Add initial helper functions (#39)

build.go

@@ -142,6 +142,7 @@ func buildPackage(ctx context.Context, script string, mgr manager.Manager) ([]st
 	runner, err := interp.New(
 		interp.Env(expand.ListEnviron(env...)),
 		interp.StdIO(os.Stdin, os.Stdout, os.Stderr),
+		interp.ExecHandler(helpers.ExecHandler),
 	)
 	if err != nil {
 		return nil, nil, err

helpers.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"go.arsenm.dev/lure/internal/shutils"
+	"mvdan.cc/sh/v3/interp"
+)
+
+var helpers = shutils.ExecFuncs{
+	"install-bin":          installHelperCmd("/usr/bin", 0o755),
+	"install-systemd-user": installHelperCmd("/usr/lib/systemd/user", 0o644),
+	"install-systemd":      installHelperCmd("/usr/lib/systemd/system", 0o644),
+	"install-config":       installHelperCmd("/etc", 0o644),
+	"install-license":      installHelperCmd("/usr/share/licenses", 0o644),
+	"install-manual":       installHelperCmd("/usr/share/man/man1", 0o644),
+	"install-desktop":      installHelperCmd("/usr/share/applications", 0o644),
+}
+
+func installHelperCmd(prefix string, perms os.FileMode) shutils.ExecFunc {
+	return func(hc interp.HandlerContext, cmd string, args []string) error {
+		if len(args) < 1 {
+			return shutils.InsufficientArgsError(cmd, 1, len(args))
+		}
+
+		from := args[0]
+		to := ""
+		if len(args) > 1 {
+			to = filepath.Join(hc.Env.Get("pkgdir").Str, prefix, args[1])
+		} else {
+			to = filepath.Join(hc.Env.Get("pkgdir").Str, prefix, filepath.Base(from))
+		}
+
+		err := helperInstall(from, to, perms)
+		if err != nil {
+			return fmt.Errorf("%s: %w", cmd, err)
+		}
+		return nil
+	}
+}
+
+func helperInstall(from, to string, perms os.FileMode) error {
+	err := os.MkdirAll(filepath.Dir(to), 0o755)
+	if err != nil {
+		return err
+	}
+
+	src, err := os.Open(from)
+	if err != nil {
+		return err
+	}
+	defer src.Close()
+
+	dst, err := os.OpenFile(to, os.O_TRUNC|os.O_CREATE|os.O_RDWR, perms)
+	if err != nil {
+		return err
+	}
+	defer dst.Close()
+
+	_, err = io.Copy(dst, src)
+	return err
+}

internal/shutils/exec.go

@@ -20,21 +20,34 @@ package shutils
 
 import (
 	"context"
+	"fmt"
 	"time"
 
 	"mvdan.cc/sh/v3/interp"
 )
 
-type ExecFuncs map[string]func(interp.HandlerContext, []string) uint8
+func InsufficientArgsError(cmd string, exp, got int) error {
+	argsWord := "arguments"
+	if exp == 1 {
+		argsWord = "argument"
+	}
+
+	return fmt.Errorf("%s: command requires at least %d %s, got %d", cmd, exp, argsWord, got)
+}
+
+type ExecFunc func(hc interp.HandlerContext, name string, args []string) error
+
+type ExecFuncs map[string]ExecFunc
 
 func (ef ExecFuncs) ExecHandler(ctx context.Context, args []string) error {
 	name := args[0]
 
 	if fn, ok := ef[name]; ok {
 		hctx := interp.HandlerCtx(ctx)
-		ec := fn(hctx, args)
+		if len(args) > 1 {
-		if ec != 0 {
+			return fn(hctx, args[0], args[1:])
-			return interp.NewExitStatus(ec)
+		} else {
+			return fn(hctx, args[0], nil)
 		}
 	}