From 0323970550b9e2b52d46b3e7bb3c776bbb3c5c91 Mon Sep 17 00:00:00 2001
From: Kenneth Russell <kbr@chromium.org>
Date: Mon, 30 Mar 2026 18:13:36 -0700
Subject: [PATCH] Metal: Fix pitch computation for compressed textures in PBOs.

Correctly detect block formats and adjust the row and depth pitch
computation. Inspiration taken from ANGLE's Vulkan backend.

Authored with gemini-cli, with guidance from domain experts.

Fixed: angleproject:489579953
Change-Id: I5656b02bc235bbe068191a0fb2049afcea9a094e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/7699417
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
---

diff --git a/src/libANGLE/renderer/metal/TextureMtl.mm b/src/libANGLE/renderer/metal/TextureMtl.mm
index a671ff7..6f75fde 100644
--- a/src/libANGLE/renderer/metal/TextureMtl.mm
+++ b/src/libANGLE/renderer/metal/TextureMtl.mm
@@ -2470,7 +2470,29 @@
                                                      ? imageFormat.textureLoadFunctions(type)
                                                      : LoadImageFunctionInfo();
         const angle::Format &dstFormat         = angle::Format::Get(imageFormat.actualFormatId);
-        const size_t dstRowPitch               = dstFormat.pixelBytes * mtlArea.size.width;
+        size_t dstRowPitch;
+        size_t dstDepthPitch;
+        if (dstFormat.isBlock)
+        {
+            const gl::InternalFormat &dstFormatInfo =
+                gl::GetSizedInternalFormatInfo(dstFormat.glInternalFormat);
+            GLuint rowPitch;
+            ANGLE_CHECK_GL_MATH(contextMtl,
+                                dstFormatInfo.computeCompressedImageRowPitch(
+                                    static_cast<GLsizei>(mtlArea.size.width), &rowPitch));
+            dstRowPitch = rowPitch;
+
+            GLuint depthPitch;
+            ANGLE_CHECK_GL_MATH(contextMtl, dstFormatInfo.computeCompressedImageDepthPitch(
+                                                static_cast<GLsizei>(mtlArea.size.height),
+                                                static_cast<GLuint>(dstRowPitch), &depthPitch));
+            dstDepthPitch = depthPitch;
+        }
+        else
+        {
+            dstRowPitch   = dstFormat.pixelBytes * mtlArea.size.width;
+            dstDepthPitch = dstRowPitch * mtlArea.size.height;
+        }
 
         // It is very important to avoid allocating a new buffer for each row during these
         // uploads.
@@ -2484,7 +2506,6 @@
                 ASSERT(loadFunctionInfo.loadFunction);
 
                 // Need to create a buffer to hold entire decompressed image.
-                const size_t dstDepthPitch = dstRowPitch * mtlArea.size.height;
                 angle::MemoryBuffer decompressBuf;
                 ANGLE_CHECK_GL_ALLOC(contextMtl,
                                      decompressBuf.resize(dstDepthPitch * mtlArea.size.depth));
@@ -2508,7 +2529,6 @@
                        static_cast<unsigned int>(imageDef.image->sizeAt0().width));
                 ASSERT(mtlArea.size.height ==
                        static_cast<unsigned int>(imageDef.image->sizeAt0().height));
-                const size_t dstDepthPitch = dstRowPitch * mtlArea.size.height;
                 ANGLE_TRY(UploadTextureContents(
                     context, dstFormat, mtlArea, mtl::kZeroNativeMipLevel, slice, pixels,
                     dstRowPitch, dstDepthPitch, kAvoidStagingBuffers, imageDef.image));
diff --git a/src/tests/gl_tests/ETCTextureTest.cpp b/src/tests/gl_tests/ETCTextureTest.cpp
index 319eb1c..0d2f732 100644
--- a/src/tests/gl_tests/ETCTextureTest.cpp
+++ b/src/tests/gl_tests/ETCTextureTest.cpp
@@ -12,6 +12,7 @@
 #endif
 
 #include "test_utils/ANGLETest.h"
+#include "test_utils/gl_raii.h"
 
 #include "media/etc2bc_srgb8_alpha8.inc"
 
