GSeekable

GSeekable — Stream seeking interface

Synopsis

#include <gio/gio.h>

                    GSeekable;
struct              GSeekableIface;
goffset             g_seekable_tell                     (GSeekable *seekable);
gboolean            g_seekable_can_seek                 (GSeekable *seekable);
gboolean            g_seekable_seek                     (GSeekable *seekable,
                                                         goffset offset,
                                                         GSeekType type,
                                                         GCancellable *cancellable,
                                                         GError **error);
gboolean            g_seekable_can_truncate             (GSeekable *seekable);
gboolean            g_seekable_truncate                 (GSeekable *seekable,
                                                         goffset offset,
                                                         GCancellable *cancellable,
                                                         GError **error);

Object Hierarchy

  GInterface
   +----GSeekable

Prerequisites

GSeekable requires GObject.

Known Implementations

GSeekable is implemented by GFileIOStream, GFileInputStream, GFileOutputStream, GMemoryInputStream and GMemoryOutputStream.

Description

GSeekable is implemented by streams (implementations of GInputStream or GOutputStream) that support seeking.

Details

GSeekable

typedef struct _GSeekable GSeekable;

Seek object for streaming operations.

struct GSeekableIface

struct GSeekableIface {
  GTypeInterface g_iface;

  /* Virtual Table */

  goffset     (* tell)	         (GSeekable    *seekable);

  gboolean    (* can_seek)       (GSeekable    *seekable);
  gboolean    (* seek)	         (GSeekable    *seekable,
				  goffset       offset,
				  GSeekType     type,
				  GCancellable *cancellable,
				  GError      **error);

  gboolean    (* can_truncate)   (GSeekable    *seekable);
  gboolean    (* truncate_fn)    (GSeekable    *seekable,
				  goffset       offset,
				  GCancellable *cancellable,
				  GError       **error);

  /* TODO: Async seek/truncate */
};

Provides an interface for implementing seekable functionality on I/O Streams.

GTypeInterface g_iface;

 The parent interface.

tell ()

 Tells the current location within a stream.

can_seek ()

 Checks if seeking is supported by the stream.

seek ()

 Seeks to a location within a stream.

can_truncate ()

 Chekcs if truncation is suppored by the stream.

truncate_fn ()

 Truncates a stream.

g_seekable_tell ()

goffset             g_seekable_tell                     (GSeekable *seekable);

Tells the current position within the stream.

seekable :

 a GSeekable.

Returns :

 the offset from the beginning of the buffer.

g_seekable_can_seek ()

gboolean            g_seekable_can_seek                 (GSeekable *seekable);

Tests if the stream supports the GSeekableIface.

seekable :

 a GSeekable.

Returns :

 TRUE if seekable can be seeked. FALSE otherwise.

g_seekable_seek ()

gboolean            g_seekable_seek                     (GSeekable *seekable,
                                                         goffset offset,
                                                         GSeekType type,
                                                         GCancellable *cancellable,
                                                         GError **error);

Seeks in the stream by the given offset, modified by type.

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.

seekable :

 a GSeekable.

offset :

 a goffset.

type :

 a GSeekType.

cancellable :

 optional GCancellable object, NULL to ignore. [allow-none]

error :

 a GError location to store the error occuring, or NULL to ignore.

Returns :

 TRUE if successful. If an error has occurred, this function will return FALSE and set error appropriately if present.

g_seekable_can_truncate ()

gboolean            g_seekable_can_truncate             (GSeekable *seekable);

Tests if the stream can be truncated.

seekable :

 a GSeekable.

Returns :

 TRUE if the stream can be truncated, FALSE otherwise.

g_seekable_truncate ()

gboolean            g_seekable_truncate                 (GSeekable *seekable,
                                                         goffset offset,
                                                         GCancellable *cancellable,
                                                         GError **error);

Truncates a stream with a given offset.

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.

Virtual: truncate_fn

seekable :

 a GSeekable.

offset :

 a goffset.

cancellable :

 optional GCancellable object, NULL to ignore. [allow-none]

error :

 a GError location to store the error occuring, or NULL to ignore.

Returns :

 TRUE if successful. If an error has occurred, this function will return FALSE and set error appropriately if present.

See Also

GInputStream, GOutputStream
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