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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 retrived 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).
"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 -->
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.
GFileAttributeInfoList *
g_file_attribute_info_list_new (void);
Creates a new file attribute info list.
GFileAttributeInfoList *
g_file_attribute_info_list_ref (GFileAttributeInfoList *list);
References a file attribute info list.
void
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.
GFileAttributeInfoList *
g_file_attribute_info_list_dup (GFileAttributeInfoList *list);
Makes a duplicate of a file attribute info list.
const GFileAttributeInfo * g_file_attribute_info_list_lookup (GFileAttributeInfoList *list,const char *name);
Gets the file attribute with the name name
from list
.
void 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
.
list |
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name |
the name of the attribute to add. |
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type |
the GFileAttributeType for the attribute. |
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flags |
GFileAttributeInfoFlags for the attribute. |
The data types for file attributes.
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indicates an invalid or uninitalized type. |
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a null terminated UTF8 string. |
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a zero terminated string of non-zero bytes. |
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a boolean value. |
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an unsigned 4-byte/32-bit integer. |
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a signed 4-byte/32-bit integer. |
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an unsigned 8-byte/64-bit integer. |
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a signed 8-byte/64-bit integer. |
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a GObject. |
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a |
typedef struct {
char *name;
GFileAttributeType type;
GFileAttributeInfoFlags flags;
} GFileAttributeInfo;
Information about a specific attribute.
the name of the attribute. |
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GFileAttributeType |
the GFileAttributeType type of the attribute. |
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GFileAttributeInfoFlags |
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 * |
an array of GFileAttributeInfos. |
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the number of values in the array. |