Kernel+LibPartition: Move EBRPartitionTable into LibPartition

3 files changed, 101 insertions, 0 deletions

diff --git a/Userland/Libraries/LibPartition/CMakeLists.txt b/Userland/Libraries/LibPartition/CMakeLists.txt
index a3f43660b8..adae3e4c98 100644
--- a/Userland/Libraries/LibPartition/CMakeLists.txt
+++ b/Userland/Libraries/LibPartition/CMakeLists.txt
@@ -1,5 +1,6 @@
 set(SOURCES
     DiskPartitionMetadata.cpp
+    EBRPartitionTable.cpp
     MBRPartitionTable.cpp
     PartitionTable.cpp
 )
diff --git a/Userland/Libraries/LibPartition/EBRPartitionTable.cpp b/Userland/Libraries/LibPartition/EBRPartitionTable.cpp
new file mode 100644
index 0000000000..ee2220d2d0
--- /dev/null
+++ b/Userland/Libraries/LibPartition/EBRPartitionTable.cpp
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2020-2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibPartition/EBRPartitionTable.h>
+
+namespace Partition {
+
+ErrorOr<NonnullOwnPtr<EBRPartitionTable>> EBRPartitionTable::try_to_initialize(Kernel::StorageDevice const& device)
+{
+    auto table = TRY(adopt_nonnull_own_or_enomem(new (nothrow) EBRPartitionTable(device)));
+    if (table->is_protective_mbr())
+        return Error::from_errno(ENOTSUP);
+    if (!table->is_valid())
+        return Error::from_errno(EINVAL);
+    return table;
+}
+
+void EBRPartitionTable::search_extended_partition(Kernel::StorageDevice const& device, MBRPartitionTable& checked_ebr, u64 current_block_offset, size_t limit)
+{
+    if (limit == 0)
+        return;
+    // EBRs should not carry more than 2 partitions (because they need to form a linked list)
+    VERIFY(checked_ebr.partitions_count() <= 2);
+    auto checked_logical_partition = checked_ebr.partition(0);
+
+    // If we are pointed to an invalid logical partition, something is seriously wrong.
+    VERIFY(checked_logical_partition.has_value());
+    m_partitions.append(checked_logical_partition.value().offset(current_block_offset));
+    if (!checked_ebr.contains_ebr())
+        return;
+    current_block_offset += checked_ebr.partition(1).value().start_block();
+    auto next_ebr = MBRPartitionTable::try_to_initialize(device, current_block_offset);
+    if (!next_ebr)
+        return;
+    search_extended_partition(device, *next_ebr, current_block_offset, (limit - 1));
+}
+
+EBRPartitionTable::EBRPartitionTable(Kernel::StorageDevice const& device)
+    : MBRPartitionTable(device)
+{
+    if (!is_header_valid())
+        return;
+    m_valid = true;
+
+    VERIFY(partitions_count() == 0);
+
+    auto& header = this->header();
+    for (size_t index = 0; index < 4; index++) {
+        auto& entry = header.entry[index];
+        // Start enumerating all logical partitions
+        if (entry.type == 0xf) {
+            auto checked_ebr = MBRPartitionTable::try_to_initialize(device, entry.offset);
+            if (!checked_ebr)
+                continue;
+            // It's quite unlikely to see that amount of partitions, so stop at 128 partitions.
+            search_extended_partition(device, *checked_ebr, entry.offset, 128);
+            continue;
+        }
+
+        if (entry.offset == 0x00) {
+            continue;
+        }
+        MUST(m_partitions.try_empend(entry.offset, (entry.offset + entry.length), entry.type));
+    }
+}
+
+EBRPartitionTable::~EBRPartitionTable() = default;
+
+}
diff --git a/Userland/Libraries/LibPartition/EBRPartitionTable.h b/Userland/Libraries/LibPartition/EBRPartitionTable.h
new file mode 100644
index 0000000000..d44f5a4490
--- /dev/null
+++ b/Userland/Libraries/LibPartition/EBRPartitionTable.h
@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2020-2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibPartition/MBRPartitionTable.h>
+
+namespace Partition {
+
+struct EBRPartitionHeader;
+class EBRPartitionTable : public MBRPartitionTable {
+public:
+    ~EBRPartitionTable();
+
+    static ErrorOr<NonnullOwnPtr<EBRPartitionTable>> try_to_initialize(Kernel::StorageDevice const&);
+    explicit EBRPartitionTable(Kernel::StorageDevice const&);
+    virtual bool is_valid() const override { return m_valid; };
+
+private:
+    void search_extended_partition(Kernel::StorageDevice const&, MBRPartitionTable&, u64, size_t limit);
+
+    bool m_valid { false };
+};
+
+}