[#BIO_read_ex]
= BIO_read_ex
:mrdocs:

Attempt to read up to `dlen` bytes from BIO `b` into `data.`

== Synopsis

Declared in `<openssl/bio.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
BIO_read_ex(
    xref:BIO.adoc[BIO]* b,
    void* data,
    size_t dlen,
    size_t* readbytes);
----

== Return Value

1 if any data was successfully read, or 0 otherwise.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *b*
| BIO to read from.
| *data*
| Destination buffer for the bytes read.
| *dlen*
| Maximum number of bytes to read.
| *readbytes*
| On success, receives the number of bytes actually read.
|===


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