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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_BUS_M..._GET_TYPE(3) sd_bus_message_get_type SD_BUS_M..._GET_TYPE(3)
sd_bus_message_get_type, sd_bus_message_get_error,
sd_bus_message_get_errno, sd_bus_message_get_creds,
sd_bus_message_is_signal, sd_bus_message_is_method_call,
sd_bus_message_is_method_error - Query bus message
addressing/credentials metadata
#include <systemd/sd-bus.h>
int sd_bus_message_get_type(sd_bus_message *m, uint8_t *type);
sd_bus_error* sd_bus_message_get_error(sd_bus_message *m);
int sd_bus_message_get_errno(sd_bus_message *m);
sd_bus_creds* sd_bus_message_get_creds(sd_bus_message *m);
int sd_bus_message_is_signal(sd_bus_message *m,
const char *interface,
const char *member);
int sd_bus_message_is_method_call(sd_bus_message *m,
const char *interface,
const char *member);
int sd_bus_message_is_method_error(sd_bus_message *m,
const char *name);
sd_bus_message_get_type() returns the type of a message in the
output parameter type, one of SD_BUS_MESSAGE_METHOD_CALL,
SD_BUS_MESSAGE_METHOD_RETURN, SD_BUS_MESSAGE_METHOD_ERROR,
SD_BUS_MESSAGE_SIGNAL. This type is either specified as a
parameter when the message is created using sd_bus_message_new(3),
or is set automatically when the message is created using
sd_bus_message_new_signal(3), sd_bus_message_new_method_call(3),
sd_bus_message_new_method_error(3) and similar functions.
sd_bus_message_get_error() returns the error stored in the message
m, if there is any. Otherwise, it returns NULL.
sd_bus_message_get_errno() returns the error stored in the message
m as a positive errno-style value, if there is any. Otherwise, it
returns zero. Errors are mapped to errno values according to the
default and any additional registered error mappings. See
sd-bus-errors(3) and sd_bus_error_add_map(3).
sd_bus_message_get_creds() returns the message credentials
attached to the message m. If no credentials are attached to the
message, it returns NULL. Ownership of the credentials instance is
not transferred to the caller and hence should not be freed.
sd_bus_message_is_signal() checks if message m is a signal
message. If interface is non-null, it also checks if the message
has the same interface set. If member is non-null, it also checks
if the message has the same member set. Also see
sd_bus_message_new_signal(3). It returns true when all checks
pass.
sd_bus_message_is_method_call() checks if message m is a method
call message. If interface is non-null, it also checks if the
message has the same interface set. If member is non-null, it also
checks if the message has the same member set. Also see
sd_bus_message_new_method_call(3). It returns true when all checks
pass.
sd_bus_message_is_method_error() checks if message m is an error
reply message. If name is non-null, it also checks if the message
has the same error identifier set. Also see
sd_bus_message_new_method_error(3). It returns true when all
checks pass.
On success, these functions (except sd_bus_message_get_error() and
sd_bus_message_get_creds()) return a non-negative integer. On
failure, they return a negative errno-style error code.
sd_bus_message_get_errno() always returns a non-negative integer,
even on failure.
Errors
Returned errors may indicate the following problems:
-EINVAL
The message parameter m or an output parameter is NULL.
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.
sd_bus_message_get_type(), sd_bus_message_is_signal(),
sd_bus_message_is_method_call(), and
sd_bus_message_is_method_error() were added in version 240.
sd_bus_message_get_error(), sd_bus_message_get_errno(), and
sd_bus_message_get_creds() were added in version 246.
systemd(1), sd-bus(3), sd_bus_message_new(3),
sd_bus_message_set_destination(3), sd-bus-errors(3),
sd_bus_error_add_map(3)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SD_BUS_M..._GET_TYPE(3)
Pages that refer to this page: sd-bus(3), sd_bus_call(3), sd_bus_creds_get_pid(3), sd_bus_creds_new_from_pid(3), sd_bus_negotiate_fds(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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