feat: add job hooks (part of #109)

api.go

@@ -106,6 +106,8 @@ Check out the {blue}{bold}guide{reset} command to get started.
 	util.Document(L, hshcomp, "Completions interface for Hilbish.")
 	L.SetField(mod, "completion", hshcomp)
 
+	jobs = newJobHandler()
+
 	L.Push(mod)
 
 	return 1

docs/hooks/job.txt

@@ -0,0 +1,12 @@
+Note: A `job` is a table with the following keys:
+- cmd: command string
+- running: boolean whether the job is running
+- id: unique id for the job
+- pid: process id for the job
+In ordinary cases you'd prefer to use the id instead of pid. The id is unique to
+Hilbish and is how you get jobs with the `hilbish.jobs` interface.
+
++ `job.start` -> job > Thrown when a new background job starts.
+
++ `job.done` -> job > Thrown when a background jobs exits.
+

exec.go

@@ -1,13 +1,16 @@
 package main
 
 import (
+	"bytes"
 	"context"
 	"errors"
+	"os/exec"
 	"fmt"
 	"os"
 	"path/filepath"
 	"runtime"
 	"strings"
+	"syscall"
 	"time"
 
 	"hilbish/util"
@@ -17,6 +20,7 @@ import (
 	//"github.com/yuin/gopher-lua/parse"
 	"mvdan.cc/sh/v3/interp"
 	"mvdan.cc/sh/v3/syntax"
+	"mvdan.cc/sh/v3/expand"
 )
 
 var errNotExec = errors.New("not executable")
@@ -92,6 +96,7 @@ func execCommand(cmd, old string) error {
 		return err
 	}
 
+	var bg bool
 	exechandle := func(ctx context.Context, args []string) error {
 		_, argstring := splitInput(strings.Join(args, " "))
 		// i dont really like this but it works
@@ -150,15 +155,138 @@ func execCommand(cmd, old string) error {
 			return interp.NewExitStatus(127)
 		}
 
-		return interp.DefaultExecHandler(2 * time.Second)(ctx, args)
+		killTimeout := 2 * time.Second
+		// from here is basically copy-paste of the default exec handler from
+		// sh/interp but with our job handling
+		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)
+		}
+
+		env := hc.Env
+		envList := 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 envList {
+					if strings.HasPrefix(kv, name+"=") {
+						envList[i] = ""
+					}
+				}
+			}
+			if vr.Exported && vr.Kind == expand.String {
+				envList = append(envList, name+"="+vr.String())
+			}
+			return true
+		})
+		cmd := exec.Cmd{
+			Path: path,
+			Args: args,
+			Env: envList,
+			Dir: hc.Dir,
+			Stdin: hc.Stdin,
+			Stdout: hc.Stdout,
+			Stderr: hc.Stderr,
+		}
+
+		err = cmd.Start()
+		job := jobs.getLatest()
+		if err == nil {
+			if bg {
+				job.start(cmd.Process.Pid)
+			}
+
+			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()
+		}
+
+		var exit uint8
+		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()
+					}
+					exit = uint8(128 + status.Signal())
+					goto end
+				}
+				exit = uint8(status.ExitStatus())
+				goto end
+			}
+			exit = 1
+			goto end
+		case *exec.Error:
+			// did not start
+			fmt.Fprintf(hc.Stderr, "%v\n", err)
+			exit = 127
+			goto end
+		case nil:
+			goto end
+		default:
+			return err
+		}
+		end:
+		if bg {
+			job.exitCode = int(exit)
+			job.finish()
+		}
+		return interp.NewExitStatus(exit)
 	}
+
 	runner, _ := interp.New(
 		interp.StdIO(os.Stdin, os.Stdout, os.Stderr),
 		interp.ExecHandler(exechandle),
 	)
-	err = runner.Run(context.TODO(), file)
 
-	return err
+	buf := new(bytes.Buffer)
+	printer := syntax.NewPrinter()
+
+	for _, stmt := range file.Stmts {
+		bg = false
+		if stmt.Background {
+			bg = true
+			printer.Print(buf, stmt.Cmd)
+
+			stmtStr := buf.String()
+			buf.Reset()
+			jobs.add(stmtStr)
+		}
+
+		err = runner.Run(context.TODO(), stmt)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
 }
 
 func lookpath(file string) error { // custom lookpath function so we know if a command is found *and* is executable

job.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"sync"
+
+	"github.com/yuin/gopher-lua"
+)
+
+var jobs *jobHandler
+
+type job struct {
+	cmd string
+	running bool
+	id int
+	pid int
+	exitCode int
+}
+
+func (j *job) start(pid int) {
+	j.pid = pid
+	j.running = true
+	hooks.Em.Emit("job.start", j.lua())
+}
+
+func (j *job) finish() {
+	j.running = false
+	hooks.Em.Emit("job.done", j.lua())
+}
+
+func (j *job) lua() *lua.LTable {
+	// returns lua table for job
+	// because userdata is gross
+	luaJob := l.NewTable()
+
+	l.SetField(luaJob, "cmd", lua.LString(j.cmd))
+	l.SetField(luaJob, "running", lua.LBool(j.running))
+	l.SetField(luaJob, "id", lua.LNumber(j.id))
+	l.SetField(luaJob, "pid", lua.LNumber(j.pid))
+	l.SetField(luaJob, "exitCode", lua.LNumber(j.exitCode))
+
+	return luaJob
+}
+
+type jobHandler struct {
+	jobs map[int]*job
+	latestID int
+	mu *sync.RWMutex
+}
+
+func newJobHandler() *jobHandler {
+	return &jobHandler{
+		jobs: make(map[int]*job),
+		latestID: 0,
+		mu: &sync.RWMutex{},
+	}
+}
+
+func (j *jobHandler) add(cmd string) {
+	j.mu.Lock()
+	defer j.mu.Unlock()
+
+	j.latestID++
+	j.jobs[j.latestID] = &job{
+		cmd: cmd,
+		running: false,
+		id: j.latestID,
+	}
+}
+
+func (j *jobHandler) getLatest() *job {
+	j.mu.RLock()
+	defer j.mu.RUnlock()
+
+	return j.jobs[j.latestID]
+}