# Gio::InputStream Class Reference
[Stream Classes]

Base class for implementing streaming input. More...

`#include <giomm/inputstream.h>`

Inheritance diagram for Gio::InputStream:
[legend]

List of all members.

## Public Member Functions

virtual | ~InputStream ()
GInputStream* | gobj ()
| Provides access to the underlying C GObject.
const GInputStream* | gobj () const
| Provides access to the underlying C GObject.
GInputStream* | gobj_copy ()
| Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.
gssize | read (void* buffer, gsize count, const Glib::RefPtr< Cancellable >& cancellable)
| Tries to read count bytes from the stream into the buffer starting at buffer.
gssize | read (void* buffer, gsize count)
| Tries to read count bytes from the stream into the buffer starting at buffer.
bool | read_all (void* buffer, gsize count, gsize& bytes_read, const Glib::RefPtr< Cancellable >& cancellable)
| Tries to read count bytes from the stream into the buffer starting at buffer.
bool | read_all (void* buffer, gsize count, gsize& bytes_read)
| Tries to read count bytes from the stream into the buffer starting at buffer.
gssize | skip (gsize count, const Glib::RefPtr< Cancellable >& cancellable)
| Tries to skip count bytes from the stream.
gssize | skip (gsize count)
| Tries to skip count bytes from the stream.
bool | close (const Glib::RefPtr< Cancellable >& cancellable)
| Closes the stream, releasing resources related to it.
bool | close ()
| Closes the stream, releasing resources related to it.
void | read_async (void* buffer, gsize count, const SlotAsyncReady& slot, const Glib::RefPtr< Cancellable >& cancellable, int io_priority=Glib::PRIORITY_DEFAULT)
| Request an asynchronous read of count bytes from the stream into the buffer starting at buffer.
void | read_async (void* buffer, gsize count, const SlotAsyncReady& slot, int io_priority=Glib::PRIORITY_DEFAULT)
| Request an asynchronous read of count bytes from the stream into the buffer starting at buffer.
gssize | read_finish (const Glib::RefPtr< AsyncResult >& result)
| Finishes an asynchronous stream read operation.
void | skip_async (gsize count, const SlotAsyncReady& slot, const Glib::RefPtr< Cancellable >& cancellable, int io_priority=Glib::PRIORITY_DEFAULT)
| Request an asynchronous skip of count bytes from the stream into the buffer starting at buffer.
void | skip_async (gsize count, const SlotAsyncReady& slot, int io_priority=Glib::PRIORITY_DEFAULT)
| Request an asynchronous skip of count bytes from the stream into the buffer starting at buffer.
gssize | skip_finish (const Glib::RefPtr< AsyncResult >& result)
| Finishes a stream skip operation.
void | close_async (const SlotAsyncReady& slot, const Glib::RefPtr< Cancellable >& cancellable, int io_priority=Glib::PRIORITY_DEFAULT)
| Requests an asynchronous closes of the stream, releasing resources related to it.
void | close_async (const SlotAsyncReady& slot, int io_priority=Glib::PRIORITY_DEFAULT)
| Requests an asynchronous closes of the stream, releasing resources related to it.
gboolean | close_finish (const Glib::RefPtr< AsyncResult >& result)
| Finishes closing a stream asynchronously, started from g_input_stream_close_async().

## Related Functions

(Note that these are not member functions.)
Glib::RefPtr< Gio::InputStream > | wrap (GInputStream* object, bool take_copy=false)
| A Glib::wrap() method for this object.

## Detailed Description

Base class for implementing streaming input.

Since glibmm 2.16:

## Constructor & Destructor Documentation

virtual Gio::InputStream::~InputStream | ( |  | ) | `[virtual]`

## Member Function Documentation

bool Gio::InputStream::close | ( |  | ) |

Closes the stream, releasing resources related to it.

Once the stream is closed, all other operations will throw a Gio::Error with CLOSED. Closing a stream multiple times will not return an error.

Streams will be automatically closed when the last reference is dropped, but you might want to call this make sure resources are released as early as possible.

Some streams might keep the backing store of the stream (e.g. a file descriptor) open after the stream is closed. See the documentation for the individual stream for details.

