BIO in memory usage....

Tomas Mraz tmraz at
Mon Jun 17 08:24:40 UTC 2019

On Sun, 2019-06-16 at 12:11 +0200, Tobias Wolf wrote:
> I`d like to understand how a memory bio can be reseted with the
> internal read counter back to zero for further reusage.
> e.g.
> I want to try to read first der and then pem
> d2i_X509
> and then:
> PEM_read_X509
> Then the second call will fail because the bio has already read some
> bytes, when I call each function with a newly created bio it is
> working fine.
> I already tried with BIO_seek, BIO_tell (returns 0?!), BIO_reset.

If the BIO is read-only (created with BIO_new_mem_buf()) the BIO_reset
will work as you expect.

Please also see the NOTES section of BIO_s_mem manpage.

Tomáš Mráz
No matter how far down the wrong road you've gone, turn back.
                                              Turkish proverb
[You'll know whether the road is wrong if you carefully listen to your

More information about the openssl-users mailing list