value

value — Simplified interface to GValue types used in libuser entities.

Synopsis




#define     LU_VALUE_INVALID_ID
char*       lu_value_strdup                 (const GValue *value);
gboolean    lu_value_init_set_attr_from_string
                                            (GValue *value,
                                             const char *attr,
                                             const char *string,
                                             lu_error_t **error);
void        lu_value_init_set_id            (GValue *value,
                                             id_t id);
id_t        lu_value_get_id                 (const GValue *value);
int         lu_values_equal                 (const GValue *a,
                                             const GValue *b);

Description

Libuser entities store attribute values as GValue, which allows representing any possible data type. Only a few types are needed in practice; the only types applications should hard-code are G_TYPE_LONG and G_TYPE_STRING (G_TYPE_STRING can usually be used as a fallback for other number types).

The only currently used data types that are not conveniently supported using the above types are uid_t and gid_t (which can be together represented in id_t), because they can support values outside of the range of glong. Helper functions are provided to convert values between id_t and GValue, even if the value is stored using G_TYPE_STRING. The GValue types used for storing id_t values are an internal implementation detail of libuser and applications should not rely on them.

Values of each attribute are expected to have a specific type, documented in the documentation of the specific attribute name. Using other types (e.g. using G_TYPE_STRING for LU_UIDNUMBER) is not allowed and results in undefined behavior.. You can use lu_value_strdup() and lu_value_init_set_attr_from_string() for conversion between strings and values appropriate for a specific attribute.

Details

LU_VALUE_INVALID_ID

#define LU_VALUE_INVALID_ID ((id_t)-1)

An id_t value that matches no valid user or group ID.


lu_value_strdup ()

char*       lu_value_strdup                 (const GValue *value);

Converts value, of any type used by libuser, to a string. Preferable to hard-coding checks for expected value types.

value : value
Returns : string, should be freed by g_free()

lu_value_init_set_attr_from_string ()

gboolean    lu_value_init_set_attr_from_string
                                            (GValue *value,
                                             const char *attr,
                                             const char *string,
                                             lu_error_t **error);

Initializes a zero-filled (uninitialized) value for storing a value of attribute attr and sets it to the contents of string. To see whether a specific type is used for an attribute, see the documentation of that attribute.

value : GValue
attr : attribute name
string : the string to convert
error : filled with a lu_error if an error occurs, or NULL if attr is unknown
Returns : TRUE on success, FALSE on error or if attr is unknown

lu_value_init_set_id ()

void        lu_value_init_set_id            (GValue *value,
                                             id_t id);

Initializes a zero-filled (uninitialized) value with an unspecified type and sets it to id.

value : GValue
id : user or group ID.

lu_value_get_id ()

id_t        lu_value_get_id                 (const GValue *value);

Get the contents of value. value should be initialized by lu_value_init_set_id() or use G_TYPE_LONG or G_TYPE_STRING.

If value does not contain a valid id_t value, LU_VALUE_INVALID_ID is returned.

value : GValue
Returns : ID value or LU_VALUE_INVALID_ID

lu_values_equal ()

int         lu_values_equal                 (const GValue *a,
                                             const GValue *b);

Check whether a and b have the same type and value.

a : GValue
b : GValue
Returns : TRUE if a and b have the same type and value