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<h1 class="title">Storage</h1>
<table class="docinfo" frame="void" rules="none">
<col class="docinfo-name" />
<col class="docinfo-content" />
<tbody valign="top">
<tr><th class="docinfo-name">Author:</th>
<td>Arvid Norberg, <a class="last reference external" href="mailto:arvid&#64;rasterbar.com">arvid&#64;rasterbar.com</a></td></tr>
<tr><th class="docinfo-name">Version:</th>
<td>1.0.0</td></tr>
</tbody>
</table>
<div class="contents topic" id="table-of-contents">
<p class="topic-title first">Table of contents</p>
<ul class="simple">
<li><a class="reference internal" href="#file-entry" id="id25">file_entry</a></li>
<li><a class="reference internal" href="#file-slice" id="id26">file_slice</a></li>
<li><a class="reference internal" href="#file-storage" id="id27">file_storage</a></li>
</ul>
</div>
<a name="file_entry"></a><div class="section" id="file-entry">
<h1>file_entry</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/file_storage.hpp">libtorrent/file_storage.hpp</a>&quot;</p>
<p>information about a file in a <a class="reference external" href="reference-Storage.html#file_storage">file_storage</a></p>
<pre class="literal-block">
struct file_entry
{
std::string path;
std::string symlink_path;
size_type offset;
size_type size;
size_type file_base;
std::time_t mtime;
sha1_hash filehash;
bool pad_file:1;
bool hidden_attribute:1;
bool executable_attribute:1;
bool symlink_attribute:1;
};
</pre>
<a name="path"></a><dl class="docutils">
<dt>path</dt>
<dd>the full path of this file. The paths are unicode strings
encoded in UTF-8.</dd>
</dl>
<a name="symlink_path"></a><dl class="docutils">
<dt>symlink_path</dt>
<dd>the path which this is a symlink to, or empty if this is
not a symlink. This field is only used if the <tt class="docutils literal">symlink_attribute</tt> is set.</dd>
</dl>
<a name="offset"></a><dl class="docutils">
<dt>offset</dt>
<dd>the offset of this file inside the torrent</dd>
</dl>
<a name="size"></a><dl class="docutils">
<dt>size</dt>
<dd>the size of the file (in bytes) and <tt class="docutils literal">offset</tt> is the byte offset
of the file within the torrent. i.e. the sum of all the sizes of the files
before it in the list.</dd>
</dl>
<a name="file_base"></a><dl class="docutils">
<dt>file_base</dt>
<dd>the offset in the file where the storage should start. The normal
case is to have this set to 0, so that the storage starts saving data at the start
if the file. In cases where multiple files are mapped into the same file though,
the <tt class="docutils literal">file_base</tt> should be set to an offset so that the different regions do
not overlap. This is used when mapping &quot;unselected&quot; files into a so-called part
file.</dd>
</dl>
<a name="mtime"></a><dl class="docutils">
<dt>mtime</dt>
<dd>the modification time of this file specified in posix time.</dd>
</dl>
<a name="filehash"></a><dl class="docutils">
<dt>filehash</dt>
<dd>a sha-1 hash of the content of the file, or zeroes, if no
file hash was present in the torrent file. It can be used to potentially
find alternative sources for the file.</dd>
</dl>
<a name="pad_file"></a><dl class="docutils">
<dt>pad_file</dt>
<dd>set to true for files that are not part of the data of the torrent.
They are just there to make sure the next file is aligned to a particular byte offset
or piece boundry. These files should typically be hidden from an end user. They are
not written to disk.</dd>
</dl>
<a name="hidden_attribute"></a><dl class="docutils">
<dt>hidden_attribute</dt>
<dd>true if the file was marked as hidden (on windows).</dd>
</dl>
<a name="executable_attribute"></a><dl class="docutils">
<dt>executable_attribute</dt>
<dd>true if the file was marked as executable (posix)</dd>
</dl>
<a name="symlink_attribute"></a><dl class="docutils">
<dt>symlink_attribute</dt>
<dd>true if the file was a symlink. If this is the case
the <tt class="docutils literal">symlink_index</tt> refers to a string which specifies the original location
where the data for this file was found.</dd>
</dl>
<a name="file_slice"></a></div>
<div class="section" id="file-slice">
<h1>file_slice</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/file_storage.hpp">libtorrent/file_storage.hpp</a>&quot;</p>
<p>represents a window of a file in a torrent.</p>
<p>The <tt class="docutils literal">file_index</tt> refers to the index of the file (in the <a class="reference external" href="reference-Core.html#torrent_info">torrent_info</a>).
