Generate template dependency file

Signed-off-by: Chris Koch <[email protected]>

cmd/gentpldeps/.gitignore

@@ -0,0 +1 @@
+gentpldeps

cmd/gentpldeps/main.go

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+// Copyright 2024 the u-root Authors. All rights reserved
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// gentpldeps generates a command dependency Go file.
+//
+// Usage:
+//   - go get $module...
+//   - create .mkuimage.yaml file with commands
+//   - gentpldeps -t <tag> -o deps.go -p <pkg>
+package main
+
+import (
+	"bytes"
+	"flag"
+	"log"
+	"os"
+	"sort"
+	"text/template"
+
+	"github.com/u-root/gobusybox/src/pkg/bb/findpkg"
+	"github.com/u-root/gobusybox/src/pkg/golang"
+	"github.com/u-root/mkuimage/uimage/mkuimage"
+	"golang.org/x/exp/maps"
+)
+
+var (
+	pkg = flag.String("p", "", "Package")
+	o   = flag.String("o", "", "Output file name")
+	tag = flag.String("t", "", "Go build tag for the file")
+)
+
+func main() {
+	tf := &mkuimage.TemplateFlags{}
+	tf.RegisterFlags(flag.CommandLine)
+	flag.Parse()
+
+	if *pkg == "" {
+		log.Fatal("Must specify package name")
+	}
+	if *tag == "" {
+		log.Fatal("Must specify Go build tag")
+	}
+	if *o == "" {
+		log.Fatal("Must specify output file name")
+	}
+
+	tpls, err := tf.Get()
+	if err != nil {
+		log.Fatal(err)
+	}
+	if tpls == nil {
+		log.Fatalf("No template found")
+	}
+
+	var cmds []string
+	for _, c := range tpls.Commands {
+		cmds = append(cmds, c...)
+	}
+	for _, conf := range tpls.Configs {
+		for _, c := range conf.Commands {
+			cmds = append(cmds, tpls.CommandsFor(c.Commands...)...)
+		}
+	}
+	paths, err := findpkg.ResolveGlobs(nil, golang.Default(), findpkg.DefaultEnv(), cmds)
+	if err != nil {
+		log.Fatal(err)
+	}
+	dedup := map[string]struct{}{}
+	for _, p := range paths {
+		dedup[p] = struct{}{}
+	}
+	c := maps.Keys(dedup)
+	sort.Strings(c)
+
+	tpl := `//go:build {{.Tag}}
+
+package {{.Package}}
+
+import ({{range .Imports}}
+	_ "{{.}}"{{end}}
+)
+`
+
+	vars := struct {
+		Tag     string
+		Package string
+		Imports []string
+	}{
+		Tag:     *tag,
+		Package: *pkg,
+		Imports: c,
+	}
+	t := template.Must(template.New("tpl").Parse(tpl))
+	var b bytes.Buffer
+	if err := t.Execute(&b, vars); err != nil {
+		log.Fatal(err)
+	}
+	if err := os.WriteFile(*o, b.Bytes(), 0o644); err != nil {
+		log.Fatal(err)
+	}
+}