sd_bus_message_new_method_error, sd_bus_message_new_method_errorf, sd_bus_message_new_method_errno, sd_bus_message_new_method_errnof — Create an error reply for a method call
#include <systemd/sd-bus.h>
int sd_bus_message_new_method_error( | sd_bus_message *call, |
| sd_bus_message **m, | |
const sd_bus_error *e); |
int sd_bus_message_new_method_errorf( | sd_bus_message *call, |
| sd_bus_message **m, | |
| const char *name, | |
| const char *format, | |
…); |
int sd_bus_message_new_method_errno( | sd_bus_message *call, |
| sd_bus_message **m, | |
| int error, | |
const sd_bus_error *p); |
int sd_bus_message_new_method_errnof( | sd_bus_message *call, |
| sd_bus_message **m, | |
| int error, | |
| const char *format, | |
…); |
The sd_bus_message_new_method_error() function creates
a new bus message object that is an error reply to the
call message, and returns it in the
m output parameter. The error information from error
e is appended: the name field of
e is used as the error identifier in the reply header (for
example an error name such as
"org.freedesktop.DBus.Error.NotSupported" or the equivalent
symbolic SD_BUS_ERROR_NOT_SUPPORTED), and the
message field is set as the human readable error message
string if present. The error e must have the
name field set, see
sd_bus_error_is_set(3).
The sd_bus_message_new_method_errorf() function
creates an error reply similarly to
sd_bus_message_new_method_error(), but instead of a ready
error structure, it takes an error identifier string name,
plus a printf(3)
format string format and corresponding arguments. An error
reply is sent with the error identifier name and the
formatted string as the message. name and
format must not be NULL.
The sd_bus_message_new_method_errno() function creates
an error reply similarly to
sd_bus_message_new_method_error(), but in addition to the
error structure p, it takes an
errno(3)
error value in parameter error. If the error
p is set (see
sd_bus_error_is_set(3)),
it is used in the reply. Otherwise, error is translated to
an error identifier and used to create a new error structure using
sd_bus_error_set_errno(3)
and that is used in the reply. (If error is zero, no error
is actually set, and an error reply with no information is created.)
The sd_bus_message_new_method_errnof() function
creates an error reply similarly to
sd_bus_message_new_method_error(). It takes an
errno(3)
error value in parameter error, plus a printf(3)
format string format and corresponding arguments.
"%m" may be used in the format string to refer to the error
string corresponding to the specified errno code. The error message is initialized
using the error identifier generated from error and the
formatted string. (If error is zero, no error is actually
set, and an error reply with no information is created.)
These functions return 0 if the error reply was successfully created, and a negative errno-style error code otherwise.
Returned errors may indicate the following problems:
-EINVAL¶The call message call or the output
parameter m are NULL.
Message call is not a method call
message.
The error e parameter to
sd_bus_message_new_method_error() is not set, see
sd_bus_error_is_set(3).
-EPERM¶Message call has been sealed.
-ENOTCONN¶The bus to which message call is
attached is not connected.
-ENOMEM¶Memory allocation failed.
Functions described here are available as a shared
library, which can be compiled against and linked to with the
libsystemd pkg-config(1)
file.
The code described here uses
getenv(3),
which is declared to be not multi-thread-safe. This means that the code calling the functions described
here must not call
setenv(3)
from a parallel thread. It is recommended to only do calls to setenv()
from an early phase of the program when no other threads have been started.