sd_bus_message_dump - Man Page

#include <systemd/sd-bus​.h>

int sd_bus_message_dump(sd_bus_message *m, FILE *f, uint64_t flags);

int sd_bus_message_dump_json(sd_bus_message *m, uint64_t flags, sd_json_variant **ret);

The sd_bus_message_dump() function writes a textual representation of the message m to the stream f​. If f is NULL, standard output (stdio) will be used​. This function is intended to be used for debugging purposes, and the output is neither stable nor designed to be machine readable​.

The sd_bus_message_dump_json() function converts the DBus message m to a JSON variant and stores it in ret​. The caller should call sd_json_variant_unref() for the acquired JSON variant after use​. Unlike sd_bus_message_dump(), the function itself does not print anything​. To print the DBus message in the JSON format, please pass the returned JSON variant to sd_json_variant_dump()​.

The flags parameter may be used to modify the output, and is a combination of zero or more of the following flags:

SD_BUS_MESSAGE_DUMP_WITH_HEADER

The header of the message that specifies the message type, flags, and several more additional metadata will be printed or included in the resulting JSON object​.

SD_BUS_MESSAGE_DUMP_SUBTREE_ONLY

Only the current container will be printed or converted​. When the flag is not specified, the contents of the whole message will be printed or converted​.

Note that these functions move the read pointer of the message​. It may be necessary to reset the position afterwards, for example with sd_bus_message_rewind(3)​.

Output for a signal message (with SD_BUS_MESSAGE_DUMP_WITH_HEADER):

>​ Type=signal  Endian=l  Flags=1  Version=1  Cookie=22
  Path=/value/a  Interface=org​.freedesktop​.DBus​.Properties  Member=PropertiesChanged
  MESSAGE "sa{sv}as" {
          STRING "org​.freedesktop​.systemd​.ValueTest";
          ARRAY "{sv}" {
                  DICT_ENTRY "sv" {
                          STRING "Value";
                          VARIANT "s" {
                                  STRING "object 0x1e, path /value/a";
                          };
                  };
          };
          ARRAY "s" {
                  STRING "Value2";
                  STRING "AnExplicitProperty";
          };
  };

On success, this function returns 0 or a positive integer​. On failure, it returns a negative errno-style error code​. No error codes are currently defined​.

Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd ​pkg-config(1) file​.

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​.

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​.

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

sd-bus(3), systemd.directives(7), systemd.index(7).

The man page sd_bus_message_dump_json(3) is an alias of sd_bus_message_dump(3).