## GBufferedInputStream

GBufferedInputStream — Buffered Input Stream

## Synopsis

    #include <gio/gio.h>

                        GBufferedInputStream;
    GInputStream*       g_buffered_input_stream_new         (GInputStream *base_stream);
    GInputStream*       g_buffered_input_stream_new_sized   (GInputStream *base_stream,
                                                             gsize size);
    gsize               g_buffered_input_stream_get_buffer_size
                                                            (GBufferedInputStream *stream);
    void                g_buffered_input_stream_set_buffer_size
                                                            (GBufferedInputStream *stream,
                                                             gsize size);
    gsize               g_buffered_input_stream_get_available
                                                            (GBufferedInputStream *stream);
    const void*         g_buffered_input_stream_peek_buffer (GBufferedInputStream *stream,
                                                             gsize *count);
    gsize               g_buffered_input_stream_peek        (GBufferedInputStream *stream,
                                                             void *buffer,
                                                             gsize offset,
                                                             gsize count);
    gssize              g_buffered_input_stream_fill        (GBufferedInputStream *stream,
                                                             gssize count,
                                                             GCancellable *cancellable,
                                                             GError **error);
    void                g_buffered_input_stream_fill_async  (GBufferedInputStream *stream,
                                                             gssize count,
                                                             int io_priority,
                                                             GCancellable *cancellable,
                                                             GAsyncReadyCallback callback,
                                                             gpointer user_data);
    gssize              g_buffered_input_stream_fill_finish (GBufferedInputStream *stream,
                                                             GAsyncResult *result,
                                                             GError **error);
    int                 g_buffered_input_stream_read_byte   (GBufferedInputStream *stream,
                                                             GCancellable *cancellable,
                                                             GError **error);

## Object Hierarchy

      GObject
       +----GInputStream
             +----GFilterInputStream
                   +----GBufferedInputStream
                         +----GDataInputStream

## Properties

      "buffer-size"              guint                 : Read / Write / Construct

## Description

Buffered input stream implements GFilterInputStream and provides for buffered reads.

By default, GBufferedInputStream's buffer size is set at 4 kilobytes.

To create a buffered input stream, use `g_buffered_input_stream_new()`, or `g_buffered_input_stream_new_sized()` to specify the buffer's size at construction.

To get the size of a buffer within a buffered input stream, use `g_buffered_input_stream_get_buffer_size()`. To change the size of a buffered input stream's buffer, use `g_buffered_input_stream_set_buffer_size()`. Note that the buffer's size cannot be reduced below the size of the data within the buffer.

## Details

### GBufferedInputStream

    typedef struct _GBufferedInputStream GBufferedInputStream;

Implements GFilterInputStream with a sized input buffer.

### g_buffered_input_stream_new ()

    GInputStream*       g_buffered_input_stream_new         (GInputStream *base_stream);

Creates a new GInputStream from the given `base_stream`, with a buffer set to the default size (4 kilobytes).

`base_stream` : | a GInputStream
Returns : | a GInputStream for the given `base_stream`.

### g_buffered_input_stream_new_sized ()

    GInputStream*       g_buffered_input_stream_new_sized   (GInputStream *base_stream,
                                                             gsize size);

Creates a new GBufferedInputStream from the given `base_stream`, with a buffer set to `size`.

`base_stream` : | a GInputStream
`size` : | a gsize
Returns : | a GInputStream.

### g_buffered_input_stream_get_buffer_size ()

    gsize               g_buffered_input_stream_get_buffer_size
                                                            (GBufferedInputStream *stream);

Gets the size of the input buffer.

`stream` : | a GBufferedInputStream
Returns : | the current buffer size.

### g_buffered_input_stream_set_buffer_size ()

    void                g_buffered_input_stream_set_buffer_size
                                                            (GBufferedInputStream *stream,
                                                             gsize size);

Sets the size of the internal buffer of `stream` to `size`, or to the size of the contents of the buffer. The buffer can never be resized smaller than its current contents.

`stream` : | a GBufferedInputStream
`size` : | a gsize

### g_buffered_input_stream_get_available ()

    gsize               g_buffered_input_stream_get_available
                                                            (GBufferedInputStream *stream);

Gets the size of the available data within the stream.

`stream` : | GBufferedInputStream
Returns : | size of the available stream.

