93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package cpuload
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import (
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"bufio"
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"bytes"
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"encoding/binary"
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"os"
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"syscall"
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)
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type Connection struct {
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// netlink socket
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fd int
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// cache pid to use in every netlink request.
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pid uint32
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// sequence number for netlink messages.
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seq uint32
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addr syscall.SockaddrNetlink
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rbuf *bufio.Reader
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}
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// Create and bind a new netlink socket.
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func newConnection() (*Connection, error) {
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fd, err := syscall.Socket(syscall.AF_NETLINK, syscall.SOCK_DGRAM, syscall.NETLINK_GENERIC)
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if err != nil {
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return nil, err
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}
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conn := new(Connection)
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conn.fd = fd
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conn.seq = 0
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conn.pid = uint32(os.Getpid())
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conn.addr.Family = syscall.AF_NETLINK
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conn.rbuf = bufio.NewReader(conn)
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err = syscall.Bind(fd, &conn.addr)
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if err != nil {
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syscall.Close(fd)
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return nil, err
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}
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return conn, err
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}
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func (self *Connection) Read(b []byte) (n int, err error) {
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n, _, err = syscall.Recvfrom(self.fd, b, 0)
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return n, err
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}
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func (self *Connection) Write(b []byte) (n int, err error) {
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err = syscall.Sendto(self.fd, b, 0, &self.addr)
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return len(b), err
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}
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func (self *Connection) Close() error {
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return syscall.Close(self.fd)
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}
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func (self *Connection) WriteMessage(msg syscall.NetlinkMessage) error {
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w := bytes.NewBuffer(nil)
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msg.Header.Len = uint32(syscall.NLMSG_HDRLEN + len(msg.Data))
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msg.Header.Seq = self.seq
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self.seq++
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msg.Header.Pid = self.pid
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binary.Write(w, binary.LittleEndian, msg.Header)
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_, err := w.Write(msg.Data)
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if err != nil {
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return err
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}
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_, err = self.Write(w.Bytes())
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return err
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}
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func (self *Connection) ReadMessage() (msg syscall.NetlinkMessage, err error) {
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binary.Read(self.rbuf, binary.LittleEndian, &msg.Header)
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msg.Data = make([]byte, msg.Header.Len-syscall.NLMSG_HDRLEN)
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_, err = self.rbuf.Read(msg.Data)
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return msg, err
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}
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