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<div class="section" id="file-objects">
<span id="fileobjects"></span><h1>File Objects<a class="headerlink" href="#file-objects" title="Permalink to this headline">¶</a></h1>
<p id="index-0">Python’s built-in file objects are implemented entirely on the <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code>
support from the C standard library. This is an implementation detail and may
change in future releases of Python.</p>
<dl class="type">
<dt id="c.PyFileObject">
<code class="descname">PyFileObject</code><a class="headerlink" href="#c.PyFileObject" title="Permalink to this definition">¶</a></dt>
<dd><p>This subtype of <a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyObject</span></code></a> represents a Python file object.</p>
</dd></dl>
<dl class="var">
<dt id="c.PyFile_Type">
<a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a> <code class="descname">PyFile_Type</code><a class="headerlink" href="#c.PyFile_Type" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-1">This instance of <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyTypeObject</span></code></a> represents the Python file type. This is
exposed to Python programs as <code class="docutils literal notranslate"><span class="pre">file</span></code> and <code class="docutils literal notranslate"><span class="pre">types.FileType</span></code>.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_Check">
int <code class="descname">PyFile_Check</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_Check" title="Permalink to this definition">¶</a></dt>
<dd><p>Return true if its argument is a <a class="reference internal" href="#c.PyFileObject" title="PyFileObject"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyFileObject</span></code></a> or a subtype of
<a class="reference internal" href="#c.PyFileObject" title="PyFileObject"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyFileObject</span></code></a>.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 2.2: </span>Allowed subtypes to be accepted.</p>
</div>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_CheckExact">
int <code class="descname">PyFile_CheckExact</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_CheckExact" title="Permalink to this definition">¶</a></dt>
<dd><p>Return true if its argument is a <a class="reference internal" href="#c.PyFileObject" title="PyFileObject"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyFileObject</span></code></a>, but not a subtype of
<a class="reference internal" href="#c.PyFileObject" title="PyFileObject"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyFileObject</span></code></a>.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.2.</span></p>
</div>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_FromString">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyFile_FromString</code><span class="sig-paren">(</span>char<em> *filename</em>, char<em> *mode</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_FromString" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-2">On success, return a new file object that is opened on the file given by
<em>filename</em>, with a file mode given by <em>mode</em>, where <em>mode</em> has the same
semantics as the standard C routine <code class="xref c c-func docutils literal notranslate"><span class="pre">fopen()</span></code>. On failure, return <em>NULL</em>.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_FromFile">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyFile_FromFile</code><span class="sig-paren">(</span>FILE<em> *fp</em>, char<em> *name</em>, char<em> *mode</em>, int (<em>*close</em>)(FILE*)<span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_FromFile" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>Create a new <a class="reference internal" href="#c.PyFileObject" title="PyFileObject"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyFileObject</span></code></a> from the already-open standard C file
pointer, <em>fp</em>. The function <em>close</em> will be called when the file should be
closed. Return <em>NULL</em> and close the file using <em>close</em> on failure.
<em>close</em> is optional and can be set to <em>NULL</em>.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_AsFile">
FILE* <code class="descname">PyFile_AsFile</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_AsFile" title="Permalink to this definition">¶</a></dt>
<dd><p>Return the file object associated with <em>p</em> as a <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code>.</p>
<p>If the caller will ever use the returned <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> object while
the <a class="reference internal" href="../glossary.html#term-gil"><span class="xref std std-term">GIL</span></a> is released it must also call the <a class="reference internal" href="#c.PyFile_IncUseCount" title="PyFile_IncUseCount"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyFile_IncUseCount()</span></code></a> and
<a class="reference internal" href="#c.PyFile_DecUseCount" title="PyFile_DecUseCount"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyFile_DecUseCount()</span></code></a> functions described below as appropriate.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_IncUseCount">
void <code class="descname">PyFile_IncUseCount</code><span class="sig-paren">(</span><a class="reference internal" href="#c.PyFileObject" title="PyFileObject">PyFileObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_IncUseCount" title="Permalink to this definition">¶</a></dt>
<dd><p>Increments the PyFileObject’s internal use count to indicate
that the underlying <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> is being used.
This prevents Python from calling f_close() on it from another thread.
Callers of this must call <a class="reference internal" href="#c.PyFile_DecUseCount" title="PyFile_DecUseCount"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyFile_DecUseCount()</span></code></a> when they are
finished with the <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code>. Otherwise the file object will
never be closed by Python.</p>
<p>The <a class="reference internal" href="../glossary.html#term-gil"><span class="xref std std-term">GIL</span></a> must be held while calling this function.</p>
<p>The suggested use is to call this after <a class="reference internal" href="#c.PyFile_AsFile" title="PyFile_AsFile"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyFile_AsFile()</span></code></a> and before
you release the GIL:</p>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="kt">FILE</span> <span class="o">*</span><span class="n">fp</span> <span class="o">=</span> <span class="n">PyFile_AsFile</span><span class="p">(</span><span class="n">p</span><span class="p">);</span>
<span class="n">PyFile_IncUseCount</span><span class="p">(</span><span class="n">p</span><span class="p">);</span>
<span class="cm">/* ... */</span>
<span class="n">Py_BEGIN_ALLOW_THREADS</span>
<span class="nf">do_something</span><span class="p">(</span><span class="n">fp</span><span class="p">);</span>
<span class="n">Py_END_ALLOW_THREADS</span>
<span class="cm">/* ... */</span>
<span class="n">PyFile_DecUseCount</span><span class="p">(</span><span class="n">p</span><span class="p">);</span>
</pre></div>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.6.</span></p>
</div>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_DecUseCount">
void <code class="descname">PyFile_DecUseCount</code><span class="sig-paren">(</span><a class="reference internal" href="#c.PyFileObject" title="PyFileObject">PyFileObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_DecUseCount" title="Permalink to this definition">¶</a></dt>
<dd><p>Decrements the PyFileObject’s internal unlocked_count member to
indicate that the caller is done with its own use of the <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code>.
This may only be called to undo a prior call to <a class="reference internal" href="#c.PyFile_IncUseCount" title="PyFile_IncUseCount"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyFile_IncUseCount()</span></code></a>.</p>
<p>The <a class="reference internal" href="../glossary.html#term-gil"><span class="xref std std-term">GIL</span></a> must be held while calling this function (see the example
above).</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.6.</span></p>
</div>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_GetLine">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyFile_GetLine</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em>, int<em> n</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_GetLine" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p id="index-3">Equivalent to <code class="docutils literal notranslate"><span class="pre">p.readline([n])</span></code>, this function reads one line from the
object <em>p</em>. <em>p</em> may be a file object or any object with a
<a class="reference internal" href="../library/io.html#io.IOBase.readline" title="io.IOBase.readline"><code class="xref py py-meth docutils literal notranslate"><span class="pre">readline()</span></code></a>
method. If <em>n</em> is <code class="docutils literal notranslate"><span class="pre">0</span></code>, exactly one line is read, regardless of the length of
the line. If <em>n</em> is greater than <code class="docutils literal notranslate"><span class="pre">0</span></code>, no more than <em>n</em> bytes will be read
from the file; a partial line can be returned. In both cases, an empty string
is returned if the end of the file is reached immediately. If <em>n</em> is less than
<code class="docutils literal notranslate"><span class="pre">0</span></code>, however, one line is read regardless of length, but <a class="reference internal" href="../library/exceptions.html#exceptions.EOFError" title="exceptions.EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a> is
raised if the end of the file is reached immediately.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_Name">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyFile_Name</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_Name" title="Permalink to this definition">¶</a></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><p>Return the name of the file specified by <em>p</em> as a string object.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_SetBufSize">
