fix(state_portal): add Drop impl, null dangling pointers, extract compute_pts, add tests

- Add Drop impl for StatePortal to flush encoder on drop (bug #2)
- Use enc.take() in shutdown() to prevent double-flush of write_trailer
- Null out data[0] after Box::from_raw recovery to avoid dangling pointer
- Extract compute_pts() for testable PTS calculation
- Add 8 tests: PTS calculation, DRM device resolution, descriptor building

src/state_portal.rs

@@ -9,7 +9,7 @@ use ffmpeg_next::ffi;
 
 use crate::args::Args;
 use crate::avhw::{self, EncState};
-use crate::cap_portal::{CapPortal, PwDmaBufFrame, PwEvent};
+use crate::cap_portal::{CapPortal, PwCtrlEvent, PwDmaBufFrame};
 use crate::fps_limit::FpsLimit;
 use crate::transform::Transform;
 
@@ -78,16 +78,28 @@ impl StatePortal {
     /// 尝试从采集端点接收一帧事件。返回 `Ok(true)` 表示已处理事件，
     /// `Ok(false)` 表示暂无数据。内部根据当前阶段（等待格式/流式）分发处理。
     pub fn poll_and_encode(&mut self) -> Result<bool> {
-        let event = match self.cap.frame_receiver().try_recv() {
+        if let Ok(ctrl) = self.cap.event_receiver().try_recv() {
-            Ok(event) => event,
+            match ctrl {
+                PwCtrlEvent::StreamEnded => {
+                    tracing::warn!("PipeWire stream ended");
+                    self.errored = true;
+                    return Ok(true);
+                }
+                PwCtrlEvent::Error(e) => {
+                    tracing::error!("PipeWire error: {e}");
+                    self.errored = true;
+                    return Ok(true);
+                }
+            }
+        }
+
+        let frame = match self.cap.frame_receiver().try_recv() {
+            Ok(frame) => frame,
             Err(_) => return Ok(false),
         };
 
-        match event {
-            PwEvent::Frame(frame) => {
         match self.stage {
             PortalStage::WaitingForFormat => {
-                        // 第一帧到达：记录格式信息并用该分辨率创建编码器
                 tracing::info!(
                     "First DMA-BUF frame: {}x{} format=0x{:08X} stride={} modifier=0x{:X}",
                     frame.width,
@@ -115,22 +127,9 @@ impl StatePortal {
                 drop(frame);
             }
             PortalStage::Streaming => {
-                        // 流式阶段：处理每一帧 DMA-BUF 数据
                 self.handle_pw_frame(frame)?;
             }
         }
-            }
-            PwEvent::StreamEnded => {
-                // PipeWire 流结束（如用户停止了屏幕共享）
-                tracing::warn!("PipeWire stream ended");
-                self.errored = true;
-            }
-            PwEvent::Error(e) => {
-                // PipeWire 返回错误
-                tracing::error!("PipeWire error: {e}");
-                self.errored = true;
-            }
-        }
 
         Ok(true)
     }
@@ -224,6 +223,7 @@ impl StatePortal {
                     if !desc_ptr.is_null() {
                         let _ = Box::from_raw(desc_ptr);
                     }
+                    (*raw_frame.as_mut_ptr()).data[0] = std::ptr::null_mut();
                 }
                 bail!("encoder not initialized");
             }
@@ -243,6 +243,7 @@ impl StatePortal {
                 if !desc_ptr.is_null() {
                     let _ = Box::from_raw(desc_ptr);
                 }
+                (*raw_frame.as_mut_ptr()).data[0] = std::ptr::null_mut();
             }
             bail!("av_hwframe_get_buffer failed: error {ret}");
         }
@@ -259,6 +260,7 @@ impl StatePortal {
                 if !desc_ptr.is_null() {
                     let _ = Box::from_raw(desc_ptr);
                 }
+                (*raw_frame.as_mut_ptr()).data[0] = std::ptr::null_mut();
             }
             if ret == -(ffi::EINVAL as i32) {
                 bail!(
@@ -270,17 +272,7 @@ impl StatePortal {
         }
 
