7.5.4. File Objects¶

Python’s built-in file objects are implemented entirely on the FILE* support from the C standard library. This is an implementation detail and may change in future releases of Python.

PyFileObject¶

This subtype of PyObject represents a Python file object.

PyTypeObject PyFile_Type¶

int PyFile_Check(PyObject *p)¶

Return true if its argument is a PyFileObject or a subtype of PyFileObject.

Changed in version 2.2: Allowed subtypes to be accepted.

int PyFile_CheckExact(PyObject *p)¶

Return true if its argument is a PyFileObject, but not a subtype of PyFileObject.

New in version 2.2.

PyObject* PyFile_FromString(char *filename, char *mode)¶

PyObject* PyFile_FromFile(FILE *fp, char *name, char *mode, int (*close)(FILE*))¶

Create a new PyFileObject from the already-open standard C file pointer, fp. The function close will be called when the file should be closed. Return NULL and close the file using close on failure. close is optional and can be set to NULL.

FILE* PyFile_AsFile(PyObject *p)¶

Return the file object associated with p as a FILE*.

If the caller will ever use the returned FILE* object while the GIL is released it must also call the PyFile_IncUseCount() and PyFile_DecUseCount() functions described below as appropriate.

void PyFile_IncUseCount(PyFileObject *p)¶

Increments the PyFileObject’s internal use count to indicate that the underlying FILE* is being used. This prevents Python from calling f_close() on it from another thread. Callers of this must call PyFile_DecUseCount() when they are finished with the FILE*. Otherwise the file object will never be closed by Python.

The GIL must be held while calling this function.

The suggested use is to call this after PyFile_AsFile() and before you release the GIL:

FILE *fp = PyFile_AsFile(p);
PyFile_IncUseCount(p);
/* ... */
Py_BEGIN_ALLOW_THREADS
do_something(fp);
Py_END_ALLOW_THREADS
/* ... */
PyFile_DecUseCount(p);

New in version 2.6.

void PyFile_DecUseCount(PyFileObject *p)¶

Decrements the PyFileObject’s internal unlocked_count member to indicate that the caller is done with its own use of the FILE*. This may only be called to undo a prior call to PyFile_IncUseCount().

The GIL must be held while calling this function (see the example above).

New in version 2.6.

PyObject* PyFile_GetLine(PyObject *p, int n)¶

PyObject* PyFile_Name(PyObject *p)¶

Return the name of the file specified by p as a string object.

void PyFile_SetBufSize(PyFileObject *p, int n)¶

int PyFile_SetEncoding(PyFileObject *p, const char *enc)¶

Set the file’s encoding for Unicode output to enc. Return 1 on success and 0 on failure.

New in version 2.3.

int PyFile_SetEncodingAndErrors(PyFileObject *p, const char *enc, *errors)¶

Set the file’s encoding for Unicode output to enc, and its error mode to err. Return 1 on success and 0 on failure.

New in version 2.6.

int PyFile_SoftSpace(PyObject *p, int newflag)¶

int PyFile_WriteObject(PyObject *obj, PyObject *p, int flags)¶

int PyFile_WriteString(const char *s, PyObject *p)¶

Write string s to file object p. Return 0 on success or -1 on failure; the appropriate exception will be set.