#define _XOPEN_SOURCE
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h> /* strerror(3) */
#include <unistd.h> /* crypt(3) */
void error(const char *);
void usage(FILE *, int);
int main(int argc, char **argv)
{
const char *hash, *key, *salt;
int opt, printed;
while ((opt = getopt(argc, argv, "h")) != -1) {
switch (opt) {
case 'h': /* Help */
usage(stdout, EXIT_SUCCESS);
break;
case '?': /* Unknown option */
usage(stderr, EXIT_FAILURE);
break;
default: /* Shouldn't happen */
abort();
}
}
/*
* If we don't have three arguments left after processing the options,
* exit with usage information and error status
*/
if (argc != 3) {
usage(stderr, EXIT_FAILURE);
}
key = argv[1];
salt = argv[2];
/*
* Create the hash, but exit immediately with the system error string
* if it returns a null pointer (error condition)
*/
if (!(hash = crypt(key, salt))) {
error(strerror(errno));
}
assert(strlen(hash) > 0);
/*
* Print the hash, and ensure we printed all of it
*/
if ((printed = printf("%s\n", hash)) < 0) {
error(strerror(errno));
}
assert(printed > 0);
if ((unsigned) printed < strlen(hash) + 1) { /* +1 for newline */
error("Incomplete print");
}
exit(EXIT_SUCCESS);
}
/*
* Exit with error message and status
*/
void error(const char *message)
{
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);
}
/*
* Show usage to given stream, and exit with given code
*/
void usage(FILE *stream, const int status)
{
fputs("USAGE: crypt [-h | KEY SALT]\n", stream);
exit(status);
}