Interprocess pipe support (for stdout/stderr capture) (#866)

- **RAII pipe handles for child process stdout/stderr capture**: `StdoutPipeHandles` is now a proper RAII type with automatic cleanup, move semantics, and partial close support. This makes it safe to use pipes for capturing child process output without risking handle/fd leaks.

- **Optional separate stderr pipe**: `CreateProcOptions` now accepts a `StderrPipe` field so callers can capture stdout and stderr independently. When null (default), stderr shares the stdout pipe as before.

- **LogStreamListener with pluggable handler**: The TCP log stream listener accepts connections from remote processes and delivers parsed log lines through a `LogStreamHandler` interface, set dynamically via `SetHandler()`. This allows any client to receive log messages without depending on a specific console implementation.

- **TcpLogStreamSink for zen::logging**: A logging sink that forwards log messages to a `LogStreamListener` over TCP, using the native `zen::logging::Sink` infrastructure with proper thread-safe synchronization.

- **Reliable child process exit codes on Linux**: `waitpid` result handling is fixed so `ProcessHandle::GetExitCode()` returns the real exit code. `ProcessHandle::Reset()` reaps zombies directly, replacing the global `IgnoreChildSignals()` which prevented exit code collection entirely. Also fixes a TOCTOU race in `ProcessHandle::Wait()` on Linux/Mac.

- **Pipe capture test suite**: Tests covering stdout/stderr capture via pipes (both shared and separate modes), RAII cleanup, move semantics, and exit code propagation using `zentest-appstub` as the child process.

- **Service command integration tests**: Shell-based integration tests for `zen service` covering the full lifecycle (install, status, start, stop, uninstall) on all three platforms — Linux (systemd), macOS (launchd), and Windows (SCM via PowerShell).

- **Test script reorganization**: Platform-specific test scripts moved from `scripts/test_scripts/` into `scripts/test_linux/`, `test_mac/`, and `test_windows/`.

