Well, there was already malloc and I did not change it. alloca has potential buffer overflow issue so needs to be used with care (properly checking allocation size). So changing code to alloca would be slightly more complicated (as it would need that malloc fallback) and I thought that following change is enough and is very simple.
On Sunday 16 November 2025 01:20:10 Kirill Makurin wrote: > How about using _alloca to allocate buffer? Assert messages are usually not > very long. > ________________________________ > From: Pali Rohár <[email protected]> > Sent: Sunday, November 16, 2025 4:40 AM > To: [email protected] > <[email protected]> > Subject: [Mingw-w64-public] [PATCH] crt: Check for malloc failures in > mingw-w64 _wassert emulation > > If malloc fails then use prepared static buffers. They are thread unsafe, > but works always. The last byte of buffers is not touched so buffers are > always nul terminated and so accessing buffers in thread unsafe way do not > cause invalid memory access. > --- > mingw-w64-crt/misc/wassert.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/mingw-w64-crt/misc/wassert.c b/mingw-w64-crt/misc/wassert.c > index 690239423b75..104cbd00302c 100644 > --- a/mingw-w64-crt/misc/wassert.c > +++ b/mingw-w64-crt/misc/wassert.c > @@ -11,18 +11,30 @@ > __MINGW_ATTRIB_NORETURN > static void __cdecl emu__wassert(const wchar_t *_Message, const wchar_t > *_File, unsigned _Line) > { > + static char static_message_buf[128]; /* thread unsafe */ > + static char static_file_buf[_MAX_PATH]; /* thread unsafe */ > char *message = NULL, *file = NULL; > size_t len; > > if ((len = wcstombs(NULL, _Message, 0)) != (size_t)-1) > { > message = malloc(len + 1); > + if (!message) > + { > + message = static_message_buf; > + len = sizeof(static_message_buf) - 2; /* -1 to not touch the > last nul byte */ > + } > wcstombs(message, _Message, len + 1); > } > > if ((len = wcstombs(NULL, _File, 0)) != (size_t)-1) > { > file = malloc(len + 1); > + if (!file) > + { > + file = static_file_buf; > + len = sizeof(static_file_buf) - 2; /* -1 to not touch the last > nul byte */ > + } > wcstombs(file, _File, len + 1); > } > > -- > 2.20.1 > > > > _______________________________________________ > Mingw-w64-public mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/mingw-w64-public _______________________________________________ Mingw-w64-public mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mingw-w64-public
