Improve documentation.

8 files changed, 47 insertions, 40 deletions

diff --git a/sd_daemon/booted.go b/sd_daemon/booted.go
index bfbc685..b833b45 100644
--- a/sd_daemon/booted.go
+++ b/sd_daemon/booted.go
@@ -17,11 +17,11 @@ package sd_daemon
 
 import "os"
 
-// Returns whether the operating system booted using the Systemd init
+// Returns whether the operating system booted using the systemd init
 // system.
 //
 // Please do not use this function.  All of the other functionality in
-// this package uses interfaces that are not Systemd-specific.
+// this package uses interfaces that are not systemd-specific.
 func SdBooted() bool {
 	fi, err := os.Lstat("/run/systemd/system")
 	return err != nil && fi.IsDir()
diff --git a/sd_daemon/doc.go b/sd_daemon/doc.go
index 8f1fb00..90616f6 100644
--- a/sd_daemon/doc.go
+++ b/sd_daemon/doc.go
@@ -21,7 +21,7 @@
 // be much simpler; modern versions of the daemon(7) page on GNU/Linux
 // systems also describe "new-style" daemons.  Though many of the
 // mechanisms described there and implemented here originated with
-// Systemd, they are all very simple mechanisms which can easily be
+// systemd, they are all very simple mechanisms which can easily be
 // implemented with a variety of service managers.
 //
 // [daemon(7)]: https://www.freedesktop.org/software/systemd/man/daemon.html
diff --git a/sd_daemon/log.go b/sd_daemon/log.go
index 9fa62d4..9b23f31 100644
--- a/sd_daemon/log.go
+++ b/sd_daemon/log.go
@@ -25,14 +25,21 @@ import (
 	"sync"
 )
 
-// Logger writes "<N>"-prefixed lines to an io.Writer, where N is a
+// A Logger writes "<N>"-prefixed lines to an io.Writer, where N is a
 // syslog priority number.  It implements mostly the same interface as
-// "log/syslog".Writer.
+// syslog.Writer.
 //
 // You probably don't need any instance of this other than the
 // constant "Log", which uses os.Stderr as the writer.  It is
 // implemented as a struct rather than a set of functions so that it
 // can be passed around as an implementation of an interface.
+//
+// Each logging operation makes a single call to the underlying
+// Writer's Write method.  A single logging operation may be multiple
+// lines; each line will have the prefix, and they will all be written
+// in the same Write.  A Logger can be used simultaneously from
+// multiple goroutines; it guarantees to serialize access to the
+// Writer.
 type Logger struct {
 	mu  sync.Mutex
 	out io.Writer
@@ -44,9 +51,9 @@ func NewLogger(w io.Writer) *Logger {
 	return &Logger{out: w}
 }
 
-// Log is a Logger that use used very similarly to
-// "log/syslog".Writer, but writes to os.Stderr under the assumption
-// that stderr is forwarded to syslog/journald.
+// Log is a Logger whose interface is very similar to syslog.Writer,
+// but writes to os.Stderr under the assumption that stderr is
+// forwarded to syslog (or journald).
 //
 // You are encouraged to use stderr unless you have a good reason to
 // talk to syslog or journald directly.
@@ -56,7 +63,7 @@ var Log = NewLogger(os.Stderr)
 //
 //     *buf = append(*buf, fmt.Sprintf("<%d>", n)...)
 func appendPrefix(buf []byte, n syslog.Priority) []byte {
-	var b [22]byte // 21 = ceil(log_10(2^64))+len("<>")
+	var b [22]byte // 22 = ceil(log_10(2^64))+len("<>")
 	b[len(b)-1] = '>'
 	i := len(b) - 2
 	for n >= 10 {
@@ -72,7 +79,7 @@ func appendPrefix(buf []byte, n syslog.Priority) []byte {
 
 // WriteString writes a message with the specified priority to the
 // log.
-func (l *Logger) WriteString(level syslog.Priority, msg string) (n int, err error) {
+func (l *Logger) WriteString(pri syslog.Priority, msg string) (n int, err error) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
 
