Adding logging and some common functions.

lib/defs.go

@@ -0,0 +1,11 @@
+package lib
+
+// Various constants used throughout the tools.
+
+const (
+	// ExitSuccess is the successful exit status.
+	ExitSuccess = 0
+
+	// ExitFailure is the failing exit status.
+	ExitFailure = 1
+)

lib/lib.go

@@ -0,0 +1,47 @@
+// Package lib contains functions useful for most programs.
+package lib
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+var progname = filepath.Base(os.Args[0])
+
+// Warnx displays a formatted error message to standard error, à la
+// warnx(3).
+func Warnx(format string, a ...interface{}) (int, error) {
+	format = fmt.Sprintf("[%s] %s", progname, format)
+	format += "\n"
+	return fmt.Fprintf(os.Stderr, format, a...)
+}
+
+// Warn displays a formatted error message to standard output,
+// appending the error string, à la warn(3).
+func Warn(err error, format string, a ...interface{}) (int, error) {
+	format = fmt.Sprintf("[%s] %s", progname, format)
+	format += ": %v\n"
+	a = append(a, err)
+	return fmt.Fprintf(os.Stderr, format, a...)
+}
+
+// Errx displays a formatted error message to standard error and exits
+// with the status code from `exit`, à la errx(3).
+func Errx(exit int, format string, a ...interface{}) {
+	format = fmt.Sprintf("[%s] %s", progname, format)
+	format += "\n"
+	fmt.Fprintf(os.Stderr, format, a...)
+	os.Exit(exit)
+}
+
+// Err displays a formatting error message to standard error,
+// appending the error string, and exits with the status code from
+// `exit`, à la err(3).
+func Err(exit int, err error, format string, a ...interface{}) {
+	format = fmt.Sprintf("[%s] %s", progname, format)
+	format += ": %v\n"
+	a = append(a, err)
+	fmt.Fprintf(os.Stderr, format, a...)
+	os.Exit(exit)
+}