GFileAttribute — Key-Value Paired File Attributes


Types and Values

Object Hierarchy

    ╰── GFileAttributeInfoList
    ├── GFileAttributeStatus
    ╰── GFileAttributeType
    ╰── GFileAttributeInfoFlags


#include <gio/gio.h>


File attributes in GIO consist of a list of key-value pairs.

Keys are strings that contain a key namespace and a key name, separated by a colon, e.g. "namespace::keyname". Namespaces are included to sort key-value pairs by namespaces for relevance. Keys can be retrieved using wildcards, e.g. "standard::*" will return all of the keys in the "standard" namespace.

The list of possible attributes for a filesystem (pointed to by a GFile) is available as a GFileAttributeInfoList. This list is queryable by key names as indicated earlier.

Information is stored within the list in GFileAttributeInfo structures. The info structure can store different types, listed in the enum GFileAttributeType. Upon creation of a GFileAttributeInfo, the type will be set to G_FILE_ATTRIBUTE_TYPE_INVALID.

Classes that implement GFileIface will create a GFileAttributeInfoList and install default keys and values for their given file system, architecture, and other possible implementation details (e.g., on a UNIX system, a file attribute key will be registered for the user id for a given file).

Default Namespaces

  • "standard": The "Standard" namespace. General file information that any application may need should be put in this namespace. Examples include the file's name, type, and size.

  • "etag: The Entity Tag namespace. Currently, the only key in this namespace is "value", which contains the value of the current entity tag.

  • "id": The "Identification" namespace. This namespace is used by file managers and applications that list directories to check for loops and to uniquely identify files.

  • "access": The "Access" namespace. Used to check if a user has the proper privileges to access files and perform file operations. Keys in this namespace are made to be generic and easily understood, e.g. the "can_read" key is TRUE if the current user has permission to read the file. UNIX permissions and NTFS ACLs in Windows should be mapped to these values.

  • "mountable": The "Mountable" namespace. Includes simple boolean keys for checking if a file or path supports mount operations, e.g. mount, unmount, eject. These are used for files of type G_FILE_TYPE_MOUNTABLE.

  • "time": The "Time" namespace. Includes file access, changed, created times.

  • "unix": The "Unix" namespace. Includes UNIX-specific information and may not be available for all files. Examples include the UNIX "UID", "GID", etc.

  • "dos": The "DOS" namespace. Includes DOS-specific information and may not be available for all files. Examples include "is_system" for checking if a file is marked as a system file, and "is_archive" for checking if a file is marked as an archive file.

  • "owner": The "Owner" namespace. Includes information about who owns a file. May not be available for all file systems. Examples include "user" for getting the user name of the file owner. This information is often mapped from some backend specific data such as a UNIX UID.

  • "thumbnail": The "Thumbnail" namespace. Includes information about file thumbnails and their location within the file system. Examples of keys in this namespace include "path" to get the location of a thumbnail, "failed" to check if thumbnailing of the file failed, and "is-valid" to check if the thumbnail is outdated.

  • "filesystem": The "Filesystem" namespace. Gets information about the file system where a file is located, such as its type, how much space is left available, and the overall size of the file system.

  • "gvfs": The "GVFS" namespace. Keys in this namespace contain information about the current GVFS backend in use.

  • "xattr": The "xattr" namespace. Gets information about extended user attributes. See attr(5). The "user." prefix of the extended user attribute name is stripped away when constructing keys in this namespace, e.g. "xattr::mime_type" for the extended attribute with the name "user.mime_type". Note that this information is only available if GLib has been built with extended attribute support.

  • "xattr-sys": The "xattr-sys" namespace. Gets information about extended attributes which are not user-specific. See attr(5). Note that this information is only available if GLib has been built with extended attribute support.

  • "selinux": The "SELinux" namespace. Includes information about the SELinux context of files. Note that this information is only available if GLib has been built with SELinux support.

Please note that these are not all of the possible namespaces. More namespaces can be added from GIO modules or by individual applications. For more information about writing GIO modules, see GIOModule.