To get the path and filename, use <tt class="docutils literal">file_at()</tt> and give the <tt class="docutils literal">file_index</tt>
as argument. The <tt class="docutils literal">offset</tt> is the byte offset in the file where the range
starts, and <tt class="docutils literal">size</tt> is the number of bytes this range is. The size + offset
will never be greater than the file size.</p>
<pre class="literal-block">
struct file_slice
{
int file_index;
size_type offset;
size_type size;
};
</pre>
<a name="file_index"></a><dl class="docutils">
<dt>file_index</dt>
<dd>the index of the file</dd>
</dl>
<a name="offset"></a><dl class="docutils">
<dt>offset</dt>
<dd>the offset from the start of the file, in bytes</dd>
</dl>
<a name="size"></a><dl class="docutils">
<dt>size</dt>
<dd>the size of the window, in bytes</dd>
</dl>
<a name="file_storage"></a></div>
<div class="section" id="file-storage">
<h1>file_storage</h1>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/file_storage.hpp">libtorrent/file_storage.hpp</a>&quot;</p>
<p>The <tt class="docutils literal">file_storage</tt> class represents a file list and the piece
size. Everything necessary to interpret a regular bittorrent storage
file structure.</p>
<pre class="literal-block">
class file_storage
{
bool <strong>is_valid</strong> () const;
void <strong>reserve</strong> (int num_files);
void <strong>add_file</strong> (std::string const&amp; p, size_type size, int flags = 0
, std::time_t mtime = 0, std::string const&amp; s_p = &quot;&quot;);
void <strong>add_file</strong> (file_entry const&amp; e, char const* filehash = 0);
void <strong>rename_file</strong> (int index, std::string const&amp; new_filename);
void <strong>rename_file_borrow</strong> (int index, char const* new_filename, int len);
std::vector&lt;file_slice&gt; <strong>map_block</strong> (int piece, size_type offset
, int size) const;
peer_request <strong>map_file</strong> (int file, size_type offset, int size) const;
int <strong>num_files</strong> () const;
file_entry <strong>at</strong> (int index) const;
size_type <strong>total_size</strong> () const;
void <strong>set_num_pieces</strong> (int n);
int <strong>num_pieces</strong> () const;
void <strong>set_piece_length</strong> (int l);
int <strong>piece_length</strong> () const;
int <strong>piece_size</strong> (int index) const;
void <strong>set_name</strong> (std::string const&amp; n);
const std::string&amp; <strong>name</strong> () const;
void <strong>swap</strong> (file_storage&amp; ti);
void <strong>optimize</strong> (int pad_file_limit = -1, int alignment = -1);
size_type <strong>file_size</strong> (int index) const;
sha1_hash <strong>hash</strong> (int index) const;
std::string <strong>file_name</strong> (int index) const;
size_type <strong>file_offset</strong> (int index) const;
time_t <strong>mtime</strong> (int index) const;
bool <strong>pad_file_at</strong> (int index) const;
std::string const&amp; <strong>symlink</strong> (int index) const;
std::string <strong>file_path</strong> (int index, std::string const&amp; save_path = &quot;&quot;) const;
int <strong>file_flags</strong> (int index) const;
void <strong>set_file_base</strong> (int index, size_type off);
size_type <strong>file_base</strong> (int index) const;
int <strong>file_index_at_offset</strong> (size_type offset) const;
char const* <strong>file_name_ptr</strong> (int index) const;
int <strong>file_name_len</strong> (int index) const;
enum flags_t
{
pad_file,
attribute_hidden,
attribute_executable,
attribute_symlink,
};
enum file_flags_t
