plan9port

commit 60d3db8e6bafa21d807ea31690eddf44bb7ef020
parent 551445b92c1f11d4f543e96790ff29762ab1ad10
Author: wkj <devnull@localhost>
Date:   Wed, 21 Apr 2004 03:06:03 +0000

Try to gather entropy from /dev/random.

Diffstat:
A
src/lib9/truerand.c
 | 
21
+++++++++++++++++++++

1 file changed, 21 insertions(+), 0 deletions(-)
diff --git a/src/lib9/truerand.c b/src/lib9/truerand.c
@@ -0,0 +1,21 @@
+#include <u.h>
+#include <libc.h>
+
+ulong
+truerand(void)
+{
+	int i, n;
+	uchar buf[sizeof(ulong)];
+	static int randfd = -1;
+
+	if(randfd < 0){
+		randfd = open("/dev/random", OREAD);
+		fcntl(randfd, F_SETFD, FD_CLOEXEC);
+	}
+	if(randfd < 0)
+		sysfatal("can't open /dev/random: %r");
+	for(i=0; i<sizeof(buf); i += n)
+		if((n = readn(randfd, buf+i, sizeof(buf)-i)) < 0)
+			sysfatal("can't read /dev/random: %r");
+	return *((ulong*)buf);
+}