Camera metadata: Fix validation alignment check, add more unit tests

- Add unit test to ensure validate_camera_metadata_structure correctly
  reports VALIDATION_SHIFTED for all shifts
- Fix alignment validation bug found by unit test - need to offset
  pointer on both sides of align check.

Test: New unit test passes, no camera CTS regression
Bug: 37980415
Change-Id: I08379bf3792b57c4eae129acc7aa4f22ab960657

2 files changed, 38 insertions, 3 deletions

diff --git a/camera/src/camera_metadata.c b/camera/src/camera_metadata.c
index c79f61c0..dc800860 100644
--- a/camera/src/camera_metadata.c
+++ b/camera/src/camera_metadata.c
@@ -420,13 +420,14 @@ int validate_camera_metadata_structure(const camera_metadata_t *metadata,
         };
 
         for (size_t i = 0; i < sizeof(alignments)/sizeof(alignments[0]); ++i) {
-            uintptr_t aligned_ptr = ALIGN_TO(metadata, alignments[i].alignment);
+            uintptr_t aligned_ptr = ALIGN_TO((uintptr_t) metadata + alignmentOffset,
+                    alignments[i].alignment);
 
             if ((uintptr_t)metadata + alignmentOffset != aligned_ptr) {
                 ALOGE("%s: Metadata pointer is not aligned (actual %p, "
-                      "expected %p) to type %s",
+                      "expected %p, offset %" PRIuPTR ") to type %s",
                       __FUNCTION__, metadata,
-                      (void*)aligned_ptr, alignments[i].name);
+                      (void*)aligned_ptr, alignmentOffset, alignments[i].name);
                 return CAMERA_METADATA_VALIDATION_ERROR;
             }
         }
diff --git a/camera/tests/camera_metadata_tests.cpp b/camera/tests/camera_metadata_tests.cpp
index 121ce19a..bcebf2e1 100644
--- a/camera/tests/camera_metadata_tests.cpp
+++ b/camera/tests/camera_metadata_tests.cpp
@@ -1870,3 +1870,37 @@ TEST(camera_metadata, data_alignment) {
         }
     }
 }
+
+TEST(camera_metadata, buffer_alignment) {
+    // Verify that misaligned metadata buffers only fail VALIDATION_SHIFTED, nothing else
+    const size_t entry_capacity = 50;
+    const size_t data_capacity = 450;
+    const size_t offsetRange = 16;
+    const uint32_t validAlignment = 8;
+
+    camera_metadata_t *m = NULL;
+    m = allocate_camera_metadata(entry_capacity, data_capacity);
+
+    add_test_metadata(m, 15);
+
+    size_t m_size = get_camera_metadata_size(m);
+    size_t dst_size = m_size + offsetRange;
+    uint8_t *dst = new uint8_t[dst_size];
+
+    for (size_t i = 0; i < offsetRange; i++) {
+        memset(dst, 0, dst_size);
+        memcpy(dst + i, m, m_size);
+        camera_metadata_t *m_shifted = (camera_metadata_t*)(dst + i);
+
+        int err = validate_camera_metadata_structure(m_shifted, &m_size);
+        if (i % validAlignment == 0) {
+            ASSERT_EQ(OK, err) << "For alignment shift " << i << ", expected OK" ;
+        } else {
+            ASSERT_EQ(CAMERA_METADATA_VALIDATION_SHIFTED, err) <<
+                    "For alignment shift " << i << ", expected VALIDATION_SHIFTED" ;
+        }
+    }
+
+    delete[] dst;
+    FINISH_USING_CAMERA_METADATA(m);
+}