{
flag_pad_file,
flag_hidden,
flag_executable,
flag_symlink,
};
};
</pre>
<a name="is_valid()"></a><div class="section" id="is-valid">
<h2>is_valid()</h2>
<pre class="literal-block">
bool <strong>is_valid</strong> () const;
</pre>
<p>returns true if the piece length has been initialized
on the <a class="reference external" href="reference-Storage.html#file_storage">file_storage</a>. This is typically taken as a proxy
of whether the <a class="reference external" href="reference-Storage.html#file_storage">file_storage</a> as a whole is initialized or
not.</p>
<a name="reserve()"></a></div>
<div class="section" id="reserve">
<h2>reserve()</h2>
<pre class="literal-block">
void <strong>reserve</strong> (int num_files);
</pre>
<p>allocates space for <tt class="docutils literal">num_files</tt> in the internal file list. This can
be used to avoid reallocating the internal file list when the number
of files to be added is known up-front.</p>
<a name="add_file()"></a></div>
<div class="section" id="add-file">
<h2>add_file()</h2>
<pre class="literal-block">
void <strong>add_file</strong> (std::string const&amp; p, size_type size, int flags = 0
, std::time_t mtime = 0, std::string const&amp; s_p = &quot;&quot;);
void <strong>add_file</strong> (file_entry const&amp; e, char const* filehash = 0);
</pre>
<p>Adds a file to the file storage. The <tt class="docutils literal">flags</tt> argument sets attributes on the file.
The file attributes is an extension and may not work in all bittorrent clients.</p>
<p>For possible file attributes, see <a class="reference external" href="reference-Storage.html#flags_t">file_storage::flags_t</a>.</p>
<p>If more files than one are added, certain restrictions to their paths apply.
In a multi-file file storage (torrent), all files must share the same root directory.</p>
<p>That is, the first path element of all files must be the same.
This shared path element is also set to the name of the torrent. It
can be changed by calling <tt class="docutils literal">set_name</tt>.</p>
<p>The built in functions to traverse a directory to add files will
make sure this requirement is fulfilled.</p>
<a name="rename_file()"></a></div>
<div class="section" id="rename-file">
<h2>rename_file()</h2>
<pre class="literal-block">
void <strong>rename_file</strong> (int index, std::string const&amp; new_filename);
</pre>
<p>renames the file at <tt class="docutils literal">index</tt> to <tt class="docutils literal">new_filename</tt>. Keep in mind
that filenames are expected to be UTF-8 encoded.</p>
<a name="rename_file_borrow()"></a></div>
<div class="section" id="rename-file-borrow">
<h2>rename_file_borrow()</h2>
<pre class="literal-block">
void <strong>rename_file_borrow</strong> (int index, char const* new_filename, int len);
</pre>
<p>this is a low-level function that sets the name of a file
by making it reference a buffer that is not owned by the <a class="reference external" href="reference-Storage.html#file_storage">file_storage</a>.
it's an optimization used when loading .torrent files, to not
duplicate names in memory.</p>
<a name="map_block()"></a></div>
<div class="section" id="map-block">
<h2>map_block()</h2>
<pre class="literal-block">
std::vector&lt;file_slice&gt; <strong>map_block</strong> (int piece, size_type offset
, int size) const;
</pre>
<p>returns a list of <a class="reference external" href="reference-Storage.html#file_slice">file_slice</a> objects representing the portions of
files the specified piece index, byte offset and size range overlaps.
