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    zip_source_function.mdoc -- create data source from function
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   <title>ZIP_SOURCE_FUNCTION(3)</title>
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 <table class="head">
   <tr>
     <td class="head-ltitle">ZIP_SOURCE_FUNCTION(3)</td>
     <td class="head-vol">Library Functions Manual</td>
     <td class="head-rtitle">ZIP_SOURCE_FUNCTION(3)</td>
   </tr>
 </table>
 <div class="manual-text">
 <section class="Sh">
 <h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
 <code class="Nm">zip_source_function</code>,
   <code class="Nm">zip_source_function_create</code> &#x2014;
 <div class="Nd">create data source from function</div>
 </section>
 <section class="Sh">
 <h1 class="Sh" id="LIBRARY"><a class="permalink" href="#LIBRARY">LIBRARY</a></h1>
 libzip (-lzip)
 </section>
 <section class="Sh">
 <h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
 <code class="In">#include &lt;<a class="In">zip.h</a>&gt;</code>
 <p class="Pp"><var class="Ft">zip_source_t *</var>
   <br/>
   <code class="Fn">zip_source_function</code>(<var class="Fa" style="white-space: nowrap;">zip_t
     *archive</var>,
     <var class="Fa" style="white-space: nowrap;">zip_source_callback fn</var>,
     <var class="Fa" style="white-space: nowrap;">void *userdata</var>);</p>
 <p class="Pp"><var class="Ft">zip_source_t *</var>
   <br/>
   <code class="Fn">zip_source_function_create</code>(<var class="Fa" style="white-space: nowrap;">zip_source_callback
     fn</var>, <var class="Fa" style="white-space: nowrap;">void *userdata</var>,
     <var class="Fa" style="white-space: nowrap;">zip_error_t *error</var>);</p>
 </section>
 <section class="Sh">
 <h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
 The functions <code class="Fn">zip_source_function</code>() and
   <code class="Fn">zip_source_function_create</code>() creates a zip source from
   the user-provided function <var class="Ar">fn</var>, which must be of the
   following type:
 <p class="Pp"><var class="Ft">typedef zip_int64_t</var>
     <code class="Fn">(*zip_source_callback)</code>(<var class="Fa">void
     *userdata</var>, <var class="Fa">void *data</var>,
     <var class="Fa">zip_uint64_t len</var>, <var class="Fa">zip_source_cmd_t
     cmd</var>);</p>
 <p class="Pp"><var class="Ar">archive</var> or <var class="Ar">error</var> are
     used for reporting errors and can be <code class="Dv">NULL</code>.</p>
 <p class="Pp">When called by the library, the first argument is the
     <var class="Ar">userdata</var> argument supplied to the function. The next
     two arguments are a buffer <var class="Ar">data</var> of size
     <var class="Ar">len</var> when data is passed in or expected to be returned,
     or else <code class="Dv">NULL</code> and 0. The last argument,
     <var class="Ar">cmd</var>, specifies which action the function should
     perform.</p>
 <p class="Pp">Depending on the uses, there are three useful sets of commands to
     be supported by a <code class="Fn">zip_source_callback</code>():</p>
 <dl class="Bl-tag">
   <dt>read source</dt>
   <dd>Providing streamed data (for file data added to archives). Must support
       <code class="Dv">ZIP_SOURCE_OPEN</code>,
       <code class="Dv">ZIP_SOURCE_READ</code>,
       <code class="Dv">ZIP_SOURCE_CLOSE</code>,
       <code class="Dv">ZIP_SOURCE_STAT</code>, and
       <code class="Dv">ZIP_SOURCE_ERROR</code>.</dd>
   <dt>seekable read source</dt>
   <dd>Same as previous, but from a source allowing reading from arbitrary
       offsets (also for read-only zip archive). Must additionally support
       <code class="Dv">ZIP_SOURCE_SEEK</code>,
       <code class="Dv">ZIP_SOURCE_TELL</code>, and
       <code class="Dv">ZIP_SOURCE_SUPPORTS</code>.</dd>
   <dt>read/write source</dt>
   <dd>Same as previous, but additionally allowing writing (also for writable zip
       archives). Must additionally support
       <code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code>,
       <code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code>,
       <code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code>,
       <code class="Dv">ZIP_SOURCE_SEEK_WRITE</code>,
       <code class="Dv">ZIP_SOURCE_TELL_WRITE</code>, and
       <code class="Dv">ZIP_SOURCE_REMOVE</code>.</dd>
 </dl>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_ACCEPT_EMPTY</code></h2>
 Return 1 if an empty source should be accepted as a valid zip archive. This is
   the default if this command is not supported by a source. File system backed
   sources should return 0.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code></h2>
 Prepare the source for writing. Use this to create any temporary file(s).
