https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103655
Bug ID: 103655
Summary: "x" does not exist on windows and dos
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: unlvsur at live dot com
Target Milestone: ---
In today's patch.
https://github.com/gcc-mirror/gcc/commit/a219139e986a4200a9105d7c1fa63735d2945994
std::ios::noreplace uses "x". However, that is not correctly supported by
msvcrt and dos djgpp.
The correct way is to directly use CreateFileW (on windows NT) or NtCreateFile
and CreateFileA on windows 9x. Then call _open_osfhandle to create an fd then
call _wfdopen(on windows NT) or _fdopen(on windows 9x) on Windows
Create an NT handle with NtCreateFile (You also need RtlNtStatusToDosError and
RtlDosPathNameToNtPathName_U_WithStatus or RtlDosPathNameToNtPathName_U).
https://github.com/tearosccebe/fast_io/blob/6081ae18b34820c3c69b81628f520f5fafcfb815/include/fast_io_hosted/platforms/nt.h#L67
Or create a win32 handle with CreateFileA (on Windows 9x) and CreateFileW (on
Windows NT)
https://github.com/tearosccebe/fast_io/blob/6081ae18b34820c3c69b81628f520f5fafcfb815/include/fast_io_hosted/platforms/win32.h#L201
Use win32 or nt handle to call _open_osfhandle to create a POSIX fd.
https://github.com/tearosccebe/fast_io/blob/6081ae18b34820c3c69b81628f520f5fafcfb815/include/fast_io_hosted/platforms/posix.h#L58
https://github.com/tearosccebe/fast_io/blob/6081ae18b34820c3c69b81628f520f5fafcfb815/include/fast_io_hosted/platforms/posix.h#L961
Then use _wfdopen on Windows NT and _fdopen on Windows 9x to open a FILE*
https://github.com/tearosccebe/fast_io/blob/6081ae18b34820c3c69b81628f520f5fafcfb815/include/fast_io_legacy_impl/c/impl.h#L29
Then construct a std::filebuf with FILE*
https://github.com/tearosccebe/fast_io/blob/6081ae18b34820c3c69b81628f520f5fafcfb815/include/fast_io_legacy_impl/filebuf/filebuf_file.h#L60
On DOS. You need __dos_creat,__dos_creatnew,__dos_open
https://github.com/tearosccebe/fast_io/blob/6081ae18b34820c3c69b81628f520f5fafcfb815/include/fast_io_hosted/platforms/posix.h#L1063
So libstdc++ using fdopen to open FILE* with fd is incorrect. On windows NT
kernel, we MUST use _wfdopen since _fdopen involves locale, which is not
thread-safe.
