[#BIO_debug_callback]
= BIO&lowbar;debug&lowbar;callback
:mrdocs:

Default legacy BIO debug logger writing to the BIO&apos;s callback&hyphen;argument BIO (deprecated)&period;

== Synopsis

Declared in `&lt;openssl&sol;bio&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
&lsqb;&lsqb;deprecated&rsqb;&rsqb;
long
BIO&lowbar;debug&lowbar;callback(
    xref:BIO.adoc[BIO]* bio,
    int cmd,
    char const* argp,
    int argi,
    long argl,
    long ret);
----

[WARNING]
====
https://en.cppreference.com/cpp/language/attributes/deprecated[Deprecated^]. Use of this entity is allowed but discouraged.
====
== Return Value

`ret` unchanged (pass&hyphen;through debug callback)&period;

== Parameters

[cols="1,4"]
|===
| Name| Description
| *bio*
| BIO whose operation is being reported&period;
| *cmd*
| BIO&lowbar;CB&lowbar;&ast; operation code (read, write, ctrl, …)&period;
| *argp*
| Pointer argument for the operation (buffer or ctrl pointer), or NULL&period;
| *argi*
| Integer argument for ctrl&hyphen;style operations&period;
| *argl*
| Long argument for ctrl&hyphen;style operations&period;
| *ret*
| Return value being reported for the operation&period;
|===


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