diff --git a/apps/bsatool/bsatool.cpp b/apps/bsatool/bsatool.cpp
index b62a438294..90685dfe1d 100644
--- a/apps/bsatool/bsatool.cpp
+++ b/apps/bsatool/bsatool.cpp
@@ -170,8 +170,8 @@ int list(std::unique_ptr<File>& bsa, Arguments& info)
             // Long format
             std::ios::fmtflags f(std::cout.flags());
             std::cout << std::setw(50) << std::left << file.name();
-            std::cout << std::setw(8) << std::left << std::dec << file.fileSize;
-            std::cout << "@ 0x" << std::hex << file.offset << std::endl;
+            std::cout << std::setw(8) << std::left << std::dec << file.mFileSize;
+            std::cout << "@ 0x" << std::hex << file.mOffset << std::endl;
             std::cout.flags(f);
         }
         else
diff --git a/apps/components_tests/CMakeLists.txt b/apps/components_tests/CMakeLists.txt
index 890998a32c..7e3fef263b 100644
--- a/apps/components_tests/CMakeLists.txt
+++ b/apps/components_tests/CMakeLists.txt
@@ -89,6 +89,9 @@ file(GLOB UNITTEST_SRC_FILES
     vfs/testpathutil.cpp
 
     sceneutil/osgacontroller.cpp
+
+    bsa/testbsafile.cpp
+    bsa/testcompressedbsafile.cpp
 )
 
