Initial commit

internal/shutils/decoder/decoder.go

@@ -0,0 +1,223 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package decoder
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"strings"
+
+	"github.com/mitchellh/mapstructure"
+	"lure.sh/lure/internal/overrides"
+	"lure.sh/lure/pkg/distro"
+	"golang.org/x/exp/slices"
+	"mvdan.cc/sh/v3/expand"
+	"mvdan.cc/sh/v3/interp"
+	"mvdan.cc/sh/v3/syntax"
+)
+
+var ErrNotPointerToStruct = errors.New("val must be a pointer to a struct")
+
+type VarNotFoundError struct {
+	name string
+}
+
+func (nfe VarNotFoundError) Error() string {
+	return "required variable '" + nfe.name + "' could not be found"
+}
+
+type InvalidTypeError struct {
+	name    string
+	vartype string
+	exptype string
+}
+
+func (ite InvalidTypeError) Error() string {
+	return "variable '" + ite.name + "' is of type " + ite.vartype + ", but " + ite.exptype + " is expected"
+}
+
+// Decoder provides methods for decoding variable values
+type Decoder struct {
+	info   *distro.OSRelease
+	Runner *interp.Runner
+	// Enable distro overrides (true by default)
+	Overrides bool
+	// Enable using like distros for overrides
+	LikeDistros bool
+}
+
+// New creates a new variable decoder
+func New(info *distro.OSRelease, runner *interp.Runner) *Decoder {
+	return &Decoder{info, runner, true, len(info.Like) > 0}
+}
+
+// DecodeVar decodes a variable to val using reflection.
+// Structs should use the "sh" struct tag.
+func (d *Decoder) DecodeVar(name string, val any) error {
+	variable := d.getVar(name)
+	if variable == nil {
+		return VarNotFoundError{name}
+	}
+
+	dec, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
+		WeaklyTypedInput: true,
+		DecodeHook: mapstructure.DecodeHookFuncValue(func(from, to reflect.Value) (interface{}, error) {
+			if strings.Contains(to.Type().String(), "db.JSON") {
+				valType := to.FieldByName("Val").Type()
+				if !from.Type().AssignableTo(valType) {
+					return nil, InvalidTypeError{name, from.Type().String(), valType.String()}
+				}
+
+				to.FieldByName("Val").Set(from)
+				return to, nil
+			}
+			return from.Interface(), nil
+		}),
+		Result:  val,
+		TagName: "sh",
+	})
+	if err != nil {
+		return err
+	}
+
+	switch variable.Kind {
+	case expand.Indexed:
+		return dec.Decode(variable.List)
+	case expand.Associative:
+		return dec.Decode(variable.Map)
+	default:
+		return dec.Decode(variable.Str)
+	}
+}
+
+// DecodeVars decodes all variables to val using reflection.
+// Structs should use the "sh" struct tag.
+func (d *Decoder) DecodeVars(val any) error {
+	valKind := reflect.TypeOf(val).Kind()
+	if valKind != reflect.Pointer {
+		return ErrNotPointerToStruct
+	} else {
+		elemKind := reflect.TypeOf(val).Elem().Kind()
+		if elemKind != reflect.Struct {
+			return ErrNotPointerToStruct
+		}
+	}
+
+	rVal := reflect.ValueOf(val).Elem()
+
+	for i := 0; i < rVal.NumField(); i++ {
+		field := rVal.Field(i)
+		fieldType := rVal.Type().Field(i)
+
+		if !fieldType.IsExported() {
+			continue
+		}
+
+		name := fieldType.Name
+		tag := fieldType.Tag.Get("sh")
+		required := false
+		if tag != "" {
+			if strings.Contains(tag, ",") {
+				splitTag := strings.Split(tag, ",")
+				name = splitTag[0]
+
+				if len(splitTag) > 1 {
+					if slices.Contains(splitTag, "required") {
+						required = true
+					}
+				}
+			} else {
+				name = tag
+			}
+		}
+
+		newVal := reflect.New(field.Type())
+		err := d.DecodeVar(name, newVal.Interface())
+		if _, ok := err.(VarNotFoundError); ok && !required {
+			continue
+		} else if err != nil {
+			return err
+		}
+
+		field.Set(newVal.Elem())
+	}
+
+	return nil
+}
+
+type ScriptFunc func(ctx context.Context, opts ...interp.RunnerOption) error
+
+// GetFunc returns a function corresponding to a bash function
+// with the given name
+func (d *Decoder) GetFunc(name string) (ScriptFunc, bool) {
+	fn := d.getFunc(name)
+	if fn == nil {
+		return nil, false
+	}
+
+	return func(ctx context.Context, opts ...interp.RunnerOption) error {
+		sub := d.Runner.Subshell()
+		for _, opt := range opts {
+			opt(sub)
+		}
+		return sub.Run(ctx, fn)
+	}, true
+}
+
+func (d *Decoder) getFunc(name string) *syntax.Stmt {
+	names, err := overrides.Resolve(d.info, overrides.DefaultOpts.WithName(name))
+	if err != nil {
+		return nil
+	}
+
+	for _, fnName := range names {
+		fn, ok := d.Runner.Funcs[fnName]
+		if ok {
+			return fn
+		}
+	}
+	return nil
+}
+
+// getVar gets a variable based on its name, taking into account
+// override variables and nameref variables.
+func (d *Decoder) getVar(name string) *expand.Variable {
+	names, err := overrides.Resolve(d.info, overrides.DefaultOpts.WithName(name))
+	if err != nil {
+		return nil
+	}
+
+	for _, varName := range names {
+		val, ok := d.Runner.Vars[varName]
+		if ok {
+			// Resolve nameref variables
+			_, resolved := val.Resolve(expand.FuncEnviron(func(s string) string {
+				if val, ok := d.Runner.Vars[s]; ok {
+					return val.String()
+				}
+				return ""
+			}))
+			val = resolved
+
+			return &val
+		}
+	}
+	return nil
+}