@@ -80,12 +87,12 @@ func (l *Logger) WriteString(level syslog.Priority, msg string) (n int, err erro
 
 	// The following is a cheap version of:
 	//
-	//    prefix := fmt.Sprintf("<%d>", level)
+	//    prefix := fmt.Sprintf("<%d>", pri)
 	//    buf := prefix + strings.Replace(msg, "\n", "\n"+prefix, -1)
 	//    return io.WriteString(l.out, buf)
 
 	l.buf = l.buf[:0]
-	l.buf = appendPrefix(l.buf, level) // possible allocation
+	l.buf = appendPrefix(l.buf, pri) // possible allocation
 	prefix := l.buf
 	nlines := strings.Count(msg, "\n") + 1
 	n = len(msg) + len(prefix)*nlines + 1
@@ -109,7 +116,7 @@ func (l *Logger) WriteString(level syslog.Priority, msg string) (n int, err erro
 
 // WriteString writes a message with the specified priority to the
 // log.
-func (l *Logger) WriteBytes(level syslog.Priority, msg []byte) (n int, err error) {
+func (l *Logger) WriteBytes(pri syslog.Priority, msg []byte) (n int, err error) {
 	// Copy/pasted from WriteString and
 	//  * `strings.` -> `bytes.`
 	//  * `"\n"` -> `[]byte{'\n'}`
@@ -119,7 +126,7 @@ func (l *Logger) WriteBytes(level syslog.Priority, msg []byte) (n int, err error
 	msg = bytes.TrimSuffix(msg, []byte{'\n'})
 
 	l.buf = l.buf[:0]
-	l.buf = appendPrefix(l.buf, level) // possible allocation
+	l.buf = appendPrefix(l.buf, pri) // possible allocation
 	prefix := l.buf
 	nlines := bytes.Count(msg, []byte{'\n'}) + 1
 	n = len(msg) + len(prefix)*nlines + 1
@@ -142,16 +149,16 @@ func (l *Logger) WriteBytes(level syslog.Priority, msg []byte) (n int, err error
 }
 
 type loggerWriter struct {
-	log   *Logger
-	level syslog.Priority
+	log *Logger
+	pri syslog.Priority
 }
 
 func (lw loggerWriter) Write(p []byte) (n int, err error) {
-	return lw.log.WriteBytes(lw.level, p)
+	return lw.log.WriteBytes(lw.pri, p)
 }
 
 // Writer returns an io.Writer that writes messages with the specified
 // priority to the log.
-func (l *Logger) Writer(level syslog.Priority) io.Writer {
-	return loggerWriter{log: l, level: level}
+func (l *Logger) Writer(pri syslog.Priority) io.Writer {
+	return loggerWriter{log: l, pri: pri}
 }
diff --git a/sd_daemon/log_test.go b/sd_daemon/log_test.go
index e2fdef9..257ccb9 100644
--- a/sd_daemon/log_test.go
+++ b/sd_daemon/log_test.go
@@ -33,8 +33,8 @@ func TestLog(t *testing.T) {
 	}))
 
 	type testcase struct {
-		level syslog.Priority
-		msg   string
+		pri syslog.Priority
+		msg string
 	}
 
 	testcases := map[testcase]string{
@@ -52,18 +52,18 @@ func TestLog(t *testing.T) {
 
 	for in, out := range testcases {
 		written = nil
-		n, err := log.WriteString(in.level, in.msg)
+		n, err := log.WriteString(in.pri, in.msg)
 		if n != len(out) || string(written) != out || err != nil {
 			t.Errorf("WriteString(%#v, %#v)\n -> expected:{%#v, %#v, %#v}\n -> got:{%#v, %#v, %#v}\n",
-				in.level, in.msg,
+				in.pri, in.msg,
 				len(out), nil, out,
 				n, err, string(written))
 		}
 		written = nil
-		n, err = log.WriteBytes(in.level, []byte(in.msg))
+		n, err = log.WriteBytes(in.pri, []byte(in.msg))
 		if n != len(out) || string(written) != out || err != nil {
 			t.Errorf("WriteBytes(%#v, %#v)\n -> expected:{%#v, %#v, %#v}\n -> got:{%#v, %#v, %#v}\n",
-				in.level, in.msg,
+				in.pri, in.msg,
 				len(out), nil, out,
 				n, err, string(written))
 		}
diff --git a/sd_daemon/log_util.go.gen b/sd_daemon/log_util.go.gen
index 95d56b0..3ca63dc 100755
--- a/sd_daemon/log_util.go.gen
+++ b/sd_daemon/log_util.go.gen
@@ -24,11 +24,11 @@ import "log/syslog"
 
