'\" t
.TH "SD_BUS_MESSAGE_APPEND_STRING_MEMFD" "3" "" "systemd 255" "sd_bus_message_append_string_memfd"
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.SH "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
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <systemd/sd\-bus\&.h>
.fi
.ft
.HP \w'int\ sd_bus_message_append_string_memfd('u
.BI "int sd_bus_message_append_string_memfd(sd_bus_message\ *" "m" ", int\ " "memfd" ");"
.HP \w'int\ sd_bus_message_append_string_iovec('u
.BI "int sd_bus_message_append_string_iovec(sd_bus_message\ *" "m" ", const\ struct\ iovec\ *" "iov" ", unsigned\ " "n" ");"
.HP \w'int\ sd_bus_message_append_string_space('u
.BI "int sd_bus_message_append_string_space(sd_bus_message\ *" "m" ", size_t\ " "size" ", char\ **" "s" ");"
.SH "DESCRIPTION"
.PP
The functions
\fBsd_bus_message_append_string_memfd()\fR
and
\fBsd_bus_message_append_string_iovec()\fR
can be used to append a single string (item of type
"s") to message
\fIm\fR\&.
.PP
In case of
\fBsd_bus_message_append_string_memfd()\fR, the contents of
\fImemfd\fR
are the string\&. They must satisfy the same constraints as described for the
"s"
type in
\fBsd_bus_message_append_basic\fR(3)\&.
.PP
In case of
\fBsd_bus_message_append_string_iovec()\fR, the payload of
\fIiov\fR
is the string\&. It must satisfy the same constraints as described for the
"s"
type in
\fBsd_bus_message_append_basic\fR(3)\&.
.PP
The
\fIiov\fR
argument must point to
\fIn\fR
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
\fIiov\fR
may be changed after this call\&.
.PP
The
\fBsd_bus_message_append_string_space()\fR
function appends space for a string to message
\fIm\fR\&. It behaves similar to
\fBsd_bus_message_append_basic()\fR
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
\fIp\fR\&. Space for the string of length
\fIsize\fR
plus the terminating
\fBNUL\fR
is allocated\&.
.SH "RETURN VALUE"
.PP
On success, those calls return 0 or a positive integer\&. On failure, they return a negative errno\-style error code\&.
.SS "Errors"
.PP
Returned errors may indicate the following problems:
.PP
\fB\-EINVAL\fR
.RS 4
Specified parameter is invalid\&.
.RE
.PP
\fB\-EPERM\fR
.RS 4
Message has been sealed\&.
.RE
.PP
\fB\-ESTALE\fR
.RS 4
Message is in invalid state\&.
.RE
.PP
\fB\-ENXIO\fR
.RS 4
Message cannot be appended to\&.
.RE
.PP
\fB\-ENOMEM\fR
.RS 4
Memory allocation failed\&.
.RE
.SH "NOTES"
.PP
Functions described here are available as a shared library, which can be compiled against and linked to with the
\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
file\&.
.PP
The code described here uses
\fBgetenv\fR(3), which is declared to be not multi\-thread\-safe\&. This means that the code calling the functions described here must not call
\fBsetenv\fR(3)
from a parallel thread\&. It is recommended to only do calls to
\fBsetenv()\fR
from an early phase of the program when no other threads have been started\&.
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsd-bus\fR(3),
\fBsd_bus_message_append_basic\fR(3),
\m[blue]\fBThe D\-Bus specification\fR\m[]\&\s-2\u[1]\d\s+2
.SH "NOTES"
.IP " 1." 4
The D-Bus specification
.RS 4
\%https://dbus.freedesktop.org/doc/dbus-specification.html
.RE