1 files changed, 380 insertions, 0 deletions

diff --git a/scripts/test_linux/service-test.sh b/scripts/test_linux/service-test.sh
new file mode 100755
index 000000000..f91339e1b
--- /dev/null
+++ b/scripts/test_linux/service-test.sh
@@ -0,0 +1,380 @@
+#!/usr/bin/env bash
+# Test zen service command lifecycle on Linux (systemd).
+#
+# Requires: root/sudo, systemd
+#
+# Usage:
+#   sudo ./scripts/test_linux/service-test.sh [path-to-zen]
+#
+# If no path is given, defaults to build/linux/x86_64/debug/zen
+# relative to the repository root.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+ZEN_BINARY="${1:-$REPO_ROOT/build/linux/x86_64/debug/zen}"
+ZENSERVER_BINARY="$(dirname "$ZEN_BINARY")/zenserver"
+SERVICE_NAME="ZenServerTest-$$"
+UNIT_NAME="com.epicgames.unreal.${SERVICE_NAME}"
+UNIT_FILE="/etc/systemd/system/${UNIT_NAME}.service"
+
+PASSED=0
+FAILED=0
+TESTS_RUN=0
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+cleanup() {
+    local exit_code=$?
+    set +e
+
+    echo ""
+    echo "--- Cleanup ---"
+
+    # Stop service if running
+    if systemctl is-active --quiet "$UNIT_NAME" 2>/dev/null; then
+        echo "Stopping test service..."
+        systemctl stop "$UNIT_NAME" 2>/dev/null
+    fi
+
+    # Disable and remove unit file
+    if [ -f "$UNIT_FILE" ]; then
+        echo "Removing test unit file..."
+        systemctl disable "$UNIT_NAME" 2>/dev/null || true
+        rm -f "$UNIT_FILE"
+        systemctl daemon-reload 2>/dev/null || true
+    fi
+
+    echo ""
+    echo "=============================="
+    printf "  Tests run:    %d\n" "$TESTS_RUN"
+    printf "  ${GREEN}Passed:       %d${NC}\n" "$PASSED"
+    if [ "$FAILED" -gt 0 ]; then
+        printf "  ${RED}Failed:       %d${NC}\n" "$FAILED"
+    else
+        printf "  Failed:       %d\n" "$FAILED"
+    fi
+    echo "=============================="
+
+    if [ "$FAILED" -gt 0 ]; then
+        exit 1
+    fi
+    exit "$exit_code"
+}
+
+trap cleanup EXIT
+
+pass() {
+    TESTS_RUN=$((TESTS_RUN + 1))
+    PASSED=$((PASSED + 1))
+    printf "  ${GREEN}PASS${NC}: %s\n" "$1"
+}
+
+fail() {
+    TESTS_RUN=$((TESTS_RUN + 1))
+    FAILED=$((FAILED + 1))
+    printf "  ${RED}FAIL${NC}: %s\n" "$1"
+    if [ -n "${2:-}" ]; then
+        printf "        %s\n" "$2"
+    fi
+}
+
+# ── Preflight checks ──────────────────────────────────────────────
+
+if [ "$(id -u)" -ne 0 ]; then
+    echo "Error: this test must be run as root (sudo)."
+    exit 1
+fi
+
+if ! command -v systemctl &>/dev/null; then
+    echo "Error: systemctl not found — this test requires systemd."
+    exit 1
+fi
+
+if [ ! -x "$ZEN_BINARY" ]; then
+    echo "Error: zen binary not found at '$ZEN_BINARY'"
+    echo "Build with: xmake config -m debug && xmake build zen"
+    exit 1
+fi
+
+if [ ! -x "$ZENSERVER_BINARY" ]; then
+    echo "Error: zenserver binary not found at '$ZENSERVER_BINARY'"
+    echo "Build with: xmake config -m debug && xmake build zenserver"
+    exit 1
+fi
+
+echo "zen binary:       $ZEN_BINARY"
+echo "zenserver binary:  $ZENSERVER_BINARY"
+echo "service name:      $SERVICE_NAME"
+echo "unit name:         $UNIT_NAME"
+echo ""
+
+# Determine which user to run the service as (the user who invoked sudo)
+SERVICE_USER="${SUDO_USER:-$(whoami)}"
+
+# ── Test: status before install (should fail) ─────────────────────
+
+echo "--- Test: status before install ---"
+
+OUTPUT=$("$ZEN_BINARY" service status "$SERVICE_NAME" 2>&1 || true)
+if echo "$OUTPUT" | grep -qi "not installed"; then
+    pass "status reports 'not installed' for non-existent service"
+else
+    fail "status should report 'not installed'" "got: $OUTPUT"
+fi
+
+# ── Test: install ─────────────────────────────────────────────────
+
+echo "--- Test: install ---"
+
+OUTPUT=$("$ZEN_BINARY" service install "$ZENSERVER_BINARY" "$SERVICE_NAME" --user "$SERVICE_USER" 2>&1)
