On 7/9/2023 7:06 AM, Anton Khirnov wrote:
It is a better interface for /dev/u?random on Linux, which avoids the
issues associated with opening files.
---
configure | 2 ++
libavutil/random_seed.c | 16 ++++++++++++++++
2 files changed, 18 insertions(+)
diff --git a/configure b/configure
index 0ab0761011..f8c809e491 100755
--- a/configure
+++ b/configure
@@ -2310,6 +2310,7 @@ SYSTEM_FUNCS="
getauxval
getenv
gethrtime
+ getrandom
getopt
GetModuleHandle
GetProcessAffinityMask
@@ -6387,6 +6388,7 @@ check_func fcntl
check_func fork
check_func gethrtime
check_func getopt
+check_func_headers "sys/random.h" getrandom
check_func getrusage
check_func gettimeofday
check_func isatty
diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c
index f167b172f2..92bf9ef8e1 100644
--- a/libavutil/random_seed.c
+++ b/libavutil/random_seed.c
@@ -35,6 +35,9 @@
#elif CONFIG_OPENSSL
#include <openssl/rand.h>
#endif
+#if HAVE_GETRANDOM
+#include <sys/random.h>
+#endif
#include <fcntl.h>
#include <math.h>
#include <time.h>
@@ -51,6 +54,7 @@
#define TEST 0
#endif
+#if !HAVE_GETRANDOM
static int read_random(uint8_t *dst, size_t len, const char *file)
{
#if HAVE_UNISTD_H
@@ -70,6 +74,7 @@ static int read_random(uint8_t *dst, size_t len, const char
*file)
return AVERROR(ENOSYS);
#endif
}
+#endif
static uint32_t get_generic_seed(void)
{
@@ -147,7 +152,18 @@ int av_random_bytes(uint8_t* buf, size_t len)
return 0;
#endif
+ // getrandom() is a better interface for /dev/(u)random on Linux,
+ // so it makes no sense to try both
+#if HAVE_GETRANDOM
+ {
+ ssize_t read = getrandom(buf, len, GRND_NONBLOCK);
+ if (read < 0)
+ return errno == EAGAIN ? AVERROR_EXTERNAL : AVERROR(errno);
+ return read != len ? AVERROR_UNKNOWN : 0;
This is returning no matter what the result, when it should only return
on success (the !err check below), or fallback to the other
implementations otherwise.
+ }
+#else
err = read_random(buf, len, "/dev/urandom");
+#endif
if (!err)
return err;
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