system/serenity
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tail: Implement byte mode into tail

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This works exactly the same as with lines but with bytes instead.
This commit is contained in:
Fabian Dellwing 2024-03-14 13:34:31 +01:00 committed by Andrew Kaster
parent 91e944d793
commit e511c553a8
1 changed files with 63 additions and 1 deletions
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64
Userland/Utilities/tail.cpp
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@ -83,6 +83,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
TRY(Core::System::pledge("stdio rpath"));
bool follow = false;
size_t wanted_byte_count = 0;
bool byte_mode = false;
size_t wanted_line_count = DEFAULT_LINE_COUNT;
bool start_from_end = true;
StringView file;
@ -114,6 +116,30 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
return true;
},
});
args_parser.add_option(Core::ArgsParser::Option {
.argument_mode = Core::ArgsParser::OptionArgumentMode::Required,
.help_string = "output the last NUM bytes; or use -c +NUM to"
" output starting with byte NUM",
.long_name = "bytes",
.short_name = 'c',
.value_name = "[+]NUM",
.accept_value = [&](StringView bytes) -> ErrorOr<bool> {
Optional<size_t> value;
if (bytes.starts_with('+')) {
value = bytes.substring_view(1, bytes.length() - 1).to_number<size_t>();
start_from_end = false;
} else {
value = bytes.to_number<size_t>();
}
if (!value.has_value()) {
warnln("Invalid number: {}", bytes);
return false;
}
wanted_byte_count = value.value();
byte_mode = true;
return true;
},
});
args_parser.add_positional_argument(file, "File path", "file", Core::ArgsParser::Required::No);
args_parser.parse(arguments);
@ -135,6 +161,26 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
size_t line_index = 0;
StringBuilder line;
if (byte_mode) {
if (start_from_end) {
if (wanted_byte_count > bytes.size()) {
out("{}", StringView { bytes });
continue;
}
out("{}", StringView { bytes }.substring_view(bytes.size() - wanted_byte_count, wanted_byte_count));
continue;
}
if (wanted_byte_count > bytes.size())
continue;
if (wanted_byte_count > 0)
out("{}", StringView { bytes }.substring_view(wanted_byte_count - 1, bytes.size() - wanted_byte_count + 1));
else
out("{}", StringView { bytes });
continue;
}
if (!line_count && wanted_line_count) {
out("{}", StringView { bytes });
continue;
@ -180,7 +226,23 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
return 0;
}
auto pos = TRY(find_seek_pos(*f, wanted_line_count, start_from_end));
off_t pos = 0;
if (byte_mode) {
auto file_size = TRY(f->size());
if (wanted_byte_count > file_size)
wanted_byte_count = file_size;
if (start_from_end) {
TRY(f->seek(wanted_byte_count * -1, SeekMode::FromEndPosition));
} else {
if (wanted_byte_count > 0 && wanted_byte_count < file_size)
TRY(f->seek(wanted_byte_count - 1, SeekMode::SetPosition));
else
TRY(f->seek(0, SeekMode::FromEndPosition));
}
pos = TRY(f->tell());
} else {
pos = TRY(find_seek_pos(*f, wanted_line_count, start_from_end));
}
TRY(tail_from_pos(*f, pos));
if (follow) {