config: add a Require message.

Also update explanation of the intended use-case for this package.

.travis.yml

@@ -4,7 +4,7 @@ go:
   - tip
   - 1.9
 script: 
-  - go get github.com/golang/lint/golint
+  - go get golang.org/x/lint/golint
   - go get golang.org/x/tools/cmd/cover
   - go get github.com/kisom/goutils/... 
   - go test -cover github.com/kisom/goutils/... 

README.md

@@ -7,6 +7,9 @@ Note that for packaging purposes, the goutils-pkg repo should be used: it
 pins the library versions to working copies and vendors all depdencies. See
 https://github.com/kisom/goutils-pkg for more details.
 
+The goutils-pkg repo [1] has stable versions of the command line
+utilities here, along with a vendored snapshot of any dependencies.
+
 Contents:
 
     ahash/          Provides hashes from string algorithm specifiers.
@@ -62,3 +65,5 @@ Each program should have a small README in the directory with more
 information.
 
 All code here is licensed under the MIT license.
+
+[1] https://github.com/kisom/goutils-pkg/

cmd/parts/README

@@ -0,0 +1,9 @@
+parts: simple parts database for electronic components
+
+Usage:  parts [id] -- query the database for a part
+	parts [-c class] [id] [description] -- store a part in the database
+
+	Options:
+		-f path		Path to parts database (default is
+				/home/kyle/.parts.json).
+

cmd/parts/main.go

@@ -0,0 +1,142 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/kisom/goutils/die"
+)
+
+const dbVersion = "1"
+
+var dbFile = filepath.Join(os.Getenv("HOME"), ".parts.json")
+var partsDB = &database{Version: dbVersion}
+
+type part struct {
+	Name        string `json:"name"`
+	Description string `json:"description"`
+	Class       string `json:"class,omitempty"`
+}
+
+func (p part) String() string {
+	return fmt.Sprintf("%s: %s", p.Name, p.Description)
+}
+
+type database struct {
+	Version    string          `json:"version"`
+	LastUpdate int64           `json:"json"`
+	Parts      map[string]part `json:"parts"`
+}
+
+func help(w io.Writer) {
+	fmt.Fprintf(w, `Usage:  parts [id] -- query the database for a part
+	parts [-c class] [id] [description] -- store a part in the database
+
+	Options:
+		-f path		Path to parts database (default is
+				%s).
+          
+`, dbFile)
+}
+
+func loadDatabase() {
+	data, err := ioutil.ReadFile(dbFile)
+	if err != nil && os.IsNotExist(err) {
+		partsDB = &database{
+			Version: dbVersion,
+			Parts:   map[string]part{},
+		}
+		return
+	}
+	die.If(err)
+
+	err = json.Unmarshal(data, partsDB)
+	die.If(err)
+}
+
+func findPart(partName string) {
+	partName = strings.ToLower(partName)
+	for name, part := range partsDB.Parts {
+		if strings.Contains(strings.ToLower(name), partName) {
+			fmt.Println(part.String())
+		}
+	}
+}
+
+func writeDB() {
+	data, err := json.Marshal(partsDB)
+	die.If(err)
+
+	err = ioutil.WriteFile(dbFile, data, 0644)
+	die.If(err)
+}
+
+func storePart(name, class, description string) {
+	p, exists := partsDB.Parts[name]
+	if exists {
+		fmt.Printf("warning: replacing part %s\n", name)
+		fmt.Printf("\t%s\n", p.String())
+	}
+
+	partsDB.Parts[name] = part{
+		Name:        name,
+		Class:       class,
+		Description: description,
+	}
+
+	writeDB()
+}
+
+func listParts() {
+	parts := make([]string, 0, len(partsDB.Parts))
+	for partName := range partsDB.Parts {
+		parts = append(parts, partName)
+	}
+
+	sort.Strings(parts)
+	for _, partName := range parts {
+		fmt.Println(partsDB.Parts[partName].String())
+	}
+}
+
+func main() {
+	var class string
+	var helpFlag bool
+
+	flag.StringVar(&class, "c", "", "device class")
+	flag.StringVar(&dbFile, "f", dbFile, "`path` to database")
+	flag.BoolVar(&helpFlag, "h", false, "Print a help message.")
+	flag.Parse()
+
+	if helpFlag {
+		help(os.Stdout)
+		return
+	}
+
+	loadDatabase()
+
+	switch flag.NArg() {
+	case 0:
+		help(os.Stdout)
+		return
+	case 1:
+		partName := flag.Arg(0)
+		if partName == "list" {
+			listParts()
+		} else {
+			findPart(flag.Arg(0))
+		}
+		return
+	default:
+		description := strings.Join(flag.Args()[1:], " ")
+		storePart(flag.Arg(0), class, description)
+		return
+	}
+}

cmd/sprox/main.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"flag"
+	"io"
+	"log"
+	"net"
+
+	"github.com/kisom/goutils/die"
+)
+
+func proxy(conn net.Conn, inside string) error {
+	proxyConn, err := net.Dial("tcp", inside)
+	if err != nil {
+		return err
+	}
+
+	defer proxyConn.Close()
+	defer conn.Close()
+
+	go func() {
+		io.Copy(conn, proxyConn)
+	}()
+	_, err = io.Copy(proxyConn, conn)
+	return err
+}
+
+func main() {
+	var outside, inside string
+	flag.StringVar(&outside, "f", "8080", "outside port")
+	flag.StringVar(&inside, "p", "4000", "inside port")
+	flag.Parse()
+
+	l, err := net.Listen("tcp", "0.0.0.0:"+outside)
+	die.If(err)
+
+	for {
+		conn, err := l.Accept()
+		if err != nil {
+			log.Println(err)
+			continue
+		}
+
+		go proxy(conn, "127.0.0.1:"+inside)
+	}
+}

config/config.go

@@ -0,0 +1,110 @@
+// Package config implements a simple global configuration system that
+// supports a file with key=value pairs and environment variables. Note
+// that the config system is global.
+//
+// This package is intended to be used for small daemons: some configuration
+// file is optionally populated at program start, then this is used to
+// transparently look up configuration values from either that file or the
+// environment.
+package config
+
+import (
+	"bufio"
+	"log"
+	"os"
+	"strings"
+)
+
+// NB: Rather than define a singleton type, everything is defined at
+// the top-level
+
+var (
+	vars   = map[string]string{}
+	prefix = ""
+)
+
+// SetEnvPrefix sets the prefix for all environment variables; it's
+// assumed to not be needed for files.
+func SetEnvPrefix(pfx string) {
+	prefix = pfx
+}
+
+func addLine(line string) {
+	if strings.HasPrefix(line, "#") || line == "" {
+		return
+	}
+
+	lineParts := strings.SplitN(line, "=", 2)
+	if len(lineParts) != 2 {
+		log.Print("skipping line: ", line)
+		return // silently ignore empty keys
+	}
+
+	lineParts[0] = strings.TrimSpace(lineParts[0])
+	lineParts[1] = strings.TrimSpace(lineParts[1])
+	vars[lineParts[0]] = lineParts[1]
+}
+
+// LoadFile scans the file at path for key=value pairs and adds them
+// to the configuration.
+func LoadFile(path string) error {
+	file, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		addLine(line)
+	}
+
+	if err = scanner.Err(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Get retrieves a value from either a configuration file or the
+// environment. Note that values from a file will override environment
+// variables.
+func Get(key string) string {
+	if v, ok := vars[key]; ok {
+		return v
+	}
+	return os.Getenv(prefix + key)
+}
+
+// GetDefault retrieves a value from either a configuration file or
+// the environment. Note that value from a file will override
+// environment variables. If a value isn't found (e.g. Get returns an
+// empty string), the default value will be used.
+func GetDefault(key, def string) string {
+	if v := Get(key); v != "" {
+		return v
+	}
+	return def
+}
+
+// Require retrieves a value from either a configuration file or the
+// environment. If the key isn't present, it will call log.Fatal, printing
+// the missing key.
+func Require(key string) string {
+	if v, ok := vars[key]; ok {
+		return v
+	}
+
+	v, ok := os.LookupEnv(prefix + key)
+	if !ok {
+		var envMessage string
+		if prefix != "" {
+			envMessage = " (note: looked for the key " + prefix + key
+			envMessage += " in the local env)"
+		}
+		log.Fatalf("missing required configuration value %s%s", key, envMessage)
+	}
+
+	return v
+}

