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FileStream Class

An extension of the StreamInterface class that enables asynchronous reading and writing from/to a file on disk. This class disables the copy constructor. You must call Open to start reading or writing the file. The methods shown are not thread-safe, and can be called on any thread.

Syntax 

class FileStream : public StreamInterface

Methods

Name Description
void Close() Closes the file. This will not send an SE_CLOSE error, because it is a deliberate action. You can call Open to open another file.
bool DisableBuffering() By default, reading and writing are buffered. Calling this method blocks all write attempts to block until the disk bytes are updated.
FileStream() Constructor.
~FileStream Destructor. Calls Close to close the file, if it has not been explicitly closed already.
bool GetPosition(size_t *position) const Retrieves the current read/write position in the file. Returns True if the call succeeded, False otherwise.
bool GetSize(size_t *size) const Retrieves the size of the file. Returns True if the call succeeded, False otherwise.
StreamState GetState() Returns the current state of the file.
bool Open(const char *filename, const char *mode) Creates or opens the file named filename. Values for mode are the same values supported by stdio::fopen.
bool OpenShare(const std::string& filename, const char* mode, int shflag) Creates or opens the file named filename with the sharing mode specified by shflag.
StreamResult Read(void *buffer, size_t buffer_len, size_t *read, int *error)

Reads a specified number of bytes from the stream. Does not return the number of bytes read if any error occurs.

  • buffer A caller-allocated buffer to hold the data to read.
  • buffer_len The size, in bytes, of buffer.
  • read The number of bytes written to buffer.
  • error Details about any error that occurred. Error values are defined in talk/base/socket.h.
bool Rewind() Resets the current read/write position to the start of the stream. Returns True if successful, False otherwise.
bool SetPosition(size_t position) Tries to move the pointer to the position position in the file. Returns True if successful, False otherwise.
StreamResult Write(const void *data, size_t data_len, size_t *written, int *error)

Writes a specified number of bytes to the stream. Does not return the number of bytes written if any error occurs.

  • data The data to write.
  • data_len The size, in bytes, of data.
  • written The number of bytes written to the stream.
  • error Details about any error that occurred. Error values are defined in talk/base/socket.h

 

Attributes: public

Declaration file: talk/base/stream.h