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, 143 insertions, 0 deletions

diff --git a/scripts/test_linux/block-clone-test.sh b/scripts/test_linux/block-clone-test.sh
new file mode 100755
index 000000000..0a74283f2
--- /dev/null
+++ b/scripts/test_linux/block-clone-test.sh
@@ -0,0 +1,143 @@
+#!/usr/bin/env bash
+# Test block-clone functionality on temporary Btrfs and XFS loopback filesystems.
+#
+# Requires: root/sudo, btrfs-progs (mkfs.btrfs), xfsprogs (mkfs.xfs)
+#
+# Usage:
+#   sudo ./scripts/test_linux/block-clone-test.sh [path-to-zencore-test]
+#
+# If no path is given, defaults to build/linux/x86_64/debug/zencore-test
+# relative to the repository root.
+#
+# Options:
+#   --btrfs-only   Only test Btrfs
+#   --xfs-only     Only test XFS
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+TEST_BINARY=""
+RUN_BTRFS=true
+RUN_XFS=true
+
+for arg in "$@"; do
+    case "$arg" in
+        --btrfs-only) RUN_XFS=false ;;
+        --xfs-only)   RUN_BTRFS=false ;;
+        *)            TEST_BINARY="$arg" ;;
+    esac
+done
+
+TEST_BINARY="${TEST_BINARY:-$REPO_ROOT/build/linux/x86_64/debug/zencore-test}"
+IMAGE_SIZE="512M"
+TEST_CASES="TryCloneFile,CopyFile.Clone,SupportsBlockRefCounting,CloneQueryInterface"
+
+# Track all temp files for cleanup
+CLEANUP_MOUNTS=()
+CLEANUP_DIRS=()
+CLEANUP_FILES=()
+
+cleanup() {
+    local exit_code=$?
+    set +e
+
+    for mnt in "${CLEANUP_MOUNTS[@]}"; do
+        if mountpoint -q "$mnt" 2>/dev/null; then
+            umount "$mnt"
+        fi
+    done
+    for dir in "${CLEANUP_DIRS[@]}"; do
+        [ -d "$dir" ] && rmdir "$dir"
+    done
+    for f in "${CLEANUP_FILES[@]}"; do
+        [ -f "$f" ] && rm -f "$f"
+    done
+
+    if [ $exit_code -ne 0 ]; then
+        echo "FAILED (exit code $exit_code)"
+    fi
+    exit $exit_code
+}
+trap cleanup EXIT
+
+# --- Preflight checks ---
+
+if [ "$(id -u)" -ne 0 ]; then
+    echo "error: this script must be run as root (for mount/umount)" >&2
+    exit 1
+fi
+
+if [ ! -x "$TEST_BINARY" ]; then
+    echo "error: test binary not found or not executable: $TEST_BINARY" >&2
+    echo "hint:  build with 'xmake config -m debug && xmake build zencore-test'" >&2
+    exit 1
+fi
+
+if $RUN_BTRFS && ! command -v mkfs.btrfs &>/dev/null; then
+    echo "warning: mkfs.btrfs not found — install btrfs-progs to test Btrfs, skipping" >&2
+    RUN_BTRFS=false
+fi
+
+if $RUN_XFS && ! command -v mkfs.xfs &>/dev/null; then
+    echo "warning: mkfs.xfs not found — install xfsprogs to test XFS, skipping" >&2
+    RUN_XFS=false
+fi
+
+if ! $RUN_BTRFS && ! $RUN_XFS; then
+    echo "error: no filesystems to test" >&2
+    exit 1
+fi
+
+# --- Helper to create, mount, and run tests on a loopback filesystem ---
+
+run_tests_on_fs() {
+    local fs_type="$1"
+    local mkfs_cmd="$2"
+
+    echo ""
+    echo "========================================"
+    echo "  Testing block-clone on $fs_type"
+    echo "========================================"
+
+    local image_path mount_path
+    image_path="$(mktemp "/tmp/${fs_type}-clone-test-XXXXXX.img")"
+    mount_path="$(mktemp -d "/tmp/${fs_type}-clone-mount-XXXXXX")"
+    CLEANUP_FILES+=("$image_path")
+    CLEANUP_DIRS+=("$mount_path")
+    CLEANUP_MOUNTS+=("$mount_path")
+
+    echo "Creating ${IMAGE_SIZE} ${fs_type} image at ${image_path} ..."
+    truncate -s "$IMAGE_SIZE" "$image_path"
+    $mkfs_cmd "$image_path"
+
+    echo "Mounting at ${mount_path} ..."
+    mount -o loop "$image_path" "$mount_path"
+    chmod 777 "$mount_path"
+
+    echo "Copying test binary ..."
+    cp "$TEST_BINARY" "$mount_path/zencore-test"
+    chmod +x "$mount_path/zencore-test"
+
+    echo "Running tests ..."
+    echo "---"
+    "$mount_path/zencore-test" \
+        --test-suite="core.filesystem" \
+        --test-case="$TEST_CASES"
+    echo "---"
+    echo "$fs_type: all block-clone tests passed."
+}
+
+# --- Run ---
+
+if $RUN_BTRFS; then
+    run_tests_on_fs "btrfs" "mkfs.btrfs -q"
+fi
+
+if $RUN_XFS; then
+    run_tests_on_fs "xfs" "mkfs.xfs -q -m reflink=1"
+fi
+
+echo ""
+echo "All block-clone tests passed."