+EXIT_CODE=$?
+
+if [ "$EXIT_CODE" -eq 0 ]; then
+    pass "install exits with code 0"
+else
+    fail "install exits with code 0" "got exit code: $EXIT_CODE, output: $OUTPUT"
+fi
+
+if [ -f "$UNIT_FILE" ]; then
+    pass "unit file created at $UNIT_FILE"
+else
+    fail "unit file created at $UNIT_FILE"
+fi
+
+# Verify unit file contents
+if [ -f "$UNIT_FILE" ]; then
+    if grep -q "ExecStart=.*zenserver" "$UNIT_FILE"; then
+        pass "unit file contains ExecStart with zenserver"
+    else
+        fail "unit file contains ExecStart with zenserver" "$(cat "$UNIT_FILE")"
+    fi
+
+    if grep -q "User=$SERVICE_USER" "$UNIT_FILE"; then
+        pass "unit file contains correct User=$SERVICE_USER"
+    else
+        fail "unit file contains correct User=$SERVICE_USER" "$(grep User "$UNIT_FILE")"
+    fi
+
+    if grep -q "Type=notify" "$UNIT_FILE"; then
+        pass "unit file uses Type=notify"
+    else
+        fail "unit file uses Type=notify"
+    fi
+
+    if grep -q "WantedBy=multi-user.target" "$UNIT_FILE"; then
+        pass "unit file has WantedBy=multi-user.target"
+    else
+        fail "unit file has WantedBy=multi-user.target"
+    fi
+
+    # Verify the service is enabled
+    if systemctl is-enabled --quiet "$UNIT_NAME" 2>/dev/null; then
+        pass "service is enabled after install"
+    else
+        fail "service is enabled after install"
+    fi
+fi
+
+# ── Test: install again (already installed, no --full) ────────────
+
+echo "--- Test: install again (idempotent) ---"
+
+OUTPUT=$("$ZEN_BINARY" service install "$ZENSERVER_BINARY" "$SERVICE_NAME" --user "$SERVICE_USER" 2>&1)
+EXIT_CODE=$?
+
+if [ "$EXIT_CODE" -eq 0 ]; then
+    pass "re-install exits with code 0"
+else
+    fail "re-install exits with code 0" "got exit code: $EXIT_CODE"
+fi
+
+if echo "$OUTPUT" | grep -qi "already installed"; then
+    pass "re-install reports service already installed"
+else
+    fail "re-install reports service already installed" "got: $OUTPUT"
+fi
+
+# ── Test: status after install (not yet started) ──────────────────
+
+echo "--- Test: status after install (stopped) ---"
+
+OUTPUT=$("$ZEN_BINARY" service status "$SERVICE_NAME" 2>&1 || true)
+# The status command throws if not running, so we expect an error message
+if echo "$OUTPUT" | grep -qi "not running"; then
+    pass "status reports 'not running' for stopped service"
+else
+    fail "status reports 'not running' for stopped service" "got: $OUTPUT"
+fi
+
+# ── Test: start ───────────────────────────────────────────────────
+
+echo "--- Test: start ---"
+
+OUTPUT=$("$ZEN_BINARY" service start "$SERVICE_NAME" 2>&1)
+EXIT_CODE=$?
+
+if [ "$EXIT_CODE" -eq 0 ]; then
+    pass "start exits with code 0"
+else
+    # The TODO comments in the code indicate start may not work perfectly
+    fail "start exits with code 0" "got exit code: $EXIT_CODE, output: $OUTPUT"
+fi
+
+# Give the service a moment to start
+sleep 1
+
+if systemctl is-active --quiet "$UNIT_NAME" 2>/dev/null; then
+    pass "service is active after start"
+
+    # ── Test: status while running ────────────────────────────────
+
+    echo "--- Test: status (running) ---"
+
+    OUTPUT=$("$ZEN_BINARY" service status "$SERVICE_NAME" 2>&1 || true)
+    if echo "$OUTPUT" | grep -qi "Running"; then
+        pass "status reports 'Running'"
+    else
+        fail "status reports 'Running'" "got: $OUTPUT"
+    fi
+
+    if echo "$OUTPUT" | grep -qi "zenserver"; then
+        pass "status shows executable path"
+    else
+        fail "status shows executable path" "got: $OUTPUT"
+    fi
+
+    # ── Test: start again (already running) ───────────────────────
+
+    echo "--- Test: start again (already running) ---"
+
+    OUTPUT=$("$ZEN_BINARY" service start "$SERVICE_NAME" 2>&1)
