An interface for simple binary IO. More...

#include <basicio.hpp>

Inheritance diagram for Exiv2::BasicIo:

[legend]

Public Types
enum	Position { beg , cur , end }
	Seek starting positions.

using	UniquePtr = std::unique_ptr< BasicIo >
	BasicIo auto_ptr type.

Public Member Functions
Creators
virtual	~BasicIo ()=default
	Destructor.

Manipulators
virtual int	open ()=0
	Open the IO source using the default access mode. The default mode should allow for reading and writing. More...

virtual int	close ()=0
	Close the IO source. After closing a BasicIo instance can not be read or written. Closing flushes any unwritten data. It is safe to call close on a closed instance. More...

virtual size_t	write (const byte *data, size_t wcount)=0
	Write data to the IO source. Current IO position is advanced by the number of bytes written. More...

virtual size_t	write (BasicIo &src)=0
	Write data that is read from another BasicIo instance to the IO source. Current IO position is advanced by the number of bytes written. More...

virtual int	putb (byte data)=0
	Write one byte to the IO source. Current IO position is advanced by one byte. More...

virtual DataBuf	read (size_t rcount)=0
	Read data from the IO source. Reading starts at the current IO position and the position is advanced by the number of bytes read. More...

virtual size_t	read (byte *buf, size_t rcount)=0
	Read data from the IO source. Reading starts at the current IO position and the position is advanced by the number of bytes read. More...

void	readOrThrow (byte *buf, size_t rcount, ErrorCode err=ErrorCode::kerCorruptedMetadata)
	Safe version of `read()` that checks for errors and throws an exception if the read was unsuccessful. More...

virtual int	getb ()=0
	Read one byte from the IO source. Current IO position is advanced by one byte. More...

virtual void	transfer (BasicIo &src)=0
	Remove all data from this object's IO source and then transfer data from the src BasicIo object into this object. More...

virtual int	seek (int64_t offset, Position pos)=0
	Move the current IO position. More...

void	seekOrThrow (int64_t offset, Position pos, ErrorCode err)
	Safe version of `seek()` that checks for errors and throws an exception if the seek was unsuccessful. More...

virtual byte *	mmap (bool isWriteable=false)=0
	Direct access to the IO data. For files, this is done by mapping the file into the process's address space; for memory blocks, this allows direct access to the memory block. More...

virtual int	munmap ()=0
	Remove a mapping established with mmap(). If the mapped area is writeable, this ensures that changes are written back. More...

Accessors
byte *	bigBlock_ {}
	this is allocated and populated by mmap()

virtual size_t	tell () const =0
	Get the current IO position. More...

virtual size_t	size () const =0
	Get the current size of the IO source in bytes. More...

virtual bool	isopen () const =0
	Returns true if the IO source is open, otherwise false.

virtual int	error () const =0
	Returns 0 if the IO source is in a valid state, otherwise nonzero.

virtual bool	eof () const =0
	Returns true if the IO position has reached the end, otherwise false.

virtual const std::string &	path () const noexcept=0
	Return the path to the IO resource. Often used to form comprehensive error messages where only a BasicIo instance is available.

virtual void	populateFakeData ()=0
	Mark all the bNone blocks to bKnow. This avoids allocating memory for parts of the file that contain image-date (non-metadata/pixel data) More...

Detailed Description

An interface for simple binary IO.

Designed to have semantics and names similar to those of C style FILE* operations. Subclasses should all behave the same so that they can be interchanged.

Member Function Documentation

◆ close()

virtual int Exiv2::BasicIo::close ( )

pure virtual

Close the IO source. After closing a BasicIo instance can not be read or written. Closing flushes any unwritten data. It is safe to call close on a closed instance.

Returns: 0 if successful;
Nonzero if failure.

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ getb()

virtual int Exiv2::BasicIo::getb ( )

pure virtual

Read one byte from the IO source. Current IO position is advanced by one byte.

Returns: The byte read from the IO source if successful;
EOF if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ mmap()

virtual byte* Exiv2::BasicIo::mmap ( bool isWriteable = false )

pure virtual

Direct access to the IO data. For files, this is done by mapping the file into the process's address space; for memory blocks, this allows direct access to the memory block.

Parameters

isWriteable Set to true if the mapped area should be writeable (default is false).

Returns: A pointer to the mapped area.

Exceptions

Error In case of failure.

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ munmap()

virtual int Exiv2::BasicIo::munmap ( )

pure virtual

Remove a mapping established with mmap(). If the mapped area is writeable, this ensures that changes are written back.

Returns: 0 if successful;
Nonzero if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ open()

virtual int Exiv2::BasicIo::open ( )

pure virtual

Open the IO source using the default access mode. The default mode should allow for reading and writing.

This method can also be used to "reopen" an IO source which will flush any unwritten data and reset the IO position to the start. Subclasses may provide custom methods to allow for opening IO sources differently.

Returns: 0 if successful;
Nonzero if failure.