this is the inverse mapping of <a class="reference external" href="reference-Core.html#map_file()">map_file()</a>.</p>
<a name="map_file()"></a></div>
<div class="section" id="map-file">
<h2>map_file()</h2>
<pre class="literal-block">
peer_request <strong>map_file</strong> (int file, size_type offset, int size) const;
</pre>
<p>returns a <a class="reference external" href="reference-Core.html#peer_request">peer_request</a> representing the piece index, byte offset
and size the specified file range overlaps. This is the inverse
mapping ove <a class="reference external" href="reference-Core.html#map_block()">map_block()</a>.</p>
<a name="num_files()"></a></div>
<div class="section" id="num-files">
<h2>num_files()</h2>
<pre class="literal-block">
int <strong>num_files</strong> () const;
</pre>
<p>returns the number of files in the <a class="reference external" href="reference-Storage.html#file_storage">file_storage</a></p>
<a name="at()"></a></div>
<div class="section" id="at">
<h2>at()</h2>
<pre class="literal-block">
file_entry <strong>at</strong> (int index) const;
</pre>
<p>returns a <a class="reference external" href="reference-Storage.html#file_entry">file_entry</a> with information about the file
at <tt class="docutils literal">index</tt>. Index must be in the range [0, <tt class="docutils literal">num_files()</tt> ).</p>
<a name="total_size()"></a></div>
<div class="section" id="total-size">
<h2>total_size()</h2>
<pre class="literal-block">
size_type <strong>total_size</strong> () const;
</pre>
<p>returns the total number of bytes all the files in this torrent spans</p>
<a name="num_pieces()"></a>
<a name="set_num_pieces()"></a></div>
<div class="section" id="num-pieces-set-num-pieces">
<h2>num_pieces() set_num_pieces()</h2>
<pre class="literal-block">
void <strong>set_num_pieces</strong> (int n);
int <strong>num_pieces</strong> () const;
</pre>
<p>set and get the number of pieces in the torrent</p>
<a name="piece_length()"></a>
<a name="set_piece_length()"></a></div>
<div class="section" id="piece-length-set-piece-length">
<h2>piece_length() set_piece_length()</h2>
<pre class="literal-block">
void <strong>set_piece_length</strong> (int l);
int <strong>piece_length</strong> () const;
</pre>
<p>set and get the size of each piece in this torrent. This size is typically an even power
of 2. It doesn't have to be though. It should be divisible by 16kiB however.</p>
<a name="piece_size()"></a></div>
<div class="section" id="piece-size">
<h2>piece_size()</h2>
<pre class="literal-block">
int <strong>piece_size</strong> (int index) const;
</pre>
<p>returns the piece size of <tt class="docutils literal">index</tt>. This will be the same as <a class="reference external" href="reference-Core.html#piece_length()">piece_length()</a>, except
for the last piece, which may be shorter.</p>
<a name="set_name()"></a>
<a name="name()"></a></div>
<div class="section" id="set-name-name">
<h2>set_name() name()</h2>
<pre class="literal-block">
void <strong>set_name</strong> (std::string const&amp; n);
const std::string&amp; <strong>name</strong> () const;
</pre>
<p>set and get the name of this torrent. For multi-file torrents, this is also
the name of the root directory all the files are stored in.</p>
<a name="swap()"></a></div>
<div class="section" id="swap">
<h2>swap()</h2>
<pre class="literal-block">
void <strong>swap</strong> (file_storage&amp; ti);
</pre>
<p>swap all content of <em>this</em> with <em>ti</em>.</p>
<a name="optimize()"></a></div>
<div class="section" id="optimize">
<h2>optimize()</h2>
<pre class="literal-block">
void <strong>optimize</strong> (int pad_file_limit = -1, int alignment = -1);
</pre>
<p>if pad_file_limit &gt;= 0, files larger than that limit will be padded,
default is to not add any padding (-1). The alignment specifies the
alignment files should be padded to. This defaults to the piece size
(-1) but it may also make sense to set it to 16 kiB, or something
divisible by 16 kiB.