<!-- TODO: Implementation note about using extended attributes on supported file systems -->

Default Keys

For a list of the built-in keys and their types, see the GFileInfo documentation.

Note that there are no predefined keys in the "xattr" and "xattr-sys" namespaces. Keys for the "xattr" namespace are constructed by stripping away the "user." prefix from the extended user attribute, and prepending "xattr::". Keys for the "xattr-sys" namespace are constructed by concatenating "xattr-sys::" with the extended attribute name. All extended attribute values are returned as hex-encoded strings in which bytes outside the ASCII range are encoded as escape sequences of the form \xnn where nn is a 2-digit hexadecimal number.


g_file_attribute_info_list_new ()

GFileAttributeInfoList *
g_file_attribute_info_list_new (void);

Creates a new file attribute info list.

g_file_attribute_info_list_ref ()

GFileAttributeInfoList *
g_file_attribute_info_list_ref (GFileAttributeInfoList *list);

References a file attribute info list.



a GFileAttributeInfoList to reference.



GFileAttributeInfoList or NULL on error.

g_file_attribute_info_list_unref ()

g_file_attribute_info_list_unref (GFileAttributeInfoList *list);

Removes a reference from the given list . If the reference count falls to zero, the list is deleted.



The GFileAttributeInfoList to unreference.


g_file_attribute_info_list_dup ()

GFileAttributeInfoList *
g_file_attribute_info_list_dup (GFileAttributeInfoList *list);

Makes a duplicate of a file attribute info list.



a GFileAttributeInfoList to duplicate.



a copy of the given list .

g_file_attribute_info_list_lookup ()

const GFileAttributeInfo *
g_file_attribute_info_list_lookup (GFileAttributeInfoList *list,
                                   const char *name);

Gets the file attribute with the name name from list .



a GFileAttributeInfoList.



the name of the attribute to look up.



a GFileAttributeInfo for the name , or NULL if an attribute isn't found.

g_file_attribute_info_list_add ()

g_file_attribute_info_list_add (GFileAttributeInfoList *list,
                                const char *name,
                                GFileAttributeType type,
                                GFileAttributeInfoFlags flags);

Adds a new attribute with name to the list , setting its type and flags .



a GFileAttributeInfoList.



the name of the attribute to add.



the GFileAttributeType for the attribute.



GFileAttributeInfoFlags for the attribute.


Types and Values

enum GFileAttributeType

The data types for file attributes.



indicates an invalid or uninitialized type.



a null terminated UTF8 string.



a zero terminated string of non-zero bytes.



a boolean value.



an unsigned 4-byte/32-bit integer.



a signed 4-byte/32-bit integer.



an unsigned 8-byte/64-bit integer.



a signed 8-byte/64-bit integer.



a GObject.



a NULL terminated char **. Since 2.22


enum GFileAttributeInfoFlags

Flags specifying the behaviour of an attribute.



no flags set.



copy the attribute values when the file is copied.



copy the attribute values when the file is moved.


enum GFileAttributeStatus

Used by g_file_set_attributes_from_info() when setting file attributes.



Attribute value is unset (empty).



Attribute value is set.



Indicates an error in setting the value.



typedef struct {
  char                    *name;
  GFileAttributeType       type;
  GFileAttributeInfoFlags  flags;
} GFileAttributeInfo;

Information about a specific attribute.


char *name;

the name of the attribute.


GFileAttributeType type;

the GFileAttributeType type of the attribute.


GFileAttributeInfoFlags flags;

a set of GFileAttributeInfoFlags.



typedef struct {
  GFileAttributeInfo *infos;
  int                 n_infos;
} GFileAttributeInfoList;

Acts as a lightweight registry for possible valid file attributes. The registry stores Key-Value pair formats as GFileAttributeInfos.


GFileAttributeInfo *infos;

an array of GFileAttributeInfos.


int n_infos;

the number of values in the array.


See Also

GFile, GFileInfo