xref: /freebsd-src/contrib/llvm-project/libcxx/src/std_stream.h (revision 06c3fb2749bda94cb5201f81ffdb8fa6c3161b2e)

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_STD_STREAM_H
#define _LIBCPP_STD_STREAM_H

#include <__config>
#include <__locale>
#include <cstdio>
#include <istream>
#include <ostream>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>


_LIBCPP_BEGIN_NAMESPACE_STD

static const int __limit = 8;

// __stdinbuf

template <class _CharT>
class _LIBCPP_HIDDEN __stdinbuf
    : public basic_streambuf<_CharT, char_traits<_CharT> >
{
public:
    typedef _CharT                           char_type;
    typedef char_traits<char_type>           traits_type;
    typedef typename traits_type::int_type   int_type;
    typedef typename traits_type::pos_type   pos_type;
    typedef typename traits_type::off_type   off_type;
    typedef typename traits_type::state_type state_type;

    __stdinbuf(FILE* __fp, state_type* __st);

protected:
    virtual int_type underflow();
    virtual int_type uflow();
    virtual int_type pbackfail(int_type __c = traits_type::eof());
    virtual void imbue(const locale& __loc);

private:

    FILE* __file_;
    const codecvt<char_type, char, state_type>* __cv_;
    state_type* __st_;
    int __encoding_;
    int_type __last_consumed_;
    bool __last_consumed_is_next_;
    bool __always_noconv_;

#if defined(_LIBCPP_WIN32API)
    static constexpr bool __is_win32api_wide_char = !is_same_v<_CharT, char>;
#else
    static constexpr bool __is_win32api_wide_char = false;
#endif

    __stdinbuf(const __stdinbuf&);
    __stdinbuf& operator=(const __stdinbuf&);

    int_type __getchar(bool __consume);
};

template <class _CharT>
__stdinbuf<_CharT>::__stdinbuf(FILE* __fp, state_type* __st)
    : __file_(__fp),
      __st_(__st),
      __last_consumed_(traits_type::eof()),
      __last_consumed_is_next_(false)
{
    imbue(this->getloc());
    // On Windows, in wchar_t mode, ignore the codecvt from the locale by
    // default and assume noconv; this passes wchar_t through unmodified from
    // getwc. If the user sets a custom locale with imbue(), that gets honored,
    // the IO is done with getc() and converted with the provided codecvt.
    if constexpr (__is_win32api_wide_char)
        __always_noconv_ = true;
}

template <class _CharT>
void
__stdinbuf<_CharT>::imbue(const locale& __loc)
{
    __cv_ = &use_facet<codecvt<char_type, char, state_type> >(__loc);
    __encoding_ = __cv_->encoding();
    __always_noconv_ = __cv_->always_noconv();
    if (__encoding_ > __limit)
        __throw_runtime_error("unsupported locale for standard input");
}

template <class _CharT>
typename __stdinbuf<_CharT>::int_type
__stdinbuf<_CharT>::underflow()
{
    return __getchar(false);
}

template <class _CharT>
typename __stdinbuf<_CharT>::int_type
__stdinbuf<_CharT>::uflow()
{
    return __getchar(true);
}

static bool __do_getc(FILE *__fp, char *__pbuf) {
    int __c = getc(__fp);
    if (__c == EOF)
        return false;
    *__pbuf = static_cast<char>(__c);
    return true;
}
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
static bool __do_getc(FILE *__fp, wchar_t *__pbuf) {
    wint_t __c = getwc(__fp);
    if (__c == WEOF)
        return false;
    *__pbuf = static_cast<wchar_t>(__c);
    return true;
}
#endif

static bool __do_ungetc(int __c, FILE *__fp, char __dummy) {
    if (ungetc(__c, __fp) == EOF)
        return false;
    return true;
}
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
static bool __do_ungetc(std::wint_t __c, FILE *__fp, wchar_t __dummy) {
    if (ungetwc(__c, __fp) == WEOF)
        return false;
    return true;
}
#endif

template <class _CharT>
typename __stdinbuf<_CharT>::int_type
__stdinbuf<_CharT>::__getchar(bool __consume)
{
    if (__last_consumed_is_next_)
    {
        int_type __result = __last_consumed_;
        if (__consume)
        {
            __last_consumed_ = traits_type::eof();
            __last_consumed_is_next_ = false;
        }
        return __result;
    }
    if (__always_noconv_) {
        char_type __1buf;
        if (!__do_getc(__file_, &__1buf))
            return traits_type::eof();
        if (!__consume)
        {
            if (!__do_ungetc(traits_type::to_int_type(__1buf), __file_, __1buf))
                return traits_type::eof();
        }
        else
            __last_consumed_ = traits_type::to_int_type(__1buf);
        return traits_type::to_int_type(__1buf);
    }

