File Transfers

## File Transfers File Transfers — Conveniently copy/move/delete files en masse |

## Synopsis

    enum                GnomeVFSXferOptions;
    enum                GnomeVFSXferProgressStatus;
    enum                GnomeVFSXferOverwriteMode;
    enum                GnomeVFSXferOverwriteAction;
    enum                GnomeVFSXferErrorMode;
    enum                GnomeVFSXferErrorAction;
    enum                GnomeVFSXferPhase;
                        GnomeVFSXferProgressInfo;
    gint                (*GnomeVFSXferProgressCallback)     (GnomeVFSXferProgressInfo *info,
                                                             gpointer user_data);
    GnomeVFSResult      gnome_vfs_xfer_uri_list             (const GList *source_uri_list,
                                                             const GList *target_uri_list,
                                                             GnomeVFSXferOptions xfer_options,
                                                             GnomeVFSXferErrorMode error_mode,
                                                             GnomeVFSXferOverwriteMode overwrite_mode,
                                                             GnomeVFSXferProgressCallback progress_callback,
                                                             gpointer data);
    GnomeVFSResult      gnome_vfs_xfer_uri                  (const GnomeVFSURI *source_uri,
                                                             const GnomeVFSURI *target_uri,
                                                             GnomeVFSXferOptions xfer_options,
                                                             GnomeVFSXferErrorMode error_mode,
                                                             GnomeVFSXferOverwriteMode overwrite_mode,
                                                             GnomeVFSXferProgressCallback progress_callback,
                                                             gpointer data);
    GnomeVFSResult      gnome_vfs_xfer_delete_list          (const GList *source_uri_list,
                                                             GnomeVFSXferErrorMode error_mode,
                                                             GnomeVFSXferOptions xfer_options,
                                                             GnomeVFSXferProgressCallback progress_callback,
                                                             gpointer data);

## Description

## Details

### enum GnomeVFSXferOptions

    typedef enum {
    	GNOME_VFS_XFER_DEFAULT = 0,
    	GNOME_VFS_XFER_UNUSED_1 = 1 << 0,
    	GNOME_VFS_XFER_FOLLOW_LINKS = 1 << 1,
    	GNOME_VFS_XFER_UNUSED_2 = 1 << 2,
    	GNOME_VFS_XFER_RECURSIVE = 1 << 3,
    	GNOME_VFS_XFER_SAMEFS = 1 << 4,
    	GNOME_VFS_XFER_DELETE_ITEMS = 1 << 5,
    	GNOME_VFS_XFER_EMPTY_DIRECTORIES = 1 << 6,
    	GNOME_VFS_XFER_NEW_UNIQUE_DIRECTORY = 1 << 7,
    	GNOME_VFS_XFER_REMOVESOURCE = 1 << 8,
    	GNOME_VFS_XFER_USE_UNIQUE_NAMES = 1 << 9,
    	GNOME_VFS_XFER_LINK_ITEMS = 1 << 10,
    	GNOME_VFS_XFER_FOLLOW_LINKS_RECURSIVE = 1 << 11,
    	GNOME_VFS_XFER_TARGET_DEFAULT_PERMS = 1 << 12
    } GnomeVFSXferOptions;

These options control the way `gnome_vfs_xfer_uri()`, `gnome_vfs_xfer_uri_list()`, `gnome_vfs_xfer_delete_list()` and `gnome_vfs_async_xfer()` work.

At a first glance the GnomeVFSXferOptions semantics are not very intuitive.

There are two types of GnomeVFSXferOptions: Those that define an operation, i.e. describe what to do, and those that influence how to execute the operation.

Table 1. Operation Selection

GnomeVFSXferOptions entry | Operation | UNIX equivalent | Comments
--- | --- | --- | ---
GNOME_VFS_XFER_DEFAULT | Copy | `cp`
GNOME_VFS_XFER_REMOVESOURCE | Move | `mv`
GNOME_VFS_XFER_LINK_ITEMS | Link | `ln -s`
GNOME_VFS_XFER_NEW_UNIQUE_DIRECTORY | Make Unique Directory | `mkdir` | implies GNOME_VFS_XFER_USE_UNIQUE_NAMES
GNOME_VFS_XFER_DELETE_ITEMS | Remove | `rm -r`
GNOME_VFS_XFER_EMPTY_DIRECTORIES | Remove Directory Contents | foreach file: `( cd file && rm -rf * )` | used to empty trash

### Note

Because GNOME_VFS_XFER_DEFAULT maps to `0`, it will always be present. Thus, not explicitly specifying any operation at all, or just specifying GNOME_VFS_XFER_DEFAULT will both execute a copy.

