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

SYNOPSIS

       #include <systemd/sd-hwdb.h>

       int sd_hwdb_new(sd_hwdb **hwdb);

       int sd_hwdb_new_from_path(const char *path, sd_hwdb **hwdb);

       sd_hwdb* sd_hwdb_ref(sd_hwdb *hwdb);

       sd_hwdb* sd_hwdb_unref(sd_hwdb *hwdb);

DESCRIPTION

       sd_hwdb_new() 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 hwdb.

       sd_hwdb_new_from_path() may be used to specify the path from which the binary hardware
       database should be opened.

       The hwdb object is reference counted.  sd_hwdb_ref() and sd_hwdb_unref() 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 sd_hwdb_new() by calling sd_hwdb_unref() when done with the
       object.

       Use sd_hwdb_seek(3), sd_hwdb_get(3), and sd_hwdb_enumerate(3) to access entries.

RETURN VALUE

       On success, sd_hwdb_new() and sd_hwdb_new_from_path() return a non-negative integer. On
       failure, a negative errno-style error code is returned.

       sd_hwdb_ref() always returns the argument.

       sd_hwdb_unref() always returns NULL.

   Errors
       Returned errors may indicate the following problems:

       -ENOENT
           The binary hardware database file could not be located. See systemd-hwdb(8) for more
           information.

           Added in version 246.

       -EINVAL
           The located binary hardware database file is in an incompatible format.

           Added in version 246.

       -ENOMEM
           Memory allocation failed.

           Added in version 246.

NOTES

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

       The code described here uses getenv(3), which is declared to be not multi-thread-safe.
       This means that the code calling the functions described here must not call setenv(3) 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.

HISTORY

       sd_hwdb_new(), sd_hwdb_ref(), and sd_hwdb_unref() were added in version 246.

       sd_hwdb_new_from_path() was added in version 252.

SEE ALSO

       systemd(1), systemd-udevd.service(8), sd-hwdb(3), systemd-hwdb(3)