fix(linux): fall back to live CRTC geometry for KMS capture

cmake/compile_definitions/linux.cmake

@@ -94,6 +94,7 @@ if(LIBDRM_FOUND)
         list(APPEND PLATFORM_LIBRARIES ${LIBDRM_LIBRARIES})
         add_compile_definitions(SUNSHINE_BUILD_DRM)
         list(APPEND PLATFORM_TARGET_FILES
+                "${CMAKE_SOURCE_DIR}/src/platform/linux/kmsgrab.h"
                 "${CMAKE_SOURCE_DIR}/src/platform/linux/kmsgrab.cpp")
         list(APPEND SUNSHINE_DEFINITIONS EGL_NO_X11=1)
     endif()

src/platform/linux/kmsgrab.cpp

@@ -21,6 +21,7 @@
 // local includes
 #include "cuda.h"
 #include "graphics.h"
+#include "kmsgrab.h"
 #include "src/config.h"
 #include "src/logging.h"
 #include "src/platform/common.h"
@@ -229,29 +230,6 @@ namespace platf {
       bool connected;  ///< Whether the DRM connector is connected.
     };
 
-    /**
-     * @brief KMS monitor capture state and DRM resources.
-     */
-    struct monitor_t {
-      // Connector attributes
-      std::uint32_t type;  ///< Type.
-      std::uint32_t index;  ///< Index.
-
-      // Monitor index in the global list
-      std::uint32_t monitor_index;  ///< Monitor index.
-
-      platf::touch_port_t viewport;  ///< Viewport.
-    };
-
-    /**
-     * @brief DRM card, device path, and render-node metadata.
-     */
-    struct card_descriptor_t {
-      std::string path;  ///< Path.
-
-      std::map<std::uint32_t, monitor_t> crtc_to_monitor;  ///< Crtc to monitor.
-    };
-
     static std::vector<card_descriptor_t> card_descriptors;
 
     static std::uint32_t from_view(const std::string_view &string) {
@@ -979,18 +957,6 @@ namespace platf {
 
             BOOST_LOG(info) << "Found monitor for DRM screencasting"sv;
 
-            // We need to find the correct /dev/dri/card{nr} to correlate the crtc_id with the monitor descriptor
-            auto pos = std::find_if(std::begin(card_descriptors), std::end(card_descriptors), [&](card_descriptor_t &cd) {
-              return cd.path == filestring;
-            });
-
-            if (pos == std::end(card_descriptors)) {
-              // This code path shouldn't happen, but it's there just in case.
-              // card_descriptors is part of the guesswork after all.
-              BOOST_LOG(error) << "Couldn't find ["sv << entry.path() << "]: This shouldn't have happened :/"sv;
-              return -1;
-            }
-
             // TODO: surf_sd = fb->to_sd();
 
             kms::print(plane.get(), fb.get(), crtc.get());
@@ -1006,40 +972,46 @@ namespace platf {
             this->env_logical_width = ::platf::kms::env_logical_width;
             this->env_logical_height = ::platf::kms::env_logical_height;
 
-            auto monitor = pos->crtc_to_monitor.find(plane->crtc_id);
-            if (monitor != std::end(pos->crtc_to_monitor)) {
-              auto &viewport = monitor->second.viewport;
-
-              width = viewport.width;
-              height = viewport.height;
-
-              logical_width = viewport.logical_width;
-              logical_height = viewport.logical_height;
-
-              switch (card.get_panel_orientation(plane->plane_id)) {
-                case DRM_MODE_ROTATE_270:
-                  BOOST_LOG(debug) << "Detected panel orientation at 90, swapping width and height.";
-                  width = viewport.height;
-                  height = viewport.width;
-                  break;
-                case DRM_MODE_ROTATE_90:
-                case DRM_MODE_ROTATE_180:
-                  BOOST_LOG(warning) << "Panel orientation is unsupported, screen capture may not work correctly.";
-                  break;
-              }
-
-              offset_x = viewport.offset_x;
-              offset_y = viewport.offset_y;
+            const platf::touch_port_t live_crtc_viewport {
+              (int) crtc->x,
+              (int) crtc->y,
+              (int) crtc->width,
+              (int) crtc->height,
+              (int) crtc->width,
+              (int) crtc->height,
+            };
+            const auto resolved_viewport = resolve_monitor_viewport(card_descriptors, filestring, plane->crtc_id, live_crtc_viewport);
+            switch (resolved_viewport.source) {
+              using enum monitor_viewport_source_e;
+
+              case live_crtc_missing_card:
+                BOOST_LOG(warning) << "DRM card ["sv << entry.path() << "] was absent from the cached monitor list; using live CRTC geometry."sv;
+                break;
+              case live_crtc_missing_monitor:
+                BOOST_LOG(warning) << "CRTC ["sv << plane->crtc_id << "] was absent from the cached monitor list; using live CRTC geometry."sv;
+                break;
+              case cached:
+                break;
             }
 
