app: fix nil pointer dereference on startup

Fix the following crash on startup:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x80 pc=0x9e2314]

goroutine 1 [running]:
git.sr.ht/~rjarry/aerc/log.PanicHandler()
        git.sr.ht/~rjarry/aerc/log/panic-logger.go:51 +0x70f
panic({0xae95a0, 0x119f9b0})
        runtime/panic.go:890 +0x263
git.sr.ht/~rjarry/aerc/app.(*Aerc).SelectedAccount(0x8503cdd28?)
        git.sr.ht/~rjarry/aerc/app/aerc.go:384 +0x14
git.sr.ht/~rjarry/aerc/app.SelectedAccount(...)
        git.sr.ht/~rjarry/aerc/app/app.go:44
git.sr.ht/~rjarry/aerc/app.(*AccountView).isSelected(...)
        git.sr.ht/~rjarry/aerc/app/account.go:225
git.sr.ht/~rjarry/aerc/app.(*AccountView).UpdateStatus(0x850364380)
        git.sr.ht/~rjarry/aerc/app/account.go:127 +0x28
git.sr.ht/~rjarry/aerc/app.(*AccountView).SetStatus(0x850364380, {0x850243a50, 0x1,
0x0?})
        git.sr.ht/~rjarry/aerc/app/account.go:123 +0x94
git.sr.ht/~rjarry/aerc/app.NewAccountView(0x8503d38c0, 0x85041bf80)
        git.sr.ht/~rjarry/aerc/app/account.go:111 +0x573
git.sr.ht/~rjarry/aerc/app.NewAerc({0xcab0c0?, 0x11fa3c8}, 0x850433860, 0xbf3040, {0xca75e8?, 0x11ca800}, 0x0?)
        git.sr.ht/~rjarry/aerc/app/aerc.go:91 +0x6ce
git.sr.ht/~rjarry/aerc/app.Init(...)
        git.sr.ht/~rjarry/aerc/app/app.go:24
main.main()
        git.sr.ht/~rjarry/aerc/main.go:242 +0x52e

There was two things very wrong:

- Access of the global aerc pointer before it was initialized.
- The host field of AccountView was left there and still accessed but
  never initialized.

Replace the global aerc pointer with a real struct value. Update code
accordingly.

Remove the AccountView.host field which is now useless.

Reported-by: Jens Grassel <jens@wegtam.com>
Reported-by: Matěj Cepl <mcepl@cepl.eu>
Fixes: bc176bd61ba7 ("app: export global functions")
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Moritz Poldrack <moritz@poldrack.dev>

6 files changed, 19 insertions, 42 deletions

diff --git a/app/account.go b/app/account.go
index bcb5028a..c7abde6f 100644
--- a/app/account.go
+++ b/app/account.go
@@ -31,7 +31,6 @@ type AccountView struct {
 	dirlist DirectoryLister
 	labels  []string
 	grid    *ui.Grid
-	host    TabHost
 	tab     *ui.Tab
 	msglist *MessageList
 	worker  *types.Worker
@@ -125,7 +124,7 @@ func (acct *AccountView) SetStatus(setters ...state.SetStateFunc) {
 
 func (acct *AccountView) UpdateStatus() {
 	if acct.isSelected() {
-		acct.host.UpdateStatus()
+		UpdateStatus()
 	}
 }
 
@@ -247,7 +246,7 @@ func (acct *AccountView) newStore(name string) *lib.MessageStore {
 			}
 		}, func() {
 			if uiConf.NewMessageBell {
-				acct.host.Beep()
+				aerc.Beep()
 			}
 		},
 		acct.updateSplitView,
diff --git a/app/aerc.go b/app/aerc.go
index 1170a6f2..21430f80 100644
--- a/app/aerc.go
+++ b/app/aerc.go
@@ -51,12 +51,12 @@ type Choice struct {
 	Command []string
 }
 
-func NewAerc(
+func (aerc *Aerc) Init(
 	crypto crypto.Provider,
 	cmd func([]string, *config.AccountConfig, *models.MessageInfo) error,
 	complete func(cmd string) ([]string, string), cmdHistory lib.History,
 	deferLoop chan struct{},
-) *Aerc {
+) {
 	tabs := ui.NewTabs(config.Ui)
 
 	statusbar := ui.NewStack(config.Ui)
@@ -74,18 +74,16 @@ func NewAerc(
 	grid.AddChild(tabs.TabContent).At(1, 0)
 	grid.AddChild(statusbar).At(2, 0)
 