internal/shutils/decoder/decoder_test.go

@@ -0,0 +1,224 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package decoder_test
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"os"
+	"reflect"
+	"strings"
+	"testing"
+
+	"lure.sh/lure/internal/shutils/decoder"
+	"lure.sh/lure/pkg/distro"
+	"mvdan.cc/sh/v3/interp"
+	"mvdan.cc/sh/v3/syntax"
+)
+
+type BuildVars struct {
+	Name          string   `sh:"name,required"`
+	Version       string   `sh:"version,required"`
+	Release       int      `sh:"release,required"`
+	Epoch         uint     `sh:"epoch"`
+	Description   string   `sh:"desc"`
+	Homepage      string   `sh:"homepage"`
+	Maintainer    string   `sh:"maintainer"`
+	Architectures []string `sh:"architectures"`
+	Licenses      []string `sh:"license"`
+	Provides      []string `sh:"provides"`
+	Conflicts     []string `sh:"conflicts"`
+	Depends       []string `sh:"deps"`
+	BuildDepends  []string `sh:"build_deps"`
+	Replaces      []string `sh:"replaces"`
+}
+
+const testScript = `
+	name='test'
+	version='0.0.1'
+	release=1
+	epoch=2
+	desc="Test package"
+	homepage='https://lure.arsenm.dev'
+	maintainer='Arsen Musayelyan <arsen@arsenm.dev>'
+	architectures=('arm64' 'amd64')
+	license=('GPL-3.0-or-later')
+	provides=('test')
+	conflicts=('test')
+	replaces=('test-old')
+	replaces_test_os=('test-legacy')
+
+	deps=('sudo')
+
+	build_deps=('golang')
+	build_deps_arch=('go')
+
+	test() {
+		echo "Test"
+	}
+
+	package() {
+		install-binary test
+	}
+`
+
+var osRelease = &distro.OSRelease{
+	ID:   "test_os",
+	Like: []string{"arch"},
+}
+
+func TestDecodeVars(t *testing.T) {
+	ctx := context.Background()
+
+	fl, err := syntax.NewParser().Parse(strings.NewReader(testScript), "lure.sh")
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	runner, err := interp.New()
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	err = runner.Run(ctx, fl)
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	dec := decoder.New(osRelease, runner)
+
+	var bv BuildVars
+	err = dec.DecodeVars(&bv)
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	expected := BuildVars{
+		Name:          "test",
+		Version:       "0.0.1",
+		Release:       1,
+		Epoch:         2,
+		Description:   "Test package",
+		Homepage:      "https://lure.arsenm.dev",
+		Maintainer:    "Arsen Musayelyan <arsen@arsenm.dev>",
+		Architectures: []string{"arm64", "amd64"},
+		Licenses:      []string{"GPL-3.0-or-later"},
+		Provides:      []string{"test"},
+		Conflicts:     []string{"test"},
+		Replaces:      []string{"test-legacy"},
+		Depends:       []string{"sudo"},
+		BuildDepends:  []string{"go"},
+	}
+
+	if !reflect.DeepEqual(bv, expected) {
+		t.Errorf("Expected %v, got %v", expected, bv)
+	}
+}
+
+func TestDecodeVarsMissing(t *testing.T) {
+	ctx := context.Background()
+
+	const testScript = `
+		name='test'
+		epoch=2
+		desc="Test package"
+		homepage='https://lure.arsenm.dev'
+		maintainer='Arsen Musayelyan <arsen@arsenm.dev>'
+		architectures=('arm64' 'amd64')
+		license=('GPL-3.0-or-later')
+		provides=('test')
+		conflicts=('test')
+		replaces=('test-old')
+		replaces_test_os=('test-legacy')
+
+		deps=('sudo')
+
+		build_deps=('golang')
+		build_deps_arch=('go')
+
+		test() {
+			echo "Test"
+		}
+
+		package() {
+			install-binary test
+		}
+	`
+
+	fl, err := syntax.NewParser().Parse(strings.NewReader(testScript), "lure.sh")
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	runner, err := interp.New()
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	err = runner.Run(ctx, fl)
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	dec := decoder.New(osRelease, runner)
+
+	var bv BuildVars
+	err = dec.DecodeVars(&bv)
+
+	var notFoundErr decoder.VarNotFoundError
+	if !errors.As(err, &notFoundErr) {
+		t.Fatalf("Expected VarNotFoundError, got %T %v", err, err)
+	}
+}
+
+func TestGetFunc(t *testing.T) {
+	ctx := context.Background()
+
+	fl, err := syntax.NewParser().Parse(strings.NewReader(testScript), "lure.sh")
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	runner, err := interp.New()
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	err = runner.Run(ctx, fl)
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	dec := decoder.New(osRelease, runner)
+	fn, ok := dec.GetFunc("test")
+	if !ok {
+		t.Fatalf("Expected test() function to exist")
+	}
+
+	buf := &bytes.Buffer{}
+	err = fn(ctx, interp.StdIO(os.Stdin, buf, buf))
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	if buf.String() != "Test\n" {
+		t.Fatalf(`Expected "Test\n", got %#v`, buf.String())
+	}
+}

internal/shutils/handlers/exec.go

@@ -0,0 +1,63 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package handlers
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"mvdan.cc/sh/v3/interp"
+)
+
+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
+
+// ExecHandler returns a new ExecHandlerFunc that falls back to fallback
+// if the command cannot be found in the map. If fallback is nil, the default
+// handler is used.
+func (ef ExecFuncs) ExecHandler(fallback interp.ExecHandlerFunc) interp.ExecHandlerFunc {
+	return func(ctx context.Context, args []string) error {
+		name := args[0]
+
+		if fn, ok := ef[name]; ok {
+			hctx := interp.HandlerCtx(ctx)
+			if len(args) > 1 {
+				return fn(hctx, args[0], args[1:])
+			} else {
+				return fn(hctx, args[0], nil)
+			}
+		}
+
+		if fallback == nil {
+			fallback = interp.DefaultExecHandler(2 * time.Second)
+		}
+		return fallback(ctx, args)
+	}
+}

