доступ к массиву элементов в сообщении (Access an array of elements in a message)
Имя (Name)
sd_bus_message_read_array - Access an array of elements in a
message
Синопсис (Synopsis)
#include <systemd/sd-bus.h>
int sd_bus_message_read_array(sd_bus_message *m, char type,
const void **ptr, size_t *size);
Описание (Description)
sd_bus_message_read_array() provides access to an array elements
in the bus message m. The "read pointer" in the message must be
right before an array of type type. As a special case, type may
be NUL, in which case any trivial type is acceptable. A pointer
to the array data is returned in the parameter ptr and the size
of array data (in bytes) is returned in the parameter size. If
the returned size parameter is 0, a valid non-null pointer will
be returned as ptr, but it may not be dereferenced. The data is
aligned as appropriate for the data type. The data is part of the
message — it may not be modified and is valid only as long as the
message is referenced. After this function returns, the "read
pointer" points at the next element after the array.
Note that this function only supports arrays of trivial types,
i.e. arrays of booleans, the various integer types, as well as
floating point numbers. In particular it may not be used for
arrays of strings, structures or similar.
Возвращаемое значение (Return value)
On success and when an array was read,
sd_bus_message_read_array() returns an integer greater than zero.
If invoked while inside a container element (such as an array,
e.g. when operating on an array of arrays) and the final element
of the outer container has been read already and the read pointer
is thus behind the last element of the outer container this call
returns 0 (and the returned pointer will be NULL and the size
will be 0). On failure, it returns a negative errno-style error
code.
Errors
Returned errors may indicate the following problems:
-EINVAL
Specified type is invalid or not a trivial type (see above),
or the message parameter or one of the output parameters are
NULL.
-EOPNOTSUPP
The byte order in the message is different than native byte
order.
-EPERM
The message is not sealed.
-EBADMSG
The message cannot be parsed.
Смотри также (See also)
systemd(1), sd-bus(3), sd_bus_message_read(3),
sd_bus_message_read_strv(3)
