Initial commit

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
+}