sd_bus_message_get_cookie(3) — Linux manual page


SD_BUS_M...ET_COOKIE(3) sd_bus_message_get_cookieSD_BUS_M...ET_COOKIE(3)

NAME         top

       sd_bus_message_get_cookie, sd_bus_message_get_reply_cookie -
       Returns the transaction cookie of a message

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       int sd_bus_message_get_cookie(sd_bus_message *message,
                                     uint64_t *cookie);

       int sd_bus_message_get_reply_cookie(sd_bus_message *message,
                                           uint64_t *cookie);

DESCRIPTION         top

       sd_bus_message_get_cookie() returns the transaction cookie of a
       message. The cookie uniquely identifies a message within each bus
       peer, but is not globally unique. It is assigned when a message
       is sent.

       sd_bus_message_get_reply_cookie() returns the transaction cookie
       of the message the specified message is a response to. When a
       reply message is generated for a method call message, its cookie
       is copied over into this field. Note that while every message
       that is transferred is identified by a cookie, only response
       messages carry a reply cookie field.

       Both functions take a message object as first parameter and a
       place to store the 64-bit cookie in.

RETURN VALUE         top

       On success, these calls return 0 or a positive integer. On
       failure, they return a negative errno-style error code.

       On success, the cookie/reply cookie is returned in the specified
       64-bit unsigned integer variable.

       Returned errors may indicate the following problems:

           A specified parameter is invalid.

           No cookie has been assigned to this message. This either
           indicates that the message has not been sent yet and hence
           has no cookie assigned, or that the message is not a method
           response message and hence carries a reply cookie field.

NOTES         top

       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

HISTORY         top

       sd_bus_message_get_cookie() and sd_bus_message_get_reply_cookie()
       were added in version 209.

SEE ALSO         top

       systemd(1), sd-bus(3), sd_bus_new(3)

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨⟩.  If you have
       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-22.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

systemd 255                                      SD_BUS_M...ET_COOKIE(3)

Pages that refer to this page: sd-bus(3)systemd.directives(7)systemd.index(7)