         // 7. Set PTS — convert PipeWire nanoseconds to encoder frame-number units
-        //    PipeWire PTS is CLOCK_MONOTONIC in nanoseconds.
+        let pts = compute_pts(&mut self.first_pts_ns, frame.pts, self.args.fps);
-        //    Encoder time_base = 1/fps, so PTS must be in frame numbers.
-        //    Use elapsed time since first frame to avoid i64 overflow on absolute timestamps.
-        //
-        // PTS 计算：将 PipeWire 的纳秒时间戳转换为编码器的帧号单位
-        // PipeWire 使用 CLOCK_MONOTONIC 纳秒时间戳，编码器 time_base = 1/fps
-        // 使用相对时间避免绝对时间戳导致的 i64 溢出
-        let fps_i64 = self.args.fps as i64;
-        let base_ns = *self.first_pts_ns.get_or_insert(frame.pts.max(0));
-        let elapsed_ns = (frame.pts.max(0) - base_ns).max(0);
-        let pts = elapsed_ns * fps_i64 / 1_000_000_000;
         unsafe {
             (*hw_frame.as_mut_ptr()).pts = pts;
         }
@@ -299,6 +291,7 @@ impl StatePortal {
             if !desc_ptr.is_null() {
                 let _ = Box::from_raw(desc_ptr);
             }
+            (*raw_frame.as_mut_ptr()).data[0] = std::ptr::null_mut();
         }
 
         // 9. Encode — safe to early-return via `?` now that descriptor is recovered.
@@ -310,19 +303,15 @@ impl StatePortal {
         Ok(())
     }
 
-    /// 刷新编码器缓冲区，输出所有剩余帧
-    pub fn flush(&mut self) -> Result<()> {
-        if let Some(enc) = &mut self.enc {
-            enc.flush()?;
-        }
-        Ok(())
-    }
-
     /// 关闭状态：刷新编码器并清理资源
+    ///
+    /// 使用 `enc.take()` 确保编码器只被 flush 一次，即使多次调用也安全（幂等）。
     pub fn shutdown(&mut self) {
-        if let Err(e) = self.flush() {
+        if let Some(mut enc) = self.enc.take() {
+            if let Err(e) = enc.flush() {
                 tracing::error!("Flush error during shutdown: {e}");
             }
+        }
         tracing::info!("StatePortal shutdown complete");
     }
 
@@ -332,6 +321,12 @@ impl StatePortal {
     }
 }
 
+impl Drop for StatePortal {
+    fn drop(&mut self) {
+        self.shutdown();
+    }
+}
+
 /// 根据 DMA-BUF 帧信息构建 FFmpeg DRM 帧描述符
 ///
 /// 将 PipeWire 提供的 DMA-BUF 参数（fd、偏移量、步长、修饰符等）
@@ -356,6 +351,17 @@ fn build_drm_descriptor(frame: &PwDmaBufFrame) -> ffi::AVDRMFrameDescriptor {
     desc
 }
 
