github.com/openebs/node-disk-manager@v1.9.1-0.20230225014141-4531f06ffa1e/pkg/udev/device.go (about)

     1  /*
     2  Copyright 2018 OpenEBS Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  // +build linux,cgo
    18  
    19  package udev
    20  
    21  /*
    22    #cgo LDFLAGS: -ludev
    23    #include <libudev.h>
    24  */
    25  import "C"
    26  import "errors"
    27  
    28  // UdevDevice wraps a libudev device object
    29  type UdevDevice struct {
    30  	udptr *C.struct_udev_device
    31  }
    32  
    33  // newUdevDevice is a private helper function and returns a pointer to a new device
    34  // it returns nil if the pointer passed is NULL.
    35  func newUdevDevice(ptr *C.struct_udev_device) (*UdevDevice, error) {
    36  	if ptr == nil {
    37  		return nil, errors.New("unable to create Udevice object for null struct struct_udev_device")
    38  	}
    39  	ud := &UdevDevice{
    40  		udptr: ptr,
    41  	}
    42  	return ud, nil
    43  }
    44  
    45  // GetPropertyValue retrieves the value of a device property
    46  func (ud *UdevDevice) GetPropertyValue(key string) string {
    47  	k := C.CString(key)
    48  	defer freeCharPtr(k)
    49  	return C.GoString(C.udev_device_get_property_value(ud.udptr, k))
    50  }
    51  
    52  // GetSysattrValue retrieves the content of a sys attribute file
    53  // returns an empty string if there is no sys attribute value.
    54  // The retrieved value is cached in the device. Repeated calls
    55  // will return the same value and not open the attribute again.
    56  func (ud *UdevDevice) GetSysattrValue(sysattr string) string {
    57  	k := C.CString(sysattr)
    58  	defer freeCharPtr(k)
    59  	return C.GoString(C.udev_device_get_sysattr_value(ud.udptr, k))
    60  }
    61  
    62  // GetDevtype returns the devtype string of the udev device.
    63  func (ud *UdevDevice) GetDevtype() string {
    64  	return C.GoString(C.udev_device_get_devtype(ud.udptr))
    65  }
    66  
    67  // GetDevnode returns the device node file name belonging to the udev device.
    68  // The path is an absolute path, and starts with the device directory.
    69  func (ud *UdevDevice) GetDevnode() string {
    70  	return C.GoString(C.udev_device_get_devnode(ud.udptr))
    71  }
    72  
    73  // GetAction returns device action when it is monitored.
    74  // It can be add,remove,online,offline,change
    75  func (ud *UdevDevice) GetAction() string {
    76  	return C.GoString(C.udev_device_get_action(ud.udptr))
    77  }
    78  
    79  // UdevDeviceUnref frees udev_device structure.
    80  func (ud *UdevDevice) UdevDeviceUnref() {
    81  	C.udev_device_unref(ud.udptr)
    82  }