 source_group(apps\\components-tests FILES ${UNITTEST_SRC_FILES})
diff --git a/apps/components_tests/bsa/operators.hpp b/apps/components_tests/bsa/operators.hpp
new file mode 100644
index 0000000000..a5098b3814
--- /dev/null
+++ b/apps/components_tests/bsa/operators.hpp
@@ -0,0 +1,40 @@
+#ifndef COMPONETS_TESTS_BSA_OPERATORS_H
+#define COMPONETS_TESTS_BSA_OPERATORS_H
+
+#include <components/bsa/bsafile.hpp>
+
+#include <ostream>
+#include <tuple>
+
+namespace Bsa
+{
+    inline auto makeTuple(const BSAFile::Hash& value)
+    {
+        return std::make_tuple(value.mLow, value.mHigh);
+    }
+
+    inline auto makeTuple(const BSAFile::FileStruct& value)
+    {
+        return std::make_tuple(
+            value.mFileSize, value.mOffset, makeTuple(value.mHash), value.mNameOffset, value.mNameSize, value.name());
+    }
+
+    inline std::ostream& operator<<(std::ostream& stream, const BSAFile::Hash& value)
+    {
+        return stream << "Hash { .mLow = " << value.mLow << ", .mHigh = " << value.mHigh << "}";
+    }
+
+    inline std::ostream& operator<<(std::ostream& stream, const BSAFile::FileStruct& value)
+    {
+        return stream << "FileStruct { .mFileSize = " << value.mFileSize << ", .mOffset = " << value.mOffset
+                      << ", .mHash = " << value.mHash << ", .mNameOffset = " << value.mNameOffset
+                      << ", .mNameSize = " << value.mNameSize << ", .name() = " << value.name() << "}";
+    }
+
+    inline bool operator==(const BSAFile::FileStruct& lhs, const BSAFile::FileStruct& rhs)
+    {
+        return makeTuple(lhs) == makeTuple(rhs);
+    }
+}
+
+#endif
diff --git a/apps/components_tests/bsa/testbsafile.cpp b/apps/components_tests/bsa/testbsafile.cpp
new file mode 100644
index 0000000000..23bff99331
--- /dev/null
+++ b/apps/components_tests/bsa/testbsafile.cpp
@@ -0,0 +1,302 @@
+#include "operators.hpp"
+
+#include <components/bsa/compressedbsafile.hpp>
+#include <components/files/memorystream.hpp>
+#include <components/testing/util.hpp>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <filesystem>
+#include <format>
+#include <fstream>
+#include <sstream>
+
+namespace Bsa
+{
+    namespace
+    {
+        using namespace ::testing;
+
+        struct Header
+        {
+            uint32_t mFormat;
+            uint32_t mDirSize;
+            uint32_t mFileCount;
+        };
+
+        struct Archive
+        {
+            Header mHeader;
+            std::vector<std::uint32_t> mOffsets;
+            std::vector<char> mStringBuffer;
+            std::vector<BSAFile::Hash> mHashes;
+            std::size_t mTailSize;
+        };
+
+        struct TestBSAFile final : public BSAFile
+        {
+            void readHeader(std::istream& input) override { BSAFile::readHeader(input); }
+
+            void writeHeader() override { throw std::logic_error("TestBSAFile::writeHeader is not implemented"); }
+        };
+
+        void writeArchive(const Archive& value, std::ostream& stream)
+        {
+            stream.write(reinterpret_cast<const char*>(&value.mHeader), sizeof(value.mHeader));
+
+            if (!value.mOffsets.empty())
+                stream.write(reinterpret_cast<const char*>(value.mOffsets.data()),
+                    value.mOffsets.size() * sizeof(std::uint32_t));
+
+            if (!value.mStringBuffer.empty())
+                stream.write(reinterpret_cast<const char*>(value.mStringBuffer.data()), value.mStringBuffer.size());
+
+            for (const BSAFile::Hash& hash : value.mHashes)
+                stream.write(reinterpret_cast<const char*>(&hash), sizeof(BSAFile::Hash));
+
+            const std::size_t chunkSize = 4096;
+            std::vector<char> chunk(chunkSize);
+            for (std::size_t i = 0; i < value.mTailSize; i += chunkSize)
+                stream.write(reinterpret_cast<const char*>(chunk.data()), std::min(chunk.size(), value.mTailSize - i));
+        }
+
+        std::filesystem::path makeOutputPath()
+        {
+            const auto testInfo = UnitTest::GetInstance()->current_test_info();
+            return TestingOpenMW::outputFilePath(
+                std::format("{}.{}.bsa", testInfo->test_suite_name(), testInfo->name()));
+        }
+
+        std::string makeBsaBuffer(std::uint32_t fileSize, std::uint32_t fileOffset)
+        {
+            std::string buffer;
+
+            buffer.reserve(static_cast<std::size_t>(fileSize) + static_cast<std::size_t>(fileOffset) + 34);
+
+            std::ostringstream stream(std::move(buffer));
+
+            const Header header{
+                .mFormat = static_cast<std::uint32_t>(BsaVersion::Uncompressed),
+                .mDirSize = 14,
+                .mFileCount = 1,
+            };
+
+            const BSAFile::Hash hash{
+                .mLow = 0xaaaabbbb,
+                .mHigh = 0xccccdddd,
+            };
+
+            const Archive archive{
+                .mHeader = header,
+                .mOffsets = { fileSize, fileOffset, 0 },
+                .mStringBuffer = { 'a', '\0' },
+                .mHashes = { hash },
+                .mTailSize = 0,
+            };
+
+            writeArchive(archive, stream);
+
+            return std::move(stream).str();
+        }
+
+        TEST(BSAFileTest, shouldHandleEmpty)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+                stream.open(path, std::ios::binary);
+            }
+
+            BSAFile file;
+            EXPECT_THROW(file.open(path), std::runtime_error);
+
+            EXPECT_THAT(file.getList(), IsEmpty());
+        }
+
+        TEST(BSAFileTest, shouldHandleZeroFiles)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+                stream.open(path, std::ios::binary);
+
+                const Header header{
+                    .mFormat = static_cast<std::uint32_t>(BsaVersion::Uncompressed),
+                    .mDirSize = 0,
+                    .mFileCount = 0,
+                };
+
+                const Archive archive{
+                    .mHeader = header,
+                    .mOffsets = {},
+                    .mStringBuffer = {},
+                    .mHashes = {},
+                    .mTailSize = 0,
+                };
+
+                writeArchive(archive, stream);
+            }
+
+            BSAFile file;
+            file.open(path);
+
+            EXPECT_THAT(file.getList(), IsEmpty());
+        }
+
+        TEST(BSAFileTest, shouldHandleSingleFile)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+                stream.open(path, std::ios::binary);
+
+                const Header header{
+                    .mFormat = static_cast<std::uint32_t>(BsaVersion::Uncompressed),
+                    .mDirSize = 14,
+                    .mFileCount = 1,
+                };
+
+                const BSAFile::Hash hash{
+                    .mLow = 0xaaaabbbb,
+                    .mHigh = 0xccccdddd,
+                };
+
+                const Archive archive{
+                    .mHeader = header,
+                    .mOffsets = { 42, 0, 0 },
+                    .mStringBuffer = { 'a', '\0' },
+                    .mHashes = { hash },
+                    .mTailSize = 42,
+                };
+
+                writeArchive(archive, stream);
+            }
+
+            BSAFile file;
+            file.open(path);
+
+            std::vector<char> namesBuffer = { 'a', '\0' };
+
+            EXPECT_THAT(file.getList(),
+                ElementsAre(BSAFile::FileStruct{
+                    .mFileSize = 42,
+                    .mOffset = 34,
+                    .mHash = BSAFile::Hash{ .mLow = 0xaaaabbbb, .mHigh = 0xccccdddd },
+                    .mNameOffset = 0,
+                    .mNameSize = 1,
+                    .mNamesBuffer = &namesBuffer,
+                }));
+        }
+
+        TEST(BSAFileTest, shouldHandleTwoFiles)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+                stream.open(path, std::ios::binary);
+
+                const std::uint32_t fileSize1 = 42;
+                const std::uint32_t fileSize2 = 13;
+
+                const Header header{
+                    .mFormat = static_cast<std::uint32_t>(BsaVersion::Uncompressed),
