[Python-Dev] getch() in msvcrt does not accept extended characters.
Hi all,
Please CC: me on any replies as I am not subscribed to this list. I
am the lead maintainer for the ntlmaps project
(http://ntlmaps.sourceforge.net). Recently a bugreport logged against
ntlmaps has brought an issue to my attention (see:
https://sourceforge.net/tracker/index.php?func=detail&aid=1224877&group_id=69259&atid=523935).
The getpass() function in module getpass does not accept extended characters
on Windows. On Windows, the getpass() source uses the msvcrt module to capture
one character at a time from stdin via the _getch() function defined in
conio.h. Microsoft support capturing extended characters via _getch (see:
http://support.microsoft.com/default.aspx?scid=kb;en-us;57888), but it requires
making a second call to getch() if one of the 'magic' returns is encountered in
the first call (0x00 or 0xE0).
The relevant chunk of code in Python that would probably need to be
changed to support this appears to be in msvcrtmodule.c:
static PyObject *
msvcrt_getch(PyObject *self, PyObject *args)
{
int ch;
char s[1];
if (!PyArg_ParseTuple(args, ":getch"))
return NULL;
Py_BEGIN_ALLOW_THREADS
ch = _getch();
Py_END_ALLOW_THREADS
s[0] = ch;
return PyString_FromStringAndSize(s, 1);
}
It would seem that it could be made to support extended characters by changing
it to:
static PyObject *
msvcrt_getch(PyObject *self, PyObject *args)
{
int ch;
char s[1];
if (!PyArg_ParseTuple(args, ":getch"))
return NULL;
Py_BEGIN_ALLOW_THREADS
ch = _getch();
+if (ch == 0x00 || ch == 0XE0)
+ch = _getch();
Py_END_ALLOW_THREADS
s[0] = ch;
return PyString_FromStringAndSize(s, 1);
}
I haven't yet read the code for PyString_FromStringAndSize(), but presumably it
can coerce unicode/extended results out of the int (or could be made to)?
What are the chances of modifying msvcrt_getch() to support extended chars?
The unix_getpass() seems to already work OK with extended characters, so this
would ~seem~ to be a logical extension to the Windows version.
Thoughts?
--
Darryl Dixon <[EMAIL PROTECTED]>
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[Python-Dev] getch() in msvcrt does not accept extended characters.
Hi, I'm sorry, I don't seem to have done a very good job at explaining the situation. I'll try again: 'getch()' is a low-level function provided on Windows to capture a single character of input from a user, /without echoing it to the screen/. As far as I can tell there's no other way of doing this with Python on Windows. The Python interface to this function is in the C code in msvcrtmodule.c, which has a (very thin) wrapper around the raw OS system call. Microsoft provide a way of accepting both normal ASCII codes, and extended characters via this system call. Currently, the Python wrapper in msvcrtmodule.c only supports the semantics of getting the bare ASCII codes, and not the extended characters. I would strongly suggest that it should support both. So, I guess in answer to the questions raised below; 1) I can't do it in Python code without getch() (hence the original email) 2) I would argue that in fact getch() is 'broken' in its current Python implementation, as it doesn't support what the OS implies /should/ be supported (and, indeed, if I input an extended character in response to a 'getch()' call, all I get back currently is an empty string). Finally, I've dug a little deeper, and it looks as though if (ch > UCHAR_MAX) then it would have to call PyUnicode_FromUnicode(s, 1) instead. Is it worth sending in a patch to the sourceforge patch-tracker implementing this? Is it OK for msvcrt_getch to return Unicode when appropriate? Thoughts? Hope this helps, D Fredrik wrote: >Darryl Dixon wrote: > >> Microsoft support capturing extended characters via _getch, but it requires making a >> second call to getch() if one of the 'magic' returns is encountered in the first call (0x00 >> or 0xE0). > >so why not do that in your python code? > >> The relevant chunk of code in Python that would probably need to be >> changed to support this appears to be in msvcrtmodule.c: > >if you change msvcrt, you'll break all the programs that uses getch() in >the prescribed way... > > -- Darryl Dixon <[EMAIL PROTECTED]> ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] getch() in msvcrt does not accept extended characters.
Hi, I'm sorry, I don't seem to have done a very good job at explaining the situation. I'll try again: 'getch()' is a low-level function provided on Windows to capture a single character of input from a user, /without echoing it to the screen/. As far as I can tell there's no other way of doing this with Python on Windows. The Python interface to this function is in the C code in msvcrtmodule.c, which has a (very thin) wrapper around the raw OS system call. Microsoft provide a way of accepting both normal ASCII codes, and extended characters via this system call. Currently, the Python wrapper in msvcrtmodule.c only supports the semantics of getting the bare ASCII codes, and not the extended characters. I would strongly suggest that it should support both. So, I guess in answer to the questions raised below; 1) I can't do it in Python code without getch() (hence the original email) 2) I would argue that in fact getch() is 'broken' in its current Python implementation, as it doesn't support what the OS implies /should/ be supported (and, indeed, if I input an extended character in response to a 'getch()' call, all I get back currently is an empty string). Hope this helps, D Fredrik wrote: >Darryl Dixon wrote: > >> Microsoft support capturing extended characters via _getch, but it requires >> making a >> second call to getch() if one of the 'magic' returns is encountered in the >> first call (0x00 >> or 0xE0). > >so why not do that in your python code? > >> The relevant chunk of code in Python that would probably need to be >> changed to support this appears to be in msvcrtmodule.c: > >if you change msvcrt, you'll break all the programs that uses getch() in >the prescribed way... > > -- Darryl Dixon <[EMAIL PROTECTED]> ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] getch() in msvcrt does not accept extended characters.
Sorry all, It seems that the list mods have finally released a duplicate message that I wrote last week when I wasn't subscribed to the list. Please ignore the message below if you have read the previous copy already. D On Thu, 2005-06-30 at 09:43 +1200, Darryl Dixon wrote: > Hi, > > I'm sorry, I don't seem to have done a very good job at explaining > the situation. I'll try again: > 'getch()' is a low-level function provided on Windows to capture a > single character of input from a user, /without echoing it to the > screen/. As far as I can tell there's no other way of doing this with > Python on Windows. The Python interface to this function is in the C > code in msvcrtmodule.c, which has a (very thin) wrapper around the raw > OS system call. Microsoft provide a way of accepting both normal ASCII > codes, and extended characters via this system call. Currently, the > Python wrapper in msvcrtmodule.c only supports the semantics of getting > the bare ASCII codes, and not the extended characters. I would strongly > suggest that it should support both. > > So, I guess in answer to the questions raised below; > > 1) I can't do it in Python code without getch() (hence the original > email) > > 2) I would argue that in fact getch() is 'broken' in its current Python > implementation, as it doesn't support what the OS implies /should/ be > supported (and, indeed, if I input an extended character in response to > a 'getch()' call, all I get back currently is an empty string). > > Hope this helps, > D > > > Fredrik wrote: > >Darryl Dixon wrote: > > > >> Microsoft support capturing extended characters via _getch, but it > >> requires making a > >> second call to getch() if one of the 'magic' returns is encountered in the > >> first call (0x00 > >> or 0xE0). > > > >so why not do that in your python code? > > > >> The relevant chunk of code in Python that would probably need to be > >> changed to support this appears to be in msvcrtmodule.c: > > > >if you change msvcrt, you'll break all the programs that uses getch() in > >the prescribed way... > > > > -- Darryl Dixon <[EMAIL PROTECTED]> ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
