diff --git a/Userland/Utilities/hexdump.cpp b/Userland/Utilities/hexdump.cpp index 4b2e21d03a..6ccfd8d7c7 100644 --- a/Userland/Utilities/hexdump.cpp +++ b/Userland/Utilities/hexdump.cpp @@ -27,8 +27,11 @@ ErrorOr serenity_main(Main::Arguments args) Core::ArgsParser args_parser; char const* path = nullptr; bool verbose = false; + Optional max_bytes; + args_parser.add_positional_argument(path, "Input", "input", Core::ArgsParser::Required::No); args_parser.add_option(verbose, "Display all input data", "verbose", 'v'); + args_parser.add_option(max_bytes, "Truncate to a fixed number of bytes", nullptr, 'n', "bytes"); args_parser.parse(args); @@ -67,18 +70,34 @@ ErrorOr serenity_main(Main::Arguments args) Array contents; Span previous_line; static_assert(LINE_LENGTH_BYTES * 2 <= contents.size(), "Buffer is too small?!"); - size_t contents_size = 0; + size_t bytes_in_buffer = 0; + size_t total_bytes_read = 0; + size_t bytes_remaining = 0; + size_t bytes_to_read = 0; int nread; auto state = State::Print; - while (true) { - nread = file->read(&contents[contents_size], BUFSIZ - contents_size); + bool is_input_remaining = true; + while (is_input_remaining) { + bytes_to_read = BUFSIZ - bytes_in_buffer; + + if (max_bytes.has_value()) { + bytes_remaining = max_bytes.value() - total_bytes_read; + if (bytes_remaining < bytes_to_read) { + bytes_to_read = bytes_remaining; + is_input_remaining = false; + } + } + + nread = file->read(&contents[bytes_in_buffer], (int)bytes_to_read); if (nread <= 0) break; - contents_size += nread; + + total_bytes_read += nread; + bytes_in_buffer += nread; size_t offset; - for (offset = 0; offset + LINE_LENGTH_BYTES - 1 < contents_size; offset += LINE_LENGTH_BYTES) { + for (offset = 0; offset + LINE_LENGTH_BYTES - 1 < bytes_in_buffer; offset += LINE_LENGTH_BYTES) { if (verbose) { print_line(&contents[offset], LINE_LENGTH_BYTES); continue; @@ -106,17 +125,17 @@ ErrorOr serenity_main(Main::Arguments args) previous_line = current_line; } - contents_size -= offset; - VERIFY(contents_size < LINE_LENGTH_BYTES); + bytes_in_buffer -= offset; + VERIFY(bytes_in_buffer < LINE_LENGTH_BYTES); // If we managed to make the buffer exactly full, &contents[BUFSIZ] would blow up. - if (contents_size > 0) { + if (bytes_in_buffer > 0) { // Regions cannot overlap due to above static_assert. - memcpy(&contents[0], &contents[offset], contents_size); + memcpy(&contents[0], &contents[offset], bytes_in_buffer); } } - VERIFY(contents_size <= LINE_LENGTH_BYTES - 1); - if (contents_size > 0) - print_line(&contents[0], contents_size); + VERIFY(bytes_in_buffer <= LINE_LENGTH_BYTES - 1); + if (bytes_in_buffer > 0) + print_line(&contents[0], bytes_in_buffer); return 0; }