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#define _GNU_SOURCE /* getline() */
#define _FORTIFY_SOURCE 2
#include <termios.h> /* struct termios, tcsetattr(),
TCSAFLUSH, tcgetattr(), ECHO */
#include <unistd.h> /* struct termios, tcsetattr(),
STDIN_FILENO, TCSAFLUSH,
tcgetattr(), ECHO */
#include <signal.h> /* sig_atomic_t, raise(), struct
sigaction, sigemptyset(),
sigaction(), sigaddset(), SIGINT,
SIGQUIT, SIGHUP, SIGTERM */
#include <stddef.h> /* NULL, size_t */
#include <sys/types.h> /* ssize_t */
#include <stdlib.h> /* EXIT_SUCCESS, EXIT_FAILURE */
#include <stdio.h> /* fprintf(), stderr, getline(),
stdin, feof(), perror(), fputc(),
stdout */
#include <errno.h> /* errno, EINVAL */
#include <iso646.h> /* or, not */
#include <stdbool.h> /* bool, false, true */
#include <string.h> /* strlen, rindex, strncmp, strcmp */
volatile bool quit_now = false;
bool debug = false;
void termination_handler(int signum){
quit_now = true;
}
int main(int argc, char **argv){
ssize_t ret = -1;
size_t n;
struct termios t_new, t_old;
char *buffer = NULL;
int status = EXIT_SUCCESS;
struct sigaction old_action,
new_action = { .sa_handler = termination_handler,
.sa_flags = 0 };
const char db[] = "--debug";
char *basename = rindex(argv[0], '/');
if(basename == NULL){
basename = argv[0];
} else {
basename++;
}
char *program_name = malloc(strlen(basename) + sizeof(db));
if (program_name == NULL){
perror("argv[0]");
return EXIT_FAILURE;
}
program_name[0] = '\0';
for (int i = 1; i < argc; i++){
if (not strncmp(argv[i], db, 5)){
strcat(strcat(strcat(program_name, db ), "="), basename);
if(not strcmp(argv[i], db) or not strcmp(argv[i], program_name)){
debug = true;
}
}
}
free(program_name);
if (debug){
fprintf(stderr, "Starting %s\n", argv[0]);
}
if (debug){
fprintf(stderr, "Storing current terminal attributes\n");
}
if (tcgetattr(STDIN_FILENO, &t_old) != 0){
return EXIT_FAILURE;
}
sigemptyset(&new_action.sa_mask);
sigaddset(&new_action.sa_mask, SIGINT);
sigaddset(&new_action.sa_mask, SIGQUIT);
sigaddset(&new_action.sa_mask, SIGHUP);
sigaddset(&new_action.sa_mask, SIGTERM);
sigaction(SIGINT, NULL, &old_action);
if (old_action.sa_handler != SIG_IGN)
sigaction(SIGINT, &new_action, NULL);
sigaction(SIGQUIT, NULL, &old_action);
if (old_action.sa_handler != SIG_IGN)
sigaction(SIGQUIT, &new_action, NULL);
sigaction(SIGHUP, NULL, &old_action);
if (old_action.sa_handler != SIG_IGN)
sigaction(SIGHUP, &new_action, NULL);
sigaction(SIGTERM, NULL, &old_action);
if (old_action.sa_handler != SIG_IGN)
sigaction(SIGTERM, &new_action, NULL);
if (debug){
fprintf(stderr, "Removing echo flag from terminal attributes\n");
}
t_new = t_old;
t_new.c_lflag &= ~ECHO;
if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t_new) != 0){
perror("tcsetattr-echo");
return EXIT_FAILURE;
}
if (debug){
fprintf(stderr, "Waiting for input from stdin \n");
}
while(true){
if (quit_now){
status = EXIT_FAILURE;
break;
}
fprintf(stderr, "Password: ");
ret = getline(&buffer, &n, stdin);
if (ret > 0){
fprintf(stdout, "%s", buffer);
status = EXIT_SUCCESS;
break;
}
// ret == 0 makes no other sence than to retry to read from stdin
if (ret < 0){
if (errno != EINTR and not feof(stdin)){
perror("getline");
status = EXIT_FAILURE;
break;
}
}
fputc('\n', stderr);
}
if (debug){
fprintf(stderr, "Restoring terminal attributes\n");
}
if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t_old) != 0){
perror("tcsetattr+echo");
}
if (debug){
fprintf(stderr, "%s is exiting\n", argv[0]);
}
return status;
}
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