+                    .mDirSize = 28,
+                    .mFileCount = 2,
+                };
+
+                const BSAFile::Hash hash1{
+                    .mLow = 0xaaaabbbb,
+                    .mHigh = 0xccccdddd,
+                };
+
+                const BSAFile::Hash hash2{
+                    .mLow = 0x11112222,
+                    .mHigh = 0x33334444,
+                };
+
+                const Archive archive{
+                    .mHeader = header,
+                    .mOffsets = { fileSize1, 0, fileSize2, fileSize1, 0, 2 },
+                    .mStringBuffer = { 'a', '\0', 'b', '\0' },
+                    .mHashes = { hash1, hash2 },
+                    .mTailSize = fileSize1 + fileSize2,
+                };
+
+                writeArchive(archive, stream);
+            }
+
+            BSAFile file;
+            file.open(path);
+
+            std::vector<char> namesBuffer = { 'a', '\0', 'b', '\0' };
+
+            EXPECT_THAT(file.getList(),
+                ElementsAre(
+                    BSAFile::FileStruct{
+                        .mFileSize = 42,
+                        .mOffset = 56,
+                        .mHash = BSAFile::Hash{ .mLow = 0xaaaabbbb, .mHigh = 0xccccdddd },
+                        .mNameOffset = 0,
+                        .mNameSize = 1,
+                        .mNamesBuffer = &namesBuffer,
+                    },
+                    BSAFile::FileStruct{
+                        .mFileSize = 13,
+                        .mOffset = 98,
+                        .mHash = BSAFile::Hash{ .mLow = 0x11112222, .mHigh = 0x33334444 },
+                        .mNameOffset = 2,
+                        .mNameSize = 1,
+                        .mNamesBuffer = &namesBuffer,
+                    }));
+        }
+
+        TEST(BSAFileTest, shouldHandleSingleFileAtTheEndOfLargeFile)
+        {
+            constexpr std::uint32_t maxUInt32 = std::numeric_limits<uint32_t>::max();
+            const std::string buffer = makeBsaBuffer(maxUInt32, maxUInt32 - 34);
+
+            TestBSAFile file;
+            // Use capacity assuming we never read beyond small header.
+            Files::IMemStream stream(buffer.data(), buffer.capacity());
+            file.readHeader(stream);
+
+            std::vector<char> namesBuffer = { 'a', '\0' };
+
+            EXPECT_THAT(file.getList(),
+                ElementsAre(BSAFile::FileStruct{
+                    .mFileSize = maxUInt32,
+                    .mOffset = maxUInt32,
+                    .mHash = BSAFile::Hash{ .mLow = 0xaaaabbbb, .mHigh = 0xccccdddd },
+                    .mNameOffset = 0,
+                    .mNameSize = 1,
+                    .mNamesBuffer = &namesBuffer,
+                }));
+        }
+
+        TEST(BSAFileTest, shouldThrowExceptionOnTooBigAbsoluteOffset)
+        {
+            constexpr std::uint32_t maxUInt32 = std::numeric_limits<uint32_t>::max();
+            const std::string buffer = makeBsaBuffer(maxUInt32, maxUInt32 - 34 + 1);
+
+            TestBSAFile file;
+            // Use capacity assuming we never read beyond small header.
+            Files::IMemStream stream(buffer.data(), buffer.capacity());
+            EXPECT_THROW(file.readHeader(stream), std::runtime_error);
+
+            EXPECT_THAT(file.getList(), IsEmpty());
+        }
+    }
+}
diff --git a/apps/components_tests/bsa/testcompressedbsafile.cpp b/apps/components_tests/bsa/testcompressedbsafile.cpp
new file mode 100644
index 0000000000..d6343ccaec
--- /dev/null
+++ b/apps/components_tests/bsa/testcompressedbsafile.cpp
@@ -0,0 +1,360 @@
+#include "operators.hpp"
+
+#include <components/bsa/compressedbsafile.hpp>
+#include <components/testing/util.hpp>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <filesystem>
+#include <format>
+#include <fstream>
+#include <string>
+
+namespace Bsa
+{
+    namespace
+    {
+        using namespace ::testing;
+
+        struct FileRecord
+        {
+            std::uint64_t mHash;
+            std::uint32_t mSize;
+            std::uint32_t mOffset;
+            std::string mName;
+        };
+
+        struct NonSSEFolderRecord
+        {
+            std::uint64_t mHash;
+            std::uint32_t mCount;
+            std::int32_t mOffset;
+            std::string mName;
+            std::vector<FileRecord> mFiles;
+        };
+
+        struct Archive
+        {
+            CompressedBSAFile::Header mHeader;
+            std::vector<NonSSEFolderRecord> mFolders;
+        };
+
+        void writeArchive(const Archive& value, std::ostream& stream)
+        {
+            stream.write(reinterpret_cast<const char*>(&value.mHeader), sizeof(value.mHeader));
+
+            for (const NonSSEFolderRecord& folder : value.mFolders)
+            {
+                stream.write(reinterpret_cast<const char*>(&folder.mHash), sizeof(folder.mHash));
+                stream.write(reinterpret_cast<const char*>(&folder.mCount), sizeof(folder.mCount));
+                stream.write(reinterpret_cast<const char*>(&folder.mOffset), sizeof(folder.mOffset));
+            }
+
+            for (const NonSSEFolderRecord& folder : value.mFolders)
+            {
+                const std::uint8_t folderNameSize = static_cast<std::uint8_t>(folder.mName.size() + 1);
+
+                stream.write(reinterpret_cast<const char*>(&folderNameSize), sizeof(folderNameSize));
+                stream.write(reinterpret_cast<const char*>(folder.mName.data()), folder.mName.size());
+                stream.put('\0');
+
+                for (const FileRecord& file : folder.mFiles)
+                {
+                    stream.write(reinterpret_cast<const char*>(&file.mHash), sizeof(file.mHash));
+                    stream.write(reinterpret_cast<const char*>(&file.mSize), sizeof(file.mSize));
+                    stream.write(reinterpret_cast<const char*>(&file.mOffset), sizeof(file.mOffset));
+                }
+            }
+
+            for (const NonSSEFolderRecord& folder : value.mFolders)
+            {
+                for (const FileRecord& file : folder.mFiles)
+                {
+                    stream.write(reinterpret_cast<const char*>(file.mName.data()), file.mName.size());
+                    stream.put('\0');
+                }
+            }
+        }
+
+        std::filesystem::path makeOutputPath()
+        {
+            const auto testInfo = UnitTest::GetInstance()->current_test_info();
+            return TestingOpenMW::outputFilePath(
+                std::format("{}.{}.bsa", testInfo->test_suite_name(), testInfo->name()));
+        }
+
+        TEST(CompressedBSAFileTest, shouldHandleEmpty)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+                stream.open(path, std::ios::binary);
+            }
+
+            CompressedBSAFile file;
+            EXPECT_THROW(file.open(path), std::runtime_error);
+
+            EXPECT_THAT(file.getList(), IsEmpty());
+        }
+
+        TEST(CompressedBSAFileTest, shouldHandleSingleFile)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+                stream.open(path, std::ios::binary);
+
+                const CompressedBSAFile::Header header{
+                    .mFormat = static_cast<std::uint32_t>(BsaVersion::Compressed),
+                    .mVersion = CompressedBSAFile::Version_TES4,
+                    .mFoldersOffset = sizeof(CompressedBSAFile::Header),
+                    .mFlags = CompressedBSAFile::ArchiveFlag_FolderNames | CompressedBSAFile::ArchiveFlag_FileNames,
+                    .mFolderCount = 1,
+                    .mFileCount = 1,
+                    .mFolderNamesLength = 7,
+                    .mFileNamesLength = 9,
+                    .mFileFlags = 0,
+                };
+
+                const FileRecord file{
+                    .mHash = 0xfedcba9876543210,
+                    .mSize = 42,
+                    .mOffset = 0,
+                    .mName = "filename",
+                };
+
+                const NonSSEFolderRecord folder{
+                    .mHash = 0xfedcba9876543210,
+                    .mCount = 1,
+                    .mOffset = 0,
+                    .mName = "folder",
+                    .mFiles = { file },
