NAME¶

sd_bus_message_dump, sd_bus_message_dump_json - Produce a string representation of a message for debugging purposes

SYNOPSIS¶

#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);

DESCRIPTION¶

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

SD_BUS_MESSAGE_DUMP_SUBTREE_ONLY

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).

EXAMPLES¶

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";


          };


  };

RETURN VALUE¶

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.

NOTES¶

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 started.

SEE ALSO¶

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