sd_bus_message_get_cookie, sd_bus_message_get_reply_cookie — Returns the transaction cookie of a message
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.
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
Both functions take a message object as first parameter and a place to store the 64-bit cookie in.
On success, these calls return 0 or a positive integer. On failure, these calls 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:
These APIs are implemented as a shared
library, which can be compiled and linked to with the