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logger.go
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logger.go
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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
*/
package device
import (
"log"
"os"
)
// A Logger provides logging for a Device.
// The functions are Printf-style functions.
// They must be safe for concurrent use.
// They do not require a trailing newline in the format.
// If nil, that level of logging will be silent.
type Logger struct {
Verbosef func(format string, args ...interface{})
Errorf func(format string, args ...interface{})
}
// Log levels for use with NewLogger.
const (
LogLevelSilent = iota
LogLevelError
LogLevelVerbose
)
// Function for use in Logger for discarding logged lines.
func DiscardLogf(format string, args ...interface{}) {}
// NewLogger constructs a Logger that writes to stdout.
// It logs at the specified log level and above.
// It decorates log lines with the log level, date, time, and prepend.
func NewLogger(level int, prepend string) *Logger {
logger := &Logger{DiscardLogf, DiscardLogf}
logf := func(prefix string) func(string, ...interface{}) {
return log.New(os.Stdout, prefix+": "+prepend, log.Ldate|log.Ltime).Printf
}
if level >= LogLevelVerbose {
logger.Verbosef = logf("DEBUG")
}
if level >= LogLevelError {
logger.Errorf = logf("ERROR")
}
return logger
}