tfrand: first cmdline argument defines random source file name.

tfrand.c

@@ -1,3 +1,5 @@
+#include <stdio.h>
+#include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -13,11 +15,25 @@ static char key[TFNG_KEY_SIZE];
 int main(int argc, char **argv)
 {
 	int fd;
+	char *randsource;
 
-	fd = open("/dev/urandom", O_RDONLY);
+	if (argc > 1 && argv[1]) {
+		if (!strcmp(argv[1], "-")) {
+			fd = 0;
+			goto _stdinrnd;
+		}
+		randsource = argv[1];
+	}
+	else randsource = "/dev/urandom";
+
+	fd = open(randsource, O_RDONLY);
 	if (fd != -1) {
-		read(fd, key, sizeof(key));
-		close(fd);
+_stdinrnd:	read(fd, key, sizeof(key));
+		if (fd != 0) close(fd);
+	}
+	else {
+		perror(argv[1]);
+		return 1;
 	}
 
 	tfng_prng_seedkey(key);