config/config_test.go

@@ -0,0 +1,66 @@
+package config
+
+import (
+	"os"
+	"testing"
+)
+
+const (
+	testFilePath = "testdata/test.env"
+
+	// Keys
+	kOrder   = "ORDER"
+	kSpecies = "SPECIES"
+	kName    = "COMMON_NAME"
+
+	// Env
+	eOrder   = "corvus"
+	eSpecies = "corvus corax"
+	eName    = "northern raven"
+
+	// File
+	fOrder   = "stringiformes"
+	fSpecies = "strix aluco"
+	// Name isn't set in the file to test fall through.
+)
+
+func init() {
+	os.Setenv(kOrder, eOrder)
+	os.Setenv(kSpecies, eSpecies)
+	os.Setenv(kName, eName)
+}
+
+func TestLoadEnvOnly(t *testing.T) {
+	order := Get(kOrder)
+	species := Get(kSpecies)
+	if order != eOrder {
+		t.Errorf("want %s, have %s", eOrder, order)
+	}
+
+	if species != eSpecies {
+		t.Errorf("want %s, have %s", eSpecies, species)
+	}
+}
+
+func TestLoadFile(t *testing.T) {
+	err := LoadFile(testFilePath)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	order := Get(kOrder)
+	species := Get(kSpecies)
+	name := Get(kName)
+
+	if order != fOrder {
+		t.Errorf("want %s, have %s", fOrder, order)
+	}
+
+	if species != fSpecies {
+		t.Errorf("want %s, have %s", fSpecies, species)
+	}
+
+	if name != eName {
+		t.Errorf("want %s, have %s", eName, name)
+	}
+}

config/testdata/test.env

@@ -0,0 +1,2 @@
+ORDER=stringiformes
+SPECIES=strix aluco

dbg/dbg.go

@@ -0,0 +1,76 @@
+// Package dbg implements a debug printer.
+package dbg
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+// A DebugPrinter is a drop-in replacement for fmt.Print*, and also acts as
+// an io.WriteCloser when enabled.
+type DebugPrinter struct {
+	// If Enabled is false, the print statements won't do anything.
+	Enabled bool
+	out     io.WriteCloser
+}
+
+// Close satisfies the Closer interface.
+func (dbg *DebugPrinter) Close() error {
+	return dbg.out.Close()
+}
+
+// Write satisfies the Writer interface.
+func (dbg *DebugPrinter) Write(p []byte) (int, error) {
+	if dbg.Enabled {
+		return dbg.out.Write(p)
+	}
+	return 0, nil
+}
+
+// New returns a new DebugPrinter on os.Stdout.
+func New() *DebugPrinter {
+	return &DebugPrinter{
+		out: os.Stdout,
+	}
+}
+
+// ToFile sets up a new DebugPrinter to a file, truncating it if it exists.
+func ToFile(path string) (*DebugPrinter, error) {
+	file, err := os.Create(path)
+	if err != nil {
+		return nil, err
+	}
+
+	return &DebugPrinter{
+		out: file,
+	}, nil
+}
+
+// To sets up a new DebugPrint to an io.WriteCloser.
+func To(w io.WriteCloser) *DebugPrinter {
+	return &DebugPrinter{
+		out: w,
+	}
+}
+
+// Print calls fmt.Print if Enabled is true.
+func (dbg DebugPrinter) Print(v ...interface{}) {
+	if dbg.Enabled {
+		fmt.Fprint(dbg.out, v...)
+	}
+}
+
+// Println calls fmt.Println if Enabled is true.
+func (dbg DebugPrinter) Println(v ...interface{}) {
+	if dbg.Enabled {
+		fmt.Fprintln(dbg.out, v...)
+	}
+}
+
+// Printf calls fmt.Printf if Enabled is true.
+func (dbg DebugPrinter) Printf(format string, v ...interface{}) {
+	if dbg.Enabled {
+		fmt.Fprintf(dbg.out, format, v...)
+	}
+}