    char __extbuf[__limit];
    int __nread = _VSTD::max(1, __encoding_);
    for (int __i = 0; __i < __nread; ++__i)
    {
        int __c = getc(__file_);
        if (__c == EOF)
            return traits_type::eof();
        __extbuf[__i] = static_cast<char>(__c);
    }
    char_type __1buf;
    const char* __enxt;
    char_type* __inxt;
    codecvt_base::result __r;
    do
    {
        state_type __sv_st = *__st_;
        __r = __cv_->in(*__st_, __extbuf, __extbuf + __nread, __enxt,
                               &__1buf, &__1buf + 1, __inxt);
        switch (__r)
        {
        case _VSTD::codecvt_base::ok:
            break;
        case codecvt_base::partial:
            *__st_ = __sv_st;
            if (__nread == sizeof(__extbuf))
                return traits_type::eof();
            {
                int __c = getc(__file_);
                if (__c == EOF)
                    return traits_type::eof();
                __extbuf[__nread] = static_cast<char>(__c);
            }
            ++__nread;
            break;
        case codecvt_base::error:
            return traits_type::eof();
        case _VSTD::codecvt_base::noconv:
            __1buf = static_cast<char_type>(__extbuf[0]);
            break;
        }
    } while (__r == _VSTD::codecvt_base::partial);
    if (!__consume)
    {
        for (int __i = __nread; __i > 0;)
        {
            if (ungetc(traits_type::to_int_type(__extbuf[--__i]), __file_) == EOF)
                return traits_type::eof();
        }
    }
    else
        __last_consumed_ = traits_type::to_int_type(__1buf);
    return traits_type::to_int_type(__1buf);
}

template <class _CharT>
typename __stdinbuf<_CharT>::int_type
__stdinbuf<_CharT>::pbackfail(int_type __c)
{
    if (traits_type::eq_int_type(__c, traits_type::eof()))
    {
        if (!__last_consumed_is_next_)
        {
            __c = __last_consumed_;
            __last_consumed_is_next_ = !traits_type::eq_int_type(__last_consumed_,
                                                                 traits_type::eof());
        }
        return __c;
    }
    if (__always_noconv_ && __last_consumed_is_next_) {
        if (!__do_ungetc(__last_consumed_, __file_,
                         traits_type::to_char_type(__last_consumed_)))
            return traits_type::eof();
    } else if (__last_consumed_is_next_) {
        char __extbuf[__limit];
        char* __enxt;
        const char_type __ci = traits_type::to_char_type(__last_consumed_);
        const char_type* __inxt;
        switch (__cv_->out(*__st_, &__ci, &__ci + 1, __inxt,
                                  __extbuf, __extbuf + sizeof(__extbuf), __enxt))
        {
        case _VSTD::codecvt_base::ok:
            break;
        case _VSTD::codecvt_base::noconv:
            __extbuf[0] = static_cast<char>(__last_consumed_);
            __enxt = __extbuf + 1;
            break;
        case codecvt_base::partial:
        case codecvt_base::error:
            return traits_type::eof();
        }
        while (__enxt > __extbuf)
            if (ungetc(*--__enxt, __file_) == EOF)
                return traits_type::eof();
    }
    __last_consumed_ = __c;
    __last_consumed_is_next_ = true;
    return __c;
}

// __stdoutbuf

template <class _CharT>
class _LIBCPP_HIDDEN __stdoutbuf
    : public basic_streambuf<_CharT, char_traits<_CharT> >
{
public:
    typedef _CharT                           char_type;
    typedef char_traits<char_type>           traits_type;
    typedef typename traits_type::int_type   int_type;
    typedef typename traits_type::pos_type   pos_type;
    typedef typename traits_type::off_type   off_type;
    typedef typename traits_type::state_type state_type;

    __stdoutbuf(FILE* __fp, state_type* __st);

protected:
    virtual int_type overflow (int_type __c = traits_type::eof());
    virtual streamsize xsputn(const char_type* __s, streamsize __n);
    virtual int sync();
    virtual void imbue(const locale& __loc);

private:
    FILE* __file_;
    const codecvt<char_type, char, state_type>* __cv_;
    state_type* __st_;
    bool __always_noconv_;

#if defined(_LIBCPP_WIN32API)
    static constexpr bool __is_win32api_wide_char = !is_same_v<_CharT, char>;
#else
    static constexpr bool __is_win32api_wide_char = false;
#endif

