forked from Bananymous/banan-os
368 lines
7.1 KiB
C++
368 lines
7.1 KiB
C++
#include <BAN/Vector.h>
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#include <BAN/String.h>
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#include <ctype.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/select.h>
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#include <termios.h>
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#include <unistd.h>
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struct config_t
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{
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bool raw { false };
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bool quit_if_one_screen { false };
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bool no_init { false };
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};
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static config_t config;
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static void usage(const char* argv0, int ret)
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{
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FILE* fout = ret ? stderr : stdout;
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fprintf(fout, "usage: %s [OPTIONS]... [--] [FILE]...\n", argv0);
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fprintf(fout, " -r, -R, --raw print ANSI control sequences\n");
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fprintf(fout, " -F, -quit-if-one-screen exit immediately if output fits in one screen\n");
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fprintf(fout, " -X, -no-init don't clear screen at the startup\n");
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fprintf(fout, " -h, --help show this message and exit\n");
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exit(ret);
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}
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static void handle_option_short(const char* argv0, char opt, bool exit_on_error)
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{
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switch (opt)
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{
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case 'r':
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case 'R':
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config.raw = true;
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break;
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case 'F':
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config.quit_if_one_screen = true;
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break;
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case 'X':
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config.no_init = true;
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break;
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case 'h':
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usage(argv0, 0);
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break;
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default:
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fprintf(stderr, "unknown option: %c\n", opt);
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fprintf(stderr, "see --help for usage\n");
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if (exit_on_error)
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exit(1);
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}
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}
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static void handle_option_long(const char* argv0, const char* opt, bool exit_on_error)
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{
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if (!strcmp(opt, "--raw"))
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config.raw = true;
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else if (!strcmp(opt, "--quit-if-one-screen"))
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config.quit_if_one_screen = true;
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else if (!strcmp(opt, "--no-init"))
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config.no_init = true;
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else if (!strcmp(opt, "--help"))
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usage(argv0, 0);
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else
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{
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fprintf(stderr, "unknown option: %s\n", opt);
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fprintf(stderr, "see --help for usage\n");
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if (exit_on_error)
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exit(1);
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}
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}
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static int parse_config_or_exit(int argc, char** argv)
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{
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// FIXME: long environment options
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if (const char* env = getenv("LESS"))
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for (size_t i = 0; env[i]; i++)
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(void)handle_option_short(argv[0], env[i], false);
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int i = 1;
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for (; i < argc; i++)
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{
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if (argv[i][0] != '-' || !strcmp(argv[i], "--"))
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break;
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if (argv[i][1] == '-')
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handle_option_long(argv[0], argv[i], true);
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else for (size_t j = 1; argv[i][j]; j++)
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handle_option_short(argv[0], argv[i][j], true);
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}
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return i;
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}
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static int get_keyboard_fd()
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{
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// if stdin is a terminal, use it
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if (isatty(STDIN_FILENO))
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return STDIN_FILENO;
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// otherwise try to open our controlling terminal
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int fd = open("/dev/tty", O_RDONLY);
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if (fd != -1)
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return fd;
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// if that fails, try stderr as the last fallback
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if (isatty(STDERR_FILENO))
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return STDERR_FILENO;
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return -1;
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}
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static int output_to_non_terminal(int fd)
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{
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for (;;)
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{
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char buffer[128];
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const ssize_t nread = read(fd, buffer, sizeof(buffer));
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if (nread == -1)
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perror("read");
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if (nread <= 0)
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break;
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ssize_t total = 0;
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while (total < nread)
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{
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const ssize_t nwrite = write(STDOUT_FILENO, buffer + total, nread - total);
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if (nwrite < 0)
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perror("write");
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if (nwrite <= 0)
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break;
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total += nwrite;
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}
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}
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return 0;
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}
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static bool read_lines(int fd, winsize ws, BAN::Vector<BAN::String>& out)
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{
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char buffer[128];
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const ssize_t nread = read(fd, buffer, sizeof(buffer));
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if (nread < 0)
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perror("read");
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if (nread <= 0)
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return false;
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if (out.empty())
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MUST(out.emplace_back());
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bool in_ansi = false;
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size_t col = 0;
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for (size_t i = 0; i < out.back().size(); i++)
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{
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if (in_ansi)
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{
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if (isalpha(out.back()[i]))
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in_ansi = false;
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}
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else if (out.back()[i] == '\e')
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in_ansi = true;
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else
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col++;
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}
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for (ssize_t i = 0; i < nread; i++)
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{
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if (in_ansi)
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{
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if (config.raw)
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MUST(out.back().push_back(buffer[i]));
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if (isalpha(buffer[i]))
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in_ansi = false;
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continue;
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}
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const auto append_char =
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[&col, &out, ws](char ch)
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{
