Exiv2::RemoteIo Class Reference

Provides remote binary file IO by implementing the BasicIo interface. This is an abstract class. The logics for remote access are implemented in HttpIo, CurlIo, SshIo which are the derived classes of RemoteIo. More...

#include <basicio.hpp>

Inheritance diagram for Exiv2::RemoteIo:

Classes
class	Impl
	Internal Pimpl abstract structure of class RemoteIo. More...

Public Member Functions
	RemoteIo ()
	Destructor. Releases all managed memory.
	RemoteIo (const RemoteIo &)=delete
RemoteIo &	operator= (const RemoteIo &)=delete
Manipulators
int	open () override
	Connect to the remote server, get the size of the remote file and allocate the array of blocksMap.
int	close () override
	Reset the IO position to the start. It does not release the data.
size_t	write (const byte *data, size_t wcount) override
	Not support this method.
size_t	write (BasicIo &src) override
	Write data that is read from another BasicIo instance to the remote file.
int	putb (byte data) override
	Not support.
DataBuf	read (size_t rcount) override
	Read data from the memory blocks. Reading starts at the current IO position and the position is advanced by the number of bytes read. If the memory blocks are not populated (False), it will connect to server and populate the data to memory blocks.
size_t	read (byte *buf, size_t rcount) override
	Read data from the memory blocks. Reading starts at the current IO position and the position is advanced by the number of bytes read. If the memory blocks are not populated (!= bMemory), it will connect to server and populate the data to memory blocks.
int	getb () override
	Read one byte from the memory blocks. The IO position is advanced by one byte. If the memory block is not populated (!= bMemory), it will connect to server and populate the data to the memory block.
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=false) override
	Not support.
int	munmap () override
	Not support.
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
std::unique_ptr< Impl >	p_
	Pointer to implementation.
size_t	tell () const override
	Get the current IO position.
size_t	size () const override
	Get the current memory buffer size in bytes.
bool	isopen () const override
	Returns true if the memory area is allocated.
int	error () const override
	Always returns 0.
bool	eof () const override
	Returns true if the IO position has reached the end, otherwise false.
const std::string &	path () const noexcept override
	Returns the URL 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)

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 remote binary file IO by implementing the BasicIo interface. This is an abstract class. The logics for remote access are implemented in HttpIo, CurlIo, SshIo which are the derived classes of RemoteIo.

Member Function Documentation

close()

int Exiv2::RemoteIo::close ( )

overridevirtual

Reset the IO position to the start. It does not release the data.

Returns

0 if successful;
Nonzero if failure.

Implements Exiv2::BasicIo.

References Exiv2::BasicIo::bigBlock_, and p_.

Referenced by open().

eof()

bool Exiv2::RemoteIo::eof ( ) const

overridevirtual

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

Implements Exiv2::BasicIo.

References p_.

error()

int Exiv2::RemoteIo::error ( ) const

overridevirtual

Always returns 0.

Implements Exiv2::BasicIo.

getb()

int Exiv2::RemoteIo::getb ( )

overridevirtual

Read one byte from the memory blocks. The IO position is advanced by one byte. If the memory block is not populated (!= bMemory), it will connect to server and populate the data to the memory block.

Returns

The byte read from the memory block if successful;
EOF if failure;

Implements Exiv2::BasicIo.

References p_.

isopen()

bool Exiv2::RemoteIo::isopen ( ) const

overridevirtual

Returns true if the memory area is allocated.

Implements Exiv2::BasicIo.

References p_.

mmap()

byte * Exiv2::RemoteIo::mmap ( bool  = false )

overridevirtual

Not support.

Returns

NULL

Implements Exiv2::BasicIo.

References Exiv2::BasicIo::bigBlock_, and p_.

munmap()

int Exiv2::RemoteIo::munmap ( )

overridevirtual

Not support.

Returns

0

Implements Exiv2::BasicIo.

open()

int Exiv2::RemoteIo::open ( )

overridevirtual

Connect to the remote server, get the size of the remote file and allocate the array of blocksMap.

If the blocksMap is already allocated (this method has been called before), it just reset IO position to the start and does not flush the old data.

Returns

0 if successful;
Nonzero if failure.

Implements Exiv2::BasicIo.

References Exiv2::BasicIo::bigBlock_, close(), and p_.

path()

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

overridevirtualnoexcept

Returns the URL of the file.

Implements Exiv2::BasicIo.

References p_.

populateFakeData()

void Exiv2::RemoteIo::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.

References p_.

putb()

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

overridevirtual

Not support.

Returns

0 means failure

Implements Exiv2::BasicIo.

read() [1/2]

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

overridevirtual

Read data from the memory blocks. Reading starts at the current IO position and the position is advanced by the number of bytes read. If the memory blocks are not populated (!= bMemory), it will connect to server and populate the data to memory blocks.

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 memory block successfully;
0 if failure;

Implements Exiv2::BasicIo.

References p_.

read() [2/2]

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

overridevirtual

Read data from the memory blocks. Reading starts at the current IO position and the position is advanced by the number of bytes read. If the memory blocks are not populated (False), it will connect to server and populate the data to memory blocks.

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.

References Exiv2::DataBuf::data(), read(), and Exiv2::DataBuf::resize().

Referenced by read().

seek()

int Exiv2::RemoteIo::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.

References p_.

size()

size_t Exiv2::RemoteIo::size ( ) const

overridevirtual

Get the current memory buffer size in bytes.

Returns

Size of the in memory data in bytes;
-1 if failure;

Implements Exiv2::BasicIo.

References p_.

tell()

size_t Exiv2::RemoteIo::tell ( ) const

overridevirtual

Get the current IO position.

Returns

Offset from the start of the memory block

Implements Exiv2::BasicIo.

References p_.

transfer()

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

overridevirtual

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

The write access is done in an efficient way. It only sends the range of different bytes between the current data and BasicIo instance to the remote machine.

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

Note

The write access is only supported by http, https, ssh.

Implements Exiv2::BasicIo.

References Exiv2::BasicIo::close(), Exiv2::BasicIo::open(), and write().

write() [1/2]

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

overridevirtual

Write data that is read from another BasicIo instance to the remote file.

The write access is done in an efficient way. It only sends the range of different bytes between the current data and BasicIo instance to the remote machine.

Parameters

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

Returns

The size of BasicIo instance;
0 if failure;

Exceptions

Error

In case of failure

Note

The write access is only supported by http, https, ssh.

Implements Exiv2::BasicIo.

References Exiv2::BasicIo::eof(), Exiv2::BasicIo::isopen(), p_, Exiv2::BasicIo::read(), Exiv2::BasicIo::seek(), and Exiv2::BasicIo::size().

write() [2/2]

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

overridevirtual

Not support this method.

Returns

0 means failure

Implements Exiv2::BasicIo.

Referenced by transfer().

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

• basicio.hpp
• basicio.cpp