If pad_file_limit is 0, every file will be padded (except empty ones).</p>
<a name="mtime()"></a>
<a name="hash()"></a>
<a name="symlink()"></a>
<a name="file_name()"></a>
<a name="pad_file_at()"></a>
<a name="file_size()"></a>
<a name="file_path()"></a>
<a name="file_offset()"></a></div>
<div class="section" id="mtime-hash-symlink-file-name-pad-file-at-file-size-file-path-file-offset">
<h2>mtime() hash() symlink() file_name() pad_file_at() file_size() file_path() file_offset()</h2>
<pre class="literal-block">
size_type <strong>file_size</strong> (int index) const;
sha1_hash <strong>hash</strong> (int index) const;
std::string <strong>file_name</strong> (int index) const;
size_type <strong>file_offset</strong> (int index) const;
time_t <strong>mtime</strong> (int index) const;
bool <strong>pad_file_at</strong> (int index) const;
std::string const&amp; <strong>symlink</strong> (int index) const;
std::string <strong>file_path</strong> (int index, std::string const&amp; save_path = &quot;&quot;) const;
</pre>
<p>These functions are used to query attributes of files at
a given index.</p>
<p>The <tt class="docutils literal">file_hash()</tt> is a sha-1 hash of the file, or 0 if none was
provided in the torrent file. This can potentially be used to
join a bittorrent network with other file sharing networks.</p>
<p>The <tt class="docutils literal">mtime()</tt> is the modification time is the posix
time when a file was last modified when the torrent
was created, or 0 if it was not included in the torrent file.</p>
<p><tt class="docutils literal">file_path()</tt> returns the full path to a file.</p>
<p><tt class="docutils literal">file_size()</tt> returns the size of a file.</p>
<p><tt class="docutils literal">pad_file_at()</tt> returns true if the file at the given
index is a pad-file.</p>
<p><tt class="docutils literal">file_name()</tt> returns <em>just</em> the name of the file, whereas
<tt class="docutils literal">file_path()</tt> returns the path (inside the torrent file) with
the filename appended.</p>
<p><tt class="docutils literal">file_offset()</tt> returns the byte offset within the torrent file
where this file starts. It can be used to map the file to a piece
index (given the piece size).</p>
<a name="file_flags()"></a></div>
<div class="section" id="file-flags">
<h2>file_flags()</h2>
<pre class="literal-block">
int <strong>file_flags</strong> (int index) const;
</pre>
<p>returns a bitmask of flags from <a class="reference external" href="reference-Storage.html#file_flags_t">file_flags_t</a> that apply
to file at <tt class="docutils literal">index</tt>.</p>
<a name="file_base()"></a>
<a name="set_file_base()"></a></div>
<div class="section" id="file-base-set-file-base">
<h2>file_base() set_file_base()</h2>
<pre class="literal-block">
void <strong>set_file_base</strong> (int index, size_type off);
size_type <strong>file_base</strong> (int index) const;
</pre>
<p>The file base of a file is the offset within the file on the filsystem
where it starts to write. For the most part, this is always 0. It's
possible to map several files (in the torrent) into a single file on
the filesystem by making them all point to the same filename, but with
different file bases, so that they don't overlap.
<a class="reference external" href="reference-Core.html#remap_files()">torrent_info::remap_files()</a> can be used to use a new file layout.</p>
<a name="file_index_at_offset()"></a></div>
<div class="section" id="file-index-at-offset">
<h2>file_index_at_offset()</h2>
<pre class="literal-block">
int <strong>file_index_at_offset</strong> (size_type offset) const;
</pre>
<p>returns the index of the file at the given offset in the torrent</p>
<a name="file_name_len()"></a>
<a name="file_name_ptr()"></a></div>
<div class="section" id="file-name-len-file-name-ptr">
<h2>file_name_len() file_name_ptr()</h2>
<pre class="literal-block">
char const* <strong>file_name_ptr</strong> (int index) const;
int <strong>file_name_len</strong> (int index) const;
</pre>
<p>low-level function. returns a pointer to the internal storage for
the filename. This string may not be null terinated!