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if (col >= ws.ws_col)
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{
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MUST(out.emplace_back());
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col = 0;
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}
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MUST(out.back().push_back(ch));
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col++;
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};
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switch (buffer[i])
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{
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case '\e':
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if (config.raw)
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MUST(out.back().push_back(buffer[i]));
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in_ansi = true;
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break;
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case '\n':
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MUST(out.emplace_back());
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col = 0;
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break;
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case '\t':
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append_char(' ');
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while (col % 8)
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append_char(' ');
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break;
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default:
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append_char(buffer[i]);
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break;
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}
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}
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return true;
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}
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static bool less_file(int fd, int kb_fd, winsize ws)
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{
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if (!isatty(STDOUT_FILENO) || kb_fd == -1 || ws.ws_col == 0 || ws.ws_row == 0)
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return output_to_non_terminal(fd);
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BAN::Vector<BAN::String> lines;
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size_t lines_size = 0;
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const auto update_lines_size =
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[&lines, &lines_size]
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{
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lines_size = lines.size();
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if (!lines.empty() && lines.back().empty())
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lines_size--;
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};
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while (lines_size < ws.ws_row)
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{
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if (!read_lines(fd, ws, lines))
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break;
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update_lines_size();
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}
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if (!config.no_init)
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{
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int y = 1;
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if (lines_size < ws.ws_row)
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y = ws.ws_row - lines_size;
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printf("\e[2J\e[%dH", y);
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}
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for (size_t i = 0; i < lines_size && i < static_cast<size_t>(ws.ws_row - 1); i++)
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printf("%s\n", lines[i].data());
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fflush(stdout);
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if (lines_size < ws.ws_row && config.quit_if_one_screen)
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return true;
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printf(":");
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fflush(stdout);
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size_t line = 0;
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for (;;)
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{
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char ch;
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if (read(kb_fd, &ch, 1) != 1)
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break;
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switch (ch)
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{
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case 'q':
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printf("\e[G\e[K");
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fflush(stdout);
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return true;
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case '\e':
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{
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if (read(kb_fd, &ch, 1) != 1 || ch != '[')
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break;
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if (read(kb_fd, &ch, 1) != 1)
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break;
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switch (ch)
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{
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case 'A':
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if (line == 0)
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break;
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line--;
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printf("\e[H");
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for (int i = 0; i < ws.ws_row - 1; i++)
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printf("%s\e[K\n", lines[line + i].data());
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printf(":\e[K");
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fflush(stdout);
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break;
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case 'B':
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while (lines_size - (line + 1) < ws.ws_row)
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{
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if (!read_lines(fd, ws, lines))
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break;
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update_lines_size();
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}
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if (lines_size - (line + 1) < static_cast<size_t>(ws.ws_row - 1))
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break;
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line++;
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printf("\e[H");
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for (int i = 0; i < ws.ws_row - 1; i++)
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printf("%s\e[K\n", lines[line + i].data());
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printf(":\e[K");
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fflush(stdout);
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break;
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}
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break;
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}
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}
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}
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return true;
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}
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int main(int argc, char** argv)
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{
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int i = parse_config_or_exit(argc, argv);
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int kb_fd = get_keyboard_fd();
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if (kb_fd != -1)
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{
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int flags = 0;
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fcntl(kb_fd, F_GETFL, &flags);
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if (flags & O_NONBLOCK)
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fcntl(kb_fd, F_SETFL, flags & ~O_NONBLOCK);
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termios termios;
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tcgetattr(kb_fd, &termios);
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termios.c_lflag &= ~(ECHO | ICANON);
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tcsetattr(kb_fd, TCSANOW, &termios);
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}
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winsize ws {};
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if (isatty(STDOUT_FILENO))
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{
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if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0)
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{
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// try to make stdout fully buffered to reduce flicker
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const size_t bufsize = 2 * ws.ws_row * ws.ws_col;
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if (char* buffer = static_cast<char*>(malloc(bufsize)))
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setvbuf(stdout, buffer, _IOFBF, bufsize);
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}
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}
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if (i == argc)
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{
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if (!less_file(STDIN_FILENO, kb_fd, ws))
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return EXIT_FAILURE;
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return EXIT_SUCCESS;
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}
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int ret = EXIT_SUCCESS;
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for (; i < argc; i++)
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{
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int fd = open(argv[i], O_RDONLY);
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if (fd == -1)
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{
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perror(argv[i]);
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continue;
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}
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if (!less_file(fd, kb_fd, ws))
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ret = EXIT_FAILURE;
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close(fd);
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}
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return ret;
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}
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