| SD_BUS_MESSAGE_GET_COOKIE(3) | sd_bus_message_get_cookie | SD_BUS_MESSAGE_GET_COOKIE(3) |
.SH "NAME" sd_bus_message_get_cookie,
sd_bus_message_get_reply_cookie - Return the transaction cookie of a
message
.SH "SYNOPSIS"
#include <systemd/sd-bus.h>
.HP 720u int
sd_bus_message_get_cookie(sd_bus_message *message,
uint64_t *cookie);
.HP 864u int
sd_bus_message_get_reply_cookie(sd_bus_message *message,
uint64_t *cookie);
.SH "DESCRIPTION"
.PP 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.
.PP 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.
.PP Both functions take a message object as first parameter and a place to
store the 64-bit cookie in.
.SH "RETURN VALUE"
.PP On success, these calls return 0 or a positive integer. On failure, they
return a negative errno-style error code.
.PP On success, the cookie/reply cookie is returned in the specified 64-bit
unsigned integer variable.
.SS "Errors"
.PP Returned errors may indicate the following problems:
.PP -EINVAL
A specified parameter is invalid.
.RE
.PP -ENODATA
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 does not carry a reply
cookie field.
.RE
.SH "NOTES"
.PP Functions described here are available as a shared library, which can be
compiled against and linked to with the
libsystemd pkg-config(1) file.
.PP All functions listed here are thread-agnostic and only a single thread
may operate on a given object at any given time. Different threads may
access the same object at different times. Multiple independent objects may
be used from different threads in parallel.
.PP 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.
.SH "HISTORY"
.PP sd_bus_message_get_cookie() and
sd_bus_message_get_reply_cookie() were added in version 209.
.SH "SEE ALSO"
.PP systemd(1), sd-bus(3), sd_bus_new(3)
| systemd 262.2 |