+                };
+
+                const Archive archive{
+                    .mHeader = header,
+                    .mFolders = { folder },
+                };
+
+                writeArchive(archive, stream);
+            }
+
+            CompressedBSAFile file;
+            file.open(path);
+
+            std::vector<char> namesBuffer;
+            constexpr std::string_view filePath = "folder\\filename";
+            namesBuffer.assign(filePath.begin(), filePath.end());
+            namesBuffer.push_back('\0');
+
+            EXPECT_THAT(file.getList(),
+                ElementsAre(BSAFile::FileStruct{
+                    .mFileSize = 42,
+                    .mOffset = 0,
+                    .mHash = BSAFile::Hash{ .mLow = 0, .mHigh = 0 },
+                    .mNameOffset = 0,
+                    .mNameSize = 15,
+                    .mNamesBuffer = &namesBuffer,
+                }));
+        }
+
+        TEST(CompressedBSAFileTest, shouldHandleEmptyFileName)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+                stream.open(path, std::ios::binary);
+
+                const CompressedBSAFile::Header header{
+                    .mFormat = static_cast<std::uint32_t>(BsaVersion::Compressed),
+                    .mVersion = CompressedBSAFile::Version_TES4,
+                    .mFoldersOffset = sizeof(CompressedBSAFile::Header),
+                    .mFlags = CompressedBSAFile::ArchiveFlag_FolderNames | CompressedBSAFile::ArchiveFlag_FileNames,
+                    .mFolderCount = 1,
+                    .mFileCount = 1,
+                    .mFolderNamesLength = 7,
+                    .mFileNamesLength = 1,
+                    .mFileFlags = 0,
+                };
+
+                const FileRecord file{
+                    .mHash = 0xfedcba9876543210,
+                    .mSize = 42,
+                    .mOffset = 0,
+                    .mName = "",
+                };
+
+                const NonSSEFolderRecord folder{
+                    .mHash = 0xfedcba9876543210,
+                    .mCount = 1,
+                    .mOffset = 0,
+                    .mName = "folder",
+                    .mFiles = { file },
+                };
+
+                const Archive archive{
+                    .mHeader = header,
+                    .mFolders = { folder },
+                };
+
+                writeArchive(archive, stream);
+            }
+
+            CompressedBSAFile file;
+            EXPECT_THROW(file.open(path), std::runtime_error);
+        }
+
+        TEST(CompressedBSAFileTest, shouldHandleFoldersWithDuplicateHash)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+                stream.open(path, std::ios::binary);
+
+                const CompressedBSAFile::Header header{
+                    .mFormat = static_cast<std::uint32_t>(BsaVersion::Compressed),
+                    .mVersion = CompressedBSAFile::Version_TES4,
+                    .mFoldersOffset = sizeof(CompressedBSAFile::Header),
+                    .mFlags = CompressedBSAFile::ArchiveFlag_FolderNames | CompressedBSAFile::ArchiveFlag_FileNames,
+                    .mFolderCount = 2,
+                    .mFileCount = 2,
+                    .mFolderNamesLength = 16,
+                    .mFileNamesLength = 18,
+                    .mFileFlags = 0,
+                };
+
+                const FileRecord file{
+                    .mHash = 0xfedcba9876543210,
+                    .mSize = 42,
+                    .mOffset = 0,
+                    .mName = "filename",
+                };
+
+                const NonSSEFolderRecord folder1{
+                    .mHash = 0xfedcba9876543210,
+                    .mCount = 1,
+                    .mOffset = 0,
+                    .mName = "folder1",
+                    .mFiles = { file },
+                };
+
+                const NonSSEFolderRecord folder2{
+                    .mHash = 0xfedcba9876543210,
+                    .mCount = 1,
+                    .mOffset = 0,
+                    .mName = "folder2",
+                    .mFiles = { file },
+                };
+
+                const Archive archive{
+                    .mHeader = header,
+                    .mFolders = { folder1, folder2 },
+                };
+
+                writeArchive(archive, stream);
+            }
+
+            CompressedBSAFile file;
+            file.open(path);
+
+            std::vector<char> namesBuffer;
+            constexpr std::string_view filePath = "folder2\\filename";
+            namesBuffer.assign(filePath.begin(), filePath.end());
+            namesBuffer.push_back('\0');
+
+            EXPECT_THAT(file.getList(),
+                ElementsAre(BSAFile::FileStruct{
+                    .mFileSize = 42,
+                    .mOffset = 0,
+                    .mHash = BSAFile::Hash{ .mLow = 0, .mHigh = 0 },
+                    .mNameOffset = 0,
+                    .mNameSize = 16,
+                    .mNamesBuffer = &namesBuffer,
+                }));
+        }
+
+        TEST(CompressedBSAFileTest, shouldHandleFilesWithDuplicateHash)
+        {
+            const std::filesystem::path path = makeOutputPath();
+
+            {
+                std::ofstream stream;
+                stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+                stream.open(path, std::ios::binary);
+
+                const CompressedBSAFile::Header header{
+                    .mFormat = static_cast<std::uint32_t>(BsaVersion::Compressed),
+                    .mVersion = CompressedBSAFile::Version_TES4,
+                    .mFoldersOffset = sizeof(CompressedBSAFile::Header),
+                    .mFlags = CompressedBSAFile::ArchiveFlag_FolderNames | CompressedBSAFile::ArchiveFlag_FileNames,
+                    .mFolderCount = 1,
+                    .mFileCount = 2,
+                    .mFolderNamesLength = 9,
+                    .mFileNamesLength = 18,
+                    .mFileFlags = 0,
+                };
+
+                const FileRecord file1{
+                    .mHash = 0xfedcba9876543210,
+                    .mSize = 42,
+                    .mOffset = 0,
+                    .mName = "filename1",
+                };
+
+                const FileRecord file2{
+                    .mHash = 0xfedcba9876543210,
+                    .mSize = 13,
+                    .mOffset = 0,
+                    .mName = "filename2",
+                };
+
+                const NonSSEFolderRecord folder{
+                    .mHash = 0xfedcba9876543210,
+                    .mCount = 2,
+                    .mOffset = 0,
+                    .mName = "folder",
+                    .mFiles = { file1, file2 },
+                };
+
+                const Archive archive{
+                    .mHeader = header,
+                    .mFolders = { folder },
+                };
+
+                writeArchive(archive, stream);
+            }
+
+            CompressedBSAFile file;
+            file.open(path);
+
+            std::vector<char> namesBuffer;
+            constexpr std::string_view filePath = "folder\\filename2";
+            namesBuffer.assign(filePath.begin(), filePath.end());
+            namesBuffer.push_back('\0');
+
+            EXPECT_THAT(file.getList(),
+                ElementsAre(BSAFile::FileStruct{
+                    .mFileSize = 13,
+                    .mOffset = 0,
+                    .mHash = BSAFile::Hash{ .mLow = 0, .mHigh = 0 },
+                    .mNameOffset = 0,
+                    .mNameSize = 16,
+                    .mNamesBuffer = &namesBuffer,
+                }));
+        }
+    }
+}
diff --git a/components/CMakeLists.txt b/components/CMakeLists.txt
index f23d54eb56..8b48080a79 100644
--- a/components/CMakeLists.txt
+++ b/components/CMakeLists.txt
@@ -321,7 +321,7 @@ ENDIF()
 add_component_dir (files
     linuxpath androidpath windowspath macospath fixedpath multidircollection collections configurationmanager
     constrainedfilestream memorystream hash configfileparser openfile constrainedfilestreambuf conversion
-    istreamptr streamwithbuffer
+    istreamptr streamwithbuffer utils
     )
 
