NAME

       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

SYNOPSIS

       #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, ...);

DESCRIPTION

       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.)

RETURN VALUE

       These functions return 0 if the error reply was successfully created, and a negative errno-style error
       code otherwise.

   Errors
       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.

NOTES

       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.

SEE ALSO

       systemd(1), sd-bus(3)