If an operation other than GNOME_VFS_XFER_DEFAULT is specified, it will override the copy operation, but you may only specify one of the other operations at a time.

This unintuitive operation selection unfortunately poses an API weakness and an obstacle in client development, and will be modified in a later revision of this API.

`GNOME_VFS_XFER_DEFAULT` | Default behavior, which is to do a straight one to one copy.
`GNOME_VFS_XFER_UNUSED_1` | Unused.
`GNOME_VFS_XFER_FOLLOW_LINKS` | Follow symbolic links when copying or moving, i.e. the target of symbolic links are copied rather than the symbolic links themselves. Note that this just refers to top-level items. If you also want to follow symbolic links inside directories you operate on, you also have to specify GNOME_VFS_XFER_FOLLOW_LINKS_RECURSIVE.
`GNOME_VFS_XFER_UNUSED_2` | Unused.
`GNOME_VFS_XFER_RECURSIVE` | Recursively copy source directories to the target. Equivalent to the cp -r option in GNU cp.
`GNOME_VFS_XFER_SAMEFS` | When copying recursively, this only picks up items on the same file system the same filesystem as their parent directory.
`GNOME_VFS_XFER_DELETE_ITEMS` | This is equivalent to an `rmdir()` for source directories, and an `unlink()` operation for all source files. Requires `NULL` target URIs.
`GNOME_VFS_XFER_EMPTY_DIRECTORIES` | Remove the whole contents of the passed-in source directories. Requires `NULL` target URIs.
`GNOME_VFS_XFER_NEW_UNIQUE_DIRECTORY` | This will create a directory if it doesn't exist in the destination area (i.e. `mkdir()`).
`GNOME_VFS_XFER_REMOVESOURCE` | This makes a copy operation equivalent to a mv, i.e. the files will be moved rather than copied. If applicable, this will use `rename()`, otherwise (i.e. across file systems), it will fall back to a copy operation followed by a source file deletion.
`GNOME_VFS_XFER_USE_UNIQUE_NAMES` | When this option is present, and a name collisions on the target occurs, the progress callback will be asked for a new name, until the newly provided name doesn't conflict or the request callback transfer cancellation.
`GNOME_VFS_XFER_LINK_ITEMS` | Executes a symlink operation for each of the source/target URI pairs, i.e. similar to GNU ln -s source target. NB: The symlink target has to be specified as source URI, and the symlink itself as target URI.
`GNOME_VFS_XFER_FOLLOW_LINKS_RECURSIVE` | This means that when doing a copy operation, symbolic links in subdirectories are dereferenced. This is typically used together with GNOME_VFS_XFER_FOLLOW_LINKS_RECURSIVE.
`GNOME_VFS_XFER_TARGET_DEFAULT_PERMS` | This means that the target file will not have the same permissions as the source file, but will instead have the default permissions of the destination location. This is useful when copying from read-only locations (CDs).

### enum GnomeVFSXferProgressStatus

    typedef enum {
    	GNOME_VFS_XFER_PROGRESS_STATUS_OK = 0,
    	GNOME_VFS_XFER_PROGRESS_STATUS_VFSERROR = 1,
    	GNOME_VFS_XFER_PROGRESS_STATUS_OVERWRITE = 2,
    	GNOME_VFS_XFER_PROGRESS_STATUS_DUPLICATE = 3
    } GnomeVFSXferProgressStatus;

The difference between GNOME_VFS_XFER_PROGRESS_STATUS_OVERWRITE and GNOME_VFS_XFER_PROGRESS_STATUS_DUPLICATE is that they will be issued at different occassions, and that the return value will be interpreted differently. For details, see GnomeVFSXferProgressCallback.

`GNOME_VFS_XFER_PROGRESS_STATUS_OK` | The file transfer is progressing normally.
`GNOME_VFS_XFER_PROGRESS_STATUS_VFSERROR` | A VFS error was detected.
`GNOME_VFS_XFER_PROGRESS_STATUS_OVERWRITE` | The current target file specified by the GnomeVFSXferProgressInfo's `target_name` field already exists.
`GNOME_VFS_XFER_PROGRESS_STATUS_DUPLICATE` | The current target file specified by the GnomeVFSXferProgressInfo's `target_name` field already exists, and the progress callback is asked to supply a new unique name.

