20110512-2206

random.c

@@ -0,0 +1,58 @@
+#include <plan9.h>
+#include <fcall.h>
+#include <u9fs.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <fcntl.h>
+
+static long
+getseed(void)
+{
+	struct timeval tv;
+	long seed;
+	int fd, len;
+
+	len = 0;
+	fd = open("/dev/urandom", O_RDONLY);
+	if(fd > 0){
+		len = readn(fd, &seed, sizeof(seed));
+		close(fd);
+	}
+	if(len != sizeof(seed)){
+		gettimeofday(&tv, nil);
+		seed = tv.tv_sec ^ tv.tv_usec ^ (getpid()<<8);
+	}
+	return seed;
+}
+
+static int seeded;
+
+void
+randombytes(uchar *r, uint nr)
+{
+	int i;
+	ulong l;
+
+	if(!seeded){
+		seeded=1;
+		srand48(getseed());
+	}
+	for(i=0; i+4<=nr; i+=4,r+=4){
+		l = (ulong)mrand48();
+		r[0] = l;
+		r[1] = l>>8;
+		r[2] = l>>16;
+		r[3] = l>>24;
+	}
+	if(i<nr){
+		l = (ulong)mrand48();
+		switch(nr-i){
+		case 3:
+			r[2] = l>>16;
+		case 2:
+			r[1] = l>>8;
+		case 1:
+			r[0] = l;
+		}
+	}
+}