'\" t
.TH "SD_BUS_MESSAGE_READ_BASIC" "3" "" "systemd 241" "sd_bus_message_read_basic"
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.SH "NAME"
sd_bus_message_read_basic \- Read a basic type from a message
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <systemd/sd\-bus\&.h>
.fi
.ft
.HP \w'int\ sd_bus_message_read_basic('u
.BI "int sd_bus_message_read_basic(sd_bus_message\ *" "m" ", char\ " "type" ", void\ *" "p" ");"
.SH "DESCRIPTION"
.PP
\fBsd_bus_message_read_basic()\fR
reads a basic type from a message and advances the read position in the message\&. The set of basic types and their ascii codes passed in
\fItype\fR
are described in the
\m[blue]\fBD\-Bus Specification\fR\m[]\&\s-2\u[1]\d\s+2\&.
.PP
If
\fIp\fR
is not
\fBNULL\fR, it should contain a pointer to an appropriate object\&. For example, if
\fItype\fR
is
\fB\*(Aqy\*(Aq\fR, the object passed in
\fIp\fR
should have type
uint8_t *\&. If
\fItype\fR
is
\fB\*(Aqs\*(Aq\fR, the object passed in
\fIp\fR
should have type
const char **\&. Note that, if the basic type is a pointer (e\&.g\&.,
const char *
in the case of a string), the pointer is only borrowed and the contents must be copied if they are to be used after the end of the messages lifetime\&. Similarly, during the lifetime of such a pointer, the message must not be modified\&. See the table below for a complete list of allowed types\&.
.sp
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.B Table\ \&1.\ \&Item type specifiers
.TS
allbox tab(:);
lB lB lB lB.
T{
Specifier
T}:T{
Constant
T}:T{
Description
T}:T{
Expected C Type
T}
.T&
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l
l l l l.
T{
"y"
T}:T{
\fBSD_BUS_TYPE_BYTE\fR
T}:T{
unsigned integer
T}:T{
uint8_t *
T}
T{
"b"
T}:T{
\fBSD_BUS_TYPE_BOOLEAN\fR
T}:T{
boolean
T}:T{
int *
T}
T{
"n"
T}:T{
\fBSD_BUS_TYPE_INT16\fR
T}:T{
signed integer
T}:T{
int16_t *
T}
T{
"q"
T}:T{
\fBSD_BUS_TYPE_UINT16\fR
T}:T{
unsigned integer
T}:T{
uint16_t *
T}
T{
"i"
T}:T{
\fBSD_BUS_TYPE_INT32\fR
T}:T{
signed integer
T}:T{
int32_t *
T}
T{
"u"
T}:T{
\fBSD_BUS_TYPE_UINT32\fR
T}:T{
unsigned integer
T}:T{
uint32_t *
T}
T{
"x"
T}:T{
\fBSD_BUS_TYPE_INT64\fR
T}:T{
signed integer
T}:T{
int64_t *
T}
T{
"t"
T}:T{
\fBSD_BUS_TYPE_UINT64\fR
T}:T{
unsigned integer
T}:T{
uint64_t *
T}
T{
"d"
T}:T{
\fBSD_BUS_TYPE_DOUBLE\fR
T}:T{
floating\-point
T}:T{
double *
T}
T{
"s"
T}:T{
\fBSD_BUS_TYPE_STRING\fR
T}:T{
Unicode string
T}:T{
const char **
T}
T{
"o"
T}:T{
\fBSD_BUS_TYPE_OBJECT_PATH\fR
T}:T{
object path
T}:T{
const char **
T}
T{
"g"
T}:T{
\fBSD_BUS_TYPE_SIGNATURE\fR
T}:T{
signature
T}:T{
const char **
T}
T{
"h"
T}:T{
\fBSD_BUS_TYPE_UNIX_FD\fR
T}:T{
UNIX file descriptor
T}:T{
int *
T}
.TE
.sp 1
.PP
If there is no object of the specified type at the current position in the message, an error is returned\&.
.SH "RETURN VALUE"
.PP
On success,
\fBsd_bus_message_read_basic()\fR
returns 0 or a positive integer\&. On failure, it returns a negative errno\-style error code\&.
.SH "ERRORS"
.PP
Returned errors may indicate the following problems:
.PP
\fB\-EINVAL\fR
.RS 4
Specified type string is invalid or the message parameter is
\fBNULL\fR\&.
.RE
.PP
\fB\-ENXIO\fR
.RS 4
The message does not contain the specified type at current position\&.
.RE
.PP
\fB\-EBADMSG\fR
.RS 4
The message cannot be parsed\&.
.RE
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsd-bus\fR(3),
\fBsd_bus_message_append_basic\fR(3),
\fBsd_bus_message_skip\fR(3),
\fBsd_bus_message_read\fR(3)
.SH "NOTES"
.IP " 1." 4
D-Bus Specification
.RS 4
\%https://dbus.freedesktop.org/doc/dbus-specification.html
.RE