sd_bus_message_append_basic

systemd
A monkey with a typewriter Zbigniew Jędrzejewski-Szmek zbyszek@in.waw.pl
sd_bus_message_append_basic 3
sd_bus_message_append_basic Attach a single part to a message

    #include <systemd/sd-bus.h>

int sd_bus_message_append_basic sd_bus_message *m char type char void *p

## Description

`sd_bus_message_append_basic` appends a single item to the message m. Parameter type determines how pointer p is interpreted. type must be one of the basic types as defined by the Basic Types section of the D-Bus specification, and listed in the table below.

Item format specifiers

Specifier | Constant | Description | Size
--- | --- | --- | ---
`y` | `SD_BUS_TYPE_BYTE` | unsigned integer | 1 byte
`b` | `SD_BUS_TYPE_BOOLEAN` | boolean | 4 bytes
`n` | `SD_BUS_TYPE_INT16` | signed integer | 2 bytes
`q` | `SD_BUS_TYPE_UINT16` | unsigned integer | 2 bytes
`i` | `SD_BUS_TYPE_INT32` | signed integer | 4 bytes
`u` | `SD_BUS_TYPE_UINT32` | unsigned integer | 4 bytes
`x` | `SD_BUS_TYPE_INT64` | signed integer | 8 bytes
`t` | `SD_BUS_TYPE_UINT64` | unsigned integer | 8 bytes
`d` | `SD_BUS_TYPE_DOUBLE` | floating-point | 8 bytes
`s` | `SD_BUS_TYPE_STRING` | Unicode string | variable
`o` | `SD_BUS_TYPE_OBJECT_PATH` | object path | variable
`g` | `SD_BUS_TYPE_SIGNATURE` | signature | variable
`h` | `SD_BUS_TYPE_UNIX_FD` | UNIX file descriptor | 4 bytes

The value of the parameter is copied into the memory area containing the message and may be changed after this call. If type is `h` (UNIX file descriptor), it is always "consumed" by this call, and either successfully appended to the message or closed.

For types `s`, `o`, and `g`, the parameter p is interpreted as a pointer to a `NUL`-terminated character sequence. As a special case, a `NULL` pointer is interpreted as an empty string. The string should be valid Unicode string encoded as UTF-8. In case of the two latter types, the additional requirements for a D-Bus object path or type signature should be satisfied. Those requirements should be verified by the recipient of the message.

## Return Value

On success, this call returns 0 or a positive integer. On failure, it returns a negative errno-style error code.

## Errors

Returned errors may indicate the following problems:

`-EINVAL`

  Specified parameter is invalid.

`-EPERM`

  Message has been sealed.

`-ESTALE`

  Message is in invalid state.

`-ENXIO`

  Message cannot be appended to.

`-ENOMEM`

  Memory allocation failed.

## Notes

The `sd_bus_append_basic()` function described here is available as a shared library, which can be compiled and linked to with the `libsystemd` pkg-config 1 file.

## See Also

systemd 1, sd-bus 3, sd_bus_message_append 3, The D-Bus specification