From 8697344f98bd0eec14a975d0298c435dacbe3e0f Mon Sep 17 00:00:00 2001
From: sammyette <38820196+TorchedSammy@users.noreply.github.com>
Date: Tue, 24 May 2022 19:15:02 -0400
Subject: [PATCH] feat: implement job foregrounding/backgrounding (#155)

---
 go.mod                   | 12 ++++++------
 go.sum                   | 10 ++++++++++
 job.go                   | 39 +++++++++++++++++++++++++++++++++++++++
 job_unix.go              | 38 ++++++++++++++++++++++++++++++++++++++
 job_windows.go           | 15 +++++++++++++++
 nature/commands/bg.lua   | 15 +++++++++++++++
 nature/commands/fg.lua   | 15 +++++++++++++++
 nature/commands/init.lua |  1 +
 signal_unix.go           |  1 +
 9 files changed, 140 insertions(+), 6 deletions(-)
 create mode 100644 job_unix.go
 create mode 100644 job_windows.go
 create mode 100644 nature/commands/bg.lua
 create mode 100644 nature/commands/fg.lua

diff --git a/go.mod b/go.mod
index 6974c6b..825dae0 100644
--- a/go.mod
+++ b/go.mod
@@ -8,8 +8,9 @@ require (
 	github.com/chuckpreslar/emission v0.0.0-20170206194824-a7ddd980baf9
 	github.com/maxlandon/readline v0.1.0-beta.0.20211027085530-2b76cabb8036
 	github.com/pborman/getopt v1.1.0
-	golang.org/x/term v0.0.0-20210927222741-03fcf44c2211
-	mvdan.cc/sh/v3 v3.4.3
+	golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a
+	golang.org/x/term v0.0.0-20220411215600-e5f449aeb171
+	mvdan.cc/sh/v3 v3.5.1
 )
 
 require (
@@ -18,12 +19,11 @@ require (
 	github.com/evilsocket/islazy v1.10.6 // indirect
 	github.com/olekukonko/ts v0.0.0-20171002115256-78ecb04241c0 // indirect
 	github.com/rivo/uniseg v0.2.0 // indirect
-	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
-	golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9 // indirect
-	golang.org/x/text v0.3.6 // indirect
+	golang.org/x/sync v0.0.0-20220513210516-0976fa681c29 // indirect
+	golang.org/x/text v0.3.7 // indirect
 )
 
-replace mvdan.cc/sh/v3 => github.com/Rosettea/sh/v3 v3.4.0-0.dev.0.20220306140409-795a84b00b4e
+replace mvdan.cc/sh/v3 => github.com/Rosettea/sh/v3 v3.4.0-0.dev.0.20220524215627-dfd9a4fa219b
 