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_BEGIN_WRITE_CLONING</code></h2>
 Prepare the source for writing, keeping the first <var class="Ar">len</var>
   bytes of the original file. Only implement this command if it is more
   efficient than copying the data, and if it does not destructively overwrite
   the original file (you still have to be able to execute
   <code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code>).
 <p class="Pp">The next write should happen at byte
   <var class="Ar">offset</var>.</p>
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_CLOSE</code></h2>
 Reading is done.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code></h2>
 Finish writing to the source. Replace the original data with the newly written
   data. Clean up temporary files or internal buffers. Subsequently opening and
   reading from the source should return the newly written data.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_ERROR</code></h2>
 Get error information. <var class="Ar">data</var> points to an array of two
   ints, which should be filled with the libzip error code and the corresponding
   system error code for the error that occurred. See
   <a class="Xr" href="zip_errors.html">zip_errors(3)</a> for details on the
   error codes. If the source stores error information in a zip_error_t, use
   <a class="Xr" href="zip_error_to_data.html">zip_error_to_data(3)</a> and
   return its return value. Otherwise, return 2 * sizeof(int).
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_FREE</code></h2>
 Clean up and free all resources, including <var class="Ar">userdata</var>. The
   callback function will not be called again.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_GET_FILE_ATTRIBUTES</code></h2>
 Provide information about various data. Then the data should be put in the
   appropriate entry in the passed <var class="Vt">zip_file_attributes_t</var>
   argument, and the appropriate <code class="Dv">ZIP_FILE_ATTRIBUTES_*</code>
   value must be or'ed into the <var class="Ar">valid</var> member to denote that
   the corresponding data has been provided. A
   <var class="Vt">zip_file_attributes_t</var> structure can be initialized using
   <a class="Xr" href="zip_file_attributes_init.html">zip_file_attributes_init(3)</a>.
 <dl class="Bl-tag">
   <dt>ASCII mode</dt>
   <dd>If a file is a plaintext file in ASCII. Can be used by extraction tools to
       automatically convert line endings (part of the interal file attributes).
       Member <var class="Ar">ascii</var>, flag
       <code class="Dv">ZIP_FILE_ATTRIBUTES_ASCII</code>.</dd>
   <dt>General Purpose Bit Flags (limited to Compression Flags)</dt>
   <dd>The general purpose bit flag in the zip in the local and central directory
       headers contain information about the compression method. Member
       <var class="Ar">general_purpose_bit_flags</var> and
       <var class="Ar">general_purpose_bit_mask</var> to denote which members
       have been set; flag
       <code class="Dv">ZIP_FILE_ATTRIBUTES_GENERAL_PURPOSE_BIT_FLAGS</code>.</dd>
   <dt>External File Attributes</dt>
   <dd>The external file attributes (usually operating system-specific). Member
       <var class="Ar">external_file_attributes</var>, flag
       <code class="Dv">ZIP_FILE_ATTRIBUTES_EXTERNAL_FILE_ATTRIBUTES</code>.</dd>
   <dt>Version Needed</dt>
   <dd>A minimum version needed required to unpack this entry (in the usual
       &quot;major * 10 + minor&quot; format). Member
       <var class="Ar">version_needed</var>, flag
       <code class="Dv">ZIP_FILE_ATTRIBUTES_VERSION_NEEDED</code>.</dd>
   <dt>Operating System</dt>
   <dd>One of the operating systems as defined by the
       <code class="Dv">ZIP_OPSYS_*</code> variables (see
       <span class="Pa">zip.h</span>). This value affects the interpretation of
       the external file attributes. Member <var class="Ar">host_system</var>,
       flag <code class="Dv">ZIP_FILE_ATTRIBUTES_HOST_SYSTEM</code>.</dd>
 </dl>
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_OPEN</code></h2>
 Prepare for reading.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_READ</code></h2>