On failure the first error that happened will be reported, but the close operation will finish as much as possible. A stream that failed to close will still throw a Gio::Error with CLOSED for all operations. Still, it is important to check and report the error to the user.

Returns:
  `true` on success, `false` on failure.

bool Gio::InputStream::close | ( | const Glib::RefPtr< Cancellable >& | cancellable | ) |

Closes the stream, releasing resources related to it.

Once the stream is closed, all other operations will throw a Gio::Error with CLOSED. Closing a stream multiple times will not return an error.

Streams will be automatically closed when the last reference is dropped, but you might want to call this function to make sure resources are released as early as possible.

Some streams might keep the backing store of the stream (e.g. a file descriptor) open after the stream is closed. See the documentation for the individual stream for details.

On failure the first error that happened will be reported, but the close operation will finish as much as possible. A stream that failed to close will still throw a Gio::Error with CLOSED for all operations. Still, it is important to check and report the error to the user.

The operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, a Gio::Error will be thrown with CANCELLED. Cancelling a close will still leave the stream closed, but some streams can use a faster close that doesn't block to e.g. check errors.

Parameters:

  | cancellable | Cancellable object.

Returns:
  `true` on success, `false` on failure.

void Gio::InputStream::close_async | ( | const SlotAsyncReady & | slot,
|  | int | io_priority = `Glib::PRIORITY_DEFAULT` |
| ) |  |  |

Requests an asynchronous closes of the stream, releasing resources related to it.

When the operation is finished slot will be called. You can then call close_finish() to get the result of the operation.

For behaviour details see close().

The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

  | slot | Callback to call when the request is satisfied.
  | io_priority | The I/O priority of the request.

void Gio::InputStream::close_async | ( | const SlotAsyncReady & | slot,
|  | const Glib::RefPtr< Cancellable >& | cancellable,
|  | int | io_priority = `Glib::PRIORITY_DEFAULT` |
| ) |  |  |

Requests an asynchronous closes of the stream, releasing resources related to it.

When the operation is finished slot will be called. You can then call close_finish() to get the result of the operation.

For behaviour details see close().

The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

  | slot | Callback to call when the request is satisfied.
  | cancellable | A Cancellable object.
  | io_priority | The I/O priority of the request.

gboolean Gio::InputStream::close_finish | ( | const Glib::RefPtr< AsyncResult >& | result | ) |

Finishes closing a stream asynchronously, started from g_input_stream_close_async().

Parameters:

  | result | A AsyncResult.

Returns:
  `true` if the stream was closed successfully.

const GInputStream* Gio::InputStream::gobj | ( |  | ) | const`[inline]`

Provides access to the underlying C GObject.

Reimplemented from Glib::ObjectBase.

Reimplemented in Gio::BufferedInputStream, Gio::DataInputStream, Gio::FileInputStream, Gio::FilterInputStream, Gio::MemoryInputStream, and Gio::UnixInputStream.

GInputStream* Gio::InputStream::gobj | ( |  | ) | `[inline]`

Provides access to the underlying C GObject.

Reimplemented from Glib::ObjectBase.

Reimplemented in Gio::BufferedInputStream, Gio::DataInputStream, Gio::FileInputStream, Gio::FilterInputStream, Gio::MemoryInputStream, and Gio::UnixInputStream.

GInputStream* Gio::InputStream::gobj_copy | ( |  | ) |

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

Reimplemented in Gio::BufferedInputStream, Gio::DataInputStream, Gio::FileInputStream, Gio::FilterInputStream, Gio::MemoryInputStream, and Gio::UnixInputStream.

gssize Gio::InputStream::read | ( | void * | buffer,
|  | gsize | count |
| ) |  |  |

Tries to read count bytes from the stream into the buffer starting at buffer.

Will block during this read.

If count is zero returns zero and does nothing. A value of count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.

On success, the number of bytes read into the buffer is returned. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file. Zero is returned on end of file (or if count is zero), but never otherwise.

On error -1 is returned.

Parameters:

  | buffer | A buffer to read data into (which should be at least count bytes long).
  | count | The number of bytes that will be read from the stream.

Returns:
  Number of bytes read, or -1 on error.

gssize Gio::InputStream::read | ( | void * | buffer,
|  | gsize | count,
|  | const Glib::RefPtr< Cancellable >& | cancellable |
| ) |  |  |

Tries to read count bytes from the stream into the buffer starting at buffer.

