The following functions are used to modify an existing LDAP
    entry. There are four variations.

            typedef struct ldapmod {
                    int                                mod_op;
                    char                               *mod_type;
                    union {
                            char                       **modv_strvals;
                            struct berval              **modv_bvals;
                            } mod_vals;
            } LDAPMod;
            #define mod_values      mod_vals.modv_strvals
            #define mod_bvalues     mod_vals.modv_bvals

            int ldap_modify_ext(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods,
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls,
                    int                               *msgidp
            );

            int ldap_modify_ext_s(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods,
                    LDAPControl                       **serverctrls,
                    LDAPControl                       **clientctrls

            );

            int ldap_modify(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods
            );

            int ldap_modify_s(
                    LDAP                              *ld,
                    const char                        *dn,
                    LDAPMod                           **mods
            );

    Parameters are as follows:

    ld             The session handle.
    dn             The name of the entry to modify.
    mods           A NULL-terminated array of modifications to make
                   to the entry.
    serverctrls    List of LDAP server controls.
    clientctrls    List of client controls.
    msgidp         This result parameter will be set to the message
                   id of the request if the ldap_modify_ext() call
                   succeeds.

    The fields in the LDAPMod structure have the following meanings:

    mod_op     The modification operation to perform. It should be
               one of LDAP_MOD_ADD(0x00), LDAP_MOD_DELETE (0x01), or
               LDAP_MOD_REPLACE(0x02). This field also indicates the
               type of values included in the mod_vals union. It is
               logically ORed with LDAP_MOD_BVALUES (0x80) to select
               the mod_bvalues form. Otherwise, the mod_values form is
               used.
    mod_type   The type of the attribute to modify.
    mod_vals   The values (if any) to add, delete, or replace. Only
               one of the mod_values or mod_bvalues variants should
               be used, selected by ORing the mod_op field with the
               constant LDAP_MOD_BVALUES. The mod_values field is
               a NULL-terminated array of zero-terminated strings
               and mod_bvalues is a NULL- terminated array of berval
               structures that can be used to pass binary values such
               as images.

    For LDAP_MOD_ADD modifications, the given values are added to the
    entry, creating the attribute if necessary.

    For LDAP_MOD_DELETE modifications, the given values are deleted
    from the entry, removing the attribute if no values remain. If
    the entire attribute is to be deleted, the mod_vals field should
    be set to NULL.

    For LDAP_MOD_REPLACE modifications, the attribute will have
    the listed values after the modification, having been created
    if necessary, or removed if the mod_vals field is NULL. All
    modifications are performed in the order in which they are
    listed.

    The ldap_modify_ext() function initiates an asynchronous modify
    operation and returns the constant LDAP_SUCCESS if the request
    was successfully sent, or another LDAP error code if not. See
    Errors for more information about possible errors and how to
    interpret them. If successful, ldap_modify_ext() places the
    message id of the request in *msgidp. A subsequent call to ldap_
    result() can be used to obtain the result of the modify.

    Similar to ldap_modify_ext(), the ldap_modify()  function
    initiates an asynchronous modify operation and returns the
    message id of the operation initiated. As for ldap_modify_ext(),
    a subsequent call to ldap_result() can be used to obtain the
    result of the modify. In case of error, ldap_modify() will return
    -1, setting the session error parameters in the LDAP structure
    appropriately.

    The synchronous ldap_modify_ext_s() and ldap_modify_s()
    functions both return the result of the operation, either the
    constant LDAP_SUCCESS if the operation was successful, or another
    LDAP error code if it was not.

    See Errors for more information about possible errors and how to
    interpret them.

    The ldap_modify_ext() and ldap_modify_ext_s()  functions support
    LDAPv3 server controls and client controls.