-	aerc := &Aerc{
-		accounts:   make(map[string]*AccountView),
-		cmd:        cmd,
-		cmdHistory: cmdHistory,
-		complete:   complete,
-		grid:       grid,
-		statusbar:  statusbar,
-		statusline: statusline,
-		prompts:    ui.NewStack(config.Ui),
-		tabs:       tabs,
-		Crypto:     crypto,
-	}
+	aerc.accounts = make(map[string]*AccountView)
+	aerc.cmd = cmd
+	aerc.cmdHistory = cmdHistory
+	aerc.complete = complete
+	aerc.grid = grid
+	aerc.statusbar = statusbar
+	aerc.statusline = statusline
+	aerc.prompts = ui.NewStack(config.Ui)
+	aerc.tabs = tabs
+	aerc.Crypto = crypto
 
 	for _, acct := range config.Accounts {
 		view, err := NewAccountView(acct, deferLoop)
@@ -121,8 +119,6 @@ func NewAerc(
 	}
 
 	aerc.showConfigWarnings()
-
-	return aerc
 }
 
 func (aerc *Aerc) showConfigWarnings() {
diff --git a/app/app.go b/app/app.go
index 80f940a3..73459cb8 100644
--- a/app/app.go
+++ b/app/app.go
@@ -13,7 +13,7 @@ import (
 	"github.com/ProtonMail/go-crypto/openpgp"
 )
 
-var aerc *Aerc
+var aerc Aerc
 
 func Init(
 	crypto crypto.Provider,
@@ -21,11 +21,11 @@ func Init(
 	complete func(cmd string) ([]string, string), history lib.History,
 	deferLoop chan struct{},
 ) {
-	aerc = NewAerc(crypto, cmd, complete, history, deferLoop)
+	aerc.Init(crypto, cmd, complete, history, deferLoop)
 }
 
-func Drawable() ui.DrawableInteractive      { return aerc }
-func IPCHandler() ipc.Handler               { return aerc }
+func Drawable() ui.DrawableInteractive      { return &aerc }
+func IPCHandler() ipc.Handler               { return &aerc }
 func HandleMessage(msg types.WorkerMessage) { aerc.HandleMessage(msg) }
 
 func CloseBackends() error { return aerc.CloseBackends() }
diff --git a/app/msglist.go b/app/msglist.go
index b60ae148..e57bfe9d 100644
--- a/app/msglist.go
+++ b/app/msglist.go
@@ -257,9 +257,6 @@ func (ml *MessageList) MouseEvent(localX int, localY int, event tcell.Event) {
 	if event, ok := event.(*tcell.EventMouse); ok {
 		switch event.Buttons() {
 		case tcell.Button1:
-			if aerc == nil {
-				return
-			}
 			selectedMsg, ok := ml.Clicked(localX, localY)
 			if ok {
 				ml.Select(selectedMsg)
diff --git a/app/status.go b/app/status.go
index fdeede19..dbedea7e 100644
--- a/app/status.go
+++ b/app/status.go
@@ -47,7 +47,7 @@ func (status *StatusLine) Draw(ctx *ui.Context) {
 		msg = runewidth.FillRight(msg, ctx.Width())
 		style := status.uiConfig().GetStyle(config.STYLE_STATUSLINE_ERROR)
 		ctx.Printf(0, 0, style, "%s", msg)
-	case aerc != nil && status.acct != nil:
+	case status.acct != nil:
 		data := state.NewDataSetter()
 		data.SetPendingKeys(aerc.pendingKeys)
 		data.SetState(&status.acct.state)
diff --git a/app/tabhost.go b/app/tabhost.go
deleted file mode 100644
index 9a206084..00000000
--- a/app/tabhost.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package app
-
-import (
-	"time"
-)
-
-type TabHost interface {
-	BeginExCommand(cmd string)
-	UpdateStatus()
-	SetError(err string)
-	PushStatus(text string, expiry time.Duration) *StatusMessage
-	PushError(text string) *StatusMessage
-	PushSuccess(text string) *StatusMessage
-	Beep()
-}