void <code class="descname">PyFile_SetBufSize</code><span class="sig-paren">(</span><a class="reference internal" href="#c.PyFileObject" title="PyFileObject">PyFileObject</a><em> *p</em>, int<em> n</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_SetBufSize" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-4">Available on systems with <code class="xref c c-func docutils literal notranslate"><span class="pre">setvbuf()</span></code> only. This should only be called
immediately after file object creation.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_SetEncoding">
int <code class="descname">PyFile_SetEncoding</code><span class="sig-paren">(</span><a class="reference internal" href="#c.PyFileObject" title="PyFileObject">PyFileObject</a><em> *p</em>, const char<em> *enc</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_SetEncoding" title="Permalink to this definition">¶</a></dt>
<dd><p>Set the file’s encoding for Unicode output to <em>enc</em>. Return <code class="docutils literal notranslate"><span class="pre">1</span></code> on success and <code class="docutils literal notranslate"><span class="pre">0</span></code>
on failure.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.3.</span></p>
</div>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_SetEncodingAndErrors">
int <code class="descname">PyFile_SetEncodingAndErrors</code><span class="sig-paren">(</span><a class="reference internal" href="#c.PyFileObject" title="PyFileObject">PyFileObject</a><em> *p</em>, const char<em> *enc</em>, *errors<span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_SetEncodingAndErrors" title="Permalink to this definition">¶</a></dt>
<dd><p>Set the file’s encoding for Unicode output to <em>enc</em>, and its error
mode to <em>err</em>. Return <code class="docutils literal notranslate"><span class="pre">1</span></code> on success and <code class="docutils literal notranslate"><span class="pre">0</span></code> on failure.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 2.6.</span></p>
</div>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_SoftSpace">
int <code class="descname">PyFile_SoftSpace</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em>, int<em> newflag</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_SoftSpace" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-5">This function exists for internal use by the interpreter. Set the
<code class="xref py py-attr docutils literal notranslate"><span class="pre">softspace</span></code> attribute of <em>p</em> to <em>newflag</em> and return the previous value.
<em>p</em> does not have to be a file object for this function to work properly; any
object is supported (thought its only interesting if the <code class="xref py py-attr docutils literal notranslate"><span class="pre">softspace</span></code>
attribute can be set). This function clears any errors, and will return <code class="docutils literal notranslate"><span class="pre">0</span></code>
as the previous value if the attribute either does not exist or if there were
errors in retrieving it. There is no way to detect errors from this function,
but doing so should not be needed.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_WriteObject">
int <code class="descname">PyFile_WriteObject</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *obj</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em>, int<em> flags</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_WriteObject" title="Permalink to this definition">¶</a></dt>
<dd><p id="index-6">Write object <em>obj</em> to file object <em>p</em>. The only supported flag for <em>flags</em> is
<code class="xref py py-const docutils literal notranslate"><span class="pre">Py_PRINT_RAW</span></code>; if given, the <a class="reference internal" href="../library/functions.html#str" title="str"><code class="xref py py-func docutils literal notranslate"><span class="pre">str()</span></code></a> of the object is written
instead of the <a class="reference internal" href="../library/functions.html#repr" title="repr"><code class="xref py py-func docutils literal notranslate"><span class="pre">repr()</span></code></a>. Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success or <code class="docutils literal notranslate"><span class="pre">-1</span></code> on failure; the
appropriate exception will be set.</p>
</dd></dl>
<dl class="function">
<dt id="c.PyFile_WriteString">
int <code class="descname">PyFile_WriteString</code><span class="sig-paren">(</span>const char<em> *s</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *p</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyFile_WriteString" title="Permalink to this definition">¶</a></dt>
<dd><p>Write string <em>s</em> to file object <em>p</em>. Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success or <code class="docutils literal notranslate"><span class="pre">-1</span></code> on
failure; the appropriate exception will be set.</p>
</dd></dl>
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