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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
This commit is contained in:
Måns Rullgård 2010-06-30 10:38:04 +00:00
parent 534a2231f6
commit 38e23c88db
1 changed files with 23 additions and 9 deletions
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32
libavutil/random_seed.c
View File

@ -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;
int err;
err = read_random(&seed, "/dev/urandom");
if (err != sizeof(seed))
err = read_random(&seed, "/dev/random");
if (err == sizeof(seed))
return seed;
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;
}
#ifdef AV_READ_TIME
seed = AV_READ_TIME();
#endif