internal/shutils/handlers/exec_test.go

@@ -0,0 +1,124 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package handlers_test
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"lure.sh/lure/internal/shutils/handlers"
+	"lure.sh/lure/internal/shutils/decoder"
+	"lure.sh/lure/pkg/distro"
+	"mvdan.cc/sh/v3/interp"
+	"mvdan.cc/sh/v3/syntax"
+)
+
+const testScript = `
+	name='test'
+	version='0.0.1'
+	release=1
+	epoch=2
+	desc="Test package"
+	homepage='https://lure.sh'
+	maintainer='Elara Musayelyan <elara@elara.ws>'
+	architectures=('arm64' 'amd64')
+	license=('GPL-3.0-or-later')
+	provides=('test')
+	conflicts=('test')
+	replaces=('test-old')
+	replaces_test_os=('test-legacy')
+
+	deps=('sudo')
+
+	build_deps=('golang')
+	build_deps_arch=('go')
+
+	test() {
+		test-cmd "Hello, World"
+		test-fb
+	}
+
+	package() {
+		install-binary test
+	}
+`
+
+var osRelease = &distro.OSRelease{
+	ID:   "test_os",
+	Like: []string{"arch"},
+}
+
+func TestExecFuncs(t *testing.T) {
+	ctx := context.Background()
+
+	fl, err := syntax.NewParser().Parse(strings.NewReader(testScript), "lure.sh")
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	runner, err := interp.New()
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	err = runner.Run(ctx, fl)
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	dec := decoder.New(osRelease, runner)
+	fn, ok := dec.GetFunc("test")
+	if !ok {
+		t.Fatalf("Expected test() function to exist")
+	}
+
+	eh := shutils.ExecFuncs{
+		"test-cmd": func(hc interp.HandlerContext, name string, args []string) error {
+			if name != "test-cmd" {
+				t.Errorf("Expected name to be 'test-cmd', got '%s'", name)
+			}
+
+			if len(args) < 1 {
+				t.Fatalf("Expected at least one argument, got %d", len(args))
+			}
+
+			if args[0] != "Hello, World" {
+				t.Errorf("Expected first argument to be 'Hello, World', got '%s'", args[0])
+			}
+
+			return nil
+		},
+	}
+
+	fbInvoked := false
+	fbHandler := func(context.Context, []string) error {
+		fbInvoked = true
+		return nil
+	}
+
+	err = fn(ctx, interp.ExecHandler(eh.ExecHandler(fbHandler)))
+	if err != nil {
+		t.Errorf("Expected no error, got %s", err)
+	}
+
+	if !fbInvoked {
+		t.Errorf("Expected fallback handler to be invoked")
+	}
+}

internal/shutils/handlers/fakeroot.go

@@ -0,0 +1,114 @@
+package handlers
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+	"strings"
+	"syscall"
+	"time"
+
+	"lure.sh/fakeroot"
+	"mvdan.cc/sh/v3/expand"
+	"mvdan.cc/sh/v3/interp"
+)
+
+// FakerootExecHandler was extracted from github.com/mvdan/sh/interp/handler.go
