From 164c99a4b414b614e5185a96ef8287331e9134eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Love=20H=C3=B6rnquist=20=C3=85strand?= <lha@kth.se>
Date: Sun, 22 Mar 2009 17:20:18 +0000
Subject: [PATCH] Do locking around file descriptor, this allows caching of the
 file descriptor in the module.

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@24901 ec53bebd-3082-4978-b11e-865c3cabbd6b
---
 lib/hcrypto/rand-unix.c | 40 ++++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/lib/hcrypto/rand-unix.c b/lib/hcrypto/rand-unix.c
index 0c2185776..07d81eb62 100644
--- a/lib/hcrypto/rand-unix.c
+++ b/lib/hcrypto/rand-unix.c
@@ -40,11 +40,15 @@ RCSID("$Id$");
 #include <stdio.h>
 #include <stdlib.h>
 #include <rand.h>
+#include <heim_threads.h>
 
 #include <roken.h>
 
 #include "randi.h"
 
+static int random_fd = -1;
+static HEIMDAL_MUTEX random_mutex = HEIMDAL_MUTEX_INITIALIZER;
+
 /*
  * Unix /dev/random
  */
@@ -88,31 +92,47 @@ unix_seed(const void *indata, int size)
 
 }
 
+
 static int
 unix_bytes(unsigned char *outdata, int size)
 {
     ssize_t count;
-    int fd;
+    int once = 0;
 
     if (size <= 0)
 	return 0;
 
-    fd = get_device_fd(O_RDONLY);
-    if (fd < 0)
-	return 0;
+    HEIMDAL_MUTEX_lock(&random_mutex);
+    if (random_fd == -1) {
+    retry:
+	random_fd = get_device_fd(O_RDONLY);
+	if (random_fd < 0) {
+	    HEIMDAL_MUTEX_unlock(&random_mutex);
+	    return 0;
+	}
+    }
 
     while (size > 0) {
-	count = read (fd, outdata, size);
-	if (count < 0 && errno == EINTR)
-	    continue;
-	else if (count <= 0) {
-	    close(fd);
+	HEIMDAL_MUTEX_unlock(&random_mutex);
+	count = read (random_fd, outdata, size);
+	HEIMDAL_MUTEX_lock(&random_mutex);
+	if (random_fd < 0) {
+	    if (errno == EINTR)
+		continue;
+	    else if (errno == EBADF && once++ == 0) {
+		close(random_fd);
+		random_fd = -1;
+		goto retry;
+	    }
+	    return 0;
+	} else if (count <= 0) {
+	    HEIMDAL_MUTEX_unlock(&random_mutex);
 	    return 0;
 	}
 	outdata += count;
 	size -= count;
     }
-    close(fd);
+    HEIMDAL_MUTEX_unlock(&random_mutex);
 
     return 1;
 }