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
#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); |
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.
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.
Returned errors may indicate the following problems:
-ENOENT¶The binary hardware database file could not be located. See systemd-hwdb(8) for more information.
-EINVAL¶The located binary hardware database file is in an incompatible format.
-ENOMEM¶Memory allocation failed.
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.