 Read data into the buffer <var class="Ar">data</var> of size
   <var class="Ar">len</var>. Return the number of bytes placed into
   <var class="Ar">data</var> on success, and zero for end-of-file.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_REMOVE</code></h2>
 Remove the underlying file. This is called if a zip archive is empty when
   closed.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code></h2>
 Abort writing to the source. Discard written data. Clean up temporary files or
   internal buffers. Subsequently opening and reading from the source should
   return the original data.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_SEEK</code></h2>
 Specify position to read next byte from, like
   <a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fseek.html">fseek(3)</a>. Use
   <a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ZIP_SOURCE_GET_ARGS.html">ZIP_SOURCE_GET_ARGS(3)</a> to
   decode the arguments into the following struct:
 <div class="Bd Pp">
 <pre>
 struct zip_source_args_seek {
     zip_int64_t offset;
     int whence;
 };
 </pre>
 </div>
 <p class="Pp">If the size of the source's data is known, use
     <a class="Xr" href="zip_source_seek_compute_offset.html">zip_source_seek_compute_offset(3)</a>
     to validate the arguments and compute the new offset.</p>
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_SEEK_WRITE</code></h2>
 Specify position to write next byte to, like
   <a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fseek.html">fseek(3)</a>. See
   <code class="Dv">ZIP_SOURCE_SEEK</code> for details.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_STAT</code></h2>
 Get meta information for the input data. <var class="Ar">data</var> points to an
   allocated <var class="Vt">struct zip_stat</var>, which should be initialized
   using <a class="Xr" href="zip_stat_init.html">zip_stat_init(3)</a> and then
   filled in.
 <p class="Pp">For uncompressed, unencrypted data, all information is optional.
     However, fill in as much information as is readily available.</p>
 <p class="Pp">If the data is compressed,
     <code class="Dv">ZIP_STAT_COMP_METHOD</code>,
     <code class="Dv">ZIP_STAT_SIZE</code>, and
     <code class="Dv">ZIP_STAT_CRC</code> must be filled in.</p>
 <p class="Pp">If the data is encrypted,
     <code class="Dv">ZIP_STAT_ENCRYPTION_METHOD</code>,
     <code class="Dv">ZIP_STAT_COMP_METHOD</code>,
     <code class="Dv">ZIP_STAT_SIZE</code>, and
     <code class="Dv">ZIP_STAT_CRC</code> must be filled in.</p>
 <p class="Pp">Information only available after the source has been read (e.g.,
     size) can be omitted in an earlier call. <i class="Em">NOTE</i>:
     <code class="Fn">zip_source_function</code>() may be called with this
     argument even after being called with
     <code class="Dv">ZIP_SOURCE_CLOSE</code>.</p>
 <p class="Pp">Return sizeof(struct zip_stat) on success.</p>
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_SUPPORTS</code></h2>
 Return bitmap specifying which commands are supported. Use
   <a class="Xr" href="zip_source_make_command_bitmap.html">zip_source_make_command_bitmap(3)</a>.
   If this command is not implemented, the source is assumed to be a read source
   without seek support.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_TELL</code></h2>
 Return the current read offset in the source, like
   <a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftell.html">ftell(3)</a>.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_TELL_WRITE</code></h2>
 Return the current write offset in the source, like
   <a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftell.html">ftell(3)</a>.
 </section>
 <section class="Ss">
 <h2 class="Ss"><code class="Dv">ZIP_SOURCE_WRITE</code></h2>
 Write data to the source. Return number of bytes written.
 </section>
 <section class="Ss">
 <h2 class="Ss" id="Return_Values"><a class="permalink" href="#Return_Values">Return
   Values</a></h2>
 Commands should return -1 on error. <code class="Dv">ZIP_SOURCE_ERROR</code>
   will be called to retrieve the error code. On success, commands return 0,
   unless specified otherwise in the description above.
