'\" t
.TH "SD_HWDB_NEW" "3" "" "systemd 256~rc3" "sd_hwdb_new"
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.SH "NAME"
sd_hwdb_new, sd_hwdb_new_from_path, sd_hwdb_ref, sd_hwdb_unref \- Create a new hwdb object and create or destroy references to it
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <systemd/sd\-hwdb\&.h>
.fi
.ft
.HP \w'int\ sd_hwdb_new('u
.BI "int sd_hwdb_new(sd_hwdb\ **" "hwdb" ");"
.HP \w'int\ sd_hwdb_new_from_path('u
.BI "int sd_hwdb_new_from_path(const\ char\ *" "path" ", sd_hwdb\ **" "hwdb" ");"
.HP \w'sd_hwdb*\ sd_hwdb_ref('u
.BI "sd_hwdb* sd_hwdb_ref(sd_hwdb\ *" "hwdb" ");"
.HP \w'sd_hwdb*\ sd_hwdb_unref('u
.BI "sd_hwdb* sd_hwdb_unref(sd_hwdb\ *" "hwdb" ");"
.SH "DESCRIPTION"
.PP
\fBsd_hwdb_new()\fR
creates a new hwdb object to access the binary hwdb database\&. Upon initialization, the file containing the binary representation of the hardware database is located and opened\&. The new object is returned in
\fIhwdb\fR\&.
.PP
\fBsd_hwdb_new_from_path()\fR
may be used to specify the path from which the binary hardware database should be opened\&.
.PP
The
\fIhwdb\fR
object is reference counted\&.
\fBsd_hwdb_ref()\fR
and
\fBsd_hwdb_unref()\fR
may be used to get a new reference or destroy an existing reference to an object\&. The caller must dispose of the reference acquired with
\fBsd_hwdb_new()\fR
by calling
\fBsd_hwdb_unref()\fR
when done with the object\&.
.PP
Use
\fBsd_hwdb_seek\fR(3),
\fBsd_hwdb_get\fR(3), and
\fBsd_hwdb_enumerate\fR(3)
to access entries\&.
.SH "RETURN VALUE"
.PP
On success,
\fBsd_hwdb_new()\fR
and
\fBsd_hwdb_new_from_path()\fR
return a non\-negative integer\&. On failure, a negative errno\-style error code is returned\&.
.PP
\fBsd_hwdb_ref()\fR
always returns the argument\&.
.PP
\fBsd_hwdb_unref()\fR
always returns
\fBNULL\fR\&.
.SS "Errors"
.PP
Returned errors may indicate the following problems:
.PP
\fB\-ENOENT\fR
.RS 4
The binary hardware database file could not be located\&. See
\fBsystemd-hwdb\fR(8)
for more information\&.
.sp
Added in version 246\&.
.RE
.PP
\fB\-EINVAL\fR
.RS 4
The located binary hardware database file is in an incompatible format\&.
.sp
Added in version 246\&.
.RE
.PP
\fB\-ENOMEM\fR
.RS 4
Memory allocation failed\&.
.sp
Added in version 246\&.
.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 "HISTORY"
.PP
\fBsd_hwdb_new()\fR,
\fBsd_hwdb_ref()\fR, and
\fBsd_hwdb_unref()\fR
were added in version 246\&.
.PP
\fBsd_hwdb_new_from_path()\fR
was added in version 252\&.
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1), \fBsystemd-udevd.service\fR(8), \fBsd-hwdb\fR(3), \fBsystemd-hwdb\fR(3)