lock.c

#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>



void message(pid_t pid )
{
	fprintf(stderr, "\nLock (pid=%d) -- terminal locker for Linux.\n", pid);
}

void usage()
{
	fprintf(stderr, "Usage:\n");
	fprintf(stderr, "\tLock \n");
	fprintf(stderr, "\tLock [password]\n");
	fprintf(stderr, "\tLock -f[file with password]\n");
}

int main(int argc, char **argv)
{

	pid_t pid;
	char *fname = "lock.pas";//"~/backup/lock.passwd";
	char *tty;
	char key[256], senha[256], senha2[256];
	int counterr=0;
	FILE *file;
		
	pid =getpid();
	message(pid);
	
	
	signal(SIGINT, SIG_IGN);
	signal(SIGQUIT, SIG_IGN);
	signal(SIGTSTP, SIG_IGN);
	signal(SIGTTIN, SIG_IGN);
	signal(SIGTTOU, SIG_IGN);

	
	if (argc > 1)
	{
		if ( !strncmp(argv[1],"-",1) )
		{
			if ( !strncmp(argv[1],"-f",2) && strlen(argv[1]) > 2 )
			{
				argv[1] += 2;
				if ( file=fopen(argv[1],"r") )
				{
					fscanf(file,"%s",&senha);
					fclose(file);
				}
				else
				{
					fprintf(stderr, "ERROR read file %s\n",argv[1]);
				}
			}
			else
			{
				usage();
				exit(1);
			}
		}
		else
		{
			strncpy(senha,argv[1],255);
		}
	}

	
	if ( !strcmp(senha,"") )
	{
		do
		{
			fprintf(stderr, "\nYour password does not need to be your login password.");
			strncpy(senha, getpass("\nEnter password: "), 255);
			senha[255]='\0';
	
			strncpy(senha2, getpass("ReEnter password: "), 255);
			senha2[255]='\0';
			if (strcmp(senha, senha2))
			{
				fprintf(stderr, "Sorry, password does not match!\n");
				counterr++;
			}
		}while(strcmp(senha, senha2) && counterr<4);
	
		if ( counterr==4 )
		{
			fprintf(stderr, "\nSorry, error to much!\n");
			exit(1);
		}
	}	

	
		
	tty = ttyname(0);
	counterr=0;
	

	while(1)
	{
		fprintf(stderr, "\nThis terminal (%s) is locked by ", tty);
		strncpy(key, getpass("\nEnter password to unlock: "), 255);
		key[255]='\0';
		if (!strcmp(senha, key))
		{
			fprintf(stderr,"Unlocked after %d errors\n\n",counterr);
			exit(0);
		}
		else
		{
			if(file=fopen(fname,"a+"))
			{
				fprintf(file,"%s\n",key);
				fclose(file);
			}

			fprintf(stderr, "\nInvalid Password\n");
			counterr++;
			if (counterr%10 == 0 )
			{
				fprintf(stderr, "Many errros, wait 15 secs\n");
				message(pid);
				sleep(10);
			}
			else
			{
				fprintf(stderr, "\n");
				sleep(1);
			}
		}
	}
}