(Feat): Minor Changes

CHANGELOG.md

@@ -27,15 +27,23 @@ first public release
 - **utmpx time field portability** — replaced hardcoded `C.__uint32_t` / `C.__int32_t` casts with a C helper function (`auth/utmpx_time.h`) that lets the compiler handle type conversion. fixes build failure on systems where `ut_tv` uses `struct timeval` instead of the 32/64 compat struct
 - **cgo pointer safety for pam** — replaced `unsafe.Pointer(&h)` (Go stack pointer passed to C) with `storeHandle`/`loadHandle` helpers that keep the `cgo.Handle` in C-heap memory. fixes `cgo argument has Go pointer to unpinned Go pointer` panic on Go 1.22+
 - **pam conversation callback** — fixed `unsafe.Slice` using `&r` (pointer-to-pointer) as the backing array instead of `r` (the calloc'd response array), which wrote password bytes into random stack memory. also now only responds to `PAM_PROMPT_ECHO_OFF`/`PAM_PROMPT_ECHO_ON` messages — info and error messages get nil. fixes `pam_unix: auth could not identify password`
+- **cgo handle lifecycle** — moved `cgo.Handle` and its C-heap backing from `Validate` (where they were `defer`-freed on return) into the `Credentials` struct so they stay alive through `OpenSession` and until `CloseSession`. fixes `misuse of an invalid Handle` panic
+- **session spawning** — replaced the broken `ForkExec` (which relaunched the same binary with made-up flags) with a direct `session.Spawn` call that drops privileges and runs the desktop in-process. fixes `flag provided but not defined: -user`
+- **renamed extra/ files** — `lemurs.pam` → `latchd.pam`, `lemurs.service` → `latchd.service`
+- **readme credits** — added a credits section acknowledging lemurs for the `extra/` directory structure and session scanning approach
 - **makefile `enable` and `update` targets** — `make enable` stops any running DM, disables the aliased display-manager, and enables latchd. `make update` runs uninstall → git pull → reinstall in one command
 - **missing `extra/` directory** — added `extra/config.toml`, `extra/xsetup.sh`, `extra/lemurs.pam`, and `extra/lemurs.service` so `make install` can find them
 - **makefile `deps` target** — added `make deps` to automatically install `libpam0g-dev` and `build-essential`, and verify go is present
 - **readme overhaul** — rewrote for clarity: added "what problem does this solve", "how it works", known issues, simpler install instructions, and proper dependency listing
+- **view cleanup** — removed the non-functional automata background overlay from `View()` (the `Frame()` was never called, and the black-space placeholder caused `EEEE` garbage characters on some terminals). also removed a hardcoded 80-char width on the top bar so it adapts to the terminal
+- **session environment setup** — `spawnSession` now calls `SetBasicVariables`, `SetDisplay`, `SetSessionParams`, `SetSeatVars`, `SetSessionVars`, and `SetXDGCommonPaths` before spawning the desktop. fixes `setupX` failing immediately with `missing DISPLAY/XDG_VTNR/HOME env vars` because none were set
+- **pam session error made non-fatal** — `pam_open_session` failure (e.g. `pam_systemd` rejecting the DM process as session leader) is now logged as a warning instead of blocking the entire session spawn. also removed `session include login` from `latchd.pam` since the DM process can't register user sessions with systemd-logind
+- **global session switching with `,` and `.`** — sessions can now be switched from any mode (not just when the switcher is focused). arrows still work when switcher is focused
 
 ### What's Missing
 
 - no tests
-- session spawning uses `ForkExec` which is less clean than the original fork-then-exec model
+- session leader is the latchd process, not the desktop — pam session tracking via systemd-logind may be imperfect
 - not all config options affect the rendering yet
 - occasional terminal state corruption on abrupt exit
-- automata background can flicker on rapid terminal resizes
+- automata background rendered as tick-only visual (not wired into the view yet)