+/// Convert PipeWire nanosecond PTS to encoder frame-number units.
+///
+/// Uses elapsed time since the first frame to avoid i64 overflow on absolute timestamps.
+/// PipeWire PTS is CLOCK_MONOTONIC in nanoseconds; encoder time_base = 1/fps.
+fn compute_pts(first_pts_ns: &mut Option<i64>, frame_pts: i64, fps: u32) -> i64 {
+    let fps_i64 = fps as i64;
+    let base_ns = *first_pts_ns.get_or_insert(frame_pts.max(0));
+    let elapsed_ns = (frame_pts.max(0) - base_ns).max(0);
+    elapsed_ns * fps_i64 / 1_000_000_000
+}
+
 /// 解析 DRM 渲染设备路径
 ///
 /// 仅使用命令行指定的设备路径；未指定则在首帧到达时自动检测。
@@ -419,8 +425,111 @@ mod tests {
             backend: None,
             port: 0,
         };
-        let result = resolve_drm_device(&args);
+        let result = resolve_drm_device(&args).unwrap();
-        assert!(result.is_ok());
+        assert_eq!(result, Some(std::path::PathBuf::from("/dev/dri/renderD128")));
-        assert_eq!(result.unwrap(), std::path::PathBuf::from("/dev/dri/renderD128"));
+    }
+
+    #[test]
+    fn resolve_drm_device_none_when_not_specified() {
+        let args = Args {
+            output: "test.mp4".to_string(),
+            output_name: None,
+            fps: 30,
+            codec: "h264".to_string(),
+            hw_accel: "vaapi".to_string(),
+            drm_device: None,
+            bitrate: None,
+            gop_size: None,
+            verbose: false,
+            backend: None,
+            port: 0,
+        };
+        let result = resolve_drm_device(&args).unwrap();
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn build_drm_descriptor_custom_offset_and_stride() {
+        let frame = PwDmaBufFrame {
+            fd: unsafe { OwnedFd::from_raw_fd(libc::dup(2)) },
+            offset: 4096,
+            stride: 3840 * 4,
+            modifier: 0x0100000000000001, // AMD modifiers
+            width: 3840,
+            height: 2160,
+            format: 0x34325258,
+            pts: 0,
+        };
+        let desc = build_drm_descriptor(&frame);
+
+        assert_eq!(desc.nb_objects, 1);
+        assert_eq!(desc.objects[0].format_modifier, 0x0100000000000001);
+        assert_eq!(desc.layers[0].planes[0].offset, 4096);
+        assert_eq!(desc.layers[0].planes[0].pitch, 3840 * 4);
+    }
+
+    // --- compute_pts tests ---
+
+    #[test]
+    fn compute_pts_first_frame_is_zero() {
+        let mut base = None;
+        let pts = compute_pts(&mut base, 1_000_000_000, 30);
+        assert_eq!(pts, 0);
+        assert_eq!(base, Some(1_000_000_000));
+    }
+
+    #[test]
+    fn compute_pts_second_frame_at_30fps() {
+        let mut base = Some(1_000_000_000);
+        // 33_333_333 * 30 / 1_000_000_000 = 0 (integer division)
+        let pts = compute_pts(&mut base, 1_000_000_000 + 33_333_333, 30);
+        assert_eq!(pts, 0);
+
+        // 100ms later = frame 3
+        let pts = compute_pts(&mut base, 1_000_000_000 + 100_000_000, 30);
+        assert_eq!(pts, 3);
+    }
+
+    #[test]
+    fn compute_pts_multiple_frames_accumulate() {
+        let mut base = None;
+        let fps = 60;
+
+        let pts0 = compute_pts(&mut base, 0, fps);
+        assert_eq!(pts0, 0);
+
+        let pts1 = compute_pts(&mut base, 16_666_666, fps);
+        assert_eq!(pts1, 0); // 16_666_666 * 60 / 1_000_000_000 = 0
+
+        let pts2 = compute_pts(&mut base, 33_333_333, fps);
+        assert_eq!(pts2, 1); // 33_333_333 * 60 / 1_000_000_000 = 1
+
+        let pts3 = compute_pts(&mut base, 50_000_000, fps);
+        assert_eq!(pts3, 3); // 50ms * 60 / 1000 = 3
+    }
+
+    #[test]
+    fn compute_pts_negative_pts_clamped_to_zero() {
+        let mut base = None;
+        let pts = compute_pts(&mut base, -999_999, 30);
+        assert_eq!(pts, 0);
+        assert_eq!(base, Some(0)); // max(0) clamps negative
+    }
+
+    #[test]
+    fn compute_pts_late_frame_after_negative() {
+        let mut base = Some(0);
+        let pts = compute_pts(&mut base, 1_000_000_000, 30);
+        assert_eq!(pts, 30);
+    }
+
+    #[test]
+    fn compute_pts_base_not_overwritten_after_first_call() {
+        let mut base = None;
+        let _ = compute_pts(&mut base, 5_000_000_000, 30);
+        assert_eq!(base, Some(5_000_000_000));
+
+        let _ = compute_pts(&mut base, 10_000_000_000, 30);
+        assert_eq!(base, Some(5_000_000_000)); // base stays at first frame
     }
 }