 </section>
 <section class="Ss">
 <h2 class="Ss" id="Calling_Conventions"><a class="permalink" href="#Calling_Conventions">Calling
   Conventions</a></h2>
 The library will always issue <code class="Dv">ZIP_SOURCE_OPEN</code> before
   issuing <code class="Dv">ZIP_SOURCE_READ</code>,
   <code class="Dv">ZIP_SOURCE_SEEK</code>, or
   <code class="Dv">ZIP_SOURCE_TELL</code>. When it no longer wishes to read from
   this source, it will issue <code class="Dv">ZIP_SOURCE_CLOSE</code>. If the
   library wishes to read the data again, it will issue
   <code class="Dv">ZIP_SOURCE_OPEN</code> a second time. If the function is
   unable to provide the data again, it should return -1.
 <p class="Pp"><code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code> or
     <code class="Dv">ZIP_SOURCE_BEGIN_WRITE_CLONING</code> will be called before
     <code class="Dv">ZIP_SOURCE_WRITE</code>,
     <code class="Dv">ZIP_SOURCE_SEEK_WRITE</code>, or
     <code class="Dv">ZIP_SOURCE_TELL_WRITE</code>. When writing is complete,
     either <code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code> or
     <code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code> will be called.</p>
 <p class="Pp"><code class="Dv">ZIP_SOURCE_ACCEPT_EMPTY</code>,
     <code class="Dv">ZIP_SOURCE_GET_FILE_ATTRIBUTES</code>, and
     <code class="Dv">ZIP_SOURCE_STAT</code> can be issued at any time.</p>
 <p class="Pp"><code class="Dv">ZIP_SOURCE_ERROR</code> will only be issued in
     response to the function returning -1.</p>
 <p class="Pp"><code class="Dv">ZIP_SOURCE_FREE</code> will be the last command
     issued; if <code class="Dv">ZIP_SOURCE_OPEN</code> was called and succeeded,
     <code class="Dv">ZIP_SOURCE_CLOSE</code> will be called before
     <code class="Dv">ZIP_SOURCE_FREE</code>, and similarly for
     <code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code> or
     <code class="Dv">ZIP_SOURCE_BEGIN_WRITE_CLONING</code> and
     <code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code> or
     <code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code>.</p>
 </section>
 </section>
 <section class="Sh">
 <h1 class="Sh" id="RETURN_VALUES"><a class="permalink" href="#RETURN_VALUES">RETURN
   VALUES</a></h1>
 Upon successful completion, the created source is returned. Otherwise,
   <code class="Dv">NULL</code> is returned and the error code in
   <var class="Ar">archive</var> or <var class="Ar">error</var> is set to
   indicate the error (unless it is <code class="Dv">NULL</code>).
 </section>
 <section class="Sh">
 <h1 class="Sh" id="ERRORS"><a class="permalink" href="#ERRORS">ERRORS</a></h1>
 <code class="Fn">zip_source_function</code>() fails if:
 <dl class="Bl-tag">
   <dt>[<a class="permalink" href="#ZIP_ER_MEMORY"><code class="Er" id="ZIP_ER_MEMORY">ZIP_ER_MEMORY</code></a>]</dt>
   <dd>Required memory could not be allocated.</dd>
 </dl>
 </section>
 <section class="Sh">
 <h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
   ALSO</a></h1>
 <a class="Xr" href="libzip.html">libzip(3)</a>,
   <a class="Xr" href="zip_file_add.html">zip_file_add(3)</a>,
   <a class="Xr" href="zip_file_attributes_init.html">zip_file_attributes_init(3)</a>,
   <a class="Xr" href="zip_file_replace.html">zip_file_replace(3)</a>,
   <a class="Xr" href="zip_source.html">zip_source(3)</a>,
   <a class="Xr" href="zip_stat_init.html">zip_stat_init(3)</a>
 </section>
 <section class="Sh">
 <h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
 <code class="Fn">zip_source_function</code>() and
   <code class="Fn">zip_source_function_create</code>() were added in libzip 1.0.