README.md

@@ -151,7 +151,8 @@ standard shell-style bindings in text fields:
 | ctrl+b/f | left/right |
 | ctrl+p/n | up/down (previous/next field) |
 | tab, shift+tab | next/prev field |
-| left/right | switch session (in switcher mode) |
+| left/right | previous/next session (switcher mode) |
+| , / . | previous/next session (any mode) |
 | f1, f2 | power controls |
 | ctrl+u | admin unlock (when account is locked) |
 
@@ -182,3 +183,7 @@ src/
 ## license
 
 MIT or Apache-2.0
+
+## credits
+
+the `extra/` directory structure and the session scanning / pam delegation approach are adapted from [lemurs](https://github.com/coastalwhite/lemurs), a rust display manager.

extra/latchd.pam

@@ -1,5 +1,4 @@
 #%PAM-1.0
 auth        include    login
 account     include    login
-session     include    login
 password    include    login

src/auth/pam.go

@@ -67,6 +67,8 @@ type Credentials struct {
 	HomeDir    string
 	Shell      string
 	pamHandle  *C.pam_handle_t
+	pamData    unsafe.Pointer
+	pamCB      cgo.Handle
 }
 
 //export latchd_pam_conv
@@ -110,16 +112,16 @@ func Validate(user, pass, service string) (*Credentials, error) {
 	defer C.free(unsafe.Pointer(cUser))
 
 	h := cgo.NewHandle(pass)
-	defer h.Delete()
 
 	cData := C.storeHandle(C.uintptr_t(h))
-	defer C.free(cData)
 
 	conv := C.makePAMConv(cData)
 
 	var pamh *C.pam_handle_t
 	ret := C.pam_start(cSvc, cUser, &conv, &pamh)
 	if ret != C.PAM_SUCCESS {
+		h.Delete()
+		C.free(cData)
 		return nil, &AuthError{ErrPAMService, fmt.Sprintf("pam_start: %s", pamErr(pamh, ret))}
 	}
 
@@ -127,6 +129,8 @@ func Validate(user, pass, service string) (*Credentials, error) {
 	if ret != C.PAM_SUCCESS {
 		msg := fmt.Sprintf("auth failed: %s", pamErr(pamh, ret))
 		C.pam_end(pamh, ret)
+		h.Delete()
+		C.free(cData)
 		return nil, &AuthError{ErrAccountValidation, msg}
 	}
 
@@ -134,12 +138,16 @@ func Validate(user, pass, service string) (*Credentials, error) {
 	if ret != C.PAM_SUCCESS {
 		msg := fmt.Sprintf("account: %s", pamErr(pamh, ret))
 		C.pam_end(pamh, ret)
+		h.Delete()
+		C.free(cData)
 		return nil, &AuthError{ErrAccountValidation, msg}
 	}
 
 	u, err := ouser.Lookup(user)
 	if err != nil {
 		C.pam_end(pamh, ret)
+		h.Delete()
+		C.free(cData)
 		return nil, &AuthError{ErrUsernameNotFound, fmt.Sprintf("lookup %s: %v", user, err)}
 	}
 
@@ -163,6 +171,8 @@ func Validate(user, pass, service string) (*Credentials, error) {
 		HomeDir:    u.HomeDir,
 		Shell:      "/bin/sh",
 		pamHandle:  pamh,
+		pamData:    cData,
+		pamCB:      h,
 	}, nil
 }
 
@@ -180,6 +190,11 @@ func (c *Credentials) CloseSession() {
 		C.pam_end(c.pamHandle, 0)
 		c.pamHandle = nil
 	}
+	if c.pamData != nil {
+		C.free(c.pamData)
+		c.pamData = nil
+	}
+	c.pamCB.Delete()
 }
 
 func pamErr(h *C.pam_handle_t, e C.int) string {

src/login/login.go

@@ -270,6 +270,25 @@ func (m *Model) handleKey(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 		return m, nil
 	}
 
