add timeout option -t

Signed-off-by: Ludwig Nussel <ludwig.nussel@suse.de>

Index: hashalot-0.3/hashalot.c
===================================================================
--- hashalot-0.3/hashalot.c.orig
+++ hashalot-0.3/hashalot.c
@@ -21,6 +21,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <assert.h>
+#include <signal.h>
 
 #include <sys/types.h>
 #include <sys/mman.h>
@@ -36,6 +37,12 @@
 
 typedef int (*phash_func_t)(char dest[], size_t dest_len, const char src[], size_t src_len);
 
+static int got_timeout;
+void alrm_handler(int num)
+{
+	got_timeout = 1;
+}
+
 static int
 phash_rmd160(char dest[], size_t dest_len, const char src[], size_t src_len)
 {
@@ -101,9 +108,9 @@ show_usage(const char argv0[])
 
 	fprintf (stdout,
 		 "usage:\n"
-		 "    hashalot [ -x ] [ -s SALT ] [ -n _#bytes_ ] [ -C itercountk ] HASHTYPE\n"
+		 "    hashalot [ -t secs ] [ -x ] [ -s SALT ] [ -n _#bytes_ ] [ -C itercountk ] HASHTYPE\n"
 		 "  or\n"
-		 "    HASHTYPE [ -x ] [ -s SALT ] [ -n _#bytes_ ] [ -C itercountk ]\n"
+		 "    HASHTYPE [ -t secs ] [ -x ] [ -s SALT ] [ -n _#bytes_ ] [ -C itercountk ]\n"
 		 "\n"
 		 "supported values for HASHTYPE: ");
 
@@ -219,8 +226,9 @@ main(int argc, char *argv[]) 
 	phash_func_t func;
 	int hex_output = 0, c;
 	unsigned long itercountk = 0;
+	unsigned timeout = 0;
 
-	while ((c = getopt(argc, argv, "n:s:xC:")) != -1) {
+	while ((c = getopt(argc, argv, "n:s:xC:t:")) != -1) {
 		switch (c) {
 		case 'n':
 			hashlen = strtoul(optarg, &p, 0);
@@ -235,6 +243,9 @@ main(int argc, char *argv[]) 
                 case 's':
                         salt = optarg;
                         break;
+		case 't':
+			timeout = atoi(optarg);
+			break;
 		case 'x':
 			hex_output++;
 			break;
@@ -273,12 +284,25 @@ main(int argc, char *argv[]) 
 		fputs("Warning: couldn't lock memory, are you root?\n", stderr);
 	}
 
+	if(timeout) {
+		struct sigaction sa;
+		sa.sa_handler = alrm_handler;
+		sigemptyset (&sa.sa_mask);
+		sa.sa_flags = 0;
+		sigaction(SIGALRM, &sa, NULL);
+		alarm(timeout);
+	}
+
 	/* here we acquire the precious passphrase... */
 	pass = xgetpass("Enter passphrase: ");
-	if(!*pass) {
+	if(got_timeout || !*pass) {
 		exit(EXIT_FAILURE);
 	}
 
+	if(timeout) {
+		alarm(0);
+	}
+
 	if (salt)
 		pass = salt_passphrase(pass, salt);
 	hashlen = func(passhash, hashlen, pass, strlen(pass));