Common C++ classes and routines used by my applications such as argument parser, IO and conversion utilities
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 

348 lines
11 KiB

#include "./nativefilestream.h"
#ifdef CPP_UTILITIES_USE_NATIVE_FILE_BUFFER
/*!
* \class
* So one gets e.g. "open failed: Permission denied" instead of
just "open failed: iostream error".
*/
/*!
* \class NativeFileStream
* \brief Provides a standard IO stream instantiated using native APIs.
*
* Using this class instead of `std::fstream` has the following benefits:
* - Under Windows, the specified file path is interpreted as UTF-8 and passed to Windows' unicode API
* to support any kind of non-ASCII characters in file paths.
* - It is possible to open a file from a native file descriptor. This is for instance useful when dealing with
* Android's `content://` URLs.
* - Better error messages at least when opening a file, e.g. "Permission denied" instead of just "basic_ios::clear".
*/
#ifdef PLATFORM_WINDOWS
#include "../conversion/stringconversion.h"
#endif
// include header files for file buffer implementation
#if defined(CPP_UTILITIES_USE_GNU_CXX_STDIO_FILEBUF)
#include <ext/stdio_filebuf.h>
#elif defined(CPP_UTILITIES_USE_BOOST_IOSTREAMS)
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
#else
#error "Configuration for NativeFileStream backend insufficient."
#endif
// include platform specific header
#if defined(PLATFORM_UNIX)
#include <cstdio>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#elif defined(PLATFORM_WINDOWS)
#include <fcntl.h>
#include <io.h>
#include <sys/stat.h> // yes, this is needed under Windows (https://msdn.microsoft.com/en-US/library/5yhhz3y7.aspx)
#include <windows.h>
#endif
#endif
using namespace std;
namespace CppUtilities {
#ifdef CPP_UTILITIES_USE_NATIVE_FILE_BUFFER
#ifdef CPP_UTILITIES_USE_GNU_CXX_STDIO_FILEBUF
using StreamBuffer = __gnu_cxx::stdio_filebuf<char>;
#else // CPP_UTILITIES_USE_BOOST_IOSTREAMS
using StreamBuffer = boost::iostreams::stream_buffer<boost::iostreams::file_descriptor>;
#endif
struct NativeFileParams {
#ifdef PLATFORM_WINDOWS
NativeFileParams(ios_base::openmode cppOpenMode)
: openMode(cppOpenMode & ios_base::binary ? _O_BINARY : 0)
, flags(cppOpenMode & ios_base::binary ? 0 : _O_TEXT)
, permissions(0)
, access(0)
, shareMode(0)
, creation(0)
{
if ((cppOpenMode & ios_base::out) && (cppOpenMode & ios_base::in)) {
openMode |= _O_RDWR;
access = GENERIC_READ | GENERIC_WRITE;
shareMode = FILE_SHARE_READ;
creation = OPEN_EXISTING;
} else if (cppOpenMode & ios_base::out) {
openMode |= _O_WRONLY | _O_CREAT;
permissions = _S_IREAD | _S_IWRITE;
access = GENERIC_WRITE;
creation = OPEN_ALWAYS;
} else if (cppOpenMode & ios_base::in) {
openMode |= _O_RDONLY;
flags |= _O_RDONLY;
access = GENERIC_READ;
shareMode = FILE_SHARE_READ;
creation = OPEN_EXISTING;
}
if (cppOpenMode & ios_base::app) {
openMode |= _O_APPEND;
flags |= _O_APPEND;
}
if (cppOpenMode & ios_base::trunc) {
openMode |= _O_TRUNC;
creation = (cppOpenMode & ios_base::in) ? TRUNCATE_EXISTING : CREATE_ALWAYS;
}
}
int openMode;
int flags;
int permissions;
DWORD access;
DWORD shareMode;
DWORD creation;
#else
NativeFileParams(ios_base::openmode cppOpenMode)
: openFlags(0)
{
if ((cppOpenMode & ios_base::in) && (cppOpenMode & ios_base::out)) {
if (cppOpenMode & ios_base::app) {
openMode = "a+";
openFlags = O_RDWR | O_APPEND;
} else if (cppOpenMode & ios_base::trunc) {
openMode = "w+";
openFlags = O_RDWR | O_TRUNC;
} else {
openMode = "r+";
openFlags = O_RDWR;
}
} else if (cppOpenMode & ios_base::in) {
openMode = 'r';
openFlags = O_RDONLY;
} else if (cppOpenMode & ios_base::out) {
if (cppOpenMode & ios_base::app) {
openMode = 'a';
openFlags = O_WRONLY | O_APPEND;
} else if (cppOpenMode & ios_base::trunc) {
openMode = 'w';
openFlags = O_WRONLY | O_TRUNC | O_CREAT;
} else {
openMode = "w";
openFlags = O_WRONLY | O_CREAT;
}
}
if (cppOpenMode & ios_base::binary) {
openMode += 'b';
}
}
std::string openMode;
int openFlags;
#endif
};
/*!