### enum GnomeVFSXferOverwriteMode

    typedef enum {
    	GNOME_VFS_XFER_OVERWRITE_MODE_ABORT = 0,
    	GNOME_VFS_XFER_OVERWRITE_MODE_QUERY = 1,
    	GNOME_VFS_XFER_OVERWRITE_MODE_REPLACE = 2,
    	GNOME_VFS_XFER_OVERWRITE_MODE_SKIP = 3
    } GnomeVFSXferOverwriteMode;

This is passed to `gnome_vfs_xfer_uri()`, `gnome_vfs_xfer_uri_list()`, `gnome_vfs_xfer_delete_list()` and `gnome_vfs_async_xfer()` and specifies what action should be taken when a target file already exists.

`GNOME_VFS_XFER_OVERWRITE_MODE_ABORT` | Abort the transfer when a target file already exists, returning the error GNOME_VFS_ERROR_FILEEXISTS.
`GNOME_VFS_XFER_OVERWRITE_MODE_QUERY` | Query the progress callback with the GnomeVFSXferProgressInfo's status field set to GNOME_VFS_XFER_PROGRESS_STATUS_VFSERROR when a target file already exists.
`GNOME_VFS_XFER_OVERWRITE_MODE_REPLACE` | Replace existing target files silently. Don't worry be happy.
`GNOME_VFS_XFER_OVERWRITE_MODE_SKIP` | Skip source files when its target already exists.

### enum GnomeVFSXferOverwriteAction

    typedef enum {
    	GNOME_VFS_XFER_OVERWRITE_ACTION_ABORT = 0,
    	GNOME_VFS_XFER_OVERWRITE_ACTION_REPLACE = 1,
    	GNOME_VFS_XFER_OVERWRITE_ACTION_REPLACE_ALL = 2,
    	GNOME_VFS_XFER_OVERWRITE_ACTION_SKIP = 3,
    	GNOME_VFS_XFER_OVERWRITE_ACTION_SKIP_ALL = 4
    } GnomeVFSXferOverwriteAction;

This defines the actions to perform before a file is being overwritten (i.e., these are the answers that can be given to a replace query).

`GNOME_VFS_XFER_OVERWRITE_ACTION_ABORT` | abort the transfer
`GNOME_VFS_XFER_OVERWRITE_ACTION_REPLACE` | replace the existing file
`GNOME_VFS_XFER_OVERWRITE_ACTION_REPLACE_ALL` | replace the existing file, and all future files without prompting the callback.
`GNOME_VFS_XFER_OVERWRITE_ACTION_SKIP` | don't copy over the existing file
`GNOME_VFS_XFER_OVERWRITE_ACTION_SKIP_ALL` | don't copy over the existing file, and all future files without prompting the callback.

### enum GnomeVFSXferErrorMode

    typedef enum {
    	GNOME_VFS_XFER_ERROR_MODE_ABORT = 0,
    	GNOME_VFS_XFER_ERROR_MODE_QUERY = 1
    } GnomeVFSXferErrorMode;

This is passed to `gnome_vfs_xfer_uri()`, `gnome_vfs_xfer_uri_list()`, `gnome_vfs_xfer_delete_list()` and `gnome_vfs_async_xfer()` and specifies what action should be taken when transfer errors are detected.

The progress callback is either a GnomeVFSXferProgressCallback for synchronous Xfer operations, or a GnomeVFSAsyncXferProgressCallback for asynchronous operations.

`GNOME_VFS_XFER_ERROR_MODE_ABORT` | abort the transfer when an error occurs
`GNOME_VFS_XFER_ERROR_MODE_QUERY` | query the progress callback with the GnomeVFSXferProgressInfo's status field set to GNOME_VFS_XFER_PROGRESS_STATUS_VFSERROR.

### enum GnomeVFSXferErrorAction

    typedef enum {
    	GNOME_VFS_XFER_ERROR_ACTION_ABORT = 0,
    	GNOME_VFS_XFER_ERROR_ACTION_RETRY = 1,
    	GNOME_VFS_XFER_ERROR_ACTION_SKIP = 2
    } GnomeVFSXferErrorAction;

This defines the possible actions to be performed after a VFS error has occurred, i.e. when a GnomeVFS file operation issued during the transfer returned a result that is not equal to GNOME_VFS_OK.

