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/* The following code declares classes to read from and write to
* file descriptor or file handles.
*
* See
* https://www.josuttis.com/cppcode
* for details and the latest version.
*
* - open:
* - integrating BUFSIZ on some systems?
* - optimized reading of multiple characters
* - stream for reading AND writing
* - i18n
*
* (C) Copyright Nicolai M. Josuttis 2001.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*
* Version: Jul 28, 2002
* History:
* Jul 28, 2002: bugfix memcpy() => memmove()
* fdinbuf::underflow(): cast for return statements
* Aug 05, 2001: first public version
*/
/* Modifications by Tom Vercauteren:
* Use cmake to check for unistd.h
* Borland needs io.h
* Replaced int by ptrdiff_t when it makes sense
* Use itk namespace instead of boost
*/
#ifndef fdstream_hxx
#define fdstream_hxx
#include <istream>
#include <ostream>
#include <streambuf>
// for EOF:
#include <cstdio>
// for memmove():
#include <cstring>
// low-level read and write functions
#ifdef ITK_HAVE_UNISTD_H
# include <unistd.h>
#else
# include <io.h>
#endif
// BEGIN namespace
namespace itk
{
/************************************************************
* fdostream
* - a stream that writes on a file descriptor
************************************************************/
class fdoutbuf : public std::streambuf
{
public:
// constructor
fdoutbuf(int _fd)
: fd(_fd)
{}
protected:
int fd; // file descriptor
// write one character
virtual int_type
overflow(int_type c)
{
if (c != EOF)
{
char z = c;
if (write(fd, &z, 1) != 1)
{
return EOF;
}
}
return c;
}
// write multiple characters
virtual std::streamsize
xsputn(const char * s, std::streamsize num)
{
return write(fd, s, num);
}
};
class fdostream : public std::ostream
{
protected:
fdoutbuf buf;
public:
fdostream(int fd)
: std::ostream(0)
, buf(fd)
{
rdbuf(&buf);
}
};
/************************************************************
* fdistream
* - a stream that reads on a file descriptor
************************************************************/
class fdinbuf : public std::streambuf
{
protected:
int fd; // file descriptor
protected:
/* data buffer:
* - at most, pbSize characters in putback area plus
* - at most, bufSize characters in ordinary read buffer
*/
static constexpr ptrdiff_t pbSize = 4; // size of putback area
static constexpr ptrdiff_t bufSize = 1024; // size of the data buffer
char buffer[bufSize + pbSize]; // data buffer
public:
/* constructor
* - initialize file descriptor
* - initialize empty data buffer
* - no putback area
* => force underflow()
*/
fdinbuf(int _fd)
: fd(_fd)
{
setg(buffer + pbSize, // beginning of putback area
buffer + pbSize, // read position
buffer + pbSize); // end position
}
protected:
// insert new characters into the buffer
virtual int_type
underflow()
{
#ifndef _MSC_VER
using std::memmove;
#endif
// is read position before end of buffer?
if (gptr() < egptr())
{
return traits_type::to_int_type(*gptr());
}
/* process size of putback area
* - use number of characters read
* - but at most size of putback area
*/
ptrdiff_t numPutback;
numPutback = gptr() - eback();
if (numPutback > pbSize)
{
numPutback = pbSize;
}
/* copy up to pbSize characters previously read into
* the putback area
*/
memmove(buffer + (pbSize - numPutback), gptr() - numPutback, numPutback);
// read at most bufSize new characters
int num;
num = read(fd, buffer + pbSize, bufSize);
if (num <= 0)
{
// ERROR or EOF
return EOF;
}
// reset buffer pointers
setg(buffer + (pbSize - numPutback), // beginning of putback area
buffer + pbSize, // read position
buffer + pbSize + num); // end of buffer
// return next character
return traits_type::to_int_type(*gptr());
}
};
class fdistream : public std::istream
{
protected:
fdinbuf buf;
public:
fdistream(int fd)
: std::istream(0)
, buf(fd)
{
rdbuf(&buf);
}
};
} // namespace itk
#endif /*include guard*/
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