Will block during this read.

If count is zero returns zero and does nothing. A value of count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.

On success, the number of bytes read into the buffer is returned. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file. Zero is returned on end of file (or if count is zero), but never otherwise.

The operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, a Gio::Error will be thrown with CANCELLED. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

Parameters:

  | buffer | A buffer to read data into (which should be at least count bytes long).
  | count | The number of bytes that will be read from the stream.
  | cancellable | Cancellable object.

Returns:
  Number of bytes read, or -1 on error.

bool Gio::InputStream::read_all | ( | void * | buffer,
|  | gsize | count,
|  | gsize & | bytes_read |
| ) |  |  |

Tries to read count bytes from the stream into the buffer starting at buffer.

Will block during this read.

This function is similar to read(), except it tries to read as many bytes as requested, only stopping on an error or end of stream.

On a successful read of count bytes, or if we reached the end of the stream, `true` is returned, and bytes_read is set to the number of bytes read into buffer .

If there is an error during the operation `false` is returned and a Gio::Error is thrown to indicate the error status, bytes_read is updated to contain the number of bytes read into buffer before the error occured.

Parameters:

  | buffer | A buffer to read data into (which should be at least count bytes long).
  | count | The number of bytes that will be read from the stream.
  | bytes_read | Location to store the number of bytes that was read from the stream.

Returns:
  `true` on success, `false` if there was an error.

bool Gio::InputStream::read_all | ( | void * | buffer,
|  | gsize | count,
|  | gsize & | bytes_read,
|  | const Glib::RefPtr< Cancellable >& | cancellable |
| ) |  |  |

Tries to read count bytes from the stream into the buffer starting at buffer.

Will block during this read.

This function is similar to g_input_stream_read(), except it tries to read as many bytes as requested, only stopping on an error or end of stream.

On a successful read of count bytes, or if we reached the end of the stream, `true` is returned, and bytes_read is set to the number of bytes read into buffer.

If there is an error during the operation `false` is returned and error is set to indicate the error status, bytes_read is updated to contain the number of bytes read into buffer before the error occurred.

Parameters:

  | buffer | A buffer to read data into (which should be at least count bytes long).
  | count | The number of bytes that will be read from the stream.
  | bytes_read | Location to store the number of bytes that was read from the stream.
  | cancellable | Optional Cancellable object, `0` to ignore.

Returns:
  `true` on success, `false` if there was an error.

void Gio::InputStream::read_async | ( | void * | buffer,
|  | gsize | count,
|  | const SlotAsyncReady & | slot,
|  | int | io_priority = `Glib::PRIORITY_DEFAULT` |
| ) |  |  |

Request an asynchronous read of count bytes from the stream into the buffer starting at buffer.

When the operation is finished slot will be called. You can then call read_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed, and will result in a Gio::Error with PENDING being thrown.

A value of count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.

On success, the number of bytes read into the buffer will be passed to the slot callback. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file, but generally we try to read as many bytes as requested. Zero is returned on end of file (or if count is zero), but never otherwise.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is PRIORITY_DEFAULT.

The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

  | buffer | A buffer to read data into (which should be at least count bytes long).
  | count | The number of bytes that will be read from the stream.
  | slot | Callback to call when the request is satisfied.
  | io_priority | The I/O priority of the request.

void Gio::InputStream::read_async | ( | void * | buffer,
|  | gsize | count,
|  | const SlotAsyncReady & | slot,
|  | const Glib::RefPtr< Cancellable >& | cancellable,
|  | int | io_priority = `Glib::PRIORITY_DEFAULT` |
| ) |  |  |

Request an asynchronous read of count bytes from the stream into the buffer starting at buffer.

When the operation is finished slot will be called. You can then call read_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed, and will result in Gio::Error with PENDING being thrown.

A value of count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.

On success, the number of bytes read into the buffer will be passed to the slot callback. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file, but generally we try to read as many bytes as requested. Zero is returned on end of file (or if count is zero), but never otherwise.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is PRIORITY_DEFAULT.