@@ -309,6 +310,45 @@
     }
 }
 
+// Tests that uploading compressed texture from a PBO with a misaligned offset doesn't crash.
+TEST_P(ETCTextureTest, PBOWithMisalignedOffset)
+{
+    // Need ES 3.0 for PBOs.
+    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3);
+
+    // Check if ETC2 is supported. Not supported, for example, on ANGLE/OpenGL on macOS.
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_ANGLE_lossy_etc_decode") &&
+                       !IsGLExtensionEnabled("GL_OES_compressed_ETC2_RGB8_texture") &&
+                       !IsGLExtensionEnabled("GL_ANGLE_compressed_texture_etc"));
+
+    constexpr GLsizei kWidth  = 512;
+    constexpr GLsizei kHeight = 512;
+    constexpr GLsizei kBPB    = 8;  // 8 bytes per block
+    constexpr GLsizei kBW     = 4;
+    constexpr GLsizei kBH     = 4;
+
+    GLsizei blocksX        = kWidth / kBW;
+    GLsizei blocksY        = kHeight / kBH;
+    GLsizei compressedSize = blocksX * blocksY * kBPB;
+
+    glBindTexture(GL_TEXTURE_2D, mTexture);
+    // Use GL_COMPRESSED_RGB8_ETC2 which is core in ES 3.0
+    glCompressedTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB8_ETC2, kWidth, kHeight, 0,
+                           compressedSize, nullptr);
+
+    // Misaligned offset to trigger the fallback path in Metal backend
+    constexpr GLsizei kPBOOffset = 1;
+
+    GLBuffer pbo;
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo);
+    glBufferData(GL_PIXEL_UNPACK_BUFFER, kPBOOffset + compressedSize, nullptr, GL_STATIC_DRAW);
+    ASSERT_GL_NO_ERROR();
+
+    glCompressedTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, kWidth, kHeight, GL_COMPRESSED_RGB8_ETC2,
+                              compressedSize, reinterpret_cast<void *>(kPBOOffset));
+    EXPECT_GL_NO_ERROR();
+}
+
 class ETCToBCTextureTest : public ANGLETest<>
 {
   protected:

diff --git a/src/tests/gl_tests/ETCTextureTest.cpp b/src/tests/gl_tests/ETCTextureTest.cpp
index 319eb1c..0d2f732 100644
--- a/src/tests/gl_tests/ETCTextureTest.cpp
+++ b/src/tests/gl_tests/ETCTextureTest.cpp
@@ -12,6 +12,7 @@
 #endif
 
 #include "test_utils/ANGLETest.h"
+#include "test_utils/gl_raii.h"
 
 #include "media/etc2bc_srgb8_alpha8.inc"
 
@@ -309,6 +310,45 @@
     }
 }
 
+// Tests that uploading compressed texture from a PBO with a misaligned offset doesn't crash.
+TEST_P(ETCTextureTest, PBOWithMisalignedOffset)
+{
+    // Need ES 3.0 for PBOs.
+    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3);
+
+    // Check if ETC2 is supported. Not supported, for example, on ANGLE/OpenGL on macOS.
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_ANGLE_lossy_etc_decode") &&
+                       !IsGLExtensionEnabled("GL_OES_compressed_ETC2_RGB8_texture") &&
+                       !IsGLExtensionEnabled("GL_ANGLE_compressed_texture_etc"));
+
+    constexpr GLsizei kWidth  = 512;
+    constexpr GLsizei kHeight = 512;
+    constexpr GLsizei kBPB    = 8;  // 8 bytes per block
+    constexpr GLsizei kBW     = 4;
+    constexpr GLsizei kBH     = 4;
+
+    GLsizei blocksX        = kWidth / kBW;
+    GLsizei blocksY        = kHeight / kBH;
+    GLsizei compressedSize = blocksX * blocksY * kBPB;
+
+    glBindTexture(GL_TEXTURE_2D, mTexture);
+    // Use GL_COMPRESSED_RGB8_ETC2 which is core in ES 3.0
+    glCompressedTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB8_ETC2, kWidth, kHeight, 0,
+                           compressedSize, nullptr);
+
+    // Misaligned offset to trigger the fallback path in Metal backend
+    constexpr GLsizei kPBOOffset = 1;
+
+    GLBuffer pbo;
+    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo);
+    glBufferData(GL_PIXEL_UNPACK_BUFFER, kPBOOffset + compressedSize, nullptr, GL_STATIC_DRAW);
+    ASSERT_GL_NO_ERROR();
+
+    glCompressedTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, kWidth, kHeight, GL_COMPRESSED_RGB8_ETC2,
+                              compressedSize, reinterpret_cast<void *>(kPBOOffset));
+    EXPECT_GL_NO_ERROR();
+}
+
 class ETCToBCTextureTest : public ANGLETest<>
 {
   protected: