1 // Copyright 2018 The gVisor Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 15 package log
16 17 import (
18 "fmt"
19 "os"
20 "runtime"
21 "strings"
22 "time"
23 )
24 25 // GoogleEmitter is a wrapper that emits logs in a format compatible with
26 // package github.com/golang/glog.
27 type GoogleEmitter struct {
28 *Writer
29 }
30 31 // pid is used for the threadid component of the header.
32 var pid = os.Getpid()
33 34 // Emit emits the message, google-style.
35 //
36 // Log lines have this form:
37 //
38 // Lmmdd hh:mm:ss.uuuuuu threadid file:line] msg...
39 //
40 // where the fields are defined as follows:
41 //
42 // L A single character, representing the log level (eg 'I' for INFO)
43 // mm The month (zero padded; ie May is '05')
44 // dd The day (zero padded)
45 // hh:mm:ss.uuuuuu Time in hours, minutes and fractional seconds
46 // threadid The space-padded thread ID as returned by GetTID()
47 // file The file name
48 // line The line number
49 // msg The user-supplied message
50 func (g GoogleEmitter) Emit(depth int, level Level, timestamp time.Time, format string, args ...any) {
51 // Log level.
52 prefix := byte('?')
53 switch level {
54 case Debug:
55 prefix = byte('D')
56 case Info:
57 prefix = byte('I')
58 case Warning:
59 prefix = byte('W')
60 }
61 62 // Timestamp.
63 _, month, day := timestamp.Date()
64 hour, minute, second := timestamp.Clock()
65 microsecond := int(timestamp.Nanosecond() / 1000)
66 67 // 0 = this frame.
68 _, file, line, ok := runtime.Caller(depth + 1)
69 if ok {
70 // Trim any directory path from the file.
71 slash := strings.LastIndexByte(file, byte('/'))
72 if slash >= 0 {
73 file = file[slash+1:]
74 }
75 } else {
76 // We don't have a filename.
77 file = "???"
78 line = 0
79 }
80 81 // Generate the message.
82 message := fmt.Sprintf(format, args...)
83 84 // Emit the formatted result.
85 fmt.Fprintf(g.Writer, "%c%02d%02d %02d:%02d:%02d.%06d % 7d %s:%d] %s\n", prefix, int(month), day, hour, minute, second, microsecond, pid, file, line, message)
86 }
87