 </section>
 <section class="Sh">
 <h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
 <span class="An">Dieter Baron</span>
   &lt;<a class="Mt" href="mailto:dillo@nih.at">dillo@nih.at</a>&gt; and
   <span class="An">Thomas Klausner</span>
   &lt;<a class="Mt" href="mailto:tk@giga.or.at">tk@giga.or.at</a>&gt;
 </section>
 </div>
 <table class="foot">
   <tr>
     <td class="foot-date">April 17, 2020</td>
     <td class="foot-os">NiH</td>
   </tr>
 </table>
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	<title>ZIP_SOURCE_FUNCTION(3)</title>
	</head>
	<body>
	<table class="head">
	<tr>
	<td class="head-ltitle">ZIP_SOURCE_FUNCTION(3)</td>
	<td class="head-vol">Library Functions Manual</td>
	<td class="head-rtitle">ZIP_SOURCE_FUNCTION(3)</td>
	</tr>
	</table>
	<div class="manual-text">
	<section class="Sh">
	<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
	<code class="Nm">zip_source_function</code>,
	<code class="Nm">zip_source_function_create</code> —
	<div class="Nd">create data source from function</div>
	</section>
	<section class="Sh">
	<h1 class="Sh" id="LIBRARY"><a class="permalink" href="#LIBRARY">LIBRARY</a></h1>
	libzip (-lzip)
	</section>
	<section class="Sh">
	<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
	<code class="In">#include <<a class="In">zip.h</a>></code>
	<p class="Pp"><var class="Ft">zip_source_t *</var>
	<br/>
	<code class="Fn">zip_source_function</code>(<var class="Fa" style="white-space: nowrap;">zip_t
	*archive</var>,
	<var class="Fa" style="white-space: nowrap;">zip_source_callback fn</var>,
	<var class="Fa" style="white-space: nowrap;">void *userdata</var>);</p>
	<p class="Pp"><var class="Ft">zip_source_t *</var>
	<br/>
	<code class="Fn">zip_source_function_create</code>(<var class="Fa" style="white-space: nowrap;">zip_source_callback
	fn</var>, <var class="Fa" style="white-space: nowrap;">void *userdata</var>,
	<var class="Fa" style="white-space: nowrap;">zip_error_t *error</var>);</p>
	</section>
	<section class="Sh">
	<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
	The functions <code class="Fn">zip_source_function</code>() and
	<code class="Fn">zip_source_function_create</code>() creates a zip source from
	the user-provided function <var class="Ar">fn</var>, which must be of the
	following type:
	<p class="Pp"><var class="Ft">typedef zip_int64_t</var>
	<code class="Fn">(*zip_source_callback)</code>(<var class="Fa">void
	userdata</var>, <var class="Fa">void data</var>,
	<var class="Fa">zip_uint64_t len</var>, <var class="Fa">zip_source_cmd_t
	cmd</var>);</p>
	<p class="Pp"><var class="Ar">archive</var> or <var class="Ar">error</var> are
	used for reporting errors and can be <code class="Dv">NULL</code>.</p>
	<p class="Pp">When called by the library, the first argument is the
	<var class="Ar">userdata</var> argument supplied to the function. The next
	two arguments are a buffer <var class="Ar">data</var> of size
	<var class="Ar">len</var> when data is passed in or expected to be returned,
	or else <code class="Dv">NULL</code> and 0. The last argument,
	<var class="Ar">cmd</var>, specifies which action the function should
	perform.</p>
	<p class="Pp">Depending on the uses, there are three useful sets of commands to
	be supported by a <code class="Fn">zip_source_callback</code>():</p>
	<dl class="Bl-tag">
	<dt>read source</dt>
	<dd>Providing streamed data (for file data added to archives). Must support
	<code class="Dv">ZIP_SOURCE_OPEN</code>,
	<code class="Dv">ZIP_SOURCE_READ</code>,
	<code class="Dv">ZIP_SOURCE_CLOSE</code>,
	<code class="Dv">ZIP_SOURCE_STAT</code>, and
	<code class="Dv">ZIP_SOURCE_ERROR</code>.</dd>
	<dt>seekable read source</dt>
	<dd>Same as previous, but from a source allowing reading from arbitrary
	offsets (also for read-only zip archive). Must additionally support
	<code class="Dv">ZIP_SOURCE_SEEK</code>,
	<code class="Dv">ZIP_SOURCE_TELL</code>, and
	<code class="Dv">ZIP_SOURCE_SUPPORTS</code>.</dd>
	<dt>read/write source</dt>
	<dd>Same as previous, but additionally allowing writing (also for writable zip
	archives). Must additionally support
	<code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code>,
	<code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code>,
	<code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code>,
	<code class="Dv">ZIP_SOURCE_SEEK_WRITE</code>,
	<code class="Dv">ZIP_SOURCE_TELL_WRITE</code>, and
	<code class="Dv">ZIP_SOURCE_REMOVE</code>.</dd>
	</dl>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_ACCEPT_EMPTY</code></h2>
	Return 1 if an empty source should be accepted as a valid zip archive. This is
	the default if this command is not supported by a source. File system backed
	sources should return 0.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code></h2>
	Prepare the source for writing. Use this to create any temporary file(s).
