https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=ada3b8f7e5a71db4881135380c407a86a08f6663
commit ada3b8f7e5a71db4881135380c407a86a08f6663
Author: Corinna Vinschen <cori...@vinschen.de>
AuthorDate: Wed Jul 23 22:42:52 2025 +0200
Commit: Corinna Vinschen <cori...@vinschen.de>
CommitDate: Thu Jul 24 11:23:27 2025 +0200
Cygwin: _sys_wcstombs: add FIXME comment
Add a FIXME comment to the conversion of private use area bytes to
"normal" bytes in _sys_wcstombs detailing the conversion difference
between _sys_wcstombs and standard wcstombs. It might be a good idea
to drop the conversion to gather compatibility with wcstombs.
Signed-off-by: Corinna Vinschen <cori...@vinschen.de>
Diff:
---
winsup/cygwin/strfuncs.cc | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/strfuncs.cc b/winsup/cygwin/strfuncs.cc
index caaf6b786295..eb6576051d90 100644
--- a/winsup/cygwin/strfuncs.cc
+++ b/winsup/cygwin/strfuncs.cc
@@ -965,8 +965,17 @@ _sys_wcstombs (char *dst, size_t len, const wchar_t *src,
size_t nwc,
/* Convert UNICODE private use area. Reverse functionality for the
ASCII area <= 0x7f (only for path names) is transform_chars above.
+
Reverse functionality for invalid bytes in a multibyte sequence is
- in _sys_mbstowcs below. */
+ in _sys_mbstowcs below.
+
+ FIXME? The conversion of invalid bytes from the private use area
+ like we do here is not actually necessary. If we skip it, the
+ generated multibyte string is not identical to the original multibyte
+ string, but it's equivalent in the sense, that another mbstowcs will
+ generate the same wide-char string. It would also be identical to
+ the same string converted by wcstombs. And while the original
+ multibyte string can't be converted by mbstowcs, this string can. */
if (is_path && (pw & 0xff00) == 0xf000
&& (((cwc = (pw & 0xff)) <= 0x7f && tfx_rev_chars[cwc] >= 0xf000)
|| (cwc >= 0x80 && MB_CUR_MAX > 1)))