    __stdoutbuf(const __stdoutbuf&);
    __stdoutbuf& operator=(const __stdoutbuf&);
};

template <class _CharT>
__stdoutbuf<_CharT>::__stdoutbuf(FILE* __fp, state_type* __st)
    : __file_(__fp),
      __cv_(&use_facet<codecvt<char_type, char, state_type> >(this->getloc())),
      __st_(__st),
      __always_noconv_(__cv_->always_noconv())
{
    // On Windows, in wchar_t mode, ignore the codecvt from the locale by
    // default and assume noconv; this passes wchar_t through unmodified to
    // fputwc, which handles it correctly depending on the actual mode of the
    // output stream. If the user sets a custom locale with imbue(), that
    // gets honored.
    if constexpr (__is_win32api_wide_char)
        __always_noconv_ = true;
}

static bool __do_fputc(char __c, FILE* __fp) {
    if (fwrite(&__c, sizeof(__c), 1, __fp) != 1)
        return false;
    return true;
}
#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
static bool __do_fputc(wchar_t __c, FILE* __fp) {
    // fputwc works regardless of wide/narrow mode of stdout, while
    // fwrite of wchar_t only works if the stream actually has been set
    // into wide mode.
    if (fputwc(__c, __fp) == WEOF)
        return false;
    return true;
}
#endif

template <class _CharT>
typename __stdoutbuf<_CharT>::int_type
__stdoutbuf<_CharT>::overflow(int_type __c)
{
    char __extbuf[__limit];
    char_type __1buf;
    if (!traits_type::eq_int_type(__c, traits_type::eof()))
    {
        __1buf = traits_type::to_char_type(__c);
        if (__always_noconv_)
        {
            if (!__do_fputc(__1buf, __file_))
                return traits_type::eof();
        }
        else
        {
            char* __extbe = __extbuf;
            codecvt_base::result __r;
            char_type* pbase = &__1buf;
            char_type* pptr = pbase + 1;
            do
            {
                const char_type* __e;
                __r = __cv_->out(*__st_, pbase, pptr, __e,
                                        __extbuf,
                                        __extbuf + sizeof(__extbuf),
                                        __extbe);
                if (__e == pbase)
                    return traits_type::eof();
                if (__r == codecvt_base::noconv)
                {
                    if (fwrite(pbase, 1, 1, __file_) != 1)
                        return traits_type::eof();
                }
                else if (__r == codecvt_base::ok || __r == codecvt_base::partial)
                {
                    size_t __nmemb = static_cast<size_t>(__extbe - __extbuf);
                    if (fwrite(__extbuf, 1, __nmemb, __file_) != __nmemb)
                        return traits_type::eof();
                    if (__r == codecvt_base::partial)
                    {
                        pbase = const_cast<char_type*>(__e);
                    }
                }
                else
                    return traits_type::eof();
            } while (__r == codecvt_base::partial);
        }
    }
    return traits_type::not_eof(__c);
}

template <class _CharT>
streamsize
__stdoutbuf<_CharT>::xsputn(const char_type* __s, streamsize __n)
{
    // For wchar_t on Windows, don't call fwrite(), but write characters one
    // at a time with fputwc(); that works both when stdout is in the default
    // mode and when it is set to Unicode mode.
    if (__always_noconv_ && !__is_win32api_wide_char)
        return fwrite(__s, sizeof(char_type), __n, __file_);
    streamsize __i = 0;
    for (; __i < __n; ++__i, ++__s)
        if (overflow(traits_type::to_int_type(*__s)) == traits_type::eof())
            break;
    return __i;
}

template <class _CharT>
int
__stdoutbuf<_CharT>::sync()
{
    char __extbuf[__limit];
    codecvt_base::result __r;
    do
    {
        char* __extbe;
        __r = __cv_->unshift(*__st_, __extbuf,
                                    __extbuf + sizeof(__extbuf),
                                    __extbe);
        size_t __nmemb = static_cast<size_t>(__extbe - __extbuf);
        if (fwrite(__extbuf, 1, __nmemb, __file_) != __nmemb)
            return -1;
    } while (__r == codecvt_base::partial);
    if (__r == codecvt_base::error)
        return -1;
    if (fflush(__file_))
        return -1;
    return 0;
}

template <class _CharT>
void
__stdoutbuf<_CharT>::imbue(const locale& __loc)
{
    sync();
    __cv_ = &use_facet<codecvt<char_type, char, state_type> >(__loc);
    __always_noconv_ = __cv_->always_noconv();
}

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP_STD_STREAM_H