It is returned by the progress callback which is either a GnomeVFSXferProgressCallback for synchronous Xfer operations, or a GnomeVFSAsyncXferProgressCallback for asynchronous operations.

`GNOME_VFS_XFER_ERROR_ACTION_ABORT` | interrupt Xfer and return `GNOME_VFS_ERROR_INTERRUPTED`.
`GNOME_VFS_XFER_ERROR_ACTION_RETRY` | retry the failed operation.
`GNOME_VFS_XFER_ERROR_ACTION_SKIP` | skip the failed operation, and continue Xfer normally.

### enum GnomeVFSXferPhase

    typedef enum {
    	GNOME_VFS_XFER_PHASE_INITIAL,
    	GNOME_VFS_XFER_CHECKING_DESTINATION,
    	GNOME_VFS_XFER_PHASE_COLLECTING,
    	GNOME_VFS_XFER_PHASE_READYTOGO,
    	GNOME_VFS_XFER_PHASE_OPENSOURCE,
    	GNOME_VFS_XFER_PHASE_OPENTARGET,
    	GNOME_VFS_XFER_PHASE_COPYING,
    	GNOME_VFS_XFER_PHASE_MOVING,
    	GNOME_VFS_XFER_PHASE_READSOURCE,
    	GNOME_VFS_XFER_PHASE_WRITETARGET,
    	GNOME_VFS_XFER_PHASE_CLOSESOURCE,
    	GNOME_VFS_XFER_PHASE_CLOSETARGET,
    	GNOME_VFS_XFER_PHASE_DELETESOURCE,
    	GNOME_VFS_XFER_PHASE_SETATTRIBUTES,
    	GNOME_VFS_XFER_PHASE_FILECOMPLETED,
    	GNOME_VFS_XFER_PHASE_CLEANUP,
    	GNOME_VFS_XFER_PHASE_COMPLETED,
    	GNOME_VFS_XFER_NUM_PHASES
    } GnomeVFSXferPhase;

Specifies the current phase of an Xfer operation that was initiated using `gnome_vfs_xfer_uri()`, `gnome_vfs_xfer_uri_list()`, `gnome_vfs_xfer_delete_list()` or `gnome_vfs_async_xfer()`.

Whenever the Xfer phase is in a phase that is highlighted with a (*), the GnomeVFSXferProgressCallback respectively GnomeVFSAsyncXferProgressCallback is never invoked with a GnomeVFSXferProgressStatus other than `GNOME_VFS_XFER_PROGRESS_STATUS_OK`.

`GNOME_VFS_XFER_PHASE_INITIAL` | initial phase.
`GNOME_VFS_XFER_CHECKING_DESTINATION` | destination is checked for being able to handle copy/move.
`GNOME_VFS_XFER_PHASE_COLLECTING` | source file list is collected.
`GNOME_VFS_XFER_PHASE_READYTOGO` | source file list has been collected (*).
`GNOME_VFS_XFER_PHASE_OPENSOURCE` | source file is opened for reading.
`GNOME_VFS_XFER_PHASE_OPENTARGET` | target file, directory or symlink is created, or opened for copying.
`GNOME_VFS_XFER_PHASE_COPYING` | data is copied from source file to target file (*).
`GNOME_VFS_XFER_PHASE_MOVING` | source file is moved to target (M).
`GNOME_VFS_XFER_PHASE_READSOURCE` | data is read from a source file, when copying.
`GNOME_VFS_XFER_PHASE_WRITETARGET` | data is written to a target file, when copying.
`GNOME_VFS_XFER_PHASE_CLOSESOURCE` | source file is closed, when copying
`GNOME_VFS_XFER_PHASE_CLOSETARGET` | target file is closed, when copying.
`GNOME_VFS_XFER_PHASE_DELETESOURCE` | source file is deleted.
`GNOME_VFS_XFER_PHASE_SETATTRIBUTES` | target file attributes are set.
`GNOME_VFS_XFER_PHASE_FILECOMPLETED` | one file was completed, ready for next file.
`GNOME_VFS_XFER_PHASE_CLEANUP` | cleanup after moving (i.e. source files deletion).
`GNOME_VFS_XFER_PHASE_COMPLETED` | operation finished (*).
`GNOME_VFS_XFER_NUM_PHASES` |

### GnomeVFSXferProgressInfo

    typedef struct {
    	GnomeVFSXferProgressStatus status;

