blob: e4010ad4df06ada54a2230057ea7605500d67422 [file] [log] [blame]
Scott Bakere7144bc2019-10-01 14:16:47 -07001// Go support for leveled logs, analogous to https://code.google.com/p/google-glog/
2//
3// Copyright 2013 Google Inc. All Rights Reserved.
4//
5// Licensed under the Apache License, Version 2.0 (the "License");
6// you may not use this file except in compliance with the License.
7// You may obtain a copy of the License at
8//
9// http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing, software
12// distributed under the License is distributed on an "AS IS" BASIS,
13// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14// See the License for the specific language governing permissions and
15// limitations under the License.
16
17// File I/O for logs.
18
19package klog
20
21import (
22 "errors"
23 "fmt"
24 "os"
25 "os/user"
26 "path/filepath"
27 "strings"
28 "sync"
29 "time"
30)
31
32// MaxSize is the maximum size of a log file in bytes.
33var MaxSize uint64 = 1024 * 1024 * 1800
34
35// logDirs lists the candidate directories for new log files.
36var logDirs []string
37
38func createLogDirs() {
39 if logging.logDir != "" {
40 logDirs = append(logDirs, logging.logDir)
41 }
42 logDirs = append(logDirs, os.TempDir())
43}
44
45var (
46 pid = os.Getpid()
47 program = filepath.Base(os.Args[0])
48 host = "unknownhost"
49 userName = "unknownuser"
50)
51
52func init() {
53 h, err := os.Hostname()
54 if err == nil {
55 host = shortHostname(h)
56 }
57
58 current, err := user.Current()
59 if err == nil {
60 userName = current.Username
61 }
62
63 // Sanitize userName since it may contain filepath separators on Windows.
64 userName = strings.Replace(userName, `\`, "_", -1)
65}
66
67// shortHostname returns its argument, truncating at the first period.
68// For instance, given "www.google.com" it returns "www".
69func shortHostname(hostname string) string {
70 if i := strings.Index(hostname, "."); i >= 0 {
71 return hostname[:i]
72 }
73 return hostname
74}
75
76// logName returns a new log file name containing tag, with start time t, and
77// the name for the symlink for tag.
78func logName(tag string, t time.Time) (name, link string) {
79 name = fmt.Sprintf("%s.%s.%s.log.%s.%04d%02d%02d-%02d%02d%02d.%d",
80 program,
81 host,
82 userName,
83 tag,
84 t.Year(),
85 t.Month(),
86 t.Day(),
87 t.Hour(),
88 t.Minute(),
89 t.Second(),
90 pid)
91 return name, program + "." + tag
92}
93
94var onceLogDirs sync.Once
95
96// create creates a new log file and returns the file and its filename, which
97// contains tag ("INFO", "FATAL", etc.) and t. If the file is created
98// successfully, create also attempts to update the symlink for that tag, ignoring
99// errors.
girishke7ca43b2019-10-10 12:30:03 +0000100// The startup argument indicates whether this is the initial startup of klog.
101// If startup is true, existing files are opened for appending instead of truncated.
102func create(tag string, t time.Time, startup bool) (f *os.File, filename string, err error) {
Scott Bakere7144bc2019-10-01 14:16:47 -0700103 if logging.logFile != "" {
girishke7ca43b2019-10-10 12:30:03 +0000104 f, err := openOrCreate(logging.logFile, startup)
Scott Bakere7144bc2019-10-01 14:16:47 -0700105 if err == nil {
106 return f, logging.logFile, nil
107 }
108 return nil, "", fmt.Errorf("log: unable to create log: %v", err)
109 }
110 onceLogDirs.Do(createLogDirs)
111 if len(logDirs) == 0 {
112 return nil, "", errors.New("log: no log dirs")
113 }
114 name, link := logName(tag, t)
115 var lastErr error
116 for _, dir := range logDirs {
117 fname := filepath.Join(dir, name)
girishke7ca43b2019-10-10 12:30:03 +0000118 f, err := openOrCreate(fname, startup)
Scott Bakere7144bc2019-10-01 14:16:47 -0700119 if err == nil {
120 symlink := filepath.Join(dir, link)
121 os.Remove(symlink) // ignore err
122 os.Symlink(name, symlink) // ignore err
123 return f, fname, nil
124 }
125 lastErr = err
126 }
127 return nil, "", fmt.Errorf("log: cannot create log: %v", lastErr)
128}
girishke7ca43b2019-10-10 12:30:03 +0000129
130// The startup argument indicates whether this is the initial startup of klog.
131// If startup is true, existing files are opened for appending instead of truncated.
132func openOrCreate(name string, startup bool) (*os.File, error) {
133 if startup {
134 f, err := os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
135 return f, err
136 }
137 f, err := os.Create(name)
138 return f, err
139}