1.1 --- a/src/os/windows/vm/os_windows.cpp Wed Aug 01 04:19:22 2018 -0400
1.2 +++ b/src/os/windows/vm/os_windows.cpp Thu Aug 02 03:54:51 2018 -0700
1.3 @@ -1837,6 +1837,42 @@
1.4 st->cr();
1.5 }
1.6
1.7 +
1.8 +int os::vsnprintf(char* buf, size_t len, const char* fmt, va_list args) {
1.9 +#if _MSC_VER >= 1900
1.10 + // Starting with Visual Studio 2015, vsnprint is C99 compliant.
1.11 + int result = ::vsnprintf(buf, len, fmt, args);
1.12 + // If an encoding error occurred (result < 0) then it's not clear
1.13 + // whether the buffer is NUL terminated, so ensure it is.
1.14 + if ((result < 0) && (len > 0)) {
1.15 + buf[len - 1] = '\0';
1.16 + }
1.17 + return result;
1.18 +#else
1.19 + // Before Visual Studio 2015, vsnprintf is not C99 compliant, so use
1.20 + // _vsnprintf, whose behavior seems to be *mostly* consistent across
1.21 + // versions. However, when len == 0, avoid _vsnprintf too, and just
1.22 + // go straight to _vscprintf. The output is going to be truncated in
1.23 + // that case, except in the unusual case of empty output. More
1.24 + // importantly, the documentation for various versions of Visual Studio
1.25 + // are inconsistent about the behavior of _vsnprintf when len == 0,
1.26 + // including it possibly being an error.
1.27 + int result = -1;
1.28 + if (len > 0) {
1.29 + result = _vsnprintf(buf, len, fmt, args);
1.30 + // If output (including NUL terminator) is truncated, the buffer
1.31 + // won't be NUL terminated. Add the trailing NUL specified by C99.
1.32 + if ((result < 0) || (result >= (int) len)) {
1.33 + buf[len - 1] = '\0';
1.34 + }
1.35 + }
1.36 + if (result < 0) {
1.37 + result = _vscprintf(fmt, args);
1.38 + }
1.39 + return result;
1.40 +#endif // _MSC_VER dispatch
1.41 +}
1.42 +
1.43 void os::print_signal_handlers(outputStream* st, char* buf, size_t buflen) {
1.44 // do nothing
1.45 }
