Provides binary file IO by implementing the BasicIo interface. More...

#include <basicio.hpp>

Inheritance diagram for Exiv2::FileIo:

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Public Member Functions
Creators
	FileIo (const std::string &path)
	Constructor that accepts the file path on which IO will be performed. The constructor does not open the file, and therefore never fails.

	~FileIo () override
	Destructor. Flushes and closes an open file.

Manipulators
int	open (const std::string &mode)
	Open the file using the specified mode.

int	open () override
	Open the file using the default access mode of "rb". This method can also be used to "reopen" a file which will flush any unwritten data and reset the IO position to the start.

int	close () override
	Flush and unwritten data and close the file . It is safe to call close on an already closed instance.

size_t	write (const byte *data, size_t wcount) override
	Write data to the file. The file position is advanced by the number of bytes written.

size_t	write (BasicIo &src) override
	Write data that is read from another BasicIo instance to the file. The file position is advanced by the number of bytes written.

int	putb (byte data) override
	Write one byte to the file. The file position is advanced by one byte.

DataBuf	read (size_t rcount) override
	Read data from the file. Reading starts at the current file position and the position is advanced by the number of bytes read.

size_t	read (byte *buf, size_t rcount) override
	Read data from the file. Reading starts at the current file position and the position is advanced by the number of bytes read.

int	getb () override
	Read one byte from the file. The file position is advanced by one byte.

void	transfer (BasicIo &src) override
	Remove the contents of the file and then transfer data from the src BasicIo object into the empty file.

int	seek (int64_t offset, Position pos) override
	Move the current IO position.

byte *	mmap (bool isWriteable=false) override
	Map the file into the process's address space. The file must be open before mmap() is called. If the mapped area is writeable, changes may not be written back to the underlying file until munmap() is called. The pointer is valid only as long as the FileIo object exists.

int	munmap () override
	Remove a mapping established with mmap(). If the mapped area is writeable, this ensures that changes are written back to the underlying file.

virtual void	setPath (const std::string &path)
	close the file source and set a new path.

Public Member Functions inherited from Exiv2::BasicIo
virtual	~BasicIo ()=default
	Destructor.

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.

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.

Accessors
size_t	tell () const override
	Get the current file position.

size_t	size () const override
	Flush any buffered writes and get the current file size in bytes.

bool	isopen () const override
	Returns true if the file is open, otherwise false.

int	error () const override
	Returns 0 if the file is in a valid state, otherwise nonzero.

bool	eof () const override
	Returns true if the file position has reached the end, otherwise false.

const std::string &	path () const noexcept override
	Returns the path of the file.

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

	FileIo (const FileIo &)=delete
	Copy constructor.

FileIo &	operator= (const FileIo &)=delete
	Assignment operator.

Additional Inherited Members
Public Types inherited from Exiv2::BasicIo
enum	Position { beg , cur , end }
	Seek starting positions.

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

Public Attributes inherited from Exiv2::BasicIo
byte *	bigBlock_ {}
	this is allocated and populated by mmap()

Detailed Description

Provides binary file IO by implementing the BasicIo interface.

Examples: metacopy.cpp, and mrwthumb.cpp.

Constructor & Destructor Documentation

◆ FileIo()

Exiv2::FileIo::FileIo ( const std::string & path )

explicit

Constructor that accepts the file path on which IO will be performed. The constructor does not open the file, and therefore never fails.

Parameters

path	The full path of a file

Member Function Documentation

◆ close()

int Exiv2::FileIo::close ( )

overridevirtual

Flush and unwritten data and close the file . It is safe to call close on an already closed instance.

Returns: 0 if successful;
Nonzero if failure;

Implements Exiv2::BasicIo.

Examples: mrwthumb.cpp.

◆ eof()

bool Exiv2::FileIo::eof ( ) const

overridevirtual

Returns true if the file position has reached the end, otherwise false.

Implements Exiv2::BasicIo.

◆ error()

int Exiv2::FileIo::error ( ) const

overridevirtual

Returns 0 if the file is in a valid state, otherwise nonzero.

Implements Exiv2::BasicIo.

◆ getb()

int Exiv2::FileIo::getb ( )

overridevirtual

Read one byte from the file. The file position is advanced by one byte.

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

Implements Exiv2::BasicIo.