+// and modified to run commands in a fakeroot environent.
+func FakerootExecHandler(killTimeout time.Duration) interp.ExecHandlerFunc {
+	return func(ctx context.Context, args []string) error {
+		hc := interp.HandlerCtx(ctx)
+		path, err := interp.LookPathDir(hc.Dir, hc.Env, args[0])
+		if err != nil {
+			fmt.Fprintln(hc.Stderr, err)
+			return interp.NewExitStatus(127)
+		}
+		cmd := &exec.Cmd{
+			Path:   path,
+			Args:   args,
+			Env:    execEnv(hc.Env),
+			Dir:    hc.Dir,
+			Stdin:  hc.Stdin,
+			Stdout: hc.Stdout,
+			Stderr: hc.Stderr,
+		}
+
+		err = fakeroot.Apply(cmd)
+		if err != nil {
+			return err
+		}
+
+		err = cmd.Start()
+		if err == nil {
+			if done := ctx.Done(); done != nil {
+				go func() {
+					<-done
+
+					if killTimeout <= 0 || runtime.GOOS == "windows" {
+						_ = cmd.Process.Signal(os.Kill)
+						return
+					}
+
+					// TODO: don't temporarily leak this goroutine
+					// if the program stops itself with the
+					// interrupt.
+					go func() {
+						time.Sleep(killTimeout)
+						_ = cmd.Process.Signal(os.Kill)
+					}()
+					_ = cmd.Process.Signal(os.Interrupt)
+				}()
+			}
+
+			err = cmd.Wait()
+		}
+
+		switch x := err.(type) {
+		case *exec.ExitError:
+			// started, but errored - default to 1 if OS
+			// doesn't have exit statuses
+			if status, ok := x.Sys().(syscall.WaitStatus); ok {
+				if status.Signaled() {
+					if ctx.Err() != nil {
+						return ctx.Err()
+					}
+					return interp.NewExitStatus(uint8(128 + status.Signal()))
+				}
+				return interp.NewExitStatus(uint8(status.ExitStatus()))
+			}
+			return interp.NewExitStatus(1)
+		case *exec.Error:
+			// did not start
+			fmt.Fprintf(hc.Stderr, "%v\n", err)
+			return interp.NewExitStatus(127)
+		default:
+			return err
+		}
+	}
+}
+
+// execEnv was extracted from github.com/mvdan/sh/interp/vars.go
+func execEnv(env expand.Environ) []string {
+	list := make([]string, 0, 64)
+	env.Each(func(name string, vr expand.Variable) bool {
+		if !vr.IsSet() {
+			// If a variable is set globally but unset in the
+			// runner, we need to ensure it's not part of the final
+			// list. Seems like zeroing the element is enough.
+			// This is a linear search, but this scenario should be
+			// rare, and the number of variables shouldn't be large.
+			for i, kv := range list {
+				if strings.HasPrefix(kv, name+"=") {
+					list[i] = ""
+				}
+			}
+		}
+		if vr.Exported && vr.Kind == expand.String {
+			list = append(list, name+"="+vr.String())
+		}
+		return true
+	})
+	return list
+}

