fopen() and open() in cpython

[Windson Yang]

Thank you so much for the answer, now it makes sense :D

eryk sun <eryksun at gmail.com> 于2019年8月15日周四 上午12:27写道：

> On 8/13/19, Windson Yang <wiwindson at gmail.com> wrote:
> > After my investigation, I found Since Python maintains its own buffer
> when
> > read/write files, the build-in python open() function will call the
> open()
> > system call instead of calling standard io fopen() for caching.  So when
> we
> > read/write a file in Python, it would not call fopen(), fopen() only use
> > for Python itself but not for python user. Am I correct?
>
> Python 2 I/O wraps C FILE streams (i.e. fopen, fclose, fread, fwrite,
> fgets). Python 3 has its own I/O stack (raw, buffered, text) that aims
> to be more reliably cross-platform than C FILE streams. Python 3 still
> uses FILE streams internally in some cases (e.g. to read pyvenv.cfg at
> startup).
>
> FYI in Windows open() or _wopen() is a C runtime library function, not
> a system function. It calls the Windows API function CreateFile, which
> calls the NT system function, NtCreateFile. It's similarly layered for
> all calls, e.g. read() calls ReadFile or ReadConsoleW, which calls
> NtReadFile or NtDeviceIoControlFile (ReadConsoleW).
>