the <tt class="docutils literal">file_name_len()</tt> function returns the length of the filename.</p>
<a name="flags_t"></a></div>
<div class="section" id="enum-flags-t">
<h2>enum flags_t</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/file_storage.hpp">libtorrent/file_storage.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="25%" />
<col width="8%" />
<col width="67%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>pad_file</td>
<td>1</td>
<td>the file is a pad file. It's required to contain zeroes
at it will not be saved to disk. Its purpose is to make
the following file start on a piece boundary.</td>
</tr>
<tr><td>attribute_hidden</td>
<td>2</td>
<td>this file has the hidden attribute set. This is primarily
a windows attribute</td>
</tr>
<tr><td>attribute_executable</td>
<td>4</td>
<td>this file has the executable attribute set.</td>
</tr>
<tr><td>attribute_symlink</td>
<td>8</td>
<td>this file is a symbilic link. It should have a link
target string associated with it.</td>
</tr>
</tbody>
</table>
<a name="file_flags_t"></a></div>
<div class="section" id="enum-file-flags-t">
<h2>enum file_flags_t</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/file_storage.hpp">libtorrent/file_storage.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="23%" />
<col width="9%" />
<col width="68%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>flag_pad_file</td>
<td>1</td>
<td>this file is a pad file. The creator of the
torrent promises the file is entirely filled with
zeroes and does not need to be downloaded. The
purpose is just to align the next file to either
a block or piece boundary.</td>
</tr>
<tr><td>flag_hidden</td>
<td>2</td>
<td>this file is hiddent (sets the hidden attribute
on windows)</td>
</tr>
<tr><td>flag_executable</td>
<td>4</td>
<td>this file is executable (sets the executable bit
on posix like systems)</td>
</tr>
<tr><td>flag_symlink</td>
<td>8</td>
<td>this file is a symlink. The symlink target is
specified in a separate field</td>
</tr>
</tbody>
</table>
<a name="default_storage_constructor()"></a></div>
<div class="section" id="default-storage-constructor">
<h2>default_storage_constructor()</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/storage_defs.hpp">libtorrent/storage_defs.hpp</a>&quot;</p>
<pre class="literal-block">
storage_interface* <strong>default_storage_constructor</strong> (
file_storage const&amp;, file_storage const* mapped, std::string const&amp;, file_pool&amp;
, std::vector&lt;boost::uint8_t&gt; const&amp;);
</pre>
<p>the constructor function for the regular file storage. This is the
default value for <a class="reference external" href="reference-Session.html#storage">add_torrent_params::storage</a>.</p>
<a name="disabled_storage_constructor()"></a></div>
<div class="section" id="disabled-storage-constructor">
<h2>disabled_storage_constructor()</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/storage_defs.hpp">libtorrent/storage_defs.hpp</a>&quot;</p>
<pre class="literal-block">
storage_interface* <strong>disabled_storage_constructor</strong> (
file_storage const&amp;, file_storage const* mapped, std::string const&amp;, file_pool&amp;
, std::vector&lt;boost::uint8_t&gt; const&amp;);
</pre>
<p>the constructor function for the disabled storage. This can be used for
testing and benchmarking. It will throw away any data written to
it and return garbage for anything read from it.</p>
<a name="storage_mode_t"></a></div>
<div class="section" id="enum-storage-mode-t">
<h2>enum storage_mode_t</h2>
<p>Declared in &quot;<a class="reference external" href="../include/libtorrent/storage_defs.hpp">libtorrent/storage_defs.hpp</a>&quot;</p>
<table border="1" class="docutils">
<colgroup>
<col width="22%" />
<col width="7%" />
<col width="72%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">name</th>
<th class="head">value</th>
<th class="head">description</th>
</tr>
</thead>
<tbody valign="top">
<tr><td>storage_mode_allocate</td>
<td>0</td>
<td>All pieces will be written to their final position, all files will be
allocated in full when the torrent is first started. This is done with
<tt class="docutils literal">fallocate()</tt> and similar calls. This mode minimizes fragmentation.</td>
</tr>
<tr><td>storage_mode_sparse</td>
<td>1</td>
<td>All pieces will be written to the place where they belong and sparse files
will be used. This is the recommended, and default mode.</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</body>
</html>