/
logexec.go
179 lines (152 loc) · 3.64 KB
/
logexec.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
package main
import (
"bufio"
"bytes"
"flag"
"fmt"
"io"
"log"
"log/syslog"
"os"
"os/exec"
"os/signal"
"strings"
"sync"
"syscall"
)
var (
stdoutLog, stderrLog *syslog.Writer
facility = logFacility(syslog.LOG_LOCAL0)
stdoutLevel = logLevel(syslog.LOG_INFO)
stderrLevel = logLevel(syslog.LOG_WARNING)
ignoreSig = false
tag string
maxLogLine = flag.Int("maxline", 8*1024,
"maximum amount of text to log in a line")
logErr = make(chan error)
sigs = make(chan os.Signal, 1)
passSigs = []os.Signal{
syscall.SIGHUP,
syscall.SIGINT,
syscall.SIGQUIT,
syscall.SIGTERM,
}
wg sync.WaitGroup
)
func init() {
flag.Var(&facility, "facility", "logging facility")
flag.Var(&stdoutLevel, "stdoutLevel", "log level for stdout")
flag.Var(&stderrLevel, "stderrLevel", "log level for stderr")
flag.BoolVar(&ignoreSig, "ignoresig", false,
"Do not pass signals on to child process")
flag.StringVar(&tag, "tag", "logexec", "Tag for all log messages")
}
func logPipe(w io.Writer, r io.Reader) {
defer wg.Done()
s := bufio.NewScanner(r)
defer func() {
if err := s.Err(); err != nil {
logErr <- err
}
}()
for s.Scan() {
l := bytes.TrimSpace(s.Bytes())
if len(l) > *maxLogLine {
l = l[:*maxLogLine]
}
_, werr := w.Write(l)
if werr != nil {
logErr <- werr
return
}
}
}
func startCmd(cmdName string, args ...string) (*exec.Cmd, error) {
var err error
lvl := syslog.Priority(stdoutLevel) | syslog.Priority(facility)
stdoutLog, err = syslog.New(lvl, tag)
if err != nil {
log.Fatalf("Error initializing stdout syslog: %v", err)
}
lvl = syslog.Priority(stderrLevel) | syslog.Priority(facility)
stderrLog, err = syslog.New(lvl, tag)
if err != nil {
log.Fatalf("Error initializing stderr syslog: %v", err)
}
cmd := exec.Command(cmdName, args...)
cmd.Stdin = os.Stdin
stdoutPipe, err := cmd.StdoutPipe()
if err != nil {
log.Fatalf("Error initializing stdout pipe: %v", err)
}
stderrPipe, err := cmd.StderrPipe()
if err != nil {
log.Fatalf("Error initializing stderr pipe: %v", err)
}
wg.Add(2)
go logPipe(stdoutLog, stdoutPipe)
go logPipe(stderrLog, stderrPipe)
return cmd, cmd.Start()
}
func getExitStatus(err error) int {
if err == nil {
return 0
}
ose, ok := err.(*exec.ExitError)
if !ok {
// Unknown error type, default to 1
return 1
}
estatus, ok := ose.Sys().(syscall.WaitStatus)
if !ok {
// Unknown sys type, default to 1
}
return estatus.ExitStatus()
}
func main() {
flag.Parse()
if flag.NArg() < 1 {
log.Fatalf("No command provided")
}
signal.Notify(sigs, passSigs...)
cmd, err := startCmd(flag.Arg(0), flag.Args()[1:]...)
if err != nil {
log.Fatalf("Error starting command: %v", err)
}
cmdChan := make(chan error)
go func() {
cmdChan <- cmd.Wait()
}()
// Signal with a channel when the loggers have completed
doneChan := make(chan bool)
go func() {
wg.Wait()
close(doneChan)
}()
for !(cmdChan == nil && doneChan == nil) {
select {
case sig := <-sigs:
if ignoreSig {
log.Printf("logexec caught signal %v, not passing through", sig)
continue
}
log.Printf("logexec caught signal %v, passing through", sig)
cmd.Process.Signal(sig)
case <-doneChan:
doneChan = nil
case err = <-cmdChan:
cmdChan = nil
if estatus := getExitStatus(err); estatus != 0 {
fmt.Fprintf(stderrLog, "Command return non-zero exit status: %v", estatus)
os.Exit(estatus)
}
case err = <-logErr:
if err != nil && err != io.EOF &&
!strings.Contains(err.Error(), "bad file descriptor") {
cmd.Process.Kill()
fmt.Fprintf(stderrLog, "Error logging command output: %v", err)
log.Fatalf("Error logging command output: %v", err)
}
}
}
}