-            // This code path shouldn't happen, but it's there just in case.
-            // crtc_to_monitor is part of the guesswork after all.
-            else {
-              BOOST_LOG(warning) << "Couldn't find crtc_id, this shouldn't have happened :\\"sv;
-              width = crtc->width;
-              height = crtc->height;
-              offset_x = crtc->x;
-              offset_y = crtc->y;
+            const auto &viewport = resolved_viewport.viewport;
+            width = viewport.width;
+            height = viewport.height;
+            logical_width = viewport.logical_width;
+            logical_height = viewport.logical_height;
+            offset_x = viewport.offset_x;
+            offset_y = viewport.offset_y;
+
+            switch (card.get_panel_orientation(plane->plane_id)) {
+              case DRM_MODE_ROTATE_270:
+                BOOST_LOG(debug) << "Detected panel orientation at 90, swapping width and height.";
+                width = viewport.height;
+                height = viewport.width;
+                break;
+              case DRM_MODE_ROTATE_90:
+              case DRM_MODE_ROTATE_180:
+                BOOST_LOG(warning) << "Panel orientation is unsupported, screen capture may not work correctly.";
+                break;
             }
 
             plane_id = plane->plane_id;

src/platform/linux/kmsgrab.h

@@ -0,0 +1,132 @@
+/**
+ * @file src/platform/linux/kmsgrab.h
+ * @brief Portable KMS monitor descriptor and viewport helpers.
+ */
+#pragma once
+
+// standard includes
+#include <algorithm>
+#include <cstdint>
+#include <iterator>
+#include <map>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+// local includes
+#include "src/platform/common.h"
+
+namespace platf::kms {
+
+  /**
+   * @brief KMS monitor capture state and DRM resources.
+   */
+  struct monitor_t {
+    // Connector attributes
+    std::uint32_t type;  ///< Type.
+    std::uint32_t index;  ///< Index.
+
+    // Monitor index in the global list
+    std::uint32_t monitor_index;  ///< Monitor index.
+
+    platf::touch_port_t viewport;  ///< Viewport.
+  };
+
+  /**
+   * @brief DRM card, device path, and monitor metadata.
+   */
+  struct card_descriptor_t {
+    /**
+     * @brief Construct a DRM card descriptor.
+     *
+     * @param card_path DRM card filename.
+     * @param monitors CRTC-to-monitor lookup.
+     */
+    card_descriptor_t(std::string card_path, std::map<std::uint32_t, monitor_t> monitors):
+        path {std::move(card_path)},
+        crtc_to_monitor {std::move(monitors)} {
+    }
+
+    /**
+     * @brief Copy a DRM card descriptor.
+     *
+     * @param other Descriptor to copy.
+     */
+    card_descriptor_t(const card_descriptor_t &other) = default;
+
+    /**
+     * @brief Move a DRM card descriptor without throwing.
+     *
+     * @param other Descriptor to move.
+     */
+    card_descriptor_t(card_descriptor_t &&other) noexcept = default;
+
+    /**
+     * @brief Copy-assign a DRM card descriptor.
+     *
+     * @param other Descriptor to copy.
+     * @return Reference to this descriptor.
+     */
+    card_descriptor_t &operator=(const card_descriptor_t &other) = default;
+
+    /**
+     * @brief Move-assign a DRM card descriptor without throwing.
+     *
+     * @param other Descriptor to move.
+     * @return Reference to this descriptor.
+     */
+    card_descriptor_t &operator=(card_descriptor_t &&other) noexcept = default;
+
+    std::string path;  ///< DRM card filename.
+    std::map<std::uint32_t, monitor_t> crtc_to_monitor;  ///< CRTC-to-monitor lookup.
+  };
+
+  /**
+   * @brief Source used to resolve a KMS monitor viewport.
+   */
+  enum class monitor_viewport_source_e {
+    cached,  ///< Viewport came from the cached card and monitor descriptor.
+    live_crtc_missing_card,  ///< Cached card was absent, so live CRTC geometry was used.
+    live_crtc_missing_monitor,  ///< Cached CRTC was absent, so live CRTC geometry was used.
+  };
+
+  /**
+   * @brief Resolved KMS viewport and its source.
+   */
+  struct monitor_viewport_result_t {
+    platf::touch_port_t viewport;  ///< Resolved viewport.
+    monitor_viewport_source_e source;  ///< Source of the resolved viewport.
+  };
+
+  /**
+   * @brief Resolve cached monitor geometry, falling back to the live CRTC.
+   *
+   * @param card_descriptors Cached KMS card descriptors from display enumeration.
+   * @param card_path Filename of the live DRM card being captured.
+   * @param crtc_id Live DRM CRTC identifier being captured.
+   * @param live_crtc_viewport Viewport derived from the live CRTC.
+   * @return Cached monitor viewport when available; otherwise the live CRTC viewport.
+   */
+  inline monitor_viewport_result_t resolve_monitor_viewport(
+    const std::vector<card_descriptor_t> &card_descriptors,
+    const std::string_view card_path,
+    const std::uint32_t crtc_id,
+    const platf::touch_port_t &live_crtc_viewport
+  ) {
+    using enum monitor_viewport_source_e;
+
+    const auto card = std::ranges::find(card_descriptors, card_path, &card_descriptor_t::path);
+    if (card == std::end(card_descriptors)) {
+      return {live_crtc_viewport, live_crtc_missing_card};
+    }
+
+    const auto monitor = card->crtc_to_monitor.find(crtc_id);
+    if (monitor == std::end(card->crtc_to_monitor)) {
+      return {live_crtc_viewport, live_crtc_missing_monitor};
+    }
+
+    return {monitor->second.viewport, cached};
+  }
+
+}  // namespace platf::kms