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ populateFakeData()

virtual void Exiv2::BasicIo::populateFakeData ( )

pure virtual

Mark all the bNone blocks to bKnow. This avoids allocating memory for parts of the file that contain image-date (non-metadata/pixel data)

Note: This method should be only called after the concerned data (metadata) are all downloaded from the remote file to memory.

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ putb()

virtual int Exiv2::BasicIo::putb ( byte data )

pure virtual

Write one byte to the IO source. Current IO position is advanced by one byte.

Parameters

data	The single byte to be written.

Returns: The value of the byte written if successful;
EOF if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ read() [1/2]

virtual size_t Exiv2::BasicIo::read	(	byte *	buf,
		size_t	rcount
	)

pure virtual

Read data from the IO source. Reading starts at the current IO position and the position is advanced by the number of bytes read.

Parameters

buf	Pointer to a block of memory into which the read data is stored. The memory block must be at least rcount bytes long.
rcount	Maximum number of bytes to read. Fewer bytes may be read if rcount bytes are not available.

Returns: Number of bytes read from IO source successfully;
0 if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ read() [2/2]

virtual DataBuf Exiv2::BasicIo::read ( size_t rcount )

pure virtual

Read data from the IO source. Reading starts at the current IO position and the position is advanced by the number of bytes read.

Parameters

rcount Maximum number of bytes to read. Fewer bytes may be read if rcount bytes are not available.

Returns: DataBuf instance containing the bytes read. Use the DataBuf::size_ member to find the number of bytes read. DataBuf::size_ will be 0 on failure.

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ readOrThrow()

void Exiv2::BasicIo::readOrThrow	(	byte *	buf,
		size_t	rcount,
		ErrorCode	err = `ErrorCode::kerCorruptedMetadata`
	)

Safe version of read() that checks for errors and throws an exception if the read was unsuccessful.

Parameters

buf	Pointer to a block of memory into which the read data is stored. The memory block must be at least rcount bytes long.
rcount	Maximum number of bytes to read. Fewer bytes may be read if rcount bytes are not available.
err	Error code to use if an exception is thrown.

◆ seek()

virtual int Exiv2::BasicIo::seek	(	int64_t	offset,
		Position	pos
	)

pure virtual

Move the current IO position.

Parameters

offset	Number of bytes to move the position relative to the starting position specified by pos
pos	Position from which the seek should start

Returns: 0 if successful;
Nonzero if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ seekOrThrow()

void Exiv2::BasicIo::seekOrThrow	(	int64_t	offset,
		Position	pos,
		ErrorCode	err
	)

Safe version of seek() that checks for errors and throws an exception if the seek was unsuccessful.

Parameters

offset	Number of bytes to move the position relative to the starting position specified by pos
pos	Position from which the seek should start
err	Error code to use if an exception is thrown.

◆ size()

virtual size_t Exiv2::BasicIo::size ( ) const

pure virtual

Get the current size of the IO source in bytes.

Returns: Size of the IO source in bytes;
-1 if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ tell()

virtual size_t Exiv2::BasicIo::tell ( ) const

pure virtual

Get the current IO position.

Returns: Offset from the start of IO

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ transfer()

virtual void Exiv2::BasicIo::transfer ( BasicIo & src )

pure virtual

Remove all data from this object's IO source and then transfer data from the src BasicIo object into this object.

The source object is invalidated by this operation and should not be used after this method returns. This method exists primarily to be used with the BasicIo::temporary() method.

Parameters

src	Reference to another BasicIo instance. The entire contents of src are transferred to this object. The src object is invalidated by the method.

Exceptions

Error In case of failure

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ write() [1/2]

virtual size_t Exiv2::BasicIo::write ( BasicIo & src )

pure virtual

Write data that is read from another BasicIo instance to the IO source. Current IO position is advanced by the number of bytes written.

Parameters

src	Reference to another BasicIo instance. Reading start at the source's current IO position

Returns: Number of bytes written to IO source successfully;
0 if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

◆ write() [2/2]

virtual size_t Exiv2::BasicIo::write	(	const byte *	data,
		size_t	wcount
	)

pure virtual

Write data to the IO source. Current IO position is advanced by the number of bytes written.

Parameters

data	Pointer to data. Data must be at least wcount bytes long
wcount	Number of bytes to be written.

Returns: Number of bytes written to IO source successfully;
0 if failure;

Implemented in Exiv2::RemoteIo, and Exiv2::MemIo.

The documentation for this class was generated from the following file:

basicio.hpp

Public Types

Public Member Functions

Accessors

Detailed Description

Member Function Documentation

◆ close()

◆ getb()

◆ mmap()

◆ munmap()

◆ open()

◆ populateFakeData()

◆ putb()

◆ read() [1/2]

◆ read() [2/2]

◆ readOrThrow()

◆ seek()

◆ seekOrThrow()

◆ size()

◆ tell()

◆ transfer()

◆ write() [1/2]

◆ write() [2/2]