytes });
TRY_OR_REPORT_ERROR(f->seek(0, SeekMode::FromEndPosition));
auto potential_error = f->seek(0, SeekMode::FromEndPosition);
if (potential_error.is_error()) {
auto error = potential_error.release_error();
warnln(error.string_literal());
event_loop.quit(error.code());
return;
}
} }
}; };
TRY(watcher->add_watch(file, Core::FileWatcherEvent::Type::ContentModified)); TRY(watcher->add_watch(file, Core::FileWatcherEvent::Type::ContentModified));