◆ isopen()

bool Exiv2::FileIo::isopen ( ) const

overridevirtual

Returns true if the file is open, otherwise false.

Implements Exiv2::BasicIo.

◆ mmap()

byte * Exiv2::FileIo::mmap ( bool isWriteable = false )

overridevirtual

Map the file into the process's address space. The file must be open before mmap() is called. If the mapped area is writeable, changes may not be written back to the underlying file until munmap() is called. The pointer is valid only as long as the FileIo object exists.

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.

Implements Exiv2::BasicIo.

◆ munmap()

int Exiv2::FileIo::munmap ( )

overridevirtual

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

Returns: 0 if successful;
Nonzero if failure;

Implements Exiv2::BasicIo.

◆ open() [1/2]

int Exiv2::FileIo::open ( )

overridevirtual

Open the file using the default access mode of "rb". This method can also be used to "reopen" a file which will flush any unwritten data and reset the IO position to the start.

Returns: 0 if successful;
Nonzero if failure.

Implements Exiv2::BasicIo.

◆ open() [2/2]

int Exiv2::FileIo::open ( const std::string & mode )

Open the file using the specified mode.

This method can also be used to "reopen" a file which will flush any unwritten data and reset the IO position to the start. Although files can be opened in binary or text mode, this class has only been tested carefully in binary mode.

Parameters

mode	Specified that type of access allowed on the file. Valid values match those of the C fopen command exactly.

Returns: 0 if successful;
Nonzero if failure.

Examples: mrwthumb.cpp.

◆ path()

const std::string & Exiv2::FileIo::path ( ) const

overridevirtualnoexcept

Returns the path of the file.

Implements Exiv2::BasicIo.

◆ populateFakeData()

void Exiv2::FileIo::populateFakeData ( )

overridevirtual

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.

Implements Exiv2::BasicIo.

◆ putb()

int Exiv2::FileIo::putb ( byte data )

overridevirtual

Write one byte to the file. The file 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;

Implements Exiv2::BasicIo.

◆ read() [1/2]

size_t Exiv2::FileIo::read	(	byte *	buf,
		size_t	rcount
	)

overridevirtual

Read data from the file. Reading starts at the current file 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 the file successfully;
0 if failure;

Implements Exiv2::BasicIo.

◆ read() [2/2]

DataBuf Exiv2::FileIo::read ( size_t rcount )

overridevirtual

Read data from the file. Reading starts at the current file 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.

Implements Exiv2::BasicIo.

◆ seek()

int Exiv2::FileIo::seek	(	int64_t	offset,
		Position	pos
	)

overridevirtual

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;

Implements Exiv2::BasicIo.

◆ size()

size_t Exiv2::FileIo::size ( ) const

overridevirtual

Flush any buffered writes and get the current file size in bytes.

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

Implements Exiv2::BasicIo.

◆ tell()

size_t Exiv2::FileIo::tell ( ) const

overridevirtual

Get the current file position.

Returns: Offset from the start of the file

Implements Exiv2::BasicIo.

◆ transfer()

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

overridevirtual

Remove the contents of the file and then transfer data from the src BasicIo object into the empty file.

This method is optimized to simply rename the source file if the source object is another FileIo instance. The source BasicIo 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.

Note: If the caller doesn't have permissions to write to the file, an exception is raised and src is deleted.

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

Implements Exiv2::BasicIo.

Reimplemented in Exiv2::XPathIo.

◆ write() [1/2]

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

overridevirtual

Write data that is read from another BasicIo instance to the file. The file 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 the file successfully;
0 if failure;

Implements Exiv2::BasicIo.

◆ write() [2/2]

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

overridevirtual

Write data to the file. The file 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 the file successfully;
0 if failure;

Implements Exiv2::BasicIo.

Examples: mrwthumb.cpp.

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

basicio.hpp

Public Member Functions

Accessors

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ FileIo()

Member Function Documentation

◆ close()

◆ eof()

◆ error()

◆ getb()

◆ isopen()

◆ mmap()

◆ munmap()

◆ open() [1/2]

◆ open() [2/2]

◆ path()

◆ populateFakeData()

◆ putb()

◆ read() [1/2]

◆ read() [2/2]

◆ seek()

◆ size()

◆ tell()

◆ transfer()

◆ write() [1/2]

◆ write() [2/2]