- template<typename _CharT, typename _Traits>
- typename basic_filebuf<_CharT, _Traits>::int_type
- basic_filebuf<_CharT, _Traits>::
- _M_really_overflow(int_type __c)
- {
- int_type __ret = traits_type::eof();
- bool __testput = _M_out_cur && _M_out_beg < _M_out_end;
- bool __testunbuffered = _M_file.is_open() && !_M_buf_size_opt;
-
- if (__testput || __testunbuffered)
+ template<typename _CharT, typename _Traits>
+ streamsize
+ basic_filebuf<_CharT, _Traits>::
+ xsgetn(_CharT* __s, streamsize __n)
+ {
+ // Clear out pback buffer before going on to the real deal...
+ streamsize __ret = 0;
+ if (_M_pback_init)
+ {
+ if (__n > 0 && this->gptr() == this->eback())
+ {
+ *__s++ = *this->gptr();
+ this->gbump(1);
+ __ret = 1;
+ --__n;
+ }
+ _M_destroy_pback();
+ }
+
+ // Optimization in the always_noconv() case, to be generalized in the
+ // future: when __n > __buflen we read directly instead of using the
+ // buffer repeatedly.
+ const bool __testin = _M_mode & ios_base::in;
+ const streamsize __buflen = _M_buf_size > 1 ? _M_buf_size - 1 : 1;
+
+ if (__n > __buflen && __check_facet(_M_codecvt).always_noconv()
+ && __testin && !_M_writing)
+ {
+ // First, copy the chars already present in the buffer.
+ const streamsize __avail = this->egptr() - this->gptr();
+ if (__avail != 0)
+ {
+ if (__avail == 1)
+ *__s = *this->gptr();
+ else
+ traits_type::copy(__s, this->gptr(), __avail);
+ __s += __avail;
+ this->gbump(__avail);
+ __ret += __avail;
+ __n -= __avail;
+ }
+
+ // Need to loop in case of short reads (relatively common
+ // with pipes).
+ streamsize __len;
+ for (;;)
+ {
+ __len = _M_file.xsgetn(reinterpret_cast<char*>(__s),
+ __n);
+ if (__len == -1)
+ __throw_ios_failure(__N("basic_filebuf::xsgetn "
+ "error reading the file"));
+ if (__len == 0)
+ break;
+
+ __n -= __len;
+ __ret += __len;
+ if (__n == 0)
+ break;
+
+ __s += __len;
+ }
+
+ if (__n == 0)
+ {
+ _M_set_buffer(0);
+ _M_reading = true;
+ }
+ else if (__len == 0)
+ {
+ // If end of file is reached, set 'uncommitted'
+ // mode, thus allowing an immediate write without
+ // an intervening seek.
+ _M_set_buffer(-1);
+ _M_reading = false;
+ }
+ }
+ else
+ __ret += __streambuf_type::xsgetn(__s, __n);
+
+ return __ret;
+ }
+
+ template<typename _CharT, typename _Traits>
+ streamsize
+ basic_filebuf<_CharT, _Traits>::
+ xsputn(const _CharT* __s, streamsize __n)
+ {
+ // Optimization in the always_noconv() case, to be generalized in the
+ // future: when __n is sufficiently large we write directly instead of
+ // using the buffer.
+ streamsize __ret = 0;
+ const bool __testout = _M_mode & ios_base::out;
+ if (__check_facet(_M_codecvt).always_noconv()
+ && __testout && !_M_reading)