These APIs are a minimal emulation of the Python 2 C API for built-in file objects, which used to rely on the buffered I/O (
FILE*
) support from the C standard library. In Python 3, files and streams use the new
io
module, which defines several layers over the low-level unbuffered I/O of the operating system. The functions described below are convenience C wrappers over these new APIs, and meant mostly for internal error reporting in the interpreter; third-party code is advised to access the
io
APIs instead.
PyFile_FromFd
(
int
fd
, const char
*name
, const char
*mode
, int
buffering
, const char
*encoding
, const char
*errors
, const char
*newline
, int
closefd
)
¶
Create a Python file object from the file descriptor of an already opened file
fd
. The arguments
name
,
encoding
,
errors
and
newline
可以是
NULL
to use the defaults;
buffering
可以是
-1
to use the default.
name
is ignored and kept for backward compatibility. Return
NULL
on failure. For a more comprehensive description of the arguments, please refer to the
io.open()
function documentation.
警告
Since Python streams have their own buffering layer, mixing them with OS-level file descriptors can produce various issues (such as unexpected ordering of data).
3.2 版改变： Ignore name 属性。
PyObject_AsFileDescriptor
(
PyObject
*p
)
¶
Return the file descriptor associated with
p
as an
int
. If the object is an integer, its value is returned. If not, the object’s
fileno()
method is called if it exists; the method must return an integer, which is returned as the file descriptor value. Sets an exception and returns
-1
当故障时。
PyFile_GetLine
(
PyObject
*p
, int
n
)
¶
相当于
p.readline([n])
, this function reads one line from the object
p
.
p
may be a file object or any object with a
readline()
方法。若
n
is
0
, exactly one line is read, regardless of the length of the line. If
n
大于
0
, no more than
n
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
n
is less than
0
, however, one line is read regardless of length, but
EOFError
is raised if the end of the file is reached immediately.