Reading and Writing Files: GnomeVFS - Filesystem Abstraction library

Reading and Writing Files

Reading and Writing Files — Reading from and writing to open file handles.

Functions

GnomeVFSResult	gnome_vfs_read ()
GnomeVFSResult	gnome_vfs_write ()
GnomeVFSResult	gnome_vfs_seek ()
GnomeVFSResult	gnome_vfs_tell ()
GnomeVFSResult	gnome_vfs_forget_cache ()

Types and Values

enum	GnomeVFSSeekPosition

Description

Reading and writing operations are explained, also gnome_vfs_seek(), which is used to move the file pointer inside the file.

Functions

gnome_vfs_read ()

GnomeVFSResult
gnome_vfs_read (GnomeVFSHandle *handle,
                gpointer buffer,
                GnomeVFSFileSize bytes,
                GnomeVFSFileSize *bytes_read);

Read bytes from handle . As with Unix system calls, the number of bytes read can effectively be less than bytes on return and will be stored in bytes_read .

Parameters

handle	handle of the file to read data from.
buffer	pointer to a buffer that must be at least `bytes` bytes large.
bytes	number of bytes to read.
bytes_read	pointer to a variable that will hold the number of bytes effectively read on return.

Returns

an integer representing the result of the operation.

gnome_vfs_write ()

GnomeVFSResult
gnome_vfs_write (GnomeVFSHandle *handle,
                 gconstpointer buffer,
                 GnomeVFSFileSize bytes,
                 GnomeVFSFileSize *bytes_written);

Write bytes into the file opened through handle . As with Unix system calls, the number of bytes written can effectively be less than bytes on return and will be stored in bytes_written .

Parameters

handle	handle of the file to write data to.
buffer	pointer to the buffer containing the data to be written.
bytes	number of bytes to write.
bytes_written	pointer to a variable that will hold the number of bytes effectively written on return.

Returns

an integer representing the result of the operation.

gnome_vfs_seek ()

GnomeVFSResult
gnome_vfs_seek (GnomeVFSHandle *handle,
                GnomeVFSSeekPosition whence,
                GnomeVFSFileOffset offset);

Set the current position for reading/writing through handle .

Parameters

handle	handle for which the current position must be changed.
whence	integer value representing the starting position.
offset	number of bytes to skip from the position specified by `whence` . (a positive value means to move forward; a negative one to move backwards).

Returns

an integer representing the result of the operation.

gnome_vfs_tell ()

GnomeVFSResult
gnome_vfs_tell (GnomeVFSHandle *handle,
                GnomeVFSFileSize *offset_return);

Return the current position on handle . This is the point in the file pointed to by handle that reads and writes will occur on.

Parameters

handle	handle for which the current position must be retrieved.
offset_return	pointer to a variable that will contain the current position on return.

Returns

an integer representing the result of the operation.

gnome_vfs_forget_cache ()

GnomeVFSResult
gnome_vfs_forget_cache (GnomeVFSHandle *handle,
                        GnomeVFSFileOffset offset,
                        GnomeVFSFileSize size);

With this call you can announce to gnome-vfs that you will no longer use the region of data starting at offset with the size of size . Any cached data for this region might then be freed.

This might be useful if you stream large files, for example.

Parameters

handle	handle of the file to affect.
offset	start point of the region to be freed.
size	length of the region to be freed (or until the end of the file if 0 is specified).

Returns

an integer representing the result of the operation.

Since: 2.12

Types and Values

enum GnomeVFSSeekPosition

This is used to specify the start position for seek operations.

Members

GNOME_VFS_SEEK_START	Start of the file.
GNOME_VFS_SEEK_CURRENT	Current position.
GNOME_VFS_SEEK_END	End of the file.