* \class NativeFileStream::FileBuffer
* \brief The NativeFileStream::FileBuffer class holds an std::basic_streambuf<char> object obtained from a file path or a native file descriptor.
*/
/*!
* \brief Constructs a new FileBuffer object taking ownership of \a buffer.
*/
NativeFileStream::FileBuffer::FileBuffer(std::basic_streambuf<char> *buffer)
: buffer(buffer)
{
}
/*!
* \brief Opens a file buffer from the specified \a path.
* \remarks See NativeFileStream::open() for remarks on how \a path must be encoded.
*/
NativeFileStream::FileBuffer::FileBuffer(const string &path, ios_base::openmode openMode)
{
#ifdef PLATFORM_WINDOWS
// convert path to UTF-16
const auto widePath(makeWidePath(path));
#endif
// compute native params
const NativeFileParams nativeParams(openMode);
// open native file handle or descriptor
#ifdef CPP_UTILITIES_USE_GNU_CXX_STDIO_FILEBUF
#ifdef PLATFORM_WINDOWS
descriptor = _wopen(widePath.get(), nativeParams.openMode, nativeParams.permissions);
if (descriptor == -1) {
throw std::ios_base::failure("_wopen failed", std::error_code(errno, std::system_category()));
}
#else
descriptor = ::open(path.data(), nativeParams.openFlags, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (descriptor == -1) {
throw std::ios_base::failure("open failed", std::error_code(errno, std::system_category()));
}
#endif
buffer = make_unique<StreamBuffer>(descriptor, openMode);
#else // CPP_UTILITIES_USE_BOOST_IOSTREAMS
#ifdef PLATFORM_WINDOWS
handle = CreateFileW(widePath.get(), nativeParams.access, nativeParams.shareMode, nullptr, nativeParams.creation, FILE_ATTRIBUTE_NORMAL, nullptr);
if (handle == INVALID_HANDLE_VALUE) {
throw std::ios_base::failure("CreateFileW failed", std::error_code(GetLastError(), std::system_category()));
}
buffer = make_unique<StreamBuffer>(handle, boost::iostreams::close_handle);
// if we wanted to open assign the descriptor as well: descriptor = _open_osfhandle(reinterpret_cast<intptr_t>(handle), nativeParams.flags);
#else
descriptor = ::open(path.data(), nativeParams.openFlags, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (descriptor == -1) {
throw std::ios_base::failure("open failed", std::error_code(errno, std::system_category()));
}
buffer = make_unique<StreamBuffer>(descriptor, boost::iostreams::close_handle);
#endif
#endif
}
/*!
* \brief Opens a file buffer from the specified \a fileDescriptor.
* \remarks
* The specified \a openMode is only used when using __gnu_cxx::stdio_filebuf<char> and must be in accordance with how \a fileDescriptor
* has been opened.