internal/shutils/handlers/nop.go

@@ -0,0 +1,55 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package handlers
+
+import (
+	"context"
+	"io"
+	"os"
+)
+
+func NopReadDir(context.Context, string) ([]os.FileInfo, error) {
+	return nil, os.ErrNotExist
+}
+
+func NopStat(context.Context, string, bool) (os.FileInfo, error) {
+	return nil, os.ErrNotExist
+}
+
+func NopExec(context.Context, []string) error {
+	return nil
+}
+
+func NopOpen(context.Context, string, int, os.FileMode) (io.ReadWriteCloser, error) {
+	return NopRWC{}, nil
+}
+
+type NopRWC struct{}
+
+func (NopRWC) Read([]byte) (int, error) {
+	return 0, io.EOF
+}
+
+func (NopRWC) Write(b []byte) (int, error) {
+	return len(b), nil
+}
+
+func (NopRWC) Close() error {
+	return nil
+}

internal/shutils/handlers/nop_test.go

@@ -0,0 +1,58 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package handlers_test
+
+import (
+	"bytes"
+	"context"
+	"os"
+	"strings"
+	"testing"
+
+	"lure.sh/lure/internal/shutils/handlers"
+	"mvdan.cc/sh/v3/interp"
+	"mvdan.cc/sh/v3/syntax"
+)
+
+func TestNopExec(t *testing.T) {
+	ctx := context.Background()
+
+	fl, err := syntax.NewParser().Parse(strings.NewReader(`/bin/echo test`), "lure.sh")
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	buf := &bytes.Buffer{}
+	runner, err := interp.New(
+		interp.ExecHandler(handlers.NopExec),
+		interp.StdIO(os.Stdin, buf, buf),
+	)
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	err = runner.Run(ctx, fl)
+	if err != nil {
+		t.Fatalf("Expected no error, got %s", err)
+	}
+
+	if buf.String() != "" {
+		t.Fatalf("Expected empty string, got %#v", buf.String())
+	}
+}

internal/shutils/handlers/restricted.go

@@ -0,0 +1,80 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package handlers
+
+import (
+	"context"
+	"io"
+	"io/fs"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"golang.org/x/exp/slices"
+	"mvdan.cc/sh/v3/interp"
+)
+
+func RestrictedReadDir(allowedPrefixes ...string) interp.ReadDirHandlerFunc {
+	return func(ctx context.Context, s string) ([]fs.FileInfo, error) {
+		path := filepath.Clean(s)
+		for _, allowedPrefix := range allowedPrefixes {
+			if strings.HasPrefix(path, allowedPrefix) {
+				return interp.DefaultReadDirHandler()(ctx, s)
+			}
+		}
+
+		return nil, fs.ErrNotExist
+	}
+}
+
+func RestrictedStat(allowedPrefixes ...string) interp.StatHandlerFunc {
+	return func(ctx context.Context, s string, b bool) (fs.FileInfo, error) {
+		path := filepath.Clean(s)
+		for _, allowedPrefix := range allowedPrefixes {
+			if strings.HasPrefix(path, allowedPrefix) {
+				return interp.DefaultStatHandler()(ctx, s, b)
+			}
+		}
+
+		return nil, fs.ErrNotExist
+	}
+}
+
+func RestrictedOpen(allowedPrefixes ...string) interp.OpenHandlerFunc {
+	return func(ctx context.Context, s string, i int, fm fs.FileMode) (io.ReadWriteCloser, error) {
+		path := filepath.Clean(s)
+		for _, allowedPrefix := range allowedPrefixes {
+			if strings.HasPrefix(path, allowedPrefix) {
+				return interp.DefaultOpenHandler()(ctx, s, i, fm)
+			}
+		}
+
+		return NopRWC{}, nil
+	}
+}
+
+func RestrictedExec(allowedCmds ...string) interp.ExecHandlerFunc {
+	return func(ctx context.Context, args []string) error {
+		if slices.Contains(allowedCmds, args[0]) {
+			return interp.DefaultExecHandler(2*time.Second)(ctx, args)
+		}
+
+		return nil
+	}
+}