+    if echo "$OUTPUT" | grep -qi "already running"; then
+        pass "start reports service already running"
+    else
+        fail "start reports service already running" "got: $OUTPUT"
+    fi
+
+    # ── Test: stop ────────────────────────────────────────────────
+
+    echo "--- Test: stop ---"
+
+    OUTPUT=$("$ZEN_BINARY" service stop "$SERVICE_NAME" 2>&1)
+    EXIT_CODE=$?
+
+    if [ "$EXIT_CODE" -eq 0 ]; then
+        pass "stop exits with code 0"
+    else
+        fail "stop exits with code 0" "got exit code: $EXIT_CODE, output: $OUTPUT"
+    fi
+
+    sleep 1
+
+    if ! systemctl is-active --quiet "$UNIT_NAME" 2>/dev/null; then
+        pass "service is inactive after stop"
+    else
+        fail "service is inactive after stop"
+    fi
+else
+    fail "service is active after start" "(skipping start-dependent tests)"
+fi
+
+# ── Test: stop when already stopped ───────────────────────────────
+
+echo "--- Test: stop when already stopped ---"
+
+# Make sure it's stopped first
+systemctl stop "$UNIT_NAME" 2>/dev/null || true
+sleep 1
+
+OUTPUT=$("$ZEN_BINARY" service stop "$SERVICE_NAME" 2>&1 || true)
+if echo "$OUTPUT" | grep -qi "not running"; then
+    pass "stop reports 'not running' when already stopped"
+else
+    fail "stop reports 'not running' when already stopped" "got: $OUTPUT"
+fi
+
+# ── Test: uninstall while running (should fail) ───────────────────
+
+echo "--- Test: uninstall while running (should fail) ---"
+
+# Start the service so we can test uninstall-while-running
+"$ZEN_BINARY" service start "$SERVICE_NAME" 2>&1 || true
+sleep 1
+
+if systemctl is-active --quiet "$UNIT_NAME" 2>/dev/null; then
+    OUTPUT=$("$ZEN_BINARY" service uninstall "$SERVICE_NAME" 2>&1 || true)
+    EXIT_CODE=$?
+
+    if [ "$EXIT_CODE" -ne 0 ] || echo "$OUTPUT" | grep -qi "running.*stop"; then
+        pass "uninstall refuses while service is running"
+    else
+        fail "uninstall refuses while service is running" "got: exit=$EXIT_CODE, output: $OUTPUT"
+    fi
+
+    # Stop it for the real uninstall test
+    "$ZEN_BINARY" service stop "$SERVICE_NAME" 2>&1 || true
+    systemctl stop "$UNIT_NAME" 2>/dev/null || true
+    sleep 1
+else
+    echo "  (skipped: could not start service for this test)"
+fi
+
+# ── Test: uninstall ───────────────────────────────────────────────
+
+echo "--- Test: uninstall ---"
+
+# Ensure stopped
+systemctl stop "$UNIT_NAME" 2>/dev/null || true
+sleep 1
+
+OUTPUT=$("$ZEN_BINARY" service uninstall "$SERVICE_NAME" 2>&1)
+EXIT_CODE=$?
+
+if [ "$EXIT_CODE" -eq 0 ]; then
+    pass "uninstall exits with code 0"
+else
+    fail "uninstall exits with code 0" "got exit code: $EXIT_CODE, output: $OUTPUT"
+fi
+
+if [ ! -f "$UNIT_FILE" ]; then
+    pass "unit file removed after uninstall"
+else
+    fail "unit file removed after uninstall"
+fi
+
+# ── Test: status after uninstall ──────────────────────────────────
+
+echo "--- Test: status after uninstall ---"
+
+OUTPUT=$("$ZEN_BINARY" service status "$SERVICE_NAME" 2>&1 || true)
+if echo "$OUTPUT" | grep -qi "not installed"; then
+    pass "status reports 'not installed' after uninstall"
+else
+    fail "status reports 'not installed' after uninstall" "got: $OUTPUT"
+fi
+
+# ── Test: uninstall when not installed (idempotent) ───────────────
+
+echo "--- Test: uninstall when not installed ---"
+
+OUTPUT=$("$ZEN_BINARY" service uninstall "$SERVICE_NAME" 2>&1)
+EXIT_CODE=$?
+
+if [ "$EXIT_CODE" -eq 0 ]; then
+    pass "uninstall of non-existent service exits with code 0"
+else
+    fail "uninstall of non-existent service exits with code 0" "got exit code: $EXIT_CODE"
+fi
+
+if echo "$OUTPUT" | grep -qi "not installed"; then
+    pass "uninstall reports service not installed"
+else
+    fail "uninstall reports service not installed" "got: $OUTPUT"
+fi