optional gio.Cancellable object, NULL to ignore
a location to place the contents of the file
a location to place the current entity tag for the file, or NULL if the entity tag is not needed
TRUE if the file's contents were successfully loaded. FALSE if there were errors.
GException on failure.
Loads the content of the file into memory. The data is always zero-terminated, but this is not included in the resultant length. The returned contents should be freed with g_free() when no longer needed.
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.