sd_hwdb_get

systemd

sd_hwdb_get

3

sd_hwdb_get

sd_hwdb_seek

sd_hwdb_enumerate

SD_HWDB_FOREACH_PROPERTY

Seek to a location in hwdb or access entries

#include <systemd/sd-hwdb.h>

int

sd_hwdb_get

sd_hwdb *

hwdb

const char *

modalias

const char *

key

const char **

value

int

sd_hwdb_seek

sd_hwdb *

hwdb

const char *

modalias

int

sd_hwdb_enumerate

sd_hwdb *

hwdb

const char **

key

const char **

value

SD_HWDB_FOREACH_PROPERTY

hwdb

modalias

key

value

Description

sd_hwdb_get() queries the hwdb object created earlier with sd_hwdb_new(3) for entries matching the specified string modalias, and returns the value corresponding to the key key. The value is returned as a NUL-terminated string in value. It must not be modified by the caller and is valid as long as a reference to hwdb is kept. When multiple patterns in the database match modalias, the one with the highest priority is used. See hwdb(7) for details.

sd_hwdb_seek() selects entries matching the specified string modalias. Subsequent queries with sd_hwdb_enumerate() will access the key-value pairs for that string.

sd_hwdb_enumerate() returns (in turn) all the key-value pairs defined for the string used with sd_hwdb_seek(). Each pair is returned as NUL-terminated strings in key and value. The strings must not be modified by the caller and are valid as long as a reference to hwdb is kept. When multiple patterns in the database match modalias, the combination of all matching key-value pairs is used. See hwdb(7) for details.

The SD_HWDB_FOREACH_PROPERTY() macro combines sd_hwdb_seek() and sd_hwdb_enumerate(). No error handling is performed and iteration simply stops on error. See the example below.

Return Value

On success, sd_hwdb_get() and sd_hwdb_seek() return a non-negative integer. On failure, they return a negative errno-style error code.

sd_hwdb_enumerate() returns a positive integer if another key-value pair was found or zero if all entries have already been enumerated. On failure, it returns a negative errno-style error code.

Errors

Returned errors may indicate the following problems:

-EINVAL
A parameter is NULL.

-ENOENT
An entry for the specified modalias was not found.

-EAGAIN
sd_hwdb_seek() was not called before sd_hwdb_enumerate().

Examples

History

sd_hwdb_get(), sd_hwdb_seek(), sd_hwdb_enumerate(), and SD_HWDB_FOREACH_PROPERTY() were added in version 246.

See Also

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