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_BEGIN_WRITE_CLONING</code></h2>
	Prepare the source for writing, keeping the first <var class="Ar">len</var>
	bytes of the original file. Only implement this command if it is more
	efficient than copying the data, and if it does not destructively overwrite
	the original file (you still have to be able to execute
	<code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code>).
	<p class="Pp">The next write should happen at byte
	<var class="Ar">offset</var>.</p>
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_CLOSE</code></h2>
	Reading is done.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code></h2>
	Finish writing to the source. Replace the original data with the newly written
	data. Clean up temporary files or internal buffers. Subsequently opening and
	reading from the source should return the newly written data.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_ERROR</code></h2>
	Get error information. <var class="Ar">data</var> points to an array of two
	ints, which should be filled with the libzip error code and the corresponding
	system error code for the error that occurred. See
	<a class="Xr" href="zip_errors.html">zip_errors(3)</a> for details on the
	error codes. If the source stores error information in a zip_error_t, use
	<a class="Xr" href="zip_error_to_data.html">zip_error_to_data(3)</a> and
	return its return value. Otherwise, return 2 * sizeof(int).
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_FREE</code></h2>
	Clean up and free all resources, including <var class="Ar">userdata</var>. The
	callback function will not be called again.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_GET_FILE_ATTRIBUTES</code></h2>
	Provide information about various data. Then the data should be put in the
	appropriate entry in the passed <var class="Vt">zip_file_attributes_t</var>
	argument, and the appropriate <code class="Dv">ZIP_FILE_ATTRIBUTES_*</code>
	value must be or'ed into the <var class="Ar">valid</var> member to denote that
	the corresponding data has been provided. A
	<var class="Vt">zip_file_attributes_t</var> structure can be initialized using
	<a class="Xr" href="zip_file_attributes_init.html">zip_file_attributes_init(3)</a>.
	<dl class="Bl-tag">
	<dt>ASCII mode</dt>
	<dd>If a file is a plaintext file in ASCII. Can be used by extraction tools to
	automatically convert line endings (part of the interal file attributes).
	Member <var class="Ar">ascii</var>, flag
	<code class="Dv">ZIP_FILE_ATTRIBUTES_ASCII</code>.</dd>
	<dt>General Purpose Bit Flags (limited to Compression Flags)</dt>
	<dd>The general purpose bit flag in the zip in the local and central directory
	headers contain information about the compression method. Member
	<var class="Ar">general_purpose_bit_flags</var> and
	<var class="Ar">general_purpose_bit_mask</var> to denote which members
	have been set; flag
	<code class="Dv">ZIP_FILE_ATTRIBUTES_GENERAL_PURPOSE_BIT_FLAGS</code>.</dd>
	<dt>External File Attributes</dt>
	<dd>The external file attributes (usually operating system-specific). Member
	<var class="Ar">external_file_attributes</var>, flag
	<code class="Dv">ZIP_FILE_ATTRIBUTES_EXTERNAL_FILE_ATTRIBUTES</code>.</dd>
	<dt>Version Needed</dt>
	<dd>A minimum version needed required to unpack this entry (in the usual
	"major * 10 + minor" format). Member
	<var class="Ar">version_needed</var>, flag
	<code class="Dv">ZIP_FILE_ATTRIBUTES_VERSION_NEEDED</code>.</dd>
	<dt>Operating System</dt>
	<dd>One of the operating systems as defined by the
	<code class="Dv">ZIP_OPSYS_*</code> variables (see
	<span class="Pa">zip.h</span>). This value affects the interpretation of
	the external file attributes. Member <var class="Ar">host_system</var>,
	flag <code class="Dv">ZIP_FILE_ATTRIBUTES_HOST_SYSTEM</code>.</dd>
	</dl>
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_OPEN</code></h2>
	Prepare for reading.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_READ</code></h2>
	Read data into the buffer <var class="Ar">data</var> of size
	<var class="Ar">len</var>. Return the number of bytes placed into
	<var class="Ar">data</var> on success, and zero for end-of-file.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_REMOVE</code></h2>
	Remove the underlying file. This is called if a zip archive is empty when