+	if len(m.envs) > 0 {
+		switch k {
+		case ",", "<":
+			m.selIdx--
+			if m.selIdx < 0 {
+				m.selIdx = len(m.envs) - 1
+			}
+			m.spring = -4
+			return m, nil
+		case ".", ">":
+			m.selIdx++
+			if m.selIdx >= len(m.envs) {
+				m.selIdx = 0
+			}
+			m.spring = 4
+			return m, nil
+		}
+	}
+
 	switch m.mode {
 	case modeSwitcher:
 		switch k {
@@ -461,11 +480,9 @@ func (m *Model) View() string {
 
 	content := m.renderLayout()
 
-	if m.automata != nil && m.width > 0 && m.height > 0 {
+	if m.width > 0 && m.height > 0 {
 		return lipgloss.Place(m.width, m.height, lipgloss.Center, lipgloss.Center,
 			content,
-			lipgloss.WithWhitespaceChars(" "),
-			lipgloss.WithWhitespaceForeground(lipgloss.Color("0")),
 		)
 	}
 	return content
@@ -474,7 +491,6 @@ func (m *Model) View() string {
 func (m *Model) renderLayout() string {
 	// top bar: power hints
 	top := m.renderPowerHints()
-	top = lipgloss.NewStyle().Width(80).Align(lipgloss.Left).Render(top)
 
 	// avatar + form side by side
 	avatar := m.renderAvatar()

src/main.go

@@ -19,6 +19,7 @@ import (
 	"latchd/auth"
 	"latchd/config"
 	"latchd/login"
+	"latchd/session"
 	"latchd/tui/bg"
 )
 
@@ -144,39 +145,37 @@ func spawnSession(res *login.Result) error {
 		return nil
 	}
 	log.Printf("spawning %s → %s (%s)", res.Username, res.Env.Title, res.Env.Kind)
+
 	creds, err := auth.Validate(res.Username, res.Password, res.Config.PAMService)
 	if err != nil {
 		return fmt.Errorf("auth: %w", err)
 	}
 	defer creds.CloseSession()
 
-	pid, err := syscall.ForkExec("/proc/self/exe", []string{
+	if err := creds.OpenSession(); err != nil {
-		"latchd-session",
+		log.Printf("pam session warning: %v", err)
-		"--user", creds.Username,
+	}
-		"--uid", fmt.Sprintf("%d", creds.UID),
+
-		"--gid", fmt.Sprintf("%d", creds.PrimaryGID),
+	session.SetBasicVariables(creds.Username, creds.HomeDir, creds.Shell, res.Config.InitialPath)
-		"--home", creds.HomeDir,
+	if res.Env.Kind == "x11" {
-		"--shell", creds.Shell,
+		session.SetDisplay(res.Config.X11.Display)
-		"--env-kind", res.Env.Kind,
+	}
-		"--env-exec", res.Env.XinitrcPath,
+	session.RemoveXDG()
-		"--tty", fmt.Sprintf("%d", res.Config.TTY),
+	session.SetSessionParams(res.Env.Kind)
-	}, &syscall.ProcAttr{
+	session.SetSeatVars(res.Config.TTY)
-		Env:   os.Environ(),
+	session.SetSessionVars(creds.UID)
-		Dir:   creds.HomeDir,
+	session.SetXDGCommonPaths(creds.HomeDir)
-		Files: []uintptr{0, 1, 2},
+
-		Sys:   &syscall.SysProcAttr{Setsid: true},
+	sess, err := session.Spawn(&res.Env, creds.UID, creds.PrimaryGID, creds.AllGIDs, &res.Config)
-	})
 	if err != nil {
-		return fmt.Errorf("fork: %w", err)
+		return fmt.Errorf("spawn: %w", err)
 	}
 
-	creds.OpenSession()
+	err = sess.Wait()
-
+	if err != nil {
-	var ws syscall.WaitStatus
+		log.Printf("session exited: %v", err)
-	if _, err := syscall.Wait4(pid, &ws, 0, nil); err != nil {
-		return fmt.Errorf("wait: %w", err)
 	}
-	log.Printf("session pid %d exited %d", pid, ws.ExitStatus())
+	log.Printf("session pid %d ended", sess.PID())
 	return nil
 }