---
name: "sd_bus_message_append_string_space"
section: "3"
platform: "linux"
package: "libsystemd-dev"
version: "257.13-1~deb13u1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/sd_bus_message_append_string_memfd"
---

# sd\_bus\_message\_append\_string\_space(3)

Attach a string to a message

Part of [sd\_bus\_message\_append\_string\_memfd(3)](/sd_bus_message_append_string_memfd/3.md).

## NAME

sd\_bus\_message\_append\_string\_memfd, sd\_bus\_message\_append\_string\_iovec, sd\_bus\_message\_append\_string\_space - Attach a string to a message

## SYNOPSIS

```
#include <systemd/sd-bus.h>
```

**int sd\_bus\_message\_append\_string\_memfd(sd\_bus\_message \****m***, int** *memfd***);**

**int sd\_bus\_message\_append\_string\_iovec(sd\_bus\_message \****m***, const struct iovec \****iov***, unsigned** *n***);**

**int sd\_bus\_message\_append\_string\_space(sd\_bus\_message \****m***, size\_t** *size***, char \*\****s***);**

## DESCRIPTION

The functions **sd\_bus\_message\_append\_string\_memfd()** and **sd\_bus\_message\_append\_string\_iovec()** can be used to append a single string (item of type "s") to message *m*.

In case of **sd\_bus\_message\_append\_string\_memfd()**, the contents of *memfd* are the string. They must satisfy the same constraints as described for the "s" type in [**sd\_bus\_message\_append\_basic**(3)](/sd_bus_message_append_basic/3.md).

In case of **sd\_bus\_message\_append\_string\_iovec()**, the payload of *iov* is the string. It must satisfy the same constraints as described for the "s" type in [**sd\_bus\_message\_append\_basic**(3)](/sd_bus_message_append_basic/3.md).

The *iov* argument must point to *n* struct iovec structures. Each structure may have the iov\_base field set, in which case the memory pointed to will be copied into the message, or unset, in which case a block of spaces (ASCII 32) of length iov\_len will be inserted. The memory pointed at by *iov* may be changed after this call.

The **sd\_bus\_message\_append\_string\_space()** function appends space for a string to message *m*. It behaves similar to **sd\_bus\_message\_append\_basic()** with type "s", but instead of copying a string into the message, it returns a pointer to the destination area to the caller in pointer *p*. Space for the string of length *size* plus the terminating **NUL** is allocated.

## RETURN VALUE

On success, those calls return 0 or a positive integer. On failure, they return 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

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

The code described here uses [**getenv**(3)](/getenv/3.md), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not call [**setenv**(3)](/setenv/3.md) 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)](/systemd/1.md), [**sd-bus**(3)](/sd-bus/3.md), [**sd\_bus\_message\_append\_basic**(3)](/sd_bus_message_append_basic/3.md), **The D-Bus specification**\[1\]

## NOTES

- 1\.

  The D-Bus specification

  https://dbus.freedesktop.org/doc/dbus-specification.html