udev

udev — libudev context

Synopsis

struct              udev;
struct udev *       udev_ref                            (struct udev *udev);
void                udev_unref                          (struct udev *udev);
struct udev *       udev_new                            (void);
void                udev_set_log_fn                     (struct udev *udev,
                                                         void (*log_fn) (struct udev *udev, int priority, const char *file, int line, const char *fn, const char *format, va_list args));
int                 udev_get_log_priority               (struct udev *udev);
void                udev_set_log_priority               (struct udev *udev,
                                                         int priority);
const char *        udev_get_sys_path                   (struct udev *udev);
const char *        udev_get_dev_path                   (struct udev *udev);
const char *        udev_get_run_path                   (struct udev *udev);
void *              udev_get_userdata                   (struct udev *udev);
void                udev_set_userdata                   (struct udev *udev,
                                                         void *userdata);

Description

The context contains the default values read from the udev config file, and is passed to all library operations.

Details

struct udev

struct udev;

Opaque object representing the library context.


udev_ref ()

struct udev *       udev_ref                            (struct udev *udev);

Take a reference of the udev library context.

udev :

udev library context

Returns :

the passed udev library context

udev_unref ()

void                udev_unref                          (struct udev *udev);

Drop a reference of the udev library context. If the refcount reaches zero, the resources of the context will be released.

udev :

udev library context

udev_new ()

struct udev *       udev_new                            (void);

Create udev library context. This reads the udev configuration file, and fills in the default values.

The initial refcount is 1, and needs to be decremented to release the resources of the udev library context.

Returns :

a new udev library context

udev_set_log_fn ()

void                udev_set_log_fn                     (struct udev *udev,
                                                         void (*log_fn) (struct udev *udev, int priority, const char *file, int line, const char *fn, const char *format, va_list args));

The built-in logging writes to stderr. It can be overridden by a custom function, to plug log messages into the users' logging functionality.

udev :

udev library context

log_fn :

function to be called for logging messages

udev_get_log_priority ()

int                 udev_get_log_priority               (struct udev *udev);

The initial logging priority is read from the udev config file at startup.

udev :

udev library context

Returns :

the current logging priority

udev_set_log_priority ()

void                udev_set_log_priority               (struct udev *udev,
                                                         int priority);

Set the current logging priority. The value controls which messages are logged.

udev :

udev library context

priority :

the new logging priority

udev_get_sys_path ()

const char *        udev_get_sys_path                   (struct udev *udev);

Retrieve the sysfs mount point. The default is "/sys". For testing purposes, it can be overridden with the environment variable SYSFS_PATH.

udev :

udev library context

Returns :

the sys mount point

udev_get_dev_path ()

const char *        udev_get_dev_path                   (struct udev *udev);

Retrieve the device directory path. The default value is "/dev", the actual value may be overridden in the udev configuration file.

udev :

udev library context

Returns :

the device directory path

udev_get_run_path ()

const char *        udev_get_run_path                   (struct udev *udev);

Retrieve the udev runtime directory path. The default is "/run/udev".

udev :

udev library context

Returns :

the runtime directory path

udev_get_userdata ()

void *              udev_get_userdata                   (struct udev *udev);

Retrieve stored data pointer from library context. This might be useful to access from callbacks like a custom logging function.

udev :

udev library context

Returns :

stored userdata

udev_set_userdata ()

void                udev_set_userdata                   (struct udev *udev,
                                                         void *userdata);

Store custom userdata in the library context.

udev :

udev library context

userdata :

data pointer