sd_bus_message_append_string_memfd, sd_bus_message_append_string_iovec,

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). 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). 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.

sd_bus_message_append_string_memfd, sd_bus_message_append_string_iovec, sd_bus_message_append_string_space - Attach a string to a message

1. The D-Bus specification https://dbus.freedesktop.org/doc/dbus-specification.html systemd 257.7 SD_BUS_MESSAGE_APPEND_STRING_MEMFD(3)

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.

systemd(1), sd-bus(3), sd_bus_message_append_basic(3), TheD-Busspecification[1]