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<!-- INDEX BEGIN -->
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<p><a name="__index__"></a></p>
<ul>
<li><a href="#name">NAME</a></li>
<li><a href="#synopsis">SYNOPSIS</a></li>
<li><a href="#description">DESCRIPTION</a></li>
<li><a href="#notes">NOTES</a></li>
<li><a href="#return_values">RETURN VALUES</a></li>
<li><a href="#examples">EXAMPLES</a></li>
<li><a href="#bugs">BUGS</a></li>
<li><a href="#see_also">SEE ALSO</a></li>
<li><a href="#copyright">COPYRIGHT</a></li>
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<p>
</p>
<hr />
<h1><a name="name">NAME</a></h1>
<p>BIO_s_file, BIO_new_file, BIO_new_fp, BIO_set_fp, BIO_get_fp,
BIO_read_filename, BIO_write_filename, BIO_append_filename,
BIO_rw_filename - FILE bio</p>
<p>
</p>
<hr />
<h1><a name="synopsis">SYNOPSIS</a></h1>
<pre>
#include <openssl/bio.h></pre>
<pre>
const BIO_METHOD *BIO_s_file(void);
BIO *BIO_new_file(const char *filename, const char *mode);
BIO *BIO_new_fp(FILE *stream, int flags);</pre>
<pre>
BIO_set_fp(BIO *b, FILE *fp, int flags);
BIO_get_fp(BIO *b, FILE **fpp);</pre>
<pre>
int BIO_read_filename(BIO *b, char *name)
int BIO_write_filename(BIO *b, char *name)
int BIO_append_filename(BIO *b, char *name)
int BIO_rw_filename(BIO *b, char *name)</pre>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<p><code>BIO_s_file()</code> returns the BIO file method. As its name implies it
is a wrapper round the stdio FILE structure and it is a
source/sink BIO.</p>
<p>Calls to <code>BIO_read_ex()</code> and <code>BIO_write_ex()</code> read and write data to the
underlying stream. <code>BIO_gets()</code> and <code>BIO_puts()</code> are supported on file BIOs.</p>
<p><code>BIO_flush()</code> on a file BIO calls the <code>fflush()</code> function on the wrapped
stream.</p>
<p><code>BIO_reset()</code> attempts to change the file pointer to the start of file
using fseek(stream, 0, 0).</p>
<p><code>BIO_seek()</code> sets the file pointer to position <strong>ofs</strong> from start of file
using fseek(stream, ofs, 0).</p>
<p><code>BIO_eof()</code> calls <code>feof()</code>.</p>
<p>Setting the BIO_CLOSE flag calls <code>fclose()</code> on the stream when the BIO
is freed.</p>
<p><code>BIO_new_file()</code> creates a new file BIO with mode <strong>mode</strong> the meaning
of <strong>mode</strong> is the same as the stdio function <code>fopen()</code>. The BIO_CLOSE
flag is set on the returned BIO.</p>
<p><code>BIO_new_fp()</code> creates a file BIO wrapping <strong>stream</strong>. Flags can be:
BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets the underlying
stream to text mode, default is binary: this only has any effect under
Win32).</p>
<p><code>BIO_set_fp()</code> sets the fp of a file BIO to <strong>fp</strong>. <strong>flags</strong> has the same
meaning as in <code>BIO_new_fp()</code>, it is a macro.</p>
<p><code>BIO_get_fp()</code> retrieves the fp of a file BIO, it is a macro.</p>
<p><code>BIO_seek()</code> is a macro that sets the position pointer to <strong>offset</strong> bytes
from the start of file.</p>
<p><code>BIO_tell()</code> returns the value of the position pointer.</p>
<p><code>BIO_read_filename()</code>, <code>BIO_write_filename()</code>, <code>BIO_append_filename()</code> and
<code>BIO_rw_filename()</code> set the file BIO <strong>b</strong> to use file <strong>name</strong> for
reading, writing, append or read write respectively.</p>
<p>
</p>
<hr />
<h1><a name="notes">NOTES</a></h1>
<p>When wrapping stdout, stdin or stderr the underlying stream should not
normally be closed so the BIO_NOCLOSE flag should be set.</p>
<p>Because the file BIO calls the underlying stdio functions any quirks
in stdio behaviour will be mirrored by the corresponding BIO.</p>
<p>On Windows BIO_new_files reserves for the filename argument to be
UTF-8 encoded. In other words if you have to make it work in multi-
lingual environment, encode filenames in UTF-8.</p>
<p>
</p>
<hr />
<h1><a name="return_values">RETURN VALUES</a></h1>
<p><code>BIO_s_file()</code> returns the file BIO method.</p>
<p><code>BIO_new_file()</code> and <code>BIO_new_fp()</code> return a file BIO or NULL if an error
occurred.</p>
<p><code>BIO_set_fp()</code> and <code>BIO_get_fp()</code> return 1 for success or 0 for failure
(although the current implementation never return 0).</p>
<p><code>BIO_seek()</code> returns the same value as the underlying <code>fseek()</code> function:
0 for success or -1 for failure.</p>
<p><code>BIO_tell()</code> returns the current file position.</p>
<p><code>BIO_read_filename()</code>, <code>BIO_write_filename()</code>, <code>BIO_append_filename()</code> and
<code>BIO_rw_filename()</code> return 1 for success or 0 for failure.</p>
<p>
</p>
<hr />
<h1><a name="examples">EXAMPLES</a></h1>
<p>File BIO "hello world":</p>
<pre>
BIO *bio_out;</pre>
<pre>
bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
BIO_printf(bio_out, "Hello World\n");</pre>
<p>Alternative technique:</p>
<pre>
BIO *bio_out;</pre>
<pre>
bio_out = BIO_new(BIO_s_file());
if (bio_out == NULL)
/* Error */
if (!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE))
/* Error */
BIO_printf(bio_out, "Hello World\n");</pre>
<p>Write to a file:</p>
<pre>
BIO *out;</pre>
<pre>
out = BIO_new_file("filename.txt", "w");
if (!out)
/* Error */
BIO_printf(out, "Hello World\n");
BIO_free(out);</pre>
<p>Alternative technique:</p>
<pre>
BIO *out;</pre>
<pre>
out = BIO_new(BIO_s_file());
if (out == NULL)
/* Error */
if (!BIO_write_filename(out, "filename.txt"))
/* Error */
BIO_printf(out, "Hello World\n");
BIO_free(out);</pre>
<p>
</p>
<hr />
<h1><a name="bugs">BUGS</a></h1>
<p><code>BIO_reset()</code> and <code>BIO_seek()</code> are implemented using <code>fseek()</code> on the underlying
stream. The return value for <code>fseek()</code> is 0 for success or -1 if an error
occurred this differs from other types of BIO which will typically return
1 for success and a non positive value if an error occurred.</p>
<p>
</p>
<hr />
<h1><a name="see_also">SEE ALSO</a></h1>
<p><em>BIO_seek(3)</em>, <em>BIO_tell(3)</em>,
<em>BIO_reset(3)</em>, <em>BIO_flush(3)</em>,
<em>BIO_read_ex(3)</em>,
<em>BIO_write_ex(3)</em>, <em>BIO_puts(3)</em>,
<em>BIO_gets(3)</em>, <em>BIO_printf(3)</em>,
<em>BIO_set_close(3)</em>, <em>BIO_get_close(3)</em></p>
<p>
</p>
<hr />
<h1><a name="copyright">COPYRIGHT</a></h1>
<p>Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.</p>
<p>Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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