### g_buffered_input_stream_peek_buffer ()

    const void*         g_buffered_input_stream_peek_buffer (GBufferedInputStream *stream,
                                                             gsize *count);

Returns the buffer with the currently available bytes. The returned buffer must not be modified and will become invalid when reading from the stream or filling the buffer.

`stream` : | a GBufferedInputStream
`count` : | a gsize to get the number of bytes available in the buffer
Returns : | read-only buffer

### g_buffered_input_stream_peek ()

    gsize               g_buffered_input_stream_peek        (GBufferedInputStream *stream,
                                                             void *buffer,
                                                             gsize offset,
                                                             gsize count);

Peeks in the buffer, copying data of size `count` into `buffer`, offset `offset` bytes.

`stream` : | a GBufferedInputStream
`buffer` : | a pointer to an allocated chunk of memory
`offset` : | a gsize
`count` : | a gsize
Returns : | a gsize of the number of bytes peeked, or -1 on error.

### g_buffered_input_stream_fill ()

    gssize              g_buffered_input_stream_fill        (GBufferedInputStream *stream,
                                                             gssize count,
                                                             GCancellable *cancellable,
                                                             GError **error);

Tries to read `count` bytes from the stream into the buffer. Will block during this read.

If `count` is zero, returns zero and does nothing. A value of `count` larger than `G_MAXSSIZE` will cause a `G_IO_ERROR_INVALID_ARGUMENT` error.

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.

If `count` is -1 then the attempted read size is equal to the number of bytes that are required to fill the buffer.

If `cancellable` is not `NULL`, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error `G_IO_ERROR_CANCELLED` will be returned. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

On error -1 is returned and `error` is set accordingly.

For the asynchronous, non-blocking, version of this function, see `g_buffered_input_stream_fill_async()`.

`stream` : | a GBufferedInputStream
`count` : | the number of bytes that will be read from the stream
`cancellable` : | optional GCancellable object, `NULL` to ignore
`error` : | location to store the error occuring, or `NULL` to ignore
Returns : | the number of bytes read into `stream`'s buffer, up to `count`, or -1 on error.

### g_buffered_input_stream_fill_async ()

    void                g_buffered_input_stream_fill_async  (GBufferedInputStream *stream,
                                                             gssize count,
                                                             int io_priority,
                                                             GCancellable *cancellable,
                                                             GAsyncReadyCallback callback,
                                                             gpointer user_data);

Reads data into `stream`'s buffer asynchronously, up to `count` size. `io_priority` can be used to prioritize reads. For the synchronous version of this function, see `g_buffered_input_stream_fill()`.

If `count` is -1 then the attempted read size is equal to the number of bytes that are required to fill the buffer.

`stream` : | a GBufferedInputStream
`count` : | the number of bytes that will be read from the stream
`io_priority` : | the I/O priority of the request
`cancellable` : | optional GCancellable object
`callback` : | a GAsyncReadyCallback
`user_data` : | a gpointer

### g_buffered_input_stream_fill_finish ()

    gssize              g_buffered_input_stream_fill_finish (GBufferedInputStream *stream,
                                                             GAsyncResult *result,
                                                             GError **error);

Finishes an asynchronous read.

`stream` : | a GBufferedInputStream
`result` : | a GAsyncResult
`error` : | a GError
Returns : | a gssize of the read stream, or `-1` on an error.

### g_buffered_input_stream_read_byte ()

    int                 g_buffered_input_stream_read_byte   (GBufferedInputStream *stream,
                                                             GCancellable *cancellable,
                                                             GError **error);

Tries to read a single byte from the stream or the buffer. Will block during this read.

On success, the byte read from the stream is returned. On end of stream -1 is returned but it's not an exceptional error and `error` is not set.

If `cancellable` is not `NULL`, then the operation can be cancelled by triggering the cancellable object from another thread. If the operation was cancelled, the error `G_IO_ERROR_CANCELLED` will be returned. If an operation was partially finished when the operation was cancelled the partial result will be returned, without an error.

On error -1 is returned and `error` is set accordingly.

`stream` : | a GBufferedInputStream
`cancellable` : | optional GCancellable object, `NULL` to ignore
`error` : | location to store the error occuring, or `NULL` to ignore
Returns : | the byte read from the `stream`, or -1 on end of stream or error.

## Property Details

### The `"buffer-size"` property

      "buffer-size"              guint                 : Read / Write / Construct

The size of the backend buffer.

Allowed values: >= 1

Default value: 4096

## See Also

GFilterInputStream, GInputStream