add all files from Hong

cmds/coredhcp-generator/main.go

@@ -0,0 +1,144 @@
+// Copyright 2018-present the CoreDHCP Authors. All rights reserved
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"html/template"
+	"log"
+	"os"
+	"path"
+	"sort"
+	"strings"
+
+	flag "github.com/spf13/pflag"
+)
+
+const (
+	defaultTemplateFile = "coredhcp.go.template"
+	importBase          = "github.com/coredhcp/coredhcp/"
+)
+
+var (
+	flagTemplate = flag.StringP("template", "t", defaultTemplateFile, "Template file name")
+	flagOutfile  = flag.StringP("outfile", "o", "", "Output file path")
+	flagFromFile = flag.StringP("from", "f", "", "Optional file name to get the plugin list from, one import path per line")
+)
+
+var funcMap = template.FuncMap{
+	"importname": func(importPath string) (string, error) {
+		parts := strings.Split(importPath, "/")
+		if len(parts) < 1 {
+			return "", fmt.Errorf("no components found in import path '%s'", importPath)
+		}
+		return "pl_" + parts[len(parts)-1], nil
+	},
+}
+
+func usage() {
+	fmt.Fprintf(flag.CommandLine.Output(),
+		"%s [-template tpl] [-outfile out] [-from pluginlist] [plugin [plugin...]]\n",
+		os.Args[0],
+	)
+	flag.PrintDefaults()
+	fmt.Fprintln(flag.CommandLine.Output(), `  plugin
+	Plugin name to include, as go import path.
+	Short names can be used for builtin coredhcp plugins (eg "serverid")`)
+}
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+
+	data, err := os.ReadFile(*flagTemplate)
+	if err != nil {
+		log.Fatalf("Failed to read template file '%s': %v", *flagTemplate, err)
+	}
+	t, err := template.New("coredhcp").Funcs(funcMap).Parse(string(data))
+	if err != nil {
+		log.Fatalf("Template parsing failed: %v", err)
+	}
+	plugins := make(map[string]bool)
+	for _, pl := range flag.Args() {
+		pl := strings.TrimSpace(pl)
+		if pl == "" {
+			continue
+		}
+		if !strings.ContainsRune(pl, '/') {
+			// A bare name was specified, not a full import path.
+			// Coredhcp plugins aren't in the standard library, and it's unlikely someone
+			// would put them at the base of $GOPATH/src.
+			// Assume this is one of the builtin plugins. If needed, use the -from option
+			// which always requires (and uses) exact paths
+
+			// XXX: we could also look into github.com/coredhcp/plugins
+			pl = importBase + pl
+		}
+		plugins[pl] = true
+	}
+	if *flagFromFile != "" {
+		// additional plugin names from a text file, one line per plugin import
+		// path
+		fd, err := os.Open(*flagFromFile)
+		if err != nil {
+			log.Fatalf("Failed to read file '%s': %v", *flagFromFile, err)
+		}
+		defer func() {
+			if err := fd.Close(); err != nil {
+				log.Printf("Error closing file '%s': %v", *flagFromFile, err)
+			}
+		}()
+		sc := bufio.NewScanner(fd)
+		for sc.Scan() {
+			pl := strings.TrimSpace(sc.Text())
+			if pl == "" {
+				continue
+			}
+			plugins[pl] = true
+		}
+		if err := sc.Err(); err != nil {
+			log.Fatalf("Error reading file '%s': %v", *flagFromFile, err)
+		}
+	}
+	if len(plugins) == 0 {
+		log.Fatalf("No plugin specified!")
+	}
+	outfile := *flagOutfile
+	if outfile == "" {
+		tmpdir, err := os.MkdirTemp("", "coredhcp")
+		if err != nil {
+			log.Fatalf("Cannot create temporary directory: %v", err)
+		}
+		outfile = path.Join(tmpdir, "coredhcp.go")
+	}
+
+	log.Printf("Generating output file '%s' with %d plugin(s):", outfile, len(plugins))
+	idx := 1
+	for pl := range plugins {
+		log.Printf("% 3d) %s", idx, pl)
+		idx++
+	}
+	outFD, err := os.OpenFile(outfile, os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		log.Fatalf("Failed to create output file '%s': %v", outfile, err)
+	}
+	defer func() {
+		if err := outFD.Close(); err != nil {
+			log.Printf("Error while closing file descriptor for '%s': %v", outfile, err)
+		}
+	}()
+	// WARNING: no escaping of the provided strings is done
+	pluginList := make([]string, 0, len(plugins))
+	for pl := range plugins {
+		pluginList = append(pluginList, pl)
+	}
+	sort.Strings(pluginList)
+	if err := t.Execute(outFD, pluginList); err != nil {
+		log.Fatalf("Template execution failed: %v", err)
+	}
+	log.Printf("Generated file '%s'. You can build it by running 'go build' in the output directory.", outfile)
+	fmt.Println(path.Dir(outfile))
+}