tests/unit/platform/linux/test_kmsgrab.cpp

@@ -0,0 +1,93 @@
+/**
+ * @file tests/unit/platform/linux/test_kmsgrab.cpp
+ * @brief Tests for portable KMS monitor descriptor helpers.
+ */
+#include "../../../tests_common.h"
+
+// standard includes
+#include <algorithm>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+// local includes
+#include "src/platform/linux/kmsgrab.h"
+
+namespace {
+
+  /**
+   * @brief Input and expected output for KMS viewport resolution tests.
+   */
+  struct monitor_viewport_test_case_t {
+    std::string name;  ///< Descriptive test-case name.
+    std::vector<platf::kms::card_descriptor_t> card_descriptors;  ///< Cached card descriptors.
+    std::string card_path;  ///< Live DRM card filename.
+    std::uint32_t crtc_id;  ///< Live DRM CRTC identifier.
+    platf::touch_port_t live_crtc_viewport;  ///< Fallback live CRTC geometry.
+    platf::touch_port_t expected_viewport;  ///< Expected resolved geometry.
+    platf::kms::monitor_viewport_source_e expected_source;  ///< Expected geometry source.
+  };
+
+  /**
+   * @brief Parameterized fixture for KMS viewport resolution.
+   */
+  class KmsMonitorViewportTest: public testing::TestWithParam<monitor_viewport_test_case_t> {};
+
+  TEST_P(KmsMonitorViewportTest, ResolvesCachedOrLiveCrtcGeometry) {
+    const auto &test_case = GetParam();
+    const auto result = platf::kms::resolve_monitor_viewport(
+      test_case.card_descriptors,
+      test_case.card_path,
+      test_case.crtc_id,
+      test_case.live_crtc_viewport
+    );
+
+    EXPECT_EQ(result.source, test_case.expected_source);
+    EXPECT_EQ(result.viewport.offset_x, test_case.expected_viewport.offset_x);
+    EXPECT_EQ(result.viewport.offset_y, test_case.expected_viewport.offset_y);
+    EXPECT_EQ(result.viewport.width, test_case.expected_viewport.width);
+    EXPECT_EQ(result.viewport.height, test_case.expected_viewport.height);
+    EXPECT_EQ(result.viewport.logical_width, test_case.expected_viewport.logical_width);
+    EXPECT_EQ(result.viewport.logical_height, test_case.expected_viewport.logical_height);
+  }
+
+  INSTANTIATE_TEST_SUITE_P(
+    KmsMonitorViewportCases,
+    KmsMonitorViewportTest,
+    testing::Values(
+      monitor_viewport_test_case_t {
+        "cached monitor",
+        {{"card2", {{42, {10, 1, 0, {100, 200, 2560, 1600, 1280, 800}}}}}},
+        "card2",
+        42,
+        {0, 0, 1920, 1080, 1920, 1080},
+        {100, 200, 2560, 1600, 1280, 800},
+        platf::kms::monitor_viewport_source_e::cached,
+      },
+      monitor_viewport_test_case_t {
+        "missing secondary card",
+        {{"card1", {{17, {11, 1, 0, {0, 0, 1920, 1080, 1920, 1080}}}}}},
+        "card2",
+        42,
+        {0, 0, 2560, 1600, 2560, 1600},
+        {0, 0, 2560, 1600, 2560, 1600},
+        platf::kms::monitor_viewport_source_e::live_crtc_missing_card,
+      },
+      monitor_viewport_test_case_t {
+        "missing monitor on cached card",
+        {{"card2", {{17, {10, 1, 0, {0, 0, 1920, 1080, 1920, 1080}}}}}},
+        "card2",
+        42,
+        {300, 0, 2560, 1600, 2560, 1600},
+        {300, 0, 2560, 1600, 2560, 1600},
+        platf::kms::monitor_viewport_source_e::live_crtc_missing_monitor,
+      }
+    ),
+    [](const testing::TestParamInfo<monitor_viewport_test_case_t> &info) {
+      std::string name = info.param.name;
+      std::ranges::replace(name, ' ', '_');
+      return name;
+    }
+  );
+
+}  // namespace