	closed.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code></h2>
	Abort writing to the source. Discard written data. Clean up temporary files or
	internal buffers. Subsequently opening and reading from the source should
	return the original data.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_SEEK</code></h2>
	Specify position to read next byte from, like
	<a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fseek.html">fseek(3)</a>. Use
	<a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ZIP_SOURCE_GET_ARGS.html">ZIP_SOURCE_GET_ARGS(3)</a> to
	decode the arguments into the following struct:
	<div class="Bd Pp">
	<pre>
	struct zip_source_args_seek {
	zip_int64_t offset;
	int whence;
	};
	</pre>
	</div>
	<p class="Pp">If the size of the source's data is known, use
	<a class="Xr" href="zip_source_seek_compute_offset.html">zip_source_seek_compute_offset(3)</a>
	to validate the arguments and compute the new offset.</p>
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_SEEK_WRITE</code></h2>
	Specify position to write next byte to, like
	<a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fseek.html">fseek(3)</a>. See
	<code class="Dv">ZIP_SOURCE_SEEK</code> for details.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_STAT</code></h2>
	Get meta information for the input data. <var class="Ar">data</var> points to an
	allocated <var class="Vt">struct zip_stat</var>, which should be initialized
	using <a class="Xr" href="zip_stat_init.html">zip_stat_init(3)</a> and then
	filled in.
	<p class="Pp">For uncompressed, unencrypted data, all information is optional.
	However, fill in as much information as is readily available.</p>
	<p class="Pp">If the data is compressed,
	<code class="Dv">ZIP_STAT_COMP_METHOD</code>,
	<code class="Dv">ZIP_STAT_SIZE</code>, and
	<code class="Dv">ZIP_STAT_CRC</code> must be filled in.</p>
	<p class="Pp">If the data is encrypted,
	<code class="Dv">ZIP_STAT_ENCRYPTION_METHOD</code>,
	<code class="Dv">ZIP_STAT_COMP_METHOD</code>,
	<code class="Dv">ZIP_STAT_SIZE</code>, and
	<code class="Dv">ZIP_STAT_CRC</code> must be filled in.</p>
	<p class="Pp">Information only available after the source has been read (e.g.,
	size) can be omitted in an earlier call. <i class="Em">NOTE</i>:
	<code class="Fn">zip_source_function</code>() may be called with this
	argument even after being called with
	<code class="Dv">ZIP_SOURCE_CLOSE</code>.</p>
	<p class="Pp">Return sizeof(struct zip_stat) on success.</p>
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_SUPPORTS</code></h2>
	Return bitmap specifying which commands are supported. Use
	<a class="Xr" href="zip_source_make_command_bitmap.html">zip_source_make_command_bitmap(3)</a>.
	If this command is not implemented, the source is assumed to be a read source
	without seek support.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_TELL</code></h2>
	Return the current read offset in the source, like
	<a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftell.html">ftell(3)</a>.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_TELL_WRITE</code></h2>
	Return the current write offset in the source, like
	<a class="Xr" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftell.html">ftell(3)</a>.
	</section>
	<section class="Ss">
	<h2 class="Ss"><code class="Dv">ZIP_SOURCE_WRITE</code></h2>
	Write data to the source. Return number of bytes written.
	</section>
	<section class="Ss">
	<h2 class="Ss" id="Return_Values"><a class="permalink" href="#Return_Values">Return
	Values</a></h2>
	Commands should return -1 on error. <code class="Dv">ZIP_SOURCE_ERROR</code>
	will be called to retrieve the error code. On success, commands return 0,
	unless specified otherwise in the description above.
	</section>
	<section class="Ss">
	<h2 class="Ss" id="Calling_Conventions"><a class="permalink" href="#Calling_Conventions">Calling
	Conventions</a></h2>
	The library will always issue <code class="Dv">ZIP_SOURCE_OPEN</code> before
	issuing <code class="Dv">ZIP_SOURCE_READ</code>,
	<code class="Dv">ZIP_SOURCE_SEEK</code>, or
	<code class="Dv">ZIP_SOURCE_TELL</code>. When it no longer wishes to read from
	this source, it will issue <code class="Dv">ZIP_SOURCE_CLOSE</code>. If the
	library wishes to read the data again, it will issue
	<code class="Dv">ZIP_SOURCE_OPEN</code> a second time. If the function is
	unable to provide the data again, it should return -1.
