Конвертировать C *FILE в C++ iostream с наддувом

Question

Я довольно новичок в C++ и хотел преобразовать *FILE (например, возвращаемый popen()) в iostream для использования с такими функциями, как getline и т. Д. Я нашел следующий код http://fw-geekycoder.blogspot.co.za/2011/06/how-to-convert-c-file-to-c-iostream.html, а также аналогичный код из множества мест, но компилятор жалуется на boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink> bis(fd); а также boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink> bis(fd);

#include <iostream>
#include <cstdio>
#include <unistd.h>
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>

void write() {
    FILE* fp = fopen("whatever.txt", "w");
    if (fp == NULL) {
        perror("fopen error");
    }
    int fd = fileno(fp);
    boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink> bis(fd);
    std::ostream os(&bis);
    os << "Hello World!" << std::endl;

    fclose(fp);
}

void read() {
    FILE* fp = fopen("whatever.txt", "r");
    if (fp == NULL) {
        perror("fopen error");
    }
    int fd = fileno(fp);
    boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_source> bis(fd);
    std::istream is(&bis);
    while (is) {
        std::string line;
        std::getline(is, line);
        std::cout << line << std::endl;
    }
    fclose(fp);
}

int main() {
    write();
    read();

    return 0;
}

Кажется, что моя система находит повышение, но как будто API или что-то изменилось. В чем проблема, вот мой вывод из затмения:

make all 
Building file: ../src/boostPopenHandler.cpp
Invoking: GCC C++ Compiler
g++ -D__GXX_EXPERIMENTAL_CXX0X__ -I../../emdw/src -I../../patrecII/src -I../../ -O0 -g3 -Wall -c -fmessage-length=0 -std=c++0x -MMD -MP -MF"src/boostPopenHandler.d" -MT"src/boostPopenHandler.d" -o"src/boostPopenHandler.o" "../src/boostPopenHandler.cpp"
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = char; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5:   required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = char; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:13:83:   required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
     { open(detail::path(path), mode); }
                                    ^
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
                 from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:52:5: error:   initializing argument 1 of ‘boost::iostreams::detail::path::path(const char*)’ [-fpermissive]
     path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
     ^
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_source::file_descriptor_source(const Path&, std::ios_base::openmode) [with Path = char; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5:   required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = char; T = boost::iostreams::file_descriptor_source; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::input_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:26:85:   required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:194:36: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
     { open(detail::path(path), mode); }
                                    ^
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
                 from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:52:5: error:   initializing argument 1 of ‘boost::iostreams::detail::path::path(const char*)’ [-fpermissive]
     path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
     ^
make: *** [src/boostPopenHandler.o] Error 1

Редактировать:
После ответа от Сельчука Цихана я изменил соответствующий код на:

boost::iostreams::file_descriptor_source fds(fd);
boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink> 
...
boost::iostreams::file_descriptor_source fds(fd);
boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_source> 

Но я все еще получаю список ошибок компиляции:

