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/*************************************************************************
* Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
#include "dimensionxx.hpp"
#include <stdio.h>
// The conundrum: libdimension and libdimension-* use C I/O, with FILE*'s.
// We want to use C++ I/O with std::i/ostreams. Unfortunately, there's no
// standard way to map between them, so we use the nonportable GNU stdio
// extension fopencookie(), which creates a FILE* with custom read/write/seek
// functions. BSD also has a similar function, funopen(), which we should
// use too. Failing in all that, we should fall back on a tmpfile() buffer,
// but that would require an fclosecookie() function as well, to copy the
// buffer to the stream potentially.
namespace Dimension
{
namespace
{
// Internal cookie type to hold the C++ streams.
struct Cookie
{
public:
std::istream* istr;
std::ostream* ostr;
};
// Cookie read function
ssize_t
cookie_read(void* cookie, char* buf, size_t size)
{
Cookie* streams = reinterpret_cast<Cookie*>(cookie);
// Do the unformatted read
streams->istr->read(buf, size);
if (streams->istr->eof() || streams->istr->good()) {
return streams->istr->gcount(); // This returns 0 on an immediate EOF
// for us.
} else {
// Some non-EOF error
return -1;
}
}
// Cookie write function
ssize_t
cookie_write(void* cookie, const char* buf, size_t size)
{
Cookie* streams = reinterpret_cast<Cookie*>(cookie);
// Do the unformatted write
streams->ostr->write(buf, size);
if (streams->ostr->good()) {
// Write operation succeeded, so we must've written size bytes
return size;
} else {
// Write operation failed
return -1;
}
}
// Cookie seek function
int
cookie_seek(void* cookie, off64_t* offset, int whence)
{
Cookie* streams = reinterpret_cast<Cookie*>(cookie);
if (streams->istr) {
// If we have an input stream, seek it
switch (whence) {
case SEEK_SET:
streams->istr->seekg(*offset, std::ios::beg);
break;
case SEEK_CUR:
streams->istr->seekg(*offset, std::ios::cur);
break;
case SEEK_END:
streams->istr->seekg(*offset, std::ios::end);
break;
}
if (!streams->istr->good()) {
// Seek failed
return 1;
}
}
if (streams->ostr) {
// If we have an output stream, seek it too
switch (whence) {
case SEEK_SET:
streams->ostr->seekp(*offset, std::ios::beg);
break;
case SEEK_CUR:
streams->ostr->seekp(*offset, std::ios::cur);
break;
case SEEK_END:
streams->ostr->seekp(*offset, std::ios::end);
}
if (!streams->ostr->good()) {
// Seek failed
return 1;
}
}
// Seek succeeded
return 0;
}
// Cookie delete function
int
cookie_close(void* cookie)
{
// Free the cookie
delete reinterpret_cast<Cookie*>(cookie);
}
}
// Make an input FILE*
std::FILE*
fcookie(std::istream& istr)
{
Cookie* cookie = new Cookie;
cookie->istr = &istr;
cookie->ostr = 0;
cookie_io_functions_t io_funcs;
io_funcs.read = &cookie_read;
io_funcs.write = 0;
io_funcs.seek = &cookie_seek;
io_funcs.close = &cookie_close;
return fopencookie(reinterpret_cast<void*>(cookie), "r", io_funcs);
}
// Make an output FILE*
std::FILE*
fcookie(std::ostream& ostr)
{
Cookie* cookie = new Cookie;
cookie->istr = 0;
cookie->ostr = &ostr;
cookie_io_functions_t io_funcs;
io_funcs.read = 0;
io_funcs.write = &cookie_write;
io_funcs.seek = &cookie_seek;
io_funcs.close = &cookie_close;
return fopencookie(reinterpret_cast<void*>(cookie), "w", io_funcs);
}
// Make an I/O FILE*
std::FILE*
fcookie(std::iostream& iostr)
{
Cookie* cookie = new Cookie;
cookie->istr = &iostr;
cookie->ostr = &iostr;
cookie_io_functions_t io_funcs;
io_funcs.read = &cookie_read;
io_funcs.write = &cookie_write;
io_funcs.seek = &cookie_seek;
io_funcs.close = &cookie_close;
return fopencookie(reinterpret_cast<void*>(cookie), "r+", io_funcs);
}
}
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