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// Copyright 2021 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package kmsg
import (
"fmt"
"io"
"strconv"
"strings"
"syscall"
)
// Read reads all available kernel messages
func Read() ([]*Msg, error) {
fd, err := syscall.Open(kmsgFile, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
if err != nil {
return nil, err
}
defer syscall.Close(fd)
result := make([]*Msg, 0)
msgChan, sucChan, errChan := readKMsg(fd)
for {
select {
case err := <-errChan:
return nil, err
case <-sucChan: // finished
return result, nil
case msg := <-msgChan:
result = append(result, msg)
}
}
}
func readKMsg(fd int) (<-chan *Msg, <-chan bool, <-chan error) {
msgChan := make(chan *Msg)
sucChan := make(chan bool, 1)
errChan := make(chan error, 1)
go func() {
buf := make([]byte, 8192)
for {
n, err := syscall.Read(fd, buf)
if err != nil {
if err == io.EOF || err == syscall.EAGAIN {
// complete
sucChan <- true
return
}
if err == syscall.EPIPE {
// read failed, retry
continue
}
errChan <- err
return
}
msg, err := parseMsg(string(buf[:n]))
if err != nil {
errChan <- err
return
}
msgChan <- msg
}
}()
return msgChan, sucChan, errChan
}
func parseMsg(msg string) (*Msg, error) {
result := &Msg{}
fields := strings.Split(msg, ";")
if len(fields) < 2 {
return nil, fmt.Errorf("incorrect kernel log format")
}
result.Message = strings.TrimSuffix(fields[1], "\n")
prefix := strings.Split(fields[0], ",")
if len(prefix) < 3 {
return nil, fmt.Errorf("incorrect kernel log prefix format")
}
priority, err := strconv.Atoi(prefix[0])
if err != nil {
return result, fmt.Errorf("incorrect kernel log priority %s", prefix[0])
}
result.Facility = decodeFacility(priority)
result.Severity = decodeSeverity(priority)
seq, err := strconv.Atoi(prefix[1])
if err != nil {
return result, fmt.Errorf("incorrect kernel log sequence %s", prefix[1])
}
result.Sequence = seq
ts, err := strconv.Atoi(prefix[2])
if err != nil {
return result, fmt.Errorf("incorrect kernel log timestamp %s", prefix[2])
}
result.Timestamp = ts
return result, nil
}
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