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#define _GNU_SOURCE /* getline() */
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#define _FORTIFY_SOURCE 2
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#include <termios.h> /* struct termios, tcsetattr(),
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TCSAFLUSH, tcgetattr(), ECHO */
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#include <unistd.h> /* struct termios, tcsetattr(),
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STDIN_FILENO, TCSAFLUSH,
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#include <signal.h> /* sig_atomic_t, raise(), struct
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sigaction, sigemptyset(),
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sigaction(), sigaddset(), SIGINT,
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SIGQUIT, SIGHUP, SIGTERM */
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#include <stddef.h> /* NULL, size_t */
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#include <sys/types.h> /* ssize_t */
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#include <stdlib.h> /* EXIT_SUCCESS, EXIT_FAILURE,
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#include <stdio.h> /* fprintf(), stderr, getline(),
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stdin, feof(), perror(), fputc(),
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stdout, getopt_long */
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#include <errno.h> /* errno, EINVAL */
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#include <iso646.h> /* or, not */
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#include <stdbool.h> /* bool, false, true */
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#include <string.h> /* strlen, rindex, strncmp, strcmp */
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#include <getopt.h> /* getopt_long */
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volatile bool quit_now = false;
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void termination_handler(int signum){
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int main(int argc, char **argv){
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struct termios t_new, t_old;
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int status = EXIT_SUCCESS;
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struct sigaction old_action,
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new_action = { .sa_handler = termination_handler,
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static struct option long_options[] = {
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{"debug", no_argument, (int *)&debug, 1},
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{"prefix", required_argument, 0, 'p'},
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ret = getopt_long (argc, argv, "p:", long_options, &option_index);
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fprintf(stderr, "bad arguments\n");
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fprintf(stderr, "Starting %s\n", argv[0]);
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fprintf(stderr, "Storing current terminal attributes\n");
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if (tcgetattr(STDIN_FILENO, &t_old) != 0){
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sigemptyset(&new_action.sa_mask);
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sigaddset(&new_action.sa_mask, SIGINT);
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sigaddset(&new_action.sa_mask, SIGQUIT);
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sigaddset(&new_action.sa_mask, SIGHUP);
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sigaddset(&new_action.sa_mask, SIGTERM);
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sigaction(SIGINT, NULL, &old_action);
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if (old_action.sa_handler != SIG_IGN)
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sigaction(SIGINT, &new_action, NULL);
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sigaction(SIGQUIT, NULL, &old_action);
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if (old_action.sa_handler != SIG_IGN)
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sigaction(SIGQUIT, &new_action, NULL);
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sigaction(SIGHUP, NULL, &old_action);
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if (old_action.sa_handler != SIG_IGN)
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sigaction(SIGHUP, &new_action, NULL);
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sigaction(SIGTERM, NULL, &old_action);
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if (old_action.sa_handler != SIG_IGN)
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sigaction(SIGTERM, &new_action, NULL);
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fprintf(stderr, "Removing echo flag from terminal attributes\n");
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t_new.c_lflag &= ~ECHO;
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if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t_new) != 0){
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perror("tcsetattr-echo");
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fprintf(stderr, "Waiting for input from stdin \n");
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status = EXIT_FAILURE;
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fprintf(stderr, "%s Password: ", prefix);
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fprintf(stderr, "Password: ");
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ret = getline(&buffer, &n, stdin);
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fprintf(stdout, "%s", buffer);
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status = EXIT_SUCCESS;
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// ret == 0 makes no other sence than to retry to read from stdin
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if (errno != EINTR and not feof(stdin)){
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status = EXIT_FAILURE;
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fprintf(stderr, "Restoring terminal attributes\n");
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if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t_old) != 0){
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perror("tcsetattr+echo");
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fprintf(stderr, "%s is exiting\n", argv[0]);