1 .. highlightlang:: c 2 3 .. _fileobjects: 4 5 File Objects 6 ------------ 7 8 .. index:: object: file 9 10 These APIs are a minimal emulation of the Python 2 C API for built-in file 11 objects, which used to rely on the buffered I/O (:c:type:`FILE\*`) support 12 from the C standard library. In Python 3, files and streams use the new 13 :mod:`io` module, which defines several layers over the low-level unbuffered 14 I/O of the operating system. The functions described below are 15 convenience C wrappers over these new APIs, and meant mostly for internal 16 error reporting in the interpreter; third-party code is advised to access 17 the :mod:`io` APIs instead. 18 19 20 .. c:function:: PyFile_FromFd(int fd, const char *name, const char *mode, int buffering, const char *encoding, const char *errors, const char *newline, int closefd) 21 22 Create a Python file object from the file descriptor of an already 23 opened file *fd*. The arguments *name*, *encoding*, *errors* and *newline* 24 can be *NULL* to use the defaults; *buffering* can be *-1* to use the 25 default. *name* is ignored and kept for backward compatibility. Return 26 *NULL* on failure. For a more comprehensive description of the arguments, 27 please refer to the :func:`io.open` function documentation. 28 29 .. warning:: 30 31 Since Python streams have their own buffering layer, mixing them with 32 OS-level file descriptors can produce various issues (such as unexpected 33 ordering of data). 34 35 .. versionchanged:: 3.2 36 Ignore *name* attribute. 37 38 39 .. c:function:: int PyObject_AsFileDescriptor(PyObject *p) 40 41 Return the file descriptor associated with *p* as an :c:type:`int`. If the 42 object is an integer, its value is returned. If not, the 43 object's :meth:`~io.IOBase.fileno` method is called if it exists; the 44 method must return an integer, which is returned as the file descriptor 45 value. Sets an exception and returns ``-1`` on failure. 46 47 48 .. c:function:: PyObject* PyFile_GetLine(PyObject *p, int n) 49 50 .. index:: single: EOFError (built-in exception) 51 52 Equivalent to ``p.readline([n])``, this function reads one line from the 53 object *p*. *p* may be a file object or any object with a 54 :meth:`~io.IOBase.readline` 55 method. If *n* is ``0``, exactly one line is read, regardless of the length of 56 the line. If *n* is greater than ``0``, no more than *n* bytes will be read 57 from the file; a partial line can be returned. In both cases, an empty string 58 is returned if the end of the file is reached immediately. If *n* is less than 59 ``0``, however, one line is read regardless of length, but :exc:`EOFError` is 60 raised if the end of the file is reached immediately. 61 62 63 .. c:function:: int PyFile_WriteObject(PyObject *obj, PyObject *p, int flags) 64 65 .. index:: single: Py_PRINT_RAW 66 67 Write object *obj* to file object *p*. The only supported flag for *flags* is 68 :const:`Py_PRINT_RAW`; if given, the :func:`str` of the object is written 69 instead of the :func:`repr`. Return ``0`` on success or ``-1`` on failure; the 70 appropriate exception will be set. 71 72 73 .. c:function:: int PyFile_WriteString(const char *s, PyObject *p) 74 75 Write string *s* to file object *p*. Return ``0`` on success or ``-1`` on 76 failure; the appropriate exception will be set. 77
