restic/debug/debug.go

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// +build debug
package debug
import (
"fmt"
"log"
"os"
"path"
"runtime"
"strings"
"sync"
"syscall"
)
var opts struct {
tags map[string]bool
breaks map[string]bool
m sync.Mutex
}
var debugLogger = initDebugLogger()
func initDebugLogger() (lgr *log.Logger) {
opts.tags = make(map[string]bool)
opts.breaks = make(map[string]bool)
fmt.Fprintf(os.Stderr, "debug enabled\n")
debugfile := os.Getenv("DEBUG_LOG")
if debugfile != "" {
fmt.Fprintf(os.Stderr, "debug log file %v\n", debugfile)
// open logfile
f, err := os.OpenFile(debugfile, os.O_WRONLY|os.O_APPEND, 0600)
if err == nil {
// seek to the end
_, err = f.Seek(2, 0)
if err != nil {
fmt.Fprintf(os.Stderr, "unable to seek to the end of %v: %v\n", debugfile, err)
os.Exit(3)
}
}
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if err != nil && os.IsNotExist(err) {
// create logfile
f, err = os.OpenFile(debugfile, os.O_WRONLY|os.O_CREATE, 0600)
}
if err != nil {
fmt.Fprintf(os.Stderr, "unable to open debug log file: %v\n", err)
os.Exit(2)
}
// open logger
lgr = log.New(f, "", log.LstdFlags)
}
// defaults
opts.tags["break"] = true
// initialize tags
env := os.Getenv("DEBUG_TAGS")
if len(env) > 0 {
tags := []string{}
for _, tag := range strings.Split(env, ",") {
t := strings.TrimSpace(tag)
val := true
if t[0] == '-' {
val = false
t = t[1:]
} else if t[0] == '+' {
val = true
t = t[1:]
}
// test pattern
_, err := path.Match(t, "")
if err != nil {
fmt.Fprintf(os.Stderr, "error: invalid pattern %q: %v\n", t, err)
os.Exit(5)
}
opts.tags[t] = val
tags = append(tags, tag)
}
fmt.Fprintf(os.Stderr, "debug log enabled for: %v\n", tags)
}
// initialize break tags
env = os.Getenv("DEBUG_BREAK")
if len(env) > 0 {
breaks := []string{}
for _, tag := range strings.Split(env, ",") {
t := strings.TrimSpace(tag)
opts.breaks[t] = true
breaks = append(breaks, t)
}
fmt.Fprintf(os.Stderr, "debug breaks enabled for: %v\n", breaks)
}
return
}
func Log(tag string, f string, args ...interface{}) {
// synchronize log writes
opts.m.Lock()
defer opts.m.Unlock()
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if f[len(f)-1] != '\n' {
f += "\n"
}
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dbgprint := func() {
fmt.Fprintf(os.Stderr, "DEBUG["+tag+"]: "+f, args...)
}
if debugLogger != nil {
debugLogger.Printf("["+tag+"] "+f, args...)
}
// check if tag is enabled directly
if v, ok := opts.tags[tag]; ok {
if v {
dbgprint()
}
return
}
// check for globbing
for k, v := range opts.tags {
if m, _ := path.Match(k, tag); m {
if v {
dbgprint()
}
return
}
}
// check if tag "all" is enabled
if v, ok := opts.tags["all"]; ok && v {
dbgprint()
}
}
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// Break stops the program if the debug tag is active and the string in tag is
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// contained in the DEBUG_BREAK environment variable.
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func Break(tag string) {
// check if breaking is enabled
if v, ok := opts.breaks[tag]; !ok || !v {
return
}
_, file, line, _ := runtime.Caller(1)
Log("break", "stopping process %d at %s (%v:%v)\n", os.Getpid(), tag, file, line)
p, err := os.FindProcess(os.Getpid())
if err != nil {
panic(err)
}
err = p.Signal(syscall.SIGSTOP)
if err != nil {
panic(err)
}
}
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// BreakIf stops the program if the debug tag is active and the string in tag
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// is contained in the DEBUG_BREAK environment variable and the return value of
// fn is true.
func BreakIf(tag string, fn func() bool) {
// check if breaking is enabled
if v, ok := opts.breaks[tag]; !ok || !v {
return
}
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if fn() {
Break(tag)
}
}