//
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) Contributors to the OpenEXR Project.
//
#ifndef INCLUDED_IMF_IO_H
#define INCLUDED_IMF_IO_H
//-----------------------------------------------------------------------------
//
// Low-level file input and output for OpenEXR.
//
//-----------------------------------------------------------------------------
#include "ImfForward.h"
#include <string>
#include <cstdint>
OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER
//-----------------------------------------------------------
// class IStream -- an abstract base class for input streams.
//-----------------------------------------------------------
class IMF_EXPORT_TYPE IStream
{
public:
//-----------
// Destructor
//-----------
IMF_EXPORT virtual ~IStream ();
//-------------------------------------------------
// Does this input stream support memory-mapped IO?
//
// Memory-mapped streams can avoid an extra copy;
// memory-mapped read operations return a pointer
// to an internal buffer instead of copying data
// into a buffer supplied by the caller.
//-------------------------------------------------
IMF_EXPORT virtual bool isMemoryMapped () const;
//------------------------------------------------------
// Read from the stream:
//
// read(c,n) reads n bytes from the stream, and stores
// them in array c. If the stream contains less than n
// bytes, or if an I/O error occurs, read(c,n) throws
// an exception. If read(c,n) reads the last byte from
// the file it returns false, otherwise it returns true.
//------------------------------------------------------
virtual bool read (char c[/*n*/], int n) = 0;
//---------------------------------------------------
// Read from a memory-mapped stream:
//
// readMemoryMapped(n) reads n bytes from the stream
// and returns a pointer to the first byte. The
// returned pointer remains valid until the stream
// is closed. If there are less than n byte left to
// read in the stream or if the stream is not memory-
// mapped, readMemoryMapped(n) throws an exception.
//---------------------------------------------------
IMF_EXPORT virtual char * readMemoryMapped (int n);
//--------------------------------------------------------
// Get the current reading position, in bytes from the
// beginning of the file. If the next call to read() will
// read the first byte in the file, tellg() returns 0.
//--------------------------------------------------------
virtual uint64_t tellg () = 0;
//-------------------------------------------
// Set the current reading position.
// After calling seekg(i), tellg() returns i.
//-------------------------------------------
virtual void seekg (uint64_t pos) = 0;
//------------------------------------------------------
// Clear error conditions after an operation has failed.
//------------------------------------------------------
IMF_EXPORT virtual void clear ();
//------------------------------------------------------
// Get the name of the file associated with this stream.
//------------------------------------------------------
IMF_EXPORT const char * fileName () const;
protected:
IMF_EXPORT IStream (const char fileName[]);
private:
IStream (const IStream &) = delete;
IStream & operator = (const IStream &) = delete;
IStream (IStream &&) = delete;
IStream & operator = (IStream &&) = delete;
std::string _fileName;
};
//-----------------------------------------------------------
// class OStream -- an abstract base class for output streams
//-----------------------------------------------------------
class IMF_EXPORT_TYPE OStream
{
public:
//-----------
// Destructor
//-----------
IMF_EXPORT virtual ~OStream ();
//----------------------------------------------------------
// Write to the stream:
//
// write(c,n) takes n bytes from array c, and stores them
// in the stream. If an I/O error occurs, write(c,n) throws
// an exception.
//----------------------------------------------------------
virtual void write (const char c[/*n*/], int n) = 0;
//---------------------------------------------------------
// Get the current writing position, in bytes from the
// beginning of the file. If the next call to write() will
// start writing at the beginning of the file, tellp()
// returns 0.
//---------------------------------------------------------
virtual uint64_t tellp () = 0;
//-------------------------------------------
// Set the current writing position.
// After calling seekp(i), tellp() returns i.
//-------------------------------------------
virtual void seekp (uint64_t pos) = 0;
//------------------------------------------------------
// Get the name of the file associated with this stream.
//------------------------------------------------------
IMF_EXPORT const char * fileName () const;
protected:
IMF_EXPORT OStream (const char fileName[]);
private:
OStream (const OStream &) = delete;
OStream & operator = (const OStream &) = delete;
OStream (OStream &&) = delete;
OStream & operator = (OStream &&) = delete;
std::string _fileName;
};
//-----------------------
// Helper classes for Xdr
//-----------------------
struct StreamIO
{
static inline void
writeChars (OStream &os, const char c[/*n*/], int n)
{
os.write (c, n);
}
static inline bool
readChars (IStream &is, char c[/*n*/], int n)
{
return is.read (c, n);
}
};
struct CharPtrIO
{
static inline void
writeChars (char *&op, const char c[/*n*/], int n)
{
while (n--)
*op++ = *c++;
}
static inline bool
readChars (const char *&ip, char c[/*n*/], int n)
{
while (n--)
*c++ = *ip++;
return true;
}
};
OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT
#endif
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