[FFmpeg-devel] [PATCH v3 3/3] avutil/random_seed: add support for gcrypt and OpenSSL as source of randomness

[Marton Balint]

On Thu, 6 Jul 2023, James Almer wrote:

> On 7/6/2023 4:52 AM, Anton Khirnov wrote:
>>  Quoting James Almer (2023-07-05 15:03:07)
>>>  On 7/5/2023 9:56 AM, Anton Khirnov wrote:
>>>>  Quoting James Almer (2023-07-05 01:26:14)
>>>>>  Signed-off-by: James Almer <jamrial at gmail.com>
>>>>>  ---
>>>>>     configure               |  2 +-
>>>>>     libavutil/random_seed.c | 16 ++++++++++++++++
>>>>>     2 files changed, 17 insertions(+), 1 deletion(-)
>>>>>
>>>>>  diff --git a/configure b/configure
>>>>>  index 107d533b3e..d6e78297fe 100755
>>>>>  --- a/configure
>>>>>  +++ b/configure
>>>>>  @@ -3892,7 +3892,7 @@ avfilter_deps="avutil"
>>>>>     avfilter_suggest="libm stdatomic"
>>>>>     avformat_deps="avcodec avutil"
>>>>>     avformat_suggest="libm network zlib stdatomic"
>>>>>  -avutil_suggest="clock_gettime ffnvcodec libm libdrm libmfx opencl
>>>>>  user32 vaapi vulkan videotoolbox corefoundation corevideo coremedia
>>>>>  bcrypt stdatomic"
>>>>>  +avutil_suggest="clock_gettime ffnvcodec gcrypt libm libdrm libmfx
>>>>>  opencl openssl user32 vaapi vulkan videotoolbox corefoundation
>>>>>  corevideo coremedia bcrypt stdatomic"
>>>>
>>>>  What will this do exactly?
>>>
>>>  It's a soft dependency. Only if OpenSSL or GCrypt are enabled they will
>>>  be added to avutil's library dependencies.
>>>  Notice the bcrypt entry, also used in random_seed, and all the hwcontext
>>>  backends.
>>
>>  Ok then.
>
> Any opinion on the order of function calls? Should i leave /dev/urandom as 
> last resort after all (if any) external lib implementations failed, 
> considering what Remí mentioned?

I think it is fine as is. Buffering can be turned off with
setvbuf(f, NULL, _IONBF, 0); so that should not relevant.

Regards,
Marton