GFileIOStream

GFileIOStream — File read and write streaming operations

Synopsis

#include <gio/gio.h>

                    GFileIOStream;
char *              g_file_io_stream_get_etag           (GFileIOStream *stream);
GFileInfo *         g_file_io_stream_query_info         (GFileIOStream *stream,
                                                         const char *attributes,
                                                         GCancellable *cancellable,
                                                         GError **error);
void                g_file_io_stream_query_info_async   (GFileIOStream *stream,
                                                         const char *attributes,
                                                         int io_priority,
                                                         GCancellable *cancellable,
                                                         GAsyncReadyCallback callback,
                                                         gpointer user_data);
GFileInfo *         g_file_io_stream_query_info_finish  (GFileIOStream *stream,
                                                         GAsyncResult *result,
                                                         GError **error);

Object Hierarchy

  GObject
   +----GIOStream
         +----GFileIOStream

Implemented Interfaces

GFileIOStream implements GSeekable.

Description

GFileIOStream provides io streams that both read and write to the same file handle.

GFileIOStream implements GSeekable, which allows the io stream to jump to arbitrary positions in the file and to truncate the file, provided the filesystem of the file supports these operations.

To find the position of a file io stream, use g_seekable_tell().

To find out if a file io stream supports seeking, use g_seekable_can_seek(). To position a file io stream, use g_seekable_seek(). To find out if a file io stream supports truncating, use g_seekable_can_truncate(). To truncate a file io stream, use g_seekable_truncate().

The default implementation of all the GFileIOStream operations and the implementation of GSeekable just call into the same operations on the output stream.

Details

GFileIOStream

typedef struct _GFileIOStream GFileIOStream;

A subclass of GIOStream for opened files. This adds a few file-specific operations and seeking and truncating.

GFileIOStream implements GSeekable.

g_file_io_stream_get_etag ()

char *              g_file_io_stream_get_etag           (GFileIOStream *stream);

Gets the entity tag for the file when it has been written. This must be called after the stream has been written and closed, as the etag can change while writing.

stream :

 a GFileIOStream.

Returns :

 the entity tag for the stream.

Since 2.22

g_file_io_stream_query_info ()

GFileInfo *         g_file_io_stream_query_info         (GFileIOStream *stream,
                                                         const char *attributes,
                                                         GCancellable *cancellable,
                                                         GError **error);

Queries a file io stream for the given attributes. This function blocks while querying the stream. For the asynchronous version of this function, see g_file_io_stream_query_info_async(). While the stream is blocked, the stream will set the pending flag internally, and any other operations on the stream will fail with G_IO_ERROR_PENDING.

Can fail if the stream was already closed (with error being set to G_IO_ERROR_CLOSED), the stream has pending operations (with error being set to G_IO_ERROR_PENDING), or if querying info is not supported for the stream's interface (with error being set to G_IO_ERROR_NOT_SUPPORTED). I all cases of failure, NULL will be returned.

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 set, and NULL will be returned.

stream :

 a GFileIOStream.

attributes :

 a file attribute query string.

cancellable :

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

error :

 a GError, NULL to ignore.

Returns :

 a GFileInfo for the stream, or NULL on error. [transfer full]

Since 2.22

g_file_io_stream_query_info_async ()

void                g_file_io_stream_query_info_async   (GFileIOStream *stream,
                                                         const char *attributes,
                                                         int io_priority,
                                                         GCancellable *cancellable,
                                                         GAsyncReadyCallback callback,
                                                         gpointer user_data);

Asynchronously queries the stream for a GFileInfo. When completed, callback will be called with a GAsyncResult which can be used to finish the operation with g_file_io_stream_query_info_finish().

For the synchronous version of this function, see g_file_io_stream_query_info().

stream :

 a GFileIOStream.

attributes :

 a file attribute query string.

io_priority :

 the I/O priority of the request.

cancellable :

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

callback :

 callback to call when the request is satisfied. [scope async]

user_data :

 the data to pass to callback function. [closure]

Since 2.22

g_file_io_stream_query_info_finish ()

GFileInfo *         g_file_io_stream_query_info_finish  (GFileIOStream *stream,
                                                         GAsyncResult *result,
                                                         GError **error);

Finalizes the asynchronous query started by g_file_io_stream_query_info_async().

stream :

 a GFileIOStream.

result :

 a GAsyncResult.

error :

 a GError, NULL to ignore.

Returns :

 A GFileInfo for the finished query. [transfer full]

Since 2.22

See Also

GIOStream, GFileInputStream, GFileOutputStream, GSeekable
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