92 lines
2.1 KiB
Go
92 lines
2.1 KiB
Go
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package journal
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import (
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"net"
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"sync"
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)
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const (
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// WellKnownSocketPath is where we generally expect to find the systemd
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// journal daemon's socket.
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WellKnownSocketPath = "/run/systemd/journal/socket"
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)
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// Conn represents an active, open connection to the systemd journal that is
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// ready to write log entries.
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type Conn struct {
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// Common attributes which are emitted for all messages.
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Common []Attr
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// ErrHandler is called if there is an error writing to the log. If nil,
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// the error is silently discarded.
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ErrHandler func(error)
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s *net.UnixConn
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bufs sync.Pool
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}
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// Connect to the systemd journal. If the path string is empty, then it uses the
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// well-known socket path.
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func Connect(path string) (*Conn, error) {
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if path == "" {
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path = WellKnownSocketPath
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}
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s, err := net.DialUnix("unixgram", nil, &net.UnixAddr{
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Name: path,
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Net: "unixgram",
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})
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if err != nil {
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return nil, err
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}
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return &Conn{
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s: s,
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bufs: sync.Pool{
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New: func() any {
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return &net.Buffers{}
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},
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},
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}, nil
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}
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var messageAttrKey = AttrKey{key: "MESSAGE"}
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// Entry emits a log entry. It will add PRIORITY and MESSAGE key/value pairs
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// as well as any Common attributes.
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//
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// Note: to avoid allocation / garbage, ensure attrs has capacity for an extra
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// 2+len(c.Common) values.
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func (c *Conn) Entry(pri Priority, msg string, attrs []Attr) {
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err := c.EntryErr(pri, msg, attrs)
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switch {
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case err == nil:
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return
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case c.ErrHandler == nil:
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return
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default:
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c.ErrHandler(err)
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}
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}
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// EntryErr is like Entry, but will propagate errors to the caller, rather than
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// using the built-in error handler.
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func (c *Conn) EntryErr(pri Priority, msg string, attrs []Attr) error {
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attrs = append(attrs, pri.Attr(), Attr{
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Key: messageAttrKey,
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Value: []byte(msg),
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})
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attrs = append(attrs, c.Common...)
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return c.WriteAttrs(attrs)
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}
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// WriteAttrs is a low-level method which writes a journal entry comprised of
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// only the given set of attributes.
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func (c *Conn) WriteAttrs(attrs []Attr) error {
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buf := c.bufs.Get().(*net.Buffers)
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*buf = (*buf)[:0]
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err := WireWrite(buf, c.s, attrs)
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c.bufs.Put(buf)
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return err
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}
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