The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

  | buffer | A buffer to read data into (which should be at least count bytes long).
  | count | The number of bytes that will be read from the stream.
  | slot | Callback to call when the request is satisfied.
  | cancellable | A Cancellable object.
  | io_priority | The I/O priority of the request.

gssize Gio::InputStream::read_finish | ( | const Glib::RefPtr< AsyncResult >& | result | ) |

Finishes an asynchronous stream read operation.

Parameters:

  | result | A AsyncResult.

Returns:
  Number of bytes read in, or -1 on error.

gssize Gio::InputStream::skip | ( | gsize | count | ) |

Tries to skip count bytes from the stream.

Will block during the operation.

This is identical to read(), from a behaviour standpoint, but the bytes that are skipped are not returned to the user. Some streams have an implementation that is more efficient than reading the data.

This function is optional for inherited classes, as the default implementation emulates it using read.

Parameters:

  | count | The number of bytes that will be skipped from the stream.

Returns:
  Number of bytes skipped, or -1 on error.

gssize Gio::InputStream::skip | ( | gsize | count,
|  | const Glib::RefPtr< Cancellable >& | cancellable |
| ) |  |  |

Tries to skip count bytes from the stream.

Will block during the operation.

This is identical to g_input_stream_read(), from a behaviour standpoint, but the bytes that are skipped are not returned to the user. Some streams have an implementation that is more efficient than reading the data.

This function is optional for inherited classes, as the default implementation emulates it using read.

The operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, a Gio::Error will be thrown with CANCELLED. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

Parameters:

  | count | The number of bytes that will be skipped from the stream.
  | cancellable | Cancellable object.

Returns:
  Number of bytes skipped, or -1 on error.

void Gio::InputStream::skip_async | ( | gsize | count,
|  | const SlotAsyncReady & | slot,
|  | int | io_priority = `Glib::PRIORITY_DEFAULT` |
| ) |  |  |

Request an asynchronous skip of count bytes from the stream into the buffer starting at buffer.

When the operation is finished slot will be called. You can then call skip_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed, and will result in Gio::Error with PENDING being thrown.

A value of count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.

On success, the number of bytes skipped will be passed to the callback. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file, but generally we try to skip as many bytes as requested. Zero is returned on end of file (or if count is zero), but never otherwise.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is PRIORITY_DEFAULT.

The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

  | count | The number of bytes that will be skipped from the stream.
  | slot | Callback to call when the request is satisfied.
  | io_priority | The I/O priority of the request.

void Gio::InputStream::skip_async | ( | gsize | count,
|  | const SlotAsyncReady & | slot,
|  | const Glib::RefPtr< Cancellable >& | cancellable,
|  | int | io_priority = `Glib::PRIORITY_DEFAULT` |
| ) |  |  |

Request an asynchronous skip of count bytes from the stream into the buffer starting at buffer.

When the operation is finished slot will be called. You can then call skip_finish() to get the result of the operation.

During an async request no other sync and async calls are allowed, and will result in Gio::Error with PENDING being thrown.

A value of count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.

On success, the number of bytes skipped will be passed to the callback. It is not an error if this is not the same as the requested size, as it can happen e.g. near the end of a file, but generally we try to skip as many bytes as requested. Zero is returned on end of file (or if count is zero), but never otherwise.

Any outstanding i/o request with higher priority (lower numerical value) will be executed before an outstanding request with lower priority. Default priority is PRIORITY_DEFAULT.

The asyncronous methods have a default fallback that uses threads to implement asynchronicity, so they are optional for inheriting classes. However, if you override one you must override all.

Parameters:

  | count | The number of bytes that will be skipped from the stream.
  | slot | Callback to call when the request is satisfied.
  | cancellable | A Cancellable object.
  | io_priority | The I/O priority of the request.

gssize Gio::InputStream::skip_finish | ( | const Glib::RefPtr< AsyncResult >& | result | ) |

Finishes a stream skip operation.

Parameters:

  | result | A AsyncResult.

Returns:
  The size of the bytes skipped, or -1 on error.

## Friends And Related Function Documentation

Glib::RefPtr< Gio::InputStream > wrap | ( | GInputStream * | object,
|  | bool | take_copy = `false` |
| ) |  |  | `[related]`

A Glib::wrap() method for this object.

Parameters:

  | object | The C instance.
  | take_copy | False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns:
  A C++ instance that wraps this C instance.