From 38e23c88db9a6b1ce15a2eca431b824f65b214bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C3=A5ns=20Rullg=C3=A5rd?= <mans@mansr.com>
Date: Wed, 30 Jun 2010 10:38:04 +0000
Subject: [PATCH] Make av_get_random_seed() non-blocking
Attempt to read from /dev/urandom and /dev/random with O_NONBLOCK set.
If neither succeeds, proceed with fallbacks.
Originally committed as revision 23903 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavutil/random_seed.c | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)
diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c
index 00d6317241c..a2b388549c6 100644
--- a/libavutil/random_seed.c
+++ b/libavutil/random_seed.c
@@ -24,19 +24,33 @@
#include "random_seed.h"
#include "avutil.h"
+static int read_random(uint32_t *dst, const char *file)
+{
+ int fd = open(file, O_RDONLY);
+ int err = -1;
+
+ if (fd == -1)
+ return -1;
+#if HAVE_FCNTL && defined(O_NONBLOCK)
+ if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_NONBLOCK) != -1)
+#endif
+ err = read(fd, dst, sizeof(*dst));
+ close(fd);
+
+ return err;
+}
+
uint32_t av_get_random_seed(void)
{
uint32_t seed;
- int fd;
-
- if ((fd = open("/dev/random", O_RDONLY)) == -1)
- fd = open("/dev/urandom", O_RDONLY);
- if (fd != -1){
- int err = read(fd, &seed, 4);
- close(fd);
- if (err == 4)
- return seed;
- }
+ int err;
+
+ err = read_random(&seed, "/dev/urandom");
+ if (err != sizeof(seed))
+ err = read_random(&seed, "/dev/random");
+ if (err == sizeof(seed))
+ return seed;
+
#ifdef AV_READ_TIME
seed = AV_READ_TIME();
#endif
--
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