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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |NOTES |HISTORY |SEE ALSO |COLOPHON | |
SD_BUS_M..._GET_TYPE(3) sd_bus_message_get_typeSD_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 parametertype, one ofSD_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 usingsd_bus_message_new(3), or is set automatically when the message is created usingsd_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 messagem, if there is any. Otherwise, it returnsNULL.sd_bus_message_get_errno()returns the error stored in the messagem 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. Seesd-bus-errors(3) andsd_bus_error_add_map(3).sd_bus_message_get_creds()returns the message credentials attached to the messagem. If no credentials are attached to the message, it returnsNULL. Ownership of the credentials instance is not transferred to the caller and hence should not be freed.sd_bus_message_is_signal()checks if messagem is a signal message. Ifinterface is non-null, it also checks if the message has the same interface set. Ifmember is non-null, it also checks if the message has the same member set. Also seesd_bus_message_new_signal(3). It returns true when all checks pass.sd_bus_message_is_method_call()checks if messagem is a method call message. Ifinterface is non-null, it also checks if the message has the same interface set. Ifmember is non-null, it also checks if the message has the same member set. Also seesd_bus_message_new_method_call(3). It returns true when all checks pass.sd_bus_message_is_method_error()checks if messagem is an error reply message. Ifname is non-null, it also checks if the message has the same error identifier set. Also seesd_bus_message_new_method_error(3). It returns true when all checks pass.
On success, these functions (exceptsd_bus_message_get_error()andsd_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 parameterm or an output parameter isNULL.
Functions described here are available as a shared library, which can be compiled against and linked to with thelibsystemd pkg-config(1) file. The code described here usesgetenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not callsetenv(3) from a parallel thread. It is recommended to only do calls tosetenv()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(), andsd_bus_message_is_method_error()were added in version 240.sd_bus_message_get_error(),sd_bus_message_get_errno(), andsd_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 thesystemd (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 isnot part of the original manual page), send a mail to man-pages@man7.orgsystemd 258~rc2SD_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)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |