inline int
fileno_hack(const std::basic_ios<charT, traits>& stream)
{
// Some C++ runtime libraries shipped with ancient GCC, Sun Pro,
// Sun WS/Forte 5/6, Compaq C++ supported non-standard file descriptor
// access basic_filebuf<>::fd(). Alas, starting from GCC 3.1, the GNU C++
// runtime removes all non-standard std::filebuf methods and provides an
// extension template class __gnu_cxx::stdio_filebuf on all systems where
// that appears to make sense (i.e. at least all Unix systems). Starting
// from GCC 3.4, there is an __gnu_cxx::stdio_sync_filebuf, in addition.
// Sorry, darling, I must get brutal to fetch the darn file descriptor!
// Please complain to your compiler/libstdc++ vendor...
#if defined(__GLIBCXX__) || defined(__GLIBCPP__)
// OK, stop reading here, because it's getting obscene. Cross fingers!
# if defined(__GLIBCXX__) // >= GCC 3.4.0
// This applies to cin, cout and cerr when not synced with stdio:
typedef __gnu_cxx::stdio_filebuf<charT, traits> unix_filebuf_t;
unix_filebuf_t* fbuf = dynamic_cast<unix_filebuf_t*>(stream.rdbuf());
if (fbuf != NULL) {
return fbuf->fd();
}
// This applies to filestreams:
typedef std::basic_filebuf<charT, traits> filebuf_t;
filebuf_t* bbuf = dynamic_cast<filebuf_t*>(stream.rdbuf());
if (bbuf != NULL) {
// This subclass is only there for accessing the FILE*. Ouuwww, sucks!
struct my_filebuf : public std::basic_filebuf<charT, traits> {
int fd() { return this->_M_file.fd(); }
};
return static_cast<my_filebuf*>(bbuf)->fd();
}
// This applies to cin, cout and cerr when synced with stdio:
typedef __gnu_cxx::stdio_sync_filebuf<charT, traits> sync_filebuf_t;
sync_filebuf_t* sbuf = dynamic_cast<sync_filebuf_t*>(stream.rdbuf());
if (sbuf != NULL) {
# if (__GLIBCXX__<20040906) // GCC < 3.4.2
// This subclass is only there for accessing the FILE*.
// See GCC PR#14600 and PR#16411.
struct my_filebuf : public sync_filebuf_t {
my_filebuf(); // Dummy ctor keeps the compiler happy.
// Note: stdio_sync_filebuf has a FILE* as its first (but private)
// member variable. However, it is derived from basic_streambuf<>
// and the FILE* is the first non-inherited member variable.
FILE* c_file() {
return *(FILE**)((char*)this + sizeof(std::basic_streambuf<charT, traits>));
}
};
return ::fileno(static_cast<my_filebuf*>(sbuf)->c_file());
# else
return ::fileno(sbuf->file());
# endif
}
# else // GCC < 3.4.0 used __GLIBCPP__
# if (__GLIBCPP__>=20020514) // GCC >= 3.1.0
// This applies to cin, cout and cerr:
typedef __gnu_cxx::stdio_filebuf<charT, traits> unix_filebuf_t;
unix_filebuf_t* buf = dynamic_cast<unix_filebuf_t*>(stream.rdbuf());
if (buf != NULL) {
return buf->fd();
}
// This applies to filestreams:
typedef std::basic_filebuf<charT, traits> filebuf_t;
filebuf_t* bbuf = dynamic_cast<filebuf_t*>(stream.rdbuf());
if (bbuf != NULL) {
// This subclass is only there for accessing the FILE*. Ouuwww, sucks!
struct my_filebuf : public std::basic_filebuf<charT, traits> {
// Note: _M_file is of type __basic_file<char> which has a
// FILE* as its first (but private) member variable.
FILE* c_file() { return *(FILE**)(&this->_M_file); }
};
FILE* c_file = static_cast<my_filebuf*>(bbuf)->c_file();
if (c_file != NULL) { // Could be NULL for failed ifstreams.
return ::fileno(c_file);
}
}
# else // GCC 3.0.x
typedef std::basic_filebuf<charT, traits> filebuf_t;
filebuf_t* fbuf = dynamic_cast<filebuf_t*>(stream.rdbuf());
if (fbuf != NULL) {
struct my_filebuf : public filebuf_t {
// Note: basic_filebuf<charT, traits> has a __basic_file<charT>* as
// its first (but private) member variable. Since it is derived
// from basic_streambuf<charT, traits> we can guess its offset.
// __basic_file<charT> in turn has a FILE* as its first (but
// private) member variable. Get it by brute force. Oh, geez!
FILE* c_file() {
std::__basic_file<charT>* ptr_M_file = *(std::__basic_file<charT>**)((char*)this + sizeof(std::basic_streambuf<charT, traits>));
# if _GLIBCPP_BASIC_FILE_INHERITANCE
// __basic_file<charT> inherits from __basic_file_base<charT>
return *(FILE**)((char*)ptr_M_file + sizeof(std::__basic_file_base<charT>));
# else
// __basic_file<charT> is base class, but with vptr.
return *(FILE**)((char*)ptr_M_file + sizeof(void*));
# endif
}
};
return ::fileno(static_cast<my_filebuf*>(fbuf)->c_file());
}
# endif
# endif
#else
#ifdef _LIBCPP_VERSION // llvm libc++
typedef std::basic_filebuf<charT, traits> filebuf_t;
filebuf_t* fbuf = stream.rdbuf();
basic_streambuf_override(std::basic_ios<char_type>& Ios, std::basic_streambuf<char_type>& Buf) :
m_Ios(Ios),
m_OriginalBuffer(*Ios.rdbuf())
{
m_Ios.rdbuf(&Buf);
}