fix(autostart): a launch agent left half-written reads as Open at log…

internal/autostart/autostart_android.go

@@ -4,6 +4,8 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/yetone/magpie/internal/edit"
 )
 
 // Termux:Boot runs executable scripts in ~/.termux/boot after Android boots.
@@ -25,7 +27,7 @@ func enable(exe string) error {
 	// Android's shell is available even before Termux's PATH is loaded.
 	q := "'" + strings.ReplaceAll(exe, "'", "'\"'\"'") + "'"
 	body := "#!/system/bin/sh\nexec " + q + " serve </dev/null >/dev/null 2>&1 &\n"
-	if err := os.WriteFile(p, []byte(body), 0o700); err != nil {
+	if err := edit.WriteAtomic(p, []byte(body)); err != nil {
 		return err
 	}
 	return os.Chmod(p, 0o700)

internal/autostart/autostart_darwin.go

@@ -7,6 +7,8 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+
+	"github.com/yetone/magpie/internal/edit"
 )
 
 const label = "com.yetone.magpie"
@@ -16,9 +18,14 @@ func record() string {
 	return filepath.Join(home, "Library", "LaunchAgents", label+".plist")
 }
 
+// launchd loads no job that names neither its own label nor a program to
+// run: a record a write left short of either sits in LaunchAgents, is
+// refused, and magpie never opens at login however long the file is there.
+var ourLabel = regexp.MustCompile(`<key>Label</key>\s*<string>` + regexp.QuoteMeta(label) + `</string>`)
+
 func enabled() bool {
-	_, err := os.Stat(record())
-	return err == nil
+	b, err := os.ReadFile(record())
+	return err == nil && ourLabel.Match(b) && program.Match(b)
 }
 
 // a launch agent the system loads at the next login: the app itself, run
@@ -28,7 +35,7 @@ func enable(exe string) error {
 	if err := os.MkdirAll(filepath.Dir(p), 0o755); err != nil {
 		return err
 	}
-	return os.WriteFile(p, plist(exe), 0o644)
+	return edit.WriteAtomic(p, plist(exe))
 }
 
 // plist is the launch agent for exe. AbandonProcessGroup: launchd kills
@@ -72,7 +79,7 @@ func refresh() error {
 	if bytes.Equal(b, want) {
 		return nil
 	}
-	return os.WriteFile(p, want, 0o644)
+	return edit.WriteAtomic(p, want)
 }
 
 func disable() error {

internal/autostart/autostart_darwin_test.go

@@ -84,3 +84,39 @@ func TestRefreshOlderLaunchAgent(t *testing.T) {
 		t.Fatalf("a launch agent magpie didn't write was changed:\n%s", b)
 	}
 }
+
+// A record a write cut short is not one that opens magpie at login: launchd
+// refuses a job with no program to run, and one with nothing in it at all,
+// so Open at login reads off rather than saying on for a record that never
+// starts anything.
+func TestSetThenTruncatedRecordReadsAsOff(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	t.Setenv("USERPROFILE", home)
+	if err := Set(true); err != nil {
+		t.Fatal(err)
+	}
+	if !Enabled() {
+		t.Fatal("not on after Set(true)")
+	}
+	p := record()
+	b, err := os.ReadFile(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// the head of the launch agent, cut off before the program it names,
+	// which is what a write that goes no further leaves behind
+	head := b[:strings.Index(string(b), "<key>ProgramArguments</key>")]
+	if err := os.WriteFile(p, head, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if Enabled() {
+		t.Errorf("a launch agent with no ProgramArguments reads as on:\n%s", head)
+	}
+	if err := os.WriteFile(p, nil, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if Enabled() {
+		t.Error("an empty launch agent reads as on")
+	}
+}

internal/autostart/autostart_other.go

@@ -5,9 +5,11 @@ package autostart
 import (
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/yetone/magpie/internal/appdir"
+	"github.com/yetone/magpie/internal/edit"
 )
 
 func record() string {
@@ -19,9 +21,17 @@ func record() string {
 	return filepath.Join(dir, "autostart", "magpie.desktop")
 }
 
+// the two keys a desktop entry needs before the desktop starts it at login:
+// no Type and it is not an application entry, no Exec and it names nothing
+// to run. A .desktop a write left short of either reads as off, not as on.
+var (
+	entryType = regexp.MustCompile(`(?m)^Type=Application$`)
+	entryExec = regexp.MustCompile(`(?m)^Exec=`)
+)
+
 func enabled() bool {
-	_, err := os.Stat(record())
-	return err == nil
+	b, err := os.ReadFile(record())
+	return err == nil && entryType.Match(b) && entryExec.Match(b)
 }
 
 // an XDG autostart entry, which the desktop starts at login
@@ -34,7 +44,7 @@ func enable(exe string) error {
 	q := strings.NewReplacer(`\`, `\\`, `"`, `\"`, "`", "\\`", `$`, `\$`).Replace(exe)
 	body := "[Desktop Entry]\nType=Application\nName=magpie\nComment=one place to pick every agent's model\n" +
 		"Exec=\"" + q + "\" " + Arg + "\nTerminal=false\nX-GNOME-Autostart-enabled=true\n"
-	return os.WriteFile(p, []byte(body), 0o644)
+	return edit.WriteAtomic(p, []byte(body))
 }
 
 func disable() error {

internal/autostart/autostart_other_test.go

@@ -0,0 +1,47 @@
+//go:build !darwin && !windows && !android
+
+package autostart
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+// A record a write cut short is not one that opens magpie at login: the
+// desktop starts no entry with no Exec, and none at all with nothing in it,
+// so Open at login reads off rather than saying on for a record that never
+// starts anything.
+func TestSetThenTruncatedRecordReadsAsOff(t *testing.T) {
+	home := t.TempDir()
+	t.Setenv("HOME", home)
+	t.Setenv("USERPROFILE", home)
+	t.Setenv("XDG_CONFIG_HOME", home+"/.config")
+	t.Setenv("APPIMAGE", "/opt/my apps/magpie.AppImage")
+	if err := Set(true); err != nil {
+		t.Fatal(err)
+	}
+	if !Enabled() {
+		t.Fatal("not on after Set(true)")
+	}
+	p := record()
+	b, err := os.ReadFile(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// the head of the entry, cut off before the Exec that names the
+	// program, which is what a write that goes no further leaves behind
+	head := b[:strings.Index(string(b), "Exec=")]
+	if err := os.WriteFile(p, head, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if Enabled() {
+		t.Errorf("a desktop entry with no Exec reads as on:\n%s", head)
+	}
+	if err := os.WriteFile(p, nil, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if Enabled() {
+		t.Error("an empty desktop entry reads as on")
+	}
+}