/* * Copyright (c) 2021, Peter Elliott * * SPDX-License-Identifier: BSD-2-Clause */ #include #include #include #include #include #include #include #include #include #include #include #include #include static struct termios g_save; static struct winsize g_wsize; static void setup_tty(bool switch_buffer) { // Save previous tty settings. if (tcgetattr(STDOUT_FILENO, &g_save) == -1) { perror("tcgetattr(3)"); } // Get the window size. if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &g_wsize) == -1) { perror("ioctl(2)"); } struct termios raw = g_save; raw.c_lflag &= ~(ECHO | ICANON); // Disable echo and line buffering if (tcsetattr(STDOUT_FILENO, TCSAFLUSH, &raw) == -1) { perror("tcsetattr(3)"); } if (switch_buffer) { // Save cursor and switch to alternate buffer. out("\e[s\e[?1047h"); } } static void teardown_tty(bool switch_buffer) { if (tcsetattr(STDOUT_FILENO, TCSAFLUSH, &g_save) == -1) { perror("tcsetattr(3)"); } if (switch_buffer) { out("\e[?1047l\e[u"); } } static Vector wrap_line(Utf8View const& string, size_t width) { Vector lines; StringBuilder builder; size_t offset = 0; bool in_ansi = false; for (auto codepoint : string) { if (offset >= width) { builder.append('\n'); lines.append(builder.build()); builder.clear(); offset = 0; } builder.append(codepoint); if (codepoint == '\e') in_ansi = true; if (!in_ansi) // FIXME: calcuate the printed width of the character. offset++; if (isalpha(codepoint)) in_ansi = false; } if (builder.length() > 0) lines.append(builder.build()); return lines; } class Pager { public: Pager(FILE* file, FILE* tty, size_t width, size_t height) : m_file(file) , m_tty(tty) , m_width(width) , m_height(height) { } void up() { up_n(1); } void down() { down_n(1); } void up_page() { up_n(m_height - 1); } void down_page() { down_n(m_height - 1); } void up_n(size_t n) { if (m_line == 0) return; m_line = (m_line > n) ? m_line - n : 0; // Clear screen and reset cursor position. out("\e[2J\e[0G\e[0d"); write_range(m_line, m_height - 1); status_line(); fflush(m_tty); } void down_n(size_t n) { clear_status(); while (n - (m_lines.size() - m_line) + m_height - 1 > 0) { if (!read_line()) break; } m_line += write_range(min(m_line + m_height - 1, m_line + (m_lines.size() - m_line)), n); status_line(); fflush(m_tty); } void top() { up_n(m_line); } void bottom() { while (read_line()) ; down_n(m_lines.size() - m_line); } void up_half_page() { up_n(m_height / 2); } void down_half_page() { down_n(m_height / 2); } void go_to_line(size_t line_num) { if (line_num < m_line) { up_n(m_line - line_num); } else { down_n(line_num - m_line); } } void init() { while (m_lines.size() < m_height) { if (!read_line()) break; } write_range(0, m_height - 1); status_line(); m_line = 0; fflush(m_tty); } size_t write_range(size_t start, size_t length) { size_t lines = min(length, m_lines.size() - start); for (size_t i = 0; i < lines; ++i) { out(m_tty, "{}", m_lines[start + i]); } return lines; } void clear_status() { out(m_tty, "\e[2K\r"); } void status_line() { out(m_tty, "\e[7m "); render_status_line(m_prompt); out(m_tty, " \e[27m"); } void set_filename(StringView const& filename) { m_filename = filename; } void set_prompt(StringView const& prompt) { m_prompt = prompt; } bool read_line() { char* line = nullptr; size_t n = 0; ssize_t size = getline(&line, &n, m_file); if (size == -1) return false; m_lines.extend(wrap_line(Utf8View(line), m_width)); free(line); return true; } bool at_end() { return (m_line + m_height - 1) >= m_lines.size() && feof(m_file); } private: size_t render_status_line(StringView const& prompt, size_t off = 0, char end = '\0', bool ignored = false) { for (; prompt[off] != end && off < prompt.length(); ++off) { if (ignored) continue; if (off + 1 >= prompt.length()) { // Don't parse any multi-character sequences if we are at the end of input. out(m_tty, "{}", prompt[off]); continue; } switch (prompt[off]) { case '?': switch (prompt[++off]) { case 'f': off = render_status_line(prompt, off + 1, ':', m_file == stdin); off = render_status_line(prompt, off + 1, '.', m_file != stdin); break; case 'e': off = render_status_line(prompt, off + 1, ':', !at_end()); off = render_status_line(prompt, off + 1, '.', at_end()); break; default: // Unknown flags are never true. off = render_status_line(prompt, off + 1, ':', true); off = render_status_line(prompt, off + 1, '.', false); } break; case '%': switch (prompt[++off]) { case 'f': out(m_tty, "{}", m_filename); break; case 'l': out(m_tty, "{}", m_line); break; default: out(m_tty, "?"); } break; case '\\': ++off; [[fallthrough]]; default: out(m_tty, "{}", prompt[off]); } } return off; } // FIXME: Don't save scrollback when emulating more. Vector m_lines; size_t m_line { 0 }; FILE* m_file; FILE* m_tty; size_t m_width; size_t m_height; String m_filename; String m_prompt; }; static String get_key_sequence() { // We need a buffer to handle ansi sequences. char buff[8]; ssize_t n = read(STDOUT_FILENO, buff, sizeof(buff)); return String(buff, n); } static void cat_file(FILE* file) { ByteBuffer buffer = ByteBuffer::create_uninitialized(4096); while (!feof(file)) { size_t n = fread(buffer.data(), 1, buffer.size(), file); if (n == 0 && ferror(file)) { perror("fread"); exit(1); } n = fwrite(buffer.data(), 1, n, stdout); if (n == 0 && ferror(stdout)) { perror("fwrite"); exit(1); } } } int main(int argc, char** argv) { if (pledge("stdio rpath tty", nullptr) < 0) { perror("pledge"); return 1; } char const* filename = "-"; char const* prompt = "?f%f :.(line %l)?e (END):."; bool dont_switch_buffer = false; bool quit_at_eof = false; bool emulate_more = false; if (LexicalPath::basename(argv[0]) == "more"sv) emulate_more = true; Core::ArgsParser args_parser; args_parser.add_positional_argument(filename, "The paged file", "file", Core::ArgsParser::Required::No); args_parser.add_option(prompt, "Prompt line", "prompt", 'P', "Prompt"); args_parser.add_option(dont_switch_buffer, "Don't use xterm alternate buffer", "no-init", 'X'); args_parser.add_option(quit_at_eof, "Exit when the end of the file is reached", "quit-at-eof", 'e'); args_parser.add_option(emulate_more, "Pretend that we are more(1)", "emulate-more", 'm'); args_parser.parse(argc, argv); FILE* file; if (String("-") == filename) { file = stdin; } else if ((file = fopen(filename, "r")) == nullptr) { perror("fopen"); exit(1); } if (pledge("stdio tty", nullptr) < 0) { perror("pledge"); return 1; } if (emulate_more) { // Configure options that match more's behavior dont_switch_buffer = true; quit_at_eof = true; prompt = "--More--"; } if (!isatty(STDOUT_FILENO)) { cat_file(file); return 0; } setup_tty(!dont_switch_buffer); Pager pager(file, stdout, g_wsize.ws_col, g_wsize.ws_row); pager.set_filename(filename); pager.set_prompt(prompt); pager.init(); StringBuilder modifier_buffer = StringBuilder(10); for (String sequence;; sequence = get_key_sequence()) { if (sequence.to_uint().has_value()) { modifier_buffer.append(sequence); } else { if (sequence == "" || sequence == "q") { break; } else if (sequence == "j" || sequence == "\e[B" || sequence == "\n") { if (!emulate_more) { if (!modifier_buffer.is_empty()) pager.down_n(modifier_buffer.build().to_uint().value_or(1)); else pager.down(); } } else if (sequence == "k" || sequence == "\e[A") { if (!emulate_more) { if (!modifier_buffer.is_empty()) pager.up_n(modifier_buffer.build().to_uint().value_or(1)); else pager.up(); } } else if (sequence == "g") { if (!emulate_more) { if (!modifier_buffer.is_empty()) pager.go_to_line(modifier_buffer.build().to_uint().value()); else pager.top(); } } else if (sequence == "G") { if (!emulate_more) { if (!modifier_buffer.is_empty()) pager.go_to_line(modifier_buffer.build().to_uint().value()); else pager.bottom(); } } else if (sequence == " " || sequence == "\e[6~") { pager.down_page(); } else if (sequence == "\e[5~" && !emulate_more) { pager.up_page(); } else if (sequence == "d") { pager.down_half_page(); } else if (sequence == "u" && !emulate_more) { pager.up_half_page(); } modifier_buffer.clear(); } if (quit_at_eof && pager.at_end()) break; } pager.clear_status(); teardown_tty(!dont_switch_buffer); return 0; }