	<p class="Pp"><code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code> or
	<code class="Dv">ZIP_SOURCE_BEGIN_WRITE_CLONING</code> will be called before
	<code class="Dv">ZIP_SOURCE_WRITE</code>,
	<code class="Dv">ZIP_SOURCE_SEEK_WRITE</code>, or
	<code class="Dv">ZIP_SOURCE_TELL_WRITE</code>. When writing is complete,
	either <code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code> or
	<code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code> will be called.</p>
	<p class="Pp"><code class="Dv">ZIP_SOURCE_ACCEPT_EMPTY</code>,
	<code class="Dv">ZIP_SOURCE_GET_FILE_ATTRIBUTES</code>, and
	<code class="Dv">ZIP_SOURCE_STAT</code> can be issued at any time.</p>
	<p class="Pp"><code class="Dv">ZIP_SOURCE_ERROR</code> will only be issued in
	response to the function returning -1.</p>
	<p class="Pp"><code class="Dv">ZIP_SOURCE_FREE</code> will be the last command
	issued; if <code class="Dv">ZIP_SOURCE_OPEN</code> was called and succeeded,
	<code class="Dv">ZIP_SOURCE_CLOSE</code> will be called before
	<code class="Dv">ZIP_SOURCE_FREE</code>, and similarly for
	<code class="Dv">ZIP_SOURCE_BEGIN_WRITE</code> or
	<code class="Dv">ZIP_SOURCE_BEGIN_WRITE_CLONING</code> and
	<code class="Dv">ZIP_SOURCE_COMMIT_WRITE</code> or
	<code class="Dv">ZIP_SOURCE_ROLLBACK_WRITE</code>.</p>
	</section>
	</section>
	<section class="Sh">
	<h1 class="Sh" id="RETURN_VALUES"><a class="permalink" href="#RETURN_VALUES">RETURN
	VALUES</a></h1>
	Upon successful completion, the created source is returned. Otherwise,
	<code class="Dv">NULL</code> is returned and the error code in
	<var class="Ar">archive</var> or <var class="Ar">error</var> is set to
	indicate the error (unless it is <code class="Dv">NULL</code>).
	</section>
	<section class="Sh">
	<h1 class="Sh" id="ERRORS"><a class="permalink" href="#ERRORS">ERRORS</a></h1>
	<code class="Fn">zip_source_function</code>() fails if:
	<dl class="Bl-tag">
	<dt>[<a class="permalink" href="#ZIP_ER_MEMORY"><code class="Er" id="ZIP_ER_MEMORY">ZIP_ER_MEMORY</code></a>]</dt>
	<dd>Required memory could not be allocated.</dd>
	</dl>
	</section>
	<section class="Sh">
	<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
	ALSO</a></h1>
	<a class="Xr" href="libzip.html">libzip(3)</a>,
	<a class="Xr" href="zip_file_add.html">zip_file_add(3)</a>,
	<a class="Xr" href="zip_file_attributes_init.html">zip_file_attributes_init(3)</a>,
	<a class="Xr" href="zip_file_replace.html">zip_file_replace(3)</a>,
	<a class="Xr" href="zip_source.html">zip_source(3)</a>,
	<a class="Xr" href="zip_stat_init.html">zip_stat_init(3)</a>
	</section>
	<section class="Sh">
	<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
	<code class="Fn">zip_source_function</code>() and
	<code class="Fn">zip_source_function_create</code>() were added in libzip 1.0.
	</section>
	<section class="Sh">
	<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
	<span class="An">Dieter Baron</span>
	<<a class="Mt" href="mailto:dillo@nih.at">dillo@nih.at</a>> and
	<span class="An">Thomas Klausner</span>
	<<a class="Mt" href="mailto:tk@giga.or.at">tk@giga.or.at</a>>
	</section>
	</div>
	<table class="foot">
	<tr>
	<td class="foot-date">April 17, 2020</td>
	<td class="foot-os">NiH</td>
	</tr>
	</table>
	</body>
	</html>