internal/shutils/helpers/helpers.go

@@ -0,0 +1,284 @@
+/*
+ * LURE - Linux User REpository
+ * Copyright (C) 2023 Elara Musayelyan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package helpers
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"unsafe"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing/object"
+	"golang.org/x/exp/slices"
+	"lure.sh/lure/internal/shutils/handlers"
+	"mvdan.cc/sh/v3/interp"
+)
+
+var (
+	ErrNoPipe         = errors.New("command requires data to be piped in")
+	ErrNoDetectManNum = errors.New("manual number cannot be detected from the filename")
+)
+
+// Helpers contains all the helper commands
+var Helpers = handlers.ExecFuncs{
+	"install-binary":       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-desktop":      installHelperCmd("/usr/share/applications", 0o644),
+	"install-icon":         installHelperCmd("/usr/share/pixmaps", 0o644),
+	"install-manual":       installManualCmd,
+	"install-completion":   installCompletionCmd,
+	"install-library":      installLibraryCmd,
+	"git-version":          gitVersionCmd,
+}
+
+// Restricted contains restricted read-only helper commands
+// that don't modify any state
+var Restricted = handlers.ExecFuncs{
+	"git-version": gitVersionCmd,
+}
+
+func installHelperCmd(prefix string, perms os.FileMode) handlers.ExecFunc {
+	return func(hc interp.HandlerContext, cmd string, args []string) error {
+		if len(args) < 1 {
+			return handlers.InsufficientArgsError(cmd, 1, len(args))
+		}
+
+		from := resolvePath(hc, 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 installManualCmd(hc interp.HandlerContext, cmd string, args []string) error {
+	if len(args) < 1 {
+		return handlers.InsufficientArgsError(cmd, 1, len(args))
+	}
+
+	from := resolvePath(hc, args[0])
+	number := filepath.Base(from)
+	// The man page may be compressed with gzip.
+	// If it is, the .gz extension must be removed to properly
+	// detect the number at the end of the filename.
+	number = strings.TrimSuffix(number, ".gz")
+	number = strings.TrimPrefix(filepath.Ext(number), ".")
+
+	// If number is not actually a number, return an error
+	if _, err := strconv.Atoi(number); err != nil {
+		return fmt.Errorf("install-manual: %w", ErrNoDetectManNum)
+	}
+
+	prefix := "/usr/share/man/man" + number
+	to := filepath.Join(hc.Env.Get("pkgdir").Str, prefix, filepath.Base(from))
+
+	return helperInstall(from, to, 0o644)
+}
+
+func installCompletionCmd(hc interp.HandlerContext, cmd string, args []string) error {
+	// If the command's stdin is the same as the system's,
+	// that means nothing was piped in. In this case, return an error.
+	if hc.Stdin == os.Stdin {
+		return fmt.Errorf("install-completion: %w", ErrNoPipe)
+	}
+
+	if len(args) < 2 {
+		return handlers.InsufficientArgsError(cmd, 2, len(args))
+	}
+
+	shell := args[0]
+	name := args[1]
+
+	var prefix string
+	switch shell {
+	case "bash":
+		prefix = "/usr/share/bash-completion/completions"
+	case "zsh":
+		prefix = "/usr/share/zsh/site-functions"
+		name = "_" + name
+	case "fish":
+		prefix = "/usr/share/fish/vendor_completions.d"