 if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND NOT CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
diff --git a/components/bsa/ba2dx10file.cpp b/components/bsa/ba2dx10file.cpp
index d4f14926c6..c16a3bacd2 100644
--- a/components/bsa/ba2dx10file.cpp
+++ b/components/bsa/ba2dx10file.cpp
@@ -4,13 +4,15 @@
 #include <cassert>
 #include <cstring>
 #include <filesystem>
-#include <fstream>
+#include <format>
+#include <istream>
 
 #include <zlib.h>
 
 #include <components/esm/fourcc.hpp>
 #include <components/files/constrainedfilestream.hpp>
 #include <components/files/conversion.hpp>
+#include <components/files/utils.hpp>
 #include <components/misc/strings/lower.hpp>
 
 #include "ba2file.hpp"
@@ -73,19 +75,11 @@ namespace Bsa
     }
 
     /// Read header information from the input source
-    void BA2DX10File::readHeader()
+    void BA2DX10File::readHeader(std::istream& input)
     {
         assert(!mIsLoaded);
 
-        std::ifstream input(mFilepath, std::ios_base::binary);
-
-        // Total archive size
-        std::streamoff fsize = 0;
-        if (input.seekg(0, std::ios_base::end))
-        {
-            fsize = input.tellg();
-            input.seekg(0);
-        }
+        const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
         if (fsize < 24) // header is 24 bytes
             fail("File too small to be a valid BSA archive");
@@ -135,23 +129,22 @@ namespace Bsa
             std::vector<char> fileName;
             uint16_t fileNameSize;
             input.read(reinterpret_cast<char*>(&fileNameSize), sizeof(uint16_t));
-            fileName.resize(fileNameSize);
-            input.read(fileName.data(), fileName.size());
-            fileName.push_back('\0');
+            fileName.resize(fileNameSize + 1);
+            input.read(fileName.data(), fileNameSize);
             mFileNames.push_back(std::move(fileName));
-            mFiles[i].setNameInfos(0, &mFileNames.back());
+            mFiles[i].mNameOffset = 0;
+            mFiles[i].mNameSize = fileNameSize;
+            mFiles[i].mNamesBuffer = &mFileNames.back();
         }
-
-        mIsLoaded = true;
     }
 
-    std::optional<BA2DX10File::FileRecord> BA2DX10File::getFileRecord(const std::string& str) const
+    std::optional<BA2DX10File::FileRecord> BA2DX10File::getFileRecord(std::string_view str) const
     {
         for (const auto c : str)
         {
             if (((static_cast<unsigned>(c) >> 7U) & 1U) != 0U)
             {
-                fail("File record " + str + " contains unicode characters, refusing to load.");
+                fail(std::format("File record {} contains unicode characters, refusing to load.", str));
             }
         }
 
@@ -161,7 +154,7 @@ namespace Bsa
         // Force-convert the path into something UNIX can handle first
         // to make sure std::filesystem::path doesn't think the entire path is the filename on Linux
         // and subsequently purge it to determine the file folder.
-        std::string path = str;
+        std::string path(str);
         std::replace(path.begin(), path.end(), '\\', '/');
 #endif
 
diff --git a/components/bsa/ba2dx10file.hpp b/components/bsa/ba2dx10file.hpp
index c902a4ccb0..aed727dc1a 100644
--- a/components/bsa/ba2dx10file.hpp
+++ b/components/bsa/ba2dx10file.hpp
@@ -41,7 +41,7 @@ namespace Bsa
 
         std::list<std::vector<char>> mFileNames;
 
-        std::optional<FileRecord> getFileRecord(const std::string& str) const;
+        std::optional<FileRecord> getFileRecord(std::string_view str) const;
 
         Files::IStreamPtr getFile(const FileRecord& fileRecord);
 
@@ -57,7 +57,7 @@ namespace Bsa
         virtual ~BA2DX10File();
 
         /// Read header information from the input source
-        void readHeader() override;
+        void readHeader(std::istream& stream) override;
 
         Files::IStreamPtr getFile(const char* filePath);
         Files::IStreamPtr getFile(const FileStruct* fileStruct);
diff --git a/components/bsa/ba2gnrlfile.cpp b/components/bsa/ba2gnrlfile.cpp
index dcef09296e..30e9b1eb0a 100644
--- a/components/bsa/ba2gnrlfile.cpp
+++ b/components/bsa/ba2gnrlfile.cpp
@@ -3,6 +3,7 @@
 #include <algorithm>
 #include <cassert>
 #include <filesystem>
+#include <format>
 #include <fstream>
 
 #include <zlib.h>
@@ -10,6 +11,7 @@
 #include <components/esm/fourcc.hpp>
 #include <components/files/constrainedfilestream.hpp>
 #include <components/files/conversion.hpp>
+#include <components/files/utils.hpp>
 #include <components/misc/strings/lower.hpp>
 
 #include "ba2file.hpp"
@@ -61,26 +63,18 @@ namespace Bsa
             mFolders[dirHash][{ nameHash, extHash }] = file;
 
             FileStruct fileStruct{};
-            fileStruct.fileSize = file.size;
-            fileStruct.offset = file.offset;
+            fileStruct.mFileSize = file.size;
+            fileStruct.mOffset = file.offset;
             mFiles.push_back(fileStruct);
         }
     }
 
     /// Read header information from the input source
-    void BA2GNRLFile::readHeader()
+    void BA2GNRLFile::readHeader(std::istream& input)
     {
         assert(!mIsLoaded);
 
-        std::ifstream input(mFilepath, std::ios_base::binary);
-
-        // Total archive size
-        std::streamoff fsize = 0;
-        if (input.seekg(0, std::ios_base::end))
-        {
-            fsize = input.tellg();
-            input.seekg(0);
-        }
+        const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
         if (fsize < 24) // header is 24 bytes
             fail("File too small to be a valid BSA archive");
@@ -126,23 +120,22 @@ namespace Bsa
             std::vector<char> fileName;
             uint16_t fileNameSize;
             input.read(reinterpret_cast<char*>(&fileNameSize), sizeof(uint16_t));
-            fileName.resize(fileNameSize);
-            input.read(fileName.data(), fileName.size());
-            fileName.push_back('\0');
+            fileName.resize(fileNameSize + 1);
+            input.read(fileName.data(), fileNameSize);
             mFileNames.push_back(std::move(fileName));
-            mFiles[i].setNameInfos(0, &mFileNames.back());
+            mFiles[i].mNameOffset = 0;
+            mFiles[i].mNameSize = fileNameSize;
+            mFiles[i].mNamesBuffer = &mFileNames.back();
         }
-
-        mIsLoaded = true;
     }
 
