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<h2 class="title" style="clear: both"><a id="db_env_set_func_ioinfo"></a>db_env_set_func_ioinfo</h2>
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<pre class="programlisting">#include <db.h>
int
db_env_set_func_ioinfo(int (*func_ioinfo)(const char *path,
int fd, u_int32_t *mbytesp, u_int32_t *bytesp, u_int32_t *iosizep)); </pre>
<p>
The Berkeley DB library requires the ability to determine the size and
I/O characteristics of a file.
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<p>
The <code class="function">db_env_set_func_ioinfo()</code> function configures all operations performed
by a process and all of its threads of control, not operations
confined to a single database environment.
</p>
<p>
Although the <code class="function">db_env_set_func_ioinfo()</code> function may be called at any time
during the life of the application, it should normally be called
before making calls to the <a class="xref" href="envcreate.html" title="db_env_create">db_env_create</a> or
<a class="xref" href="dbcreate.html" title="db_create">db_create</a> methods.
</p>
<p>
The <code class="function">db_env_set_func_ioinfo()</code> <span>
function returns a non-zero error value on failure and 0 on success.
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<h3 class="title"><a id="idp55638192"></a>Parameters</h3>
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<h4 class="title"><a id="idp55638384"></a>func_ioinfo</h4>
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<p>
The <span class="bold"><strong>func_ioinfo</strong></span> parameter is the
function which returns the size and I/O characteristics of a file.
</p>
<p>
The <span class="bold"><strong>path</strong></span> parameter is the pathname of
the file to be checked, and the <span class="bold"><strong>fd</strong></span>
parameter is an open file descriptor on the file.
</p>
<p>
If the <span class="bold"><strong>mbytesp</strong></span> and <span class="bold"><strong>bytesp</strong></span> parameters are non-NULL, the <span class="bold"><strong>ioinfo</strong></span> function must return in them the size of
the file: the number of megabytes in the file into the memory location
to which the <span class="bold"><strong>mbytesp</strong></span> parameter
refers, and the number of bytes over and above that number of
megabytes into the memory location to which the <span class="bold"><strong>bytesp</strong></span> parameter refers.
</p>
<p>
In addition, if the <span class="bold"><strong>iosizep</strong></span> parameter
is non-NULL, the <span class="bold"><strong>ioinfo</strong></span> function must
return the optimum granularity for I/O operations to the file into the
memory location to which it refers.
</p>
<p>
The <span class="bold"><strong>func_ioinfo</strong></span> function must return
the value of <span class="bold"><strong>errno</strong></span> on failure and 0
on success.
</p>
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<h3 class="title"><a id="idp55632920"></a>See Also</h3>
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<a href="../../programmer_reference/program_runtime.html" class="olink">Run-time configuration</a>
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