+		name += ".fish"
+	}
+
+	path := filepath.Join(hc.Env.Get("pkgdir").Str, prefix, name)
+
+	err := os.MkdirAll(filepath.Dir(path), 0o755)
+	if err != nil {
+		return err
+	}
+
+	dst, err := os.OpenFile(path, os.O_TRUNC|os.O_CREATE|os.O_RDWR, 0o644)
+	if err != nil {
+		return err
+	}
+	defer dst.Close()
+
+	_, err = io.Copy(dst, hc.Stdin)
+	return err
+}
+
+func installLibraryCmd(hc interp.HandlerContext, cmd string, args []string) error {
+	prefix := getLibPrefix(hc)
+	fn := installHelperCmd(prefix, 0o755)
+	return fn(hc, cmd, args)
+}
+
+// See https://wiki.debian.org/Multiarch/Tuples
+var multiarchTupleMap = map[string]string{
+	"386":      "i386-linux-gnu",
+	"amd64":    "x86_64-linux-gnu",
+	"arm5":     "arm-linux-gnueabi",
+	"arm6":     "arm-linux-gnueabihf",
+	"arm7":     "arm-linux-gnueabihf",
+	"arm64":    "aarch64-linux-gnu",
+	"mips":     "mips-linux-gnu",
+	"mipsle":   "mipsel-linux-gnu",
+	"mips64":   "mips64-linux-gnuabi64",
+	"mips64le": "mips64el-linux-gnuabi64",
+	"ppc64":    "powerpc64-linux-gnu",
+	"ppc64le":  "powerpc64le-linux-gnu",
+	"s390x":    "s390x-linux-gnu",
+	"riscv64":  "riscv64-linux-gnu",
+	"loong64":  "loongarch64-linux-gnu",
+}
+
+// usrLibDistros is a list of distros that don't support
+// /usr/lib64, and must use /usr/lib
+var usrLibDistros = []string{
+	"arch",
+	"alpine",
+	"void",
+	"chimera",
+}
+
+// Based on CMake's GNUInstallDirs
+func getLibPrefix(hc interp.HandlerContext) string {
+	if dir, ok := os.LookupEnv("LURE_LIB_DIR"); ok {
+		return dir
+	}
+
+	out := "/usr/lib"
+
+	distroID := hc.Env.Get("DISTRO_ID").Str
+	distroLike := strings.Split(hc.Env.Get("DISTRO_ID_LIKE").Str, " ")
+
+	for _, usrLibDistro := range usrLibDistros {
+		if distroID == usrLibDistro || slices.Contains(distroLike, usrLibDistro) {
+			return out
+		}
+	}
+
+	wordSize := unsafe.Sizeof(uintptr(0))
+	if wordSize == 8 {
+		out = "/usr/lib64"
+	}
+
+	architecture := hc.Env.Get("ARCH").Str
+
+	if distroID == "debian" || slices.Contains(distroLike, "debian") ||
+		distroID == "ubuntu" || slices.Contains(distroLike, "ubuntu") {
+
+		tuple, ok := multiarchTupleMap[architecture]
+		if ok {
+			out = filepath.Join("/usr/lib", tuple)
+		}
+	}
+
+	return out
+}
+
+func gitVersionCmd(hc interp.HandlerContext, cmd string, args []string) error {
+	path := hc.Dir
+	if len(args) > 0 {
+		path = resolvePath(hc, args[0])
+	}
+
+	r, err := git.PlainOpen(path)
+	if err != nil {
+		return fmt.Errorf("git-version: %w", err)
+	}
+
+	revNum := 0
+	commits, err := r.Log(&git.LogOptions{})
+	if err != nil {
+		return fmt.Errorf("git-version: %w", err)
+	}
+
+	commits.ForEach(func(*object.Commit) error {
+		revNum++
+		return nil
+	})
+
+	HEAD, err := r.Head()
+	if err != nil {
+		return fmt.Errorf("git-version: %w", err)
+	}
+
+	hash := HEAD.Hash().String()
+
+	fmt.Fprintf(hc.Stdout, "%d.%s\n", revNum, hash[:7])
+
+	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
+}
+
+func resolvePath(hc interp.HandlerContext, path string) string {
+	if !filepath.IsAbs(path) {
+		return filepath.Join(hc.Dir, path)
+	}
+	return path
+}