forked from bonsai/harakit
148 lines
4.0 KiB
C
148 lines
4.0 KiB
C
/*
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* Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU Affero General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see https://www.gnu.org/licenses/.
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*/
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#include <signal.h> /* sigaction(2), signal(2), struct sigaction, SIGINT */
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#include <stdbool.h> /* bool */
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#include <stdio.h> /* fprintf(3), fgetc(3), perror(3), fputc(3), stderr, stdin,
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* stdout, EOF, NULL */
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#include <stdlib.h> /* exit(3), EXIT_FAILURE */
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#include <sysexits.h> /* EX_IOERR, EX_OK, EX_USAGE */
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#include <termios.h> /* tcgetattr(3), tcsetattr(3), struct termios, ECHO */
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#include <unistd.h> /* getopt(3), isatty(3), pledge(2), unveil(2),
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* STDIN_FILENO */
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char *program_name = "peek";
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/* Restores terminal echo; otherwise when a user ^Cs the terminal would
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* continue to not display typed text. If sig isn't zero, this will terminate
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* the program. */
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static void
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restore_echo(int sig) {
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static struct termios t;
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/* Failure isn't reported because this is the termination routine anyway;
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* errors will be obvious. */
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if (tcgetattr(STDIN_FILENO, &t) == 0) {
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t.c_lflag |= ECHO;
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(void)tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
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}
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if (sig != 0) { exit(EXIT_FAILURE); } /* Terminated by signal. */
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return;
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}
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static int
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ioerr(char *argv0) {
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perror(argv0);
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restore_echo(0);
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return EX_IOERR;
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}
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static int
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usage(char *argv0) {
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(void)fprintf(stderr, "Usage: %s [-i]\n", argv0);
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return EX_USAGE;
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}
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int main(int argc, char *argv[]){
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bool is_term; /* Is stdin a terminal? */
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bool must_be_term = 1; /* Must it be? */
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#ifdef __OpenBSD__
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if (pledge("stdio tty unveil", "") != 0 || unveil(NULL, NULL) != 0) {
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/* This isn't fatal; these return values could be cast to void just as
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* easily. */
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(void)perror(argv[0] == NULL ? argv[0] : program_name);
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}
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#endif
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is_term = isatty(STDIN_FILENO);
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if (argc > 0) { /* option parsing */
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int c;
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program_name = argv[0];
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while ((c = getopt(argc, argv, "i")) != -1) {
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switch (c) {
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case 'i': must_be_term = 0; break;
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default: return usage(argv[0]);
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}
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}
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if (argc > optind) { return usage(argv[0]); }
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}
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if (!is_term && must_be_term) {
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(void)fprintf(
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stderr,
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"%s: Must be run in a terminal (specify -i to skip this check)\n",
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argv[0]
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);
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return EX_USAGE;
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}
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if (is_term) {
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{ /* Install signal handler */
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/* There isn't a difference in functionality between the signal(2)
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* and sigaction(2) methods. sigaction(2) is vastly preferred for
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* portability but some older systems only have signal(2). */
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/* Errors aren't terminating because the worst that happens is some
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* terminal phooeyness if things go awry. */
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#if defined _POSIX_C_SOURCE
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struct sigaction act = { 0 };
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act.sa_handler = restore_echo;
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if (sigaction(SIGINT, &act, NULL) != 0) { perror(program_name); }
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#else
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if (signal(SIGINT, restore_echo) == SIG_ERR) {
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perror(program_name);
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}
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#endif
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}
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{ /* Banish terminal echo */
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/* This terminates when it fails because it's the whole point of
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* the program. */
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struct termios t;
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if (tcgetattr(STDIN_FILENO, &t) != 0) {
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return ioerr(program_name);
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}
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t.c_lflag ^= ECHO;
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if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t) != 0) {
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return ioerr(program_name);
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}
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}
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}
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{ /* Input loop */
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int c;
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while ((c = fgetc(stdin)) != EOF) {
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if (fputc(c, stdout) == EOF) { return ioerr(program_name); }
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}
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}
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if (is_term) { restore_echo(0); }
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return EX_OK;
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}
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