-    BA2GNRLFile::FileRecord BA2GNRLFile::getFileRecord(const std::string& str) const
+    BA2GNRLFile::FileRecord BA2GNRLFile::getFileRecord(std::string_view str) const
     {
         for (const auto c : str)
         {
             if (((static_cast<unsigned>(c) >> 7U) & 1U) != 0U)
             {
-                fail("File record " + str + " contains unicode characters, refusing to load.");
+                fail(std::format("File record {} contains unicode characters, refusing to load.", str));
             }
         }
 
@@ -152,7 +145,7 @@ namespace Bsa
         // Force-convert the path into something UNIX can handle first
         // to make sure std::filesystem::path doesn't think the entire path is the filename on Linux
         // and subsequently purge it to determine the file folder.
-        std::string path = str;
+        std::string path(str);
         std::replace(path.begin(), path.end(), '\\', '/');
 #endif
 
diff --git a/components/bsa/ba2gnrlfile.hpp b/components/bsa/ba2gnrlfile.hpp
index 080ba3a8df..371fe3d072 100644
--- a/components/bsa/ba2gnrlfile.hpp
+++ b/components/bsa/ba2gnrlfile.hpp
@@ -29,7 +29,7 @@ namespace Bsa
 
         std::list<std::vector<char>> mFileNames;
 
-        FileRecord getFileRecord(const std::string& str) const;
+        FileRecord getFileRecord(std::string_view str) const;
 
         Files::IStreamPtr getFile(const FileRecord& fileRecord);
 
@@ -45,7 +45,7 @@ namespace Bsa
         virtual ~BA2GNRLFile();
 
         /// Read header information from the input source
-        void readHeader() override;
+        void readHeader(std::istream& input) override;
 
         Files::IStreamPtr getFile(const char* filePath);
         Files::IStreamPtr getFile(const FileStruct* fileStruct);
diff --git a/components/bsa/bsafile.cpp b/components/bsa/bsafile.cpp
index 948b9dac8d..979ea4376a 100644
--- a/components/bsa/bsafile.cpp
+++ b/components/bsa/bsafile.cpp
@@ -25,12 +25,17 @@
 
 #include <algorithm>
 #include <cassert>
+#include <cerrno>
 #include <cstring>
 #include <filesystem>
+#include <format>
 #include <fstream>
+#include <istream>
+#include <system_error>
 
 #include <components/esm/fourcc.hpp>
 #include <components/files/constrainedfilestream.hpp>
+#include <components/files/utils.hpp>
 
 using namespace Bsa;
 
@@ -54,7 +59,7 @@ BSAFile::Hash getHash(const std::string& name)
         sum ^= (((unsigned)(name[i])) << (off & 0x1F));
         off += 8;
     }
-    hash.low = sum;
+    hash.mLow = sum;
 
     for (sum = off = 0; i < name.size(); i++)
     {
@@ -64,12 +69,12 @@ BSAFile::Hash getHash(const std::string& name)
         sum = (sum << (32 - n)) | (sum >> n); // binary "rotate right"
         off += 8;
     }
-    hash.high = sum;
+    hash.mHigh = sum;
     return hash;
 }
 
 /// Read header information from the input source
-void BSAFile::readHeader()
+void BSAFile::readHeader(std::istream& input)
 {
     /*
      * The layout of a BSA archive is as follows:
@@ -103,27 +108,24 @@ void BSAFile::readHeader()
      */
     assert(!mIsLoaded);
 
-    std::ifstream input(mFilepath, std::ios_base::binary);
-
     // Total archive size
-    std::streamoff fsize = 0;
-    if (input.seekg(0, std::ios_base::end))
-    {
-        fsize = input.tellg();
-        input.seekg(0);
-    }
+    const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
     if (fsize < 12)
         fail("File too small to be a valid BSA archive");
 
     // Get essential header numbers
-    size_t dirsize, filenum;
+    std::streamsize dirsize;
+    std::streamsize filenum;
     {
         // First 12 bytes
         uint32_t head[3];
 
         input.read(reinterpret_cast<char*>(head), 12);
 
+        if (input.fail())
+            fail(std::format("Failed to read head: {}", std::generic_category().message(errno)));
+
         if (head[0] != 0x100)
             fail("Unrecognized BSA header");
 
@@ -138,62 +140,83 @@ void BSAFile::readHeader()
     // Each file must take up at least 21 bytes of data in the bsa. So
     // if files*21 overflows the file size then we are guaranteed that
     // the archive is corrupt.
-    if ((filenum * 21 > unsigned(fsize - 12)) || (dirsize + 8 * filenum > unsigned(fsize - 12)))
+    if (filenum * 21 > fsize - 12 || dirsize + 8 * filenum > fsize - 12)
         fail("Directory information larger than entire archive");
 
     // Read the offset info into a temporary buffer
     std::vector<uint32_t> offsets(3 * filenum);
     input.read(reinterpret_cast<char*>(offsets.data()), 12 * filenum);
 
+    if (input.fail())
+        fail(std::format("Failed to read offsets: {}", std::generic_category().message(errno)));
+
     // Read the string table
     mStringBuf.resize(dirsize - 12 * filenum);
     input.read(mStringBuf.data(), mStringBuf.size());
 
+    if (input.fail())
+        fail(std::format("Failed to read string table: {}", std::generic_category().message(errno)));
+
     // Check our position
     assert(input.tellg() == std::streampos(12 + dirsize));
     std::vector<Hash> hashes(filenum);
     static_assert(sizeof(Hash) == 8);
     input.read(reinterpret_cast<char*>(hashes.data()), 8 * filenum);
 
+    if (input.fail())
+        fail(std::format("Failed to read hashes: {}", std::generic_category().message(errno)));
+
     // Calculate the offset of the data buffer. All file offsets are
     // relative to this. 12 header bytes + directory + hash table
     // (skipped)
-    size_t fileDataOffset = 12 + dirsize + 8 * filenum;
+    const std::streamsize fileDataOffset = 12 + dirsize + 8 * filenum;
 
