Added inv-alias and hosto

scripts/bin/hosto

@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+
+POSITIONAL_ARGS=()
+INVENTORY_FILE="$(pwd)/inventory"
+
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    -i|--inv-file)
+      INVENTORY_FILE="$2"
+      shift
+      shift
+      ;;
+    -*|--*)
+      echo "hosto: Unknown option $1"
+      exit 1
+      ;;
+    *)
+      POSITIONAL_ARGS+=("$1")
+      shift
+      ;;
+  esac
+done
+
+if [ -f $INVENTORY_FILE ]; then
+    sudo inv-alias add $INVENTORY_FILE
+    eval "${POSITIONAL_ARGS[@]}"
+    sudo inv-alias rm $INVENTORY_FILE
+else
+    echo "hosto: Could not find inventory file in $PWD"
+    eval "${POSITIONAL_ARGS[@]}"
+fi

scripts/inv-alias.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"io/fs"
+	"io/ioutil"
+	"log"
+	"os"
+	"regexp"
+	"strings"
+)
+
+type AliasMap map[string]string
+
+const (
+	HostsFile string = "/etc/hosts"
+)
+
+func FixedSplit(s, sep string, parts int) []string {
+	n := make([]string, parts)
+	p := strings.SplitN(s, sep, parts)
+	copy(n, p)
+	return n
+}
+
+func IsLegalLine(line string) bool {
+	c := line[0]
+	return c != '[' && c != '#'
+}
+
+func BuildRegionString(regionName string, aliases AliasMap) string {
+	b := strings.Builder{}
+	b.WriteString("#region ")
+	b.WriteString(regionName)
+	b.WriteString("\n")
+
+	for ip, alias := range aliases {
+		b.WriteString(ip)
+		b.WriteString("\t")
+		b.WriteString(alias)
+		b.WriteString("\n")
+	}
+
+	b.WriteString("#endregion")
+	return b.String()
+}
+
+func BuildRegionRegexp(regionName string) *regexp.Regexp {
+	b := strings.Builder{}
+	b.WriteString("(?s)\n#region ")
+	b.WriteString(regexp.QuoteMeta(regionName))
+	b.WriteString(".*#endregion")
+	r := regexp.MustCompile(b.String())
+	return r
+}
+
+func ScanAliases(fileReader io.Reader) (AliasMap, error) {
+	aliasMap := AliasMap{}
+	scanner := bufio.NewScanner(fileReader)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if IsLegalLine(line) {
+			s := FixedSplit(line, "#", 2)
+			ip, alias := strings.TrimSpace(s[0]), strings.TrimSpace(s[1])
+			if _, ok := aliasMap[ip]; !ok && alias != "" {
+				aliasMap[ip] = alias
+			}
+		}
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return aliasMap, nil
+}
+
+func AddAliases(fileName string) {
+	file, err := os.Open(fileName)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	h, err := ScanAliases(file)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	file.Close()
+
+	r := BuildRegionRegexp(fileName)
+	s := BuildRegionString(fileName, h)
+
+	content, err := ioutil.ReadFile(HostsFile)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	c := r.ReplaceAllString(string(content), s)
+	if !r.MatchString(c) {
+		c += ("\n" + s)
+	}
+
+	err = os.WriteFile(HostsFile, []byte(c[:]), fs.FileMode(os.O_WRONLY|os.O_TRUNC))
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func RemoveAliases(fileName string) {
+	regionReg := BuildRegionRegexp(fileName)
+	content, err := ioutil.ReadFile(HostsFile)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	c := regionReg.ReplaceAll(content, []byte(""))
+	err = os.WriteFile(HostsFile, c, fs.FileMode(os.O_WRONLY|os.O_TRUNC))
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func main() {
+	u := fmt.Sprintf("Please use: %s <add|rm> <file:path>\n", os.Args[0])
+
+	if len(os.Args) < 3 {
+		fmt.Println(u)
+		os.Exit(1)
+	}
+
+	switch os.Args[1] {
+	case "add":
+		AddAliases(os.Args[2])
+	case "rm":
+		RemoveAliases(os.Args[2])
+	default:
+		fmt.Println(u)
+		os.Exit(1)
+	}
+}