From 501405a6eef4a19c63061ae7dd5927db30e6b088 Mon Sep 17 00:00:00 2001
From: Natalia Portillo <claunia@claunia.com>
Date: Sat, 11 Apr 2026 21:32:25 +0100
Subject: [PATCH] Recover damaged block headers.

---
 src/read.c               | 10 ++++++++++
 tests/erasure_coding.cpp | 16 +++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/read.c b/src/read.c
index 274abb9..7ddbef7 100644
--- a/src/read.c
+++ b/src/read.c
@@ -607,6 +607,16 @@ AARU_EXPORT int32_t AARU_CALL aaruf_read_sector(void *context, const uint64_t se
         return AARUF_ERROR_CANNOT_READ_HEADER;
     }
 
+    /* Sanity check: if the cached/read block header looks corrupt, skip directly to EC recovery.
+     * A corrupt header will have garbage sectorSize, compression, or identifier fields. */
+    if(block_header->identifier != DataBlock ||
+       block_header->sectorSize == 0 || block_header->sectorSize > 65536)
+    {
+        TRACE("Block header at offset %" PRIu64 " appears corrupt (id=0x%08X sectorSize=%u)",
+              block_offset, block_header->identifier, block_header->sectorSize);
+        goto ec_try_recovery;
+    }
+
     if(data == NULL || *length < block_header->sectorSize)
     {
         TRACE("Buffer too small for sector, required %u bytes", block_header->sectorSize);
diff --git a/tests/erasure_coding.cpp b/tests/erasure_coding.cpp
index 0cc00c2..f52d5c7 100644
--- a/tests/erasure_coding.cpp
+++ b/tests/erasure_coding.cpp
@@ -284,9 +284,19 @@ TEST_F(ErasureCodingTest, RecoverCorruptedDataBlock)
  */
 TEST_F(ErasureCodingTest, RecoverCorruptedBlockHeader)
 {
-    /* NOTE: Corrupted BlockHeader recovery requires cache invalidation
-     * which is not yet implemented. Skipping for now. */
-    GTEST_SKIP() << "BlockHeader corruption recovery requires cache invalidation (TODO)";
+    uint64_t golden_crc = 0;
+    ASSERT_TRUE(create_ec_image("data/mf2hd.aif", "ec_test_output.aif", 4, 2, &golden_crc));
+
+    ASSERT_TRUE(copy_file("ec_test_output.aif", "ec_test_corrupt.aif"));
+
+    /* Corrupt the first block's header at offset 512 (after alignment).
+     * Corrupt 32 bytes = entire BlockHeader, making identifier/compression/sectorSize garbage. */
+    corrupt_file("ec_test_corrupt.aif", 512, 32);
+
+    bool success = false;
+    uint64_t read_crc = compute_image_crc("ec_test_corrupt.aif", &success);
+    ASSERT_TRUE(success) << "EC recovery failed on corrupted BlockHeader";
+    EXPECT_EQ(read_crc, golden_crc);
 }
 
 /**