*/
NativeFileStream::FileBuffer::FileBuffer(int fileDescriptor, ios_base::openmode openMode)
: descriptor(fileDescriptor)
{
#ifdef CPP_UTILITIES_USE_GNU_CXX_STDIO_FILEBUF
buffer = make_unique<StreamBuffer>(descriptor, openMode);
#else // CPP_UTILITIES_USE_BOOST_IOSTREAMS
CPP_UTILITIES_UNUSED(openMode)
#ifdef PLATFORM_WINDOWS
handle = reinterpret_cast<Handle>(_get_osfhandle(descriptor));
buffer = make_unique<StreamBuffer>(handle, boost::iostreams::close_handle);
#else
buffer = make_unique<StreamBuffer>(descriptor, boost::iostreams::close_handle);
#endif
#endif
}
/*!
* \brief Constructs a new NativeFileStream which is initially closed.
*/
NativeFileStream::NativeFileStream()
: iostream(new StreamBuffer)
, m_data(rdbuf())
{
}
/*!
* \brief Moves the NativeFileStream.
*/
NativeFileStream::NativeFileStream(NativeFileStream &&other)
: iostream(other.m_data.buffer.release())
, m_data(rdbuf())
{
#ifdef PLATFORM_WINDOWS
m_data.handle = other.m_data.handle;
#endif
m_data.descriptor = other.m_data.descriptor;
}
/*!
* \brief Destroys the NativeFileStream releasing all underlying resources.
*/
NativeFileStream::~NativeFileStream()
{
}
/*!
* \brief Returns whether the file is open.
*/
bool NativeFileStream::isOpen() const
{
return m_data.buffer && static_cast<const StreamBuffer *>(m_data.buffer.get())->is_open();
}
/*!
* \brief Opens the file referenced by \a path with the specified \a openMode.
* \remarks
* Under Windows \a path is expected to be UTF-8 encoded. It is automatically converted so non-ASCII
* characters are treated correctly under Windows (in contrast to std::fstream::open() where only the
* current code page is supported).
*
* Under other platforms the \a path is just passed through so there are no assumptions made about its
* encoding.
* \throws Throws std::ios_base::failure in the error case.
* \todo Maybe use setstate() instead of throwing exceptions directly for consistent error handling
* with std::fstream::open(). However, that makes passing specific error messages difficult.
*/
void NativeFileStream::open(const string &path, ios_base::openmode openMode)
{
setData(FileBuffer(path, openMode), openMode);
}
/*!
* \brief Opens the file from the specified \a fileDescriptor with the specified \a openMode.
* \throws Throws std::ios_base::failure in the error case.
* \todo
* - Maybe use setstate() instead of throwing exceptions directly for consistent error handling
* with std::fstream::open(). However, that makes passing specific error messages difficult.
*/
void NativeFileStream::open(int fileDescriptor, ios_base::openmode openMode)
{
setData(FileBuffer(fileDescriptor, openMode), openMode);
}
/*!
* \brief Closes the file if opened; otherwise does nothing.
*/
void NativeFileStream::close()
{
if (m_data.buffer) {
static_cast<StreamBuffer *>(m_data.buffer.get())->close();
#ifdef PLATFORM_WINDOWS
m_data.handle = nullptr;
#endif
m_data.descriptor = -1;
}
}
/*!
* \brief Internally called to assign the buffer, file descriptor and handle.
*/
void NativeFileStream::setData(FileBuffer data, std::ios_base::openmode openMode)
{
rdbuf(data.buffer.get());
m_data = std::move(data);
m_openMode = openMode;
#if defined(PLATFORM_WINDOWS) && defined(CPP_UTILITIES_USE_BOOST_IOSTREAMS)
// workaround append flag dysfunctioning
if (m_openMode & ios_base::app) {
seekp(0, ios_base::end);
}
#endif
}
#ifdef PLATFORM_WINDOWS
/*!
* \brief Converts the specified UTF-8 encoded \a path to UTF-16 for passing it to WinAPI functions.
* \throws Throws std::ios_base::failure when an encoding error occurs.
*/
std::unique_ptr<wchar_t[]> NativeFileStream::makeWidePath(const std::string &path)
{
auto ec = std::error_code();
auto widePath = ::CppUtilities::convertMultiByteToWide(ec, path);
if (!widePath.first) {
throw std::ios_base::failure("converting path to UTF-16", ec);
}
return std::move(widePath.first);
}
#endif
#else
// std::fstream is used
#endif
} // namespace CppUtilities