**** Build of configuration Debug for project boostPopenHandler ****

make all 
Building file: ../src/boostPopenHandler.cpp
Invoking: GCC C++ Compiler
g++ -I../../emdw/src -I../../patrecII/src -I../../ -O0 -g3 -Wall -c -fmessage-length=0 -std=c++0x -MMD -MP -MF"src/boostPopenHandler.d" -MT"src/boostPopenHandler.d" -o"src/boostPopenHandler.o" "../src/boostPopenHandler.cpp"
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_source::file_descriptor_source(const Path&, std::ios_base::openmode) [with Path = int; std::ios_base::openmode = std::_Ios_Openmode]’:
../src/boostPopenHandler.cpp:13:52:   required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:194:36: error: invalid conversion from ‘int’ to ‘const char*’ [-fpermissive]
     { open(detail::path(path), mode); }
                                    ^
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
                 from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:52:5: error:   initializing argument 1 of ‘boost::iostreams::detail::path::path(const char*)’ [-fpermissive]
     path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
     ^
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5:   required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84:   required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: error: no matching function for call to ‘boost::iostreams::detail::path::path(const boost::iostreams::file_descriptor_source&)’
     { open(detail::path(path), mode); }
                                    ^
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: note: candidates are:
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
                 from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:138:5: note: boost::iostreams::detail::path::path(const wstring&)
     path(const std::wstring&);
     ^
/usr/include/boost/iostreams/detail/path.hpp:138:5: note:   no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const wstring& {aka const std::basic_string<wchar_t>&}’
/usr/include/boost/iostreams/detail/path.hpp:70:5: note: boost::iostreams::detail::path::path(const boost::iostreams::detail::path&)
     path(const path& p) 
     ^
/usr/include/boost/iostreams/detail/path.hpp:70:5: note:   no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const boost::iostreams::detail::path&’
/usr/include/boost/iostreams/detail/path.hpp:64:14: note: template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::codecvt_type*)
     explicit path(const Path& p, typename Path::codecvt_type* = 0)
              ^
/usr/include/boost/iostreams/detail/path.hpp:64:14: note:   template argument deduction/substitution failed:
/usr/include/boost/iostreams/detail/path.hpp: In substitution of ‘template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::codecvt_type*) [with Path = boost::iostreams::file_descriptor_source]’:
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36:   required from ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’
/usr/include/boost/iostreams/stream_buffer.hpp:94:5:   required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84:   required from here
/usr/include/boost/iostreams/detail/path.hpp:64:14: error: no type named ‘codecvt_type’ in ‘class boost::iostreams::file_descriptor_source’
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5:   required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84:   required from here
/usr/include/boost/iostreams/detail/path.hpp:57:14: note: template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::external_string_type*)
     explicit path(const Path& p, typename Path::external_string_type* = 0)
              ^
/usr/include/boost/iostreams/detail/path.hpp:57:14: note:   template argument deduction/substitution failed:
/usr/include/boost/iostreams/detail/path.hpp: In substitution of ‘template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::external_string_type*) [with Path = boost::iostreams::file_descriptor_source]’:
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36:   required from ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’
/usr/include/boost/iostreams/stream_buffer.hpp:94:5:   required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84:   required from here
/usr/include/boost/iostreams/detail/path.hpp:57:14: error: no type named ‘external_string_type’ in ‘class boost::iostreams::file_descriptor_source’
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5:   required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84:   required from here
/usr/include/boost/iostreams/detail/path.hpp:52:5: note: boost::iostreams::detail::path::path(const char*)
     path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
     ^
/usr/include/boost/iostreams/detail/path.hpp:52:5: note:   no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const char*’
/usr/include/boost/iostreams/detail/path.hpp:49:5: note: boost::iostreams::detail::path::path(const string&)
     path(const std::string& p) : narrow_(p), wide_(), is_wide_(false) { }
     ^
/usr/include/boost/iostreams/detail/path.hpp:49:5: note:   no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const string& {aka const std::basic_string<char>&}’
/usr/include/boost/iostreams/detail/path.hpp:46:5: note: boost::iostreams::detail::path::path()
     path() : narrow_(), wide_(), is_wide_(false) { }
     ^
/usr/include/boost/iostreams/detail/path.hpp:46:5: note:   candidate expects 0 arguments, 1 provided
make: *** [src/boostPopenHandler.o] Error 1

Answer 1

О, вы должны сначала объявить file_descriptor_source как в

boost::iostreams::file_descriptor_source fds(fd);

а затем приходит ваш поток буфера

boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_source> bis(fds);

Редактировать:

Извините за путаницу, что ctor с параметром int устарел, и кажется, что у вас нет этого ctor, потому что иначе ваш код скомпилировался бы идеально. Вот почему приведенный выше код требует второй обязательный параметр либо boost::iostreams::never_close_handle или же boost::iostreams::close_handle

Так что следует читать

boost::iostreams::file_descriptor_source fds(fd, boost::iostreams::close_handle);

в противном случае вы все равно получите эту ошибку. И то же самое исправление относится и к file_descriptor_sink.

Теперь о том, как вы должны прочитать ошибки:

/usr/include/boost/iostreams/device/file_descriptor.hpp: в экземпляре 'boost::iostreams::file_descriptor_source::file_descriptor_source(const Path&, std::ios_base::openmode) [with Path = char; std::ios_base::openmode = std::_Ios_Openmode] ':

Говорит, что пытался создать экземпляр file_descriptor_source с выбором параметра шаблона

[с Path = char; std:: ios_base:: openmode = std:: _ Ios_Openmode]

Поскольку вы указали только целое число, компилятор попытался сопоставить эту версию ctor и не смог выполнить преобразование.

Answer 2

Вам не нужно Boost для этого.

хотел преобразовать *FILE (такой как возвращенный popen()) в iostream

Вместо этого используйте pstreams (отказ, я написал это, если это имеет значение).

Некоторые компиляторы предоставляют расширения для создания потокового буфера из файла C без необходимости Boost, например, с помощью GCC:

#include <ext/stdio_filebuf.h>
...
__gnu_cxx::stdio_filebuf<char> fb(fp, std::ios::out);
std::ostream os(&fb);