dbg/dbg_test.go

@@ -0,0 +1,120 @@
+package dbg
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/kisom/goutils/testio"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNew(t *testing.T) {
+	buf := testio.NewBufCloser(nil)
+	dbg := New()
+	dbg.out = buf
+
+	dbg.Print("hello")
+	dbg.Println("hello")
+	dbg.Printf("hello %s", "world")
+	require.Equal(t, 0, buf.Len())
+
+	dbg.Enabled = true
+	dbg.Print("hello")              // +5
+	dbg.Println("hello")            // +6
+	dbg.Printf("hello %s", "world") // +11
+	require.Equal(t, 22, buf.Len())
+
+	err := dbg.Close()
+	require.NoError(t, err)
+}
+
+func TestTo(t *testing.T) {
+	buf := testio.NewBufCloser(nil)
+	dbg := To(buf)
+
+	dbg.Print("hello")
+	dbg.Println("hello")
+	dbg.Printf("hello %s", "world")
+	require.Equal(t, 0, buf.Len())
+
+	dbg.Enabled = true
+	dbg.Print("hello")              // +5
+	dbg.Println("hello")            // +6
+	dbg.Printf("hello %s", "world") // +11
+
+	require.Equal(t, 22, buf.Len())
+
+	err := dbg.Close()
+	require.NoError(t, err)
+}
+
+func TestToFile(t *testing.T) {
+	testFile, err := ioutil.TempFile("", "dbg")
+	require.NoError(t, err)
+	err = testFile.Close()
+	require.NoError(t, err)
+
+	testFileName := testFile.Name()
+	defer os.Remove(testFileName)
+
+	dbg, err := ToFile(testFileName)
+	require.NoError(t, err)
+
+	dbg.Print("hello")
+	dbg.Println("hello")
+	dbg.Printf("hello %s", "world")
+
+	stat, err := os.Stat(testFileName)
+	require.NoError(t, err)
+
+	require.EqualValues(t, 0, stat.Size())
+
+	dbg.Enabled = true
+	dbg.Print("hello")              // +5
+	dbg.Println("hello")            // +6
+	dbg.Printf("hello %s", "world") // +11
+
+	stat, err = os.Stat(testFileName)
+	require.NoError(t, err)
+
+	require.EqualValues(t, 22, stat.Size())
+
+	err = dbg.Close()
+	require.NoError(t, err)
+}
+
+func TestWriting(t *testing.T) {
+	data := []byte("hello, world")
+	buf := testio.NewBufCloser(nil)
+	dbg := To(buf)
+
+	n, err := dbg.Write(data)
+	require.NoError(t, err)
+	require.EqualValues(t, 0, n)
+
+	dbg.Enabled = true
+	n, err = dbg.Write(data)
+	require.NoError(t, err)
+	require.EqualValues(t, 12, n)
+
+	err = dbg.Close()
+	require.NoError(t, err)
+}
+
+func TestToFileError(t *testing.T) {
+	testFile, err := ioutil.TempFile("", "dbg")
+	require.NoError(t, err)
+	err = testFile.Chmod(0400)
+	require.NoError(t, err)
+	err = testFile.Close()
+	require.NoError(t, err)
+
+	testFileName := testFile.Name()
+
+	_, err = ToFile(testFileName)
+	require.Error(t, err)
+
+	err = os.Remove(testFileName)
+	require.NoError(t, err)
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/kisom/goutils
+
+go 1.13

lib/ftime_bsd.go

@@ -1,4 +1,4 @@
-// +build freebsd darwin netbsd
+// +build freebsd darwin,386 netbsd
 
 package lib
 

lib/ftime_unix.go

@@ -1,4 +1,4 @@
-// +build unix linux openbsd
+// +build unix linux openbsd darwin,amd64
 
 package lib
 

testio/testio.go

@@ -194,6 +194,11 @@ func (buf *BufCloser) Bytes() []byte {
 	return buf.buf.Bytes()
 }
 
+// Len returns the length of the buffer.
+func (buf *BufCloser) Len() int {
+	return buf.buf.Len()
+}
+
 // NewBufCloser creates and initializes a new BufCloser using buf as
 // its initial contents. It is intended to prepare a BufCloser to read
 // existing data. It can also be used to size the internal buffer for