 replace github.com/maxlandon/readline => ./readline
 
diff --git a/go.sum b/go.sum
index c81fd1e..c313c19 100644
--- a/go.sum
+++ b/go.sum
@@ -4,6 +4,8 @@ github.com/Rosettea/golua v0.0.0-20220518005949-116371948fe3 h1:I/wWr40FFLFF9pbT
 github.com/Rosettea/golua v0.0.0-20220518005949-116371948fe3/go.mod h1:9jzpYPiU2is0HVGCiuIOBSXdergHUW44IEjmuN1UrIE=
 github.com/Rosettea/sh/v3 v3.4.0-0.dev.0.20220306140409-795a84b00b4e h1:P2XupP8SaylWaudD1DqbWtZ3mIa8OsE9635LmR+Q+lg=
 github.com/Rosettea/sh/v3 v3.4.0-0.dev.0.20220306140409-795a84b00b4e/go.mod h1:R09vh/04ILvP2Gj8/Z9Jd0Dh0ZIvaucowMEs6abQpWs=
+github.com/Rosettea/sh/v3 v3.4.0-0.dev.0.20220524215627-dfd9a4fa219b h1:s5eDMhBk6H1BgipgLub/gv9qeyBaTuiHM0k3h2/9TSE=
+github.com/Rosettea/sh/v3 v3.4.0-0.dev.0.20220524215627-dfd9a4fa219b/go.mod h1:R09vh/04ILvP2Gj8/Z9Jd0Dh0ZIvaucowMEs6abQpWs=
 github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d h1:licZJFw2RwpHMqeKTCYkitsPqHNxTmd4SNR5r94FGM8=
 github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d/go.mod h1:asat636LX7Bqt5lYEZ27JNDcqxfjdBQuJ/MM4CN/Lzo=
 github.com/arnodel/edit v0.0.0-20220202110212-dfc8d7a13890/go.mod h1:AcpttpuZBaL9xl8/CX+Em4fBTUbwIkJ66RiAsJlNrBk=
@@ -45,6 +47,8 @@ github.com/rogpeppe/go-internal v1.8.1-0.20210923151022-86f73c517451 h1:d1PiN4Rx
 github.com/rogpeppe/go-internal v1.8.1-0.20210923151022-86f73c517451/go.mod h1:JeRgkft04UBgHMgCIwADu4Pn6Mtm5d4nPKWu0nJ5d+o=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220513210516-0976fa681c29 h1:w8s32wxx3sY+OjLlv9qltkLU5yvJzxjjgiHWLjdIcw4=
+golang.org/x/sync v0.0.0-20220513210516-0976fa681c29/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210320140829-1e4c9ba3b0c4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
@@ -52,13 +56,19 @@ golang.org/x/sys v0.0.0-20210925032602-92d5a993a665/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9 h1:nhht2DYV/Sn3qOayu8lM+cU1ii9sTLUeBQwQQfUHtrs=
 golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a h1:dGzPydgVsqGcTRVwiLJ1jVbufYwmzD3LfVPLKsKg+0k=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201210144234-2321bbc49cbf/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210916214954-140adaaadfaf/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 h1:JGgROgKl9N8DuW20oFS5gxc+lE67/N3FcwmBPMe7ArY=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/term v0.0.0-20220411215600-e5f449aeb171 h1:EH1Deb8WZJ0xc0WK//leUHXcX9aLE5SymusoTmMZye8=
+golang.org/x/term v0.0.0-20220411215600-e5f449aeb171/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7 h1:olpwvP2KacW1ZWvsR7uQhoyTYvKAupfQrRGBFM352Gk=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
diff --git a/job.go b/job.go
index a0bdcb5..5ffb61f 100644
--- a/job.go
+++ b/job.go
@@ -111,6 +111,8 @@ func (j *job) lua() rt.Value {
 	jobFuncs := map[string]util.LuaExport{
 		"stop": {j.luaStop, 0, false},
 		"start": {j.luaStart, 0, false},
+		"foreground": {j.luaForeground, 0, false},
+		"background": {j.luaBackground, 0, false},
 	}
 	luaJob := rt.NewTable()
 	util.SetExports(l, luaJob, jobFuncs)
@@ -146,9 +148,46 @@ func (j *job) luaStop(t *rt.Thread, c *rt.GoCont) (rt.Cont, error) {
 	return c.Next(), nil
 }
 
+func (j *job) luaForeground(t *rt.Thread, c *rt.GoCont) (rt.Cont, error) {
+	if !j.running {
+		return nil, errors.New("job not running")
+	}
+
+	// lua code can run in other threads and goroutines, so this exists
+	jobs.foreground = true
+	// this is kinda funny
+	// background continues the process incase it got suspended
+	err := j.background()
+	if err != nil {
+		return nil, err
+	}
+
+	err = j.foreground()
+	if err != nil {
+		return nil, err
+	}
+	jobs.foreground = false
+
+	return c.Next(), nil
+}
+
+func (j *job) luaBackground(t *rt.Thread, c *rt.GoCont) (rt.Cont, error) {
+	if !j.running {
+		return nil, errors.New("job not running")
+	}
+
+	err := j.background()
+	if err != nil {
+		return nil, err
+	}
+
+	return c.Next(), nil
+}
+
 type jobHandler struct {
 	jobs map[int]*job
 	latestID int
+	foreground bool // if job currently in the foreground
 	mu *sync.RWMutex
 }
 
