cygwin_conv_ functions and character encoding

Thomas Wolff
Fri Feb 5 15:47:00 GMT 2016

The cygwin path conversion functions ignore the current locale;
rather they seem to always use the locale environment set when the 
program was started, see test program convloc.c:

#include <locale.h>
#include <stdio.h>
#include <sys/cygwin.h>
#include <stdlib.h>
int main() {
   setlocale(LC_ALL, "C.UTF-8");
   char * utfstring = "böh";
   printf("ustring <%s>\n", utfstring);
   wchar_t * wstring = cygwin_create_path(CCP_POSIX_TO_WIN_W, utfstring);
   printf("wstring <%ls>\n", wstring);

Run in a UTF-8 terminal:
 > LC_CTYPE=de_DE ./convloc
ustring (C.UTF-8) <böh>
wstring (C.UTF-8) <D:\TEMP\böh>

In sys_wcstombs in I see:
   const char *charset = cygheap->locale.charset;
which is set in internal_setlocale ()...

In fact, the situation can be fixed by adding after setlocale():
   cygwin_internal(CW_INT_SETLOCALE);  // -> internal_setlocale();
but I think those functions should use the proper locale implicitly; 
according to the generic description in,
LC_CTYPE affects ... conversion ... functions, in my opinion this would 
include cygwin-specific conversion functions as well as implicitly 
called conversion (see open() below).
The same problem applies to the open() function (involving path conversion).
The wide string function mbstowcs behaves as expected.

The whole issue occurred to me while trying to work around a missing 
conversion functionality, just converting the pathname syntax between 
Unicode strings. The desired options would be like:
   CCP_POSIX_W_TO_WIN_W,   /* from is wchar_t *posix, to is wchar_t 
*win32  */
   CCP_WIN_W_TO_POSIX_W,   /* from is wchar_t *win32, to is wchar_t 
*posix  */


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