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//go:build linux
package logging
import (
"bytes"
"context"
"encoding/binary"
"fmt"
"log/slog"
"net"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"syscall"
netkit "go.sudomsg.com/kit/net"
"golang.org/x/sys/unix"
)
type journalSink struct {
Level slog.Level
Tag string
Conn net.Conn
Encoder Encoder
mu sync.Mutex
ReplaceAttr func(groups []string, a slog.Attr) slog.Attr
}
var _ Sink = &journalSink{}
func newJournalSink(ctx context.Context, level slog.Level, tag string, encoder Encoder, replaceAttr func(groups []string, a slog.Attr) slog.Attr) (*journalSink, error) {
conn, err := netkit.Dial(ctx, netkit.NetUnixDatagram, "/run/systemd/journal/socket")
if err != nil {
return nil, fmt.Errorf("failed to connect to journald: %w", err)
}
if encoder == nil {
encoder = MessageEncoder
}
if tag == "" {
tag = filepath.Base(os.Args[0])
}
if tag == "" {
tag = "kit"
}
return &journalSink{
Level: level,
Tag: tag,
Conn: conn,
Encoder: encoder,
ReplaceAttr: replaceAttr,
}, nil
}
func (s *journalSink) Enabled(level slog.Level) bool {
return s.Level <= level
}
func (s *journalSink) Append(r slog.Record) error {
fields := map[string]string{
"SYSLOG_IDENTIFIER": s.Tag,
}
it := RecordAll(r, func(groups []string, a slog.Attr) slog.Attr {
var key string
switch a.Key {
case slog.LevelKey:
key = "PRIORITY"
val := a.Value.Any().(slog.Leveler).Level()
fields["PRIORTY"] = fmt.Sprintf("%d", mapLevelToSyslog(val))
return slog.Attr{}
case slog.TimeKey:
fields["SYSLOG_TIMESTAMP"] = a.Value.String()
return slog.Attr{}
case slog.SourceKey:
pc := uintptr(a.Value.Uint64())
fs := runtime.CallersFrames([]uintptr{pc})
f, _ := fs.Next()
fields["CODE_FUNC"] = f.Func.Name()
fields["CODE_FILE"] = f.File
fields["CODE_LINE"] = strconv.Itoa(f.Line)
return slog.Attr{}
default:
key = sanitizeKey(strings.Join(append(groups, a.Key), "_"))
}
fields[key] = a.Value.String()
return a
})
msg, err := s.Encoder(it)
if err != nil {
return fmt.Errorf("encoding failed: %w", err)
}
fields["MESSAGE"] = msg
return s.write(fields)
}
func (s *journalSink) write(fields map[string]string) error {
var buf bytes.Buffer
for k, v := range fields {
if strings.ContainsRune(v, '\n') {
fmt.Fprintln(&buf, k)
binary.Write(&buf, binary.LittleEndian, uint64(len(v)))
fmt.Fprintln(&buf, v)
} else {
fmt.Fprintf(&buf, "%v=%v\n", k, v)
}
}
s.mu.Lock()
defer s.mu.Unlock()
if buf.Len() < 65536 {
_, err := s.Conn.Write(buf.Bytes())
return err
}
return s.writeMemfd(buf.Bytes())
}
func (s *journalSink) writeMemfd(data []byte) error {
fd, err := unix.MemfdCreate("journal_payload", unix.MFD_CLOEXEC|unix.MFD_ALLOW_SEALING)
if err != nil {
return fmt.Errorf("memfd_create failed: %w", err)
}
defer unix.Close(fd)
_, err = unix.Write(fd, data)
if err != nil {
return err
}
_, err = unix.FcntlInt(uintptr(fd), unix.F_ADD_SEALS,
unix.F_SEAL_SHRINK|unix.F_SEAL_GROW|unix.F_SEAL_WRITE|unix.F_SEAL_SEAL)
if err != nil {
return err
}
unixConn, ok := s.Conn.(*net.UnixConn)
if !ok {
return fmt.Errorf("connection is not a unix socket")
}
rights := unix.UnixRights(fd)
_, _, err = unixConn.WriteMsgUnix(nil, rights, nil)
return err
}
func sanitizeKey(k string) string {
k = strings.TrimLeft(strings.ToUpper(k), "_")
var res strings.Builder
for _, r := range k {
if (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '_' {
res.WriteRune(r)
} else {
res.WriteRune('_')
}
}
return res.String()
}
func isJournalAvailable() bool {
const socketPath = "/run/systemd/journal/socket"
fi, err := os.Stat(socketPath)
if err != nil {
return false
}
return fi.Mode()&os.ModeSocket != 0
}
func NewHostSink(ctx context.Context, level slog.Level, tag string, encoder Encoder, replaceAttr func(groups []string, a slog.Attr) slog.Attr) (Sink, error) {
if isJournalAvailable() {
return newJournalSink(ctx, level, tag, encoder, replaceAttr)
}
return DialSyslog(ctx, netkit.NetUnixDatagram, "", encoder, SyslogOptions{
Tag: tag,
Facility: FacilityUser,
Level: level,
ReplaceAttr: replaceAttr,
})
}
func IsDaemonManaged() bool {
stream := os.Getenv("JOURNAL_STREAM")
if stream == "" {
return false
}
var stat syscall.Stat_t
if err := syscall.Fstat(2, &stat); err != nil {
return false
}
expected := fmt.Sprintf("%d:%d", stat.Dev, stat.Ino)
return stream == expected
}
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