diff --git a/job_unix.go b/job_unix.go
new file mode 100644
index 0000000..5029012
--- /dev/null
+++ b/job_unix.go
@@ -0,0 +1,38 @@
+// +build darwin linux
+
+package main
+
+import (
+	"errors"
+	"os"
+	"syscall"
+	
+	"golang.org/x/sys/unix"
+)
+
+func (j *job) foreground() error {
+	if jobs.foreground {
+		return errors.New("(another) job already foregrounded")
+	}
+
+	pgid, _ := syscall.Getpgid(j.pid)
+	// tcsetpgrp
+	unix.IoctlSetPointerInt(0, unix.TIOCSPGRP, pgid)
+	proc, _ := os.FindProcess(j.pid)
+	proc.Wait()
+	
+	hshPgid, _ := syscall.Getpgid(os.Getpid())
+	unix.IoctlSetPointerInt(0, unix.TIOCSPGRP, hshPgid)
+
+	return nil
+}
+
+func (j *job) background() error {
+	proc := j.handle.Process
+	if proc == nil {
+		return nil
+	}
+
+	proc.Signal(syscall.SIGCONT)
+	return nil
+}
diff --git a/job_windows.go b/job_windows.go
new file mode 100644
index 0000000..140a5d1
--- /dev/null
+++ b/job_windows.go
@@ -0,0 +1,15 @@
+// +build windows
+
+package main
+
+import (
+	"errors"
+)
+
+func (j *job) foreground() error {
+	return errors.New("not supported on windows")
+}
+
+func (j *job) background() error {
+	return errors.New("not supported on windows")
+}
diff --git a/nature/commands/bg.lua b/nature/commands/bg.lua
new file mode 100644
index 0000000..f0aa462
--- /dev/null
+++ b/nature/commands/bg.lua
@@ -0,0 +1,15 @@
+local commander = require 'commander'
+
+commander.register('bg', function()
+	local job = hilbish.jobs.last()
+	if not job then
+		print 'bg: no last job'
+		return 1
+	end
+
+	local err = job.background()
+	if err then
+		print('bg: ' .. err)
+		return 2
+	end
+end)
diff --git a/nature/commands/fg.lua b/nature/commands/fg.lua
new file mode 100644
index 0000000..a3f1451
--- /dev/null
+++ b/nature/commands/fg.lua
@@ -0,0 +1,15 @@
+local commander = require 'commander'
+
+commander.register('fg', function()
+	local job = hilbish.jobs.last()
+	if not job then
+		print 'fg: no last job'
+		return 1
+	end
+
+	local err = job.foreground() -- waits for job; blocks
+	if err then
+		print('fg: ' .. err)
+		return 2
+	end
+end)
diff --git a/nature/commands/init.lua b/nature/commands/init.lua
index 589cbd5..bba2bb6 100644
--- a/nature/commands/init.lua
+++ b/nature/commands/init.lua
@@ -5,3 +5,4 @@ require 'nature.commands.doc'
 require 'nature.commands.exit'
 require 'nature.commands.guide'
 require 'nature.commands.disown'
+require 'nature.commands.fg'
diff --git a/signal_unix.go b/signal_unix.go
index c186512..bd5984c 100644
--- a/signal_unix.go
+++ b/signal_unix.go
@@ -10,6 +10,7 @@ import (
 
 func handleSignals() {
 	c := make(chan os.Signal)
+	signal.Ignore(syscall.SIGTTOU, syscall.SIGTTIN, syscall.SIGTSTP)
 	signal.Notify(c, os.Interrupt, syscall.SIGTERM, syscall.SIGWINCH, syscall.SIGUSR1, syscall.SIGUSR2, syscall.SIGQUIT)
 
 	for s := range c {