 EOF
 
-	for level in Emerg Alert Crit Err Warning Notice Info Debug; do
+	for pri in Emerg Alert Crit Err Warning Notice Info Debug; do
 		cat <<EOF
-// $level writes a message with priority syslog.LOG_${level^^} to the log.
-func (l *Logger) $level(msg string) error {
-	_, err := l.WriteString(syslog.LOG_${level^^}, msg)
+// $pri writes a message with priority syslog.LOG_${pri^^} to the log.
+func (l *Logger) $pri(msg string) error {
+	_, err := l.WriteString(syslog.LOG_${pri^^}, msg)
 	return err
 }
 
diff --git a/sd_daemon/lsb/exit-status.go b/sd_daemon/lsb/exit-status.go
index fbbb5e3..9004dc3 100644
--- a/sd_daemon/lsb/exit-status.go
+++ b/sd_daemon/lsb/exit-status.go
@@ -40,7 +40,7 @@ const (
 	// 100-149 are reserved for distribution use
 	// 150-199 are reserved for application use
 	// 200-254 are reserved for init system use
-
+	//
 	// Therefore, the following are taken from systemd's
 	// `src/basic/exit-status.h`
 	EXIT_CHDIR               uint8 = 200
diff --git a/sd_daemon/notify.go b/sd_daemon/notify.go
index 76ffe81..1d72cc3 100644
--- a/sd_daemon/notify.go
+++ b/sd_daemon/notify.go
@@ -41,14 +41,15 @@ import (
 //
 // It is possible to include a set of file descriptors with the
 // message.  This is useful for keeping files open across restarts, as
-// it enables the service manager will pass those files to the new
+// it enables the service manager to pass those files to the new
 // process when it is restarted (see ListenFds).  Note: The service
 // manager will only actually store the file descriptors if you
-// include "FDSTORE=1" in the state.
+// include "FDSTORE=1" in the state (again, see sd_notify(3) for
+// well-known variable assignments).
 //
 // If the service manager is not listening for notifications from this
-// process (or this has already been called with unsetEnv=true), then
-// ErrDisabled is returned.  If the service manager appears to be
+// process tree (or this has already been called with unsetEnv=true),
+// then ErrDisabled is returned.  If the service manager appears to be
 // listening, but there is an error sending the message, then that
 // error is returned.  It is generally recommended that you ignore the
 // return value: if there is an error, this is function no-op; meaning
diff --git a/sd_daemon/watchdog.go b/sd_daemon/watchdog.go
index b32f470..be96970 100644
--- a/sd_daemon/watchdog.go
+++ b/sd_daemon/watchdog.go
@@ -31,12 +31,11 @@ import (
 // WATCHDOG_USEC and WATCHDOG_PID, which will cause further calls to
 // this function to fail.
 //
-// If an error is returned, then the duration is 0.  If the service
-// manager is not expecting a keep-alive notification from this
-// process (or if this has already been called with unsetEnv=true),
-// then ErrDisabled is returned.  If there is an error parsing the
-// service manager's watchdog request, then an appropriate other error
-// is returned.
+// If an error is not returned, then the duration returned is greater
+// than 0; if an error is returned, then the duration is 0.  If the
+// service manager is not expecting a keep-alive notification from
+// this process (or if this has already been called with
+// unsetEnv=true), then the error is ErrDisabled.
 func WatchdogEnabled(unsetEnv bool) (time.Duration, error) {
 	if unsetEnv {
 		defer func() {