     // Set up the the FileStruct table
-    mFiles.resize(filenum);
+    mFiles.reserve(filenum);
     size_t endOfNameBuffer = 0;
-    for (size_t i = 0; i < filenum; i++)
+    for (std::streamsize i = 0; i < filenum; i++)
     {
-        FileStruct& fs = mFiles[i];
-        fs.fileSize = offsets[i * 2];
-        fs.offset = static_cast<uint32_t>(offsets[i * 2 + 1] + fileDataOffset);
-        auto namesOffset = offsets[2 * filenum + i];
-        fs.setNameInfos(namesOffset, &mStringBuf);
-        fs.hash = hashes[i];
+        const uint32_t fileSize = offsets[i * 2];
+        const std::streamsize offset = static_cast<std::streamsize>(offsets[i * 2 + 1]) + fileDataOffset;
 
-        if (namesOffset >= mStringBuf.size())
-        {
+        if (fileSize + offset > fsize)
+            fail(std::format("Archive contains offsets outside itself: {} + {} > {}", fileSize, offset, fsize));
+
+        if (offset > std::numeric_limits<uint32_t>::max())
+            fail(std::format(
+                "Absolute file {} offset is too large: {} > {}", i, offset, std::numeric_limits<uint32_t>::max()));
+
+        const uint32_t nameOffset = offsets[2 * filenum + i];
+
+        if (nameOffset >= mStringBuf.size())
             fail("Archive contains names offset outside itself");
-        }
-        const void* end = std::memchr(fs.name(), '\0', mStringBuf.size() - namesOffset);
-        if (!end)
-        {
+
+        const char* const begin = mStringBuf.data() + nameOffset;
+        const char* const end = reinterpret_cast<const char*>(std::memchr(begin, '\0', mStringBuf.size() - nameOffset));
+
+        if (end == nullptr)
             fail("Archive contains non-zero terminated string");
-        }
 
-        endOfNameBuffer = std::max(endOfNameBuffer, namesOffset + std::strlen(fs.name()) + 1);
+        const std::size_t nameSize = end - begin;
+
+        FileStruct fs;
+
+        fs.mFileSize = fileSize;
+        fs.mOffset = static_cast<uint32_t>(offset);
+        fs.mHash = hashes[i];
+        fs.mNameOffset = nameOffset;
+        fs.mNameSize = static_cast<uint32_t>(nameSize);
+        fs.mNamesBuffer = &mStringBuf;
+
+        mFiles.push_back(fs);
+
+        endOfNameBuffer = std::max(endOfNameBuffer, nameOffset + nameSize + 1);
         assert(endOfNameBuffer <= mStringBuf.size());
-
-        if (fs.offset + fs.fileSize > fsize)
-            fail("Archive contains offsets outside itself");
     }
     mStringBuf.resize(endOfNameBuffer);
 
     std::sort(mFiles.begin(), mFiles.end(),
-        [](const FileStruct& left, const FileStruct& right) { return left.offset < right.offset; });
-
-    mIsLoaded = true;
+        [](const FileStruct& left, const FileStruct& right) { return left.mOffset < right.mOffset; });
 }
 
 /// Write header information to the output sink
@@ -203,7 +226,7 @@ void Bsa::BSAFile::writeHeader()
 
     uint32_t head[3];
     head[0] = 0x100;
-    auto fileDataOffset = mFiles.empty() ? 12 : mFiles.front().offset;
+    auto fileDataOffset = mFiles.empty() ? 12 : mFiles.front().mOffset;
     head[1] = static_cast<uint32_t>(fileDataOffset - 12 - 8 * mFiles.size());
 
     output.seekp(0, std::ios_base::end);
@@ -213,7 +236,7 @@ void Bsa::BSAFile::writeHeader()
     output.write(reinterpret_cast<char*>(head), 12);
 
     std::sort(mFiles.begin(), mFiles.end(), [](const FileStruct& left, const FileStruct& right) {
-        return std::make_pair(left.hash.low, left.hash.high) < std::make_pair(right.hash.low, right.hash.high);
+        return std::make_pair(left.mHash.mLow, left.mHash.mHigh) < std::make_pair(right.mHash.mLow, right.mHash.mHigh);
     });
 
     size_t filenum = mFiles.size();
@@ -222,10 +245,10 @@ void Bsa::BSAFile::writeHeader()
     for (size_t i = 0; i < filenum; i++)
     {
         auto& f = mFiles[i];
-        offsets[i * 2] = f.fileSize;
-        offsets[i * 2 + 1] = f.offset - fileDataOffset;
-        offsets[2 * filenum + i] = f.namesOffset;
-        hashes[i] = f.hash;
+        offsets[i * 2] = f.mFileSize;
+        offsets[i * 2 + 1] = f.mOffset - fileDataOffset;
+        offsets[2 * filenum + i] = f.mNameOffset;
+        hashes[i] = f.mHash;
     }
     output.write(reinterpret_cast<char*>(offsets.data()), sizeof(uint32_t) * offsets.size());
     output.write(reinterpret_cast<char*>(mStringBuf.data()), mStringBuf.size());
@@ -241,7 +264,11 @@ void BSAFile::open(const std::filesystem::path& file)
 
     mFilepath = file;
     if (std::filesystem::exists(file))
-        readHeader();
+    {
+        std::ifstream input(mFilepath, std::ios_base::binary);
+        readHeader(input);
+        mIsLoaded = true;
+    }
     else
     {
         {
@@ -265,7 +292,7 @@ void Bsa::BSAFile::close()
 
 Files::IStreamPtr Bsa::BSAFile::getFile(const FileStruct* file)
 {
-    return Files::openConstrainedFileStream(mFilepath, file->offset, file->fileSize);
+    return Files::openConstrainedFileStream(mFilepath, file->mOffset, file->mFileSize);
 }
 
 void Bsa::BSAFile::addFile(const std::string& filename, std::istream& file)
@@ -281,37 +308,41 @@ void Bsa::BSAFile::addFile(const std::string& filename, std::istream& file)
 