    	GnomeVFSResult vfs_status;

    	GnomeVFSXferPhase phase;

    	/* Source URI. FIXME bugzilla.eazel.com 1206: change name? */
    	gchar *source_name;

    	/* Destination URI. FIXME bugzilla.eazel.com 1206: change name? */
    	gchar *target_name;

    	gulong file_index;

    	gulong files_total;

    	GnomeVFSFileSize bytes_total;

    	GnomeVFSFileSize file_size;

    	GnomeVFSFileSize bytes_copied;

    	GnomeVFSFileSize total_bytes_copied;

    	gchar *duplicate_name;

    	int duplicate_count;

    	gboolean top_level_item;

    	/* Reserved for future expansions to GnomeVFSXferProgressInfo
    	 * without having to break ABI compatibility */
    } GnomeVFSXferProgressInfo;

Provides progress information for the transfer operation. This is especially useful for interactive programs.

GnomeVFSXferProgressStatus `status`; | A GnomeVFSXferProgressStatus describing the current status.
GnomeVFSResult `vfs_status`; | A GnomeVFSResult describing the current VFS status.
GnomeVFSXferPhase `phase`; | A GnomeVFSXferPhase describing the current transfer phase.
gchar *`source_name`; | The Currently processed source URI.
gchar *`target_name`; | The Currently processed target URI.
gulong `file_index`; | The index of the currently processed file.
gulong `files_total`; | The total number of processed files.
GnomeVFSFileSize `bytes_total`; | The total size of all files to transfer in bytes.
GnomeVFSFileSize `file_size`; | The size of the currently processed file in bytes.
GnomeVFSFileSize `bytes_copied`; | The number of bytes that has been transferred from the current file.
GnomeVFSFileSize `total_bytes_copied`; | The total number of bytes that has been transferred.
gchar *`duplicate_name`; | The name specifying a duplicate filename. It acts as pointer to both input and output data. It is only valid input data if `status` is GNOME_VFS_XFER_PROGRESS_STATUS_DUPLICATE, in which case `duplicate_count` and `duplicate_name` should be used by the GnomeVFSXferProgressCallback to pick a new unique target name. If the callback wants to retry with a new unique name it is supposed to free the old `duplicate_name` set it to a valid string describing the new file name.
int `duplicate_count`; | The number of conflicts that ocurred when the current `duplicate_name` was set.
gboolean `top_level_item`; | This flag signals that the currently processed file is a top level item. If it is `TRUE`, one of the files passed to `gnome_vfs_xfer_uri()`, `gnome_vfs_xfer_uri_list()`, `gnome_vfs_xfer_delete_list()` or `gnome_vfs_async_xfer()` is currently processed. If it is `FALSE`, a file or directory that is inside a directory specified by the passed in source list is currently processed.

### GnomeVFSXferProgressCallback ()

    gint                (*GnomeVFSXferProgressCallback)     (GnomeVFSXferProgressInfo *info,
                                                             gpointer user_data);

This is the prototype for functions called during a transfer operation to report progress.

The interpretation of the return value of the callback depends on the GnomeVFSXferProgressStaus `status` field of GnomeVFSXferProgressInfo, some status/return value combinations require modification of particular `info` fields.

Table 2. Status/Return Value Overview

GnomeVFSXferProgressStatus status | Status | Only If | Return Value Interpretation
--- | --- | --- | ---
GNOME_VFS_XFER_PROGRESS_STATUS_OK | OK |  | `0`: abort, otherwise continue
GNOME_VFS_XFER_PROGRESS_STATUS_VFSERROR | VFS Error Ocurred | GnomeVFSXferErrorMode is GNOME_VFS_XFER_ERROR_MODE_QUERY | GnomeVFSXferErrorAction
GNOME_VFS_XFER_PROGRESS_STATUS_OVERWRITE | Conflict Ocurred, Overwrite? | GnomeVFSXferOverwriteMode is GNOME_VFS_XFER_OVERWRITE_MODE_QUERY, GnomeVFSXferOptions does not have GNOME_VFS_XFER_USE_UNIQUE_NAMES. | GnomeVFSXferOverwriteAction
GNOME_VFS_XFER_PROGRESS_STATUS_DUPLICATE | Conflict Ocurred, New Target Name? | GnomeVFSXferOptions does have GNOME_VFS_XFER_USE_UNIQUE_NAMES. | `0`: abort, otherwise retry with new `duplicate_name` in `info` (free the old one!).

### Note

Each GnomeVFSXferProgressStatus provides one value signalling abortion that maps to `0`. Therefore, returning `0` will always abort the Xfer. On abortion, if the `info`'s `vfs_status` is GNOME_VFS_OK, the Xfer operation result will be set to GNOME_VFS_ERROR_INTERRUPTED, otherwise the operation result will be set to `vfs_status` to distinguish completely user-driven aborts from those involving a problem during the Xfer.

`info` : | The GnomeVFSXferProgressInfo associated with this transfer operation.
`user_data` : | The user data passed to `gnome_vfs_xfer_uri()`, `gnome_vfs_xfer_uri_list()`, `gnome_vfs_xfer_delete_list()` or `gnome_vfs_async_xfer()`.
Returns : | Whether the process should be aborted, or whether a special action should be taken.

### gnome_vfs_xfer_uri_list ()

    GnomeVFSResult      gnome_vfs_xfer_uri_list             (const GList *source_uri_list,
                                                             const GList *target_uri_list,
                                                             GnomeVFSXferOptions xfer_options,
                                                             GnomeVFSXferErrorMode error_mode,
                                                             GnomeVFSXferOverwriteMode overwrite_mode,
                                                             GnomeVFSXferProgressCallback progress_callback,
                                                             gpointer data);

This function will transfer multiple files to multiple targets, given source URIs and destination URIs. If you want to do asynchronous file transfers, you have to use `gnome_vfs_async_xfer()` instead.

`source_uri_list` : | A GList of source GnomeVFSURIs.
`target_uri_list` : | A GList of target GnomeVFSURIs, each corresponding to one URI in `source_uri_list`.
`xfer_options` : | GnomeVFSXferOptions defining the desired operation and parameters.
`error_mode` : | A GnomeVFSErrorMode specifying how to proceed if a VFS error occurs.
`overwrite_mode` : | A GnomeVFSOverwriteMode specifying how to proceed if a file is being overwritten.
`progress_callback` : | This GnomeVFSProgressCallback is used to inform the user about the progress of a transfer, and to request further input from him if a problem occurs.
`data` : | Data to be passed back in callbacks from the xfer engine.
Returns : | If all goes well it returns `GNOME_VFS_OK`. Check GnomeVFSResult for other values.

### gnome_vfs_xfer_uri ()

    GnomeVFSResult      gnome_vfs_xfer_uri                  (const GnomeVFSURI *source_uri,
                                                             const GnomeVFSURI *target_uri,
                                                             GnomeVFSXferOptions xfer_options,
                                                             GnomeVFSXferErrorMode error_mode,
                                                             GnomeVFSXferOverwriteMode overwrite_mode,
                                                             GnomeVFSXferProgressCallback progress_callback,
                                                             gpointer data);

This function works exactly like `gnome_vfs_xfer_uri_list()`, and is a convenience wrapper for only acting on one source/target URI pair.

`source_uri` : | A source GnomeVFSURI.
`target_uri` : | A target GnomeVFSURI.
`xfer_options` : | GnomeVFSXferOptions defining the desired operation and parameters.
`error_mode` : | A GnomeVFSErrorMode specifying how to proceed if a VFS error occurs.
`overwrite_mode` : | A GnomeVFSOverwriteMode specifying how to proceed if a file is being overwritten.
`progress_callback` : | This GnomeVFSProgressCallback is used to inform the user about the progress of a transfer, and to request further input from him if a problem occurs.
`data` : | Data to be passed back in callbacks from the xfer engine.
Returns : | an integer representing the result of the operation.

### gnome_vfs_xfer_delete_list ()

    GnomeVFSResult      gnome_vfs_xfer_delete_list          (const GList *source_uri_list,
                                                             GnomeVFSXferErrorMode error_mode,
                                                             GnomeVFSXferOptions xfer_options,
                                                             GnomeVFSXferProgressCallback progress_callback,
                                                             gpointer data);

Unlinks items in the `source_uri_list` from their filesystems.

`source_uri_list` : | This is a list containing uris.
`error_mode` : | Decide how you want to deal with interruptions.
`xfer_options` : | Set whatever transfer options you need.
`progress_callback` : | Callback to check on progress of transfer.
`data` : | Data to be passed back in callbacks from the xfer engine.
Returns : | `GNOME_VFS_OK` if successful, or the appropriate error code otherwise.