     FileStruct newFile;
     file.seekg(0, std::ios::end);
-    newFile.fileSize = static_cast<uint32_t>(file.tellg());
-    newFile.setNameInfos(mStringBuf.size(), &mStringBuf);
-    newFile.hash = getHash(filename);
+    newFile.mFileSize = static_cast<uint32_t>(file.tellg());
+    newFile.mHash = getHash(filename);
 
     if (mFiles.empty())
-        newFile.offset = static_cast<uint32_t>(newStartOfDataBuffer);
+        newFile.mOffset = static_cast<uint32_t>(newStartOfDataBuffer);
     else
     {
         std::vector<char> buffer;
-        while (mFiles.front().offset < newStartOfDataBuffer)
+        while (mFiles.front().mOffset < newStartOfDataBuffer)
         {
             FileStruct& firstFile = mFiles.front();
-            buffer.resize(firstFile.fileSize);
+            buffer.resize(firstFile.mFileSize);
 
-            stream.seekg(firstFile.offset, std::ios::beg);
-            stream.read(buffer.data(), firstFile.fileSize);
+            stream.seekg(firstFile.mOffset, std::ios::beg);
+            stream.read(buffer.data(), firstFile.mFileSize);
 
             stream.seekp(0, std::ios::end);
-            firstFile.offset = static_cast<uint32_t>(stream.tellp());
+            firstFile.mOffset = static_cast<uint32_t>(stream.tellp());
 
-            stream.write(buffer.data(), firstFile.fileSize);
+            stream.write(buffer.data(), firstFile.mFileSize);
 
             // ensure sort order is preserved
             std::rotate(mFiles.begin(), mFiles.begin() + 1, mFiles.end());
         }
         stream.seekp(0, std::ios::end);
-        newFile.offset = static_cast<uint32_t>(stream.tellp());
+        newFile.mOffset = static_cast<uint32_t>(stream.tellp());
     }
 
+    newFile.mNameOffset = mStringBuf.size();
+    newFile.mNameSize = filename.size();
+    newFile.mNamesBuffer = &mStringBuf;
+
     mStringBuf.insert(mStringBuf.end(), filename.begin(), filename.end());
     mStringBuf.push_back('\0');
+
     mFiles.push_back(newFile);
 
     mHasChanged = true;
diff --git a/components/bsa/bsafile.hpp b/components/bsa/bsafile.hpp
index 7b910208d8..bc25e1f5da 100644
--- a/components/bsa/bsafile.hpp
+++ b/components/bsa/bsafile.hpp
@@ -26,6 +26,7 @@
 
 #include <cstdint>
 #include <filesystem>
+#include <iosfwd>
 #include <string>
 #include <vector>
 
@@ -54,30 +55,25 @@ namespace Bsa
 #pragma pack(1)
         struct Hash
         {
-            uint32_t low, high;
+            uint32_t mLow;
+            uint32_t mHigh;
         };
 #pragma pack(pop)
 
         /// Represents one file entry in the archive
         struct FileStruct
         {
-            void setNameInfos(size_t index, std::vector<char>* stringBuf)
-            {
-                namesOffset = static_cast<uint32_t>(index);
-                namesBuffer = stringBuf;
-            }
-
             // File size and offset in file. We store the offset from the
             // beginning of the file, not the offset into the data buffer
             // (which is what is stored in the archive.)
-            uint32_t fileSize, offset;
-            Hash hash;
+            uint32_t mFileSize = 0;
+            uint32_t mOffset = 0;
+            Hash mHash{};
+            uint32_t mNameOffset = 0;
+            uint32_t mNameSize = 0;
+            std::vector<char>* mNamesBuffer = nullptr;
 
-            // Zero-terminated file name
-            const char* name() const { return &(*namesBuffer)[namesOffset]; }
-
-            uint32_t namesOffset = 0;
-            std::vector<char>* namesBuffer = nullptr;
+            std::string_view name() const { return std::string_view(mNamesBuffer->data() + mNameOffset, mNameSize); }
         };
         typedef std::vector<FileStruct> FileList;
 
@@ -100,7 +96,7 @@ namespace Bsa
         [[noreturn]] void fail(const std::string& msg) const;
 
         /// Read header information from the input source
-        virtual void readHeader();
+        virtual void readHeader(std::istream& input);
         virtual void writeHeader();
 
     public:
@@ -151,7 +147,6 @@ namespace Bsa
         // checks version of BSA from file header
         static BsaVersion detectVersion(const std::filesystem::path& filePath);
     };
-
 }
 
 #endif
diff --git a/components/bsa/compressedbsafile.cpp b/components/bsa/compressedbsafile.cpp
index 655a4d2844..8ad7221105 100644
--- a/components/bsa/compressedbsafile.cpp
+++ b/components/bsa/compressedbsafile.cpp
@@ -26,14 +26,18 @@
 
 #include <algorithm>
 #include <cassert>
+#include <cerrno>
 #include <filesystem>
-#include <fstream>
+#include <format>
+#include <istream>
+#include <system_error>
 
 #include <lz4frame.h>
 #include <zlib.h>
 
 #include <components/files/constrainedfilestream.hpp>
 #include <components/files/conversion.hpp>
+#include <components/files/utils.hpp>
 #include <components/misc/strings/lower.hpp>
 
 #include "memorystream.hpp"
@@ -41,19 +45,11 @@
 namespace Bsa
 {
     /// Read header information from the input source
-    void CompressedBSAFile::readHeader()
+    void CompressedBSAFile::readHeader(std::istream& input)
     {
         assert(!mIsLoaded);
 
-        std::ifstream input(mFilepath, std::ios_base::binary);
-
-        // Total archive size
-        std::streamoff fsize = 0;
-        if (input.seekg(0, std::ios_base::end))
-        {
-            fsize = input.tellg();
-            input.seekg(0);
-        }
+        const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
         if (fsize < 36) // Header is 36 bytes
             fail("File too small to be a valid BSA archive");
@@ -69,8 +65,8 @@ namespace Bsa
             mHeader.mFlags &= (~ArchiveFlag_EmbeddedNames);
 
         input.seekg(mHeader.mFoldersOffset);
-        if (input.bad())
-            fail("Invalid compressed BSA folder record offset");
+        if (input.fail())
+            fail("Failed to read compressed BSA folder record offset: " + std::generic_category().message(errno));
 
         struct FlatFolderRecord
         {
@@ -81,9 +77,12 @@ namespace Bsa
         };
 
         std::vector<std::pair<FlatFolderRecord, std::vector<FileRecord>>> folders;
-        folders.resize(mHeader.mFolderCount);
-        for (auto& [folder, filelist] : folders)
+        folders.reserve(mHeader.mFolderCount);
+
+        for (std::uint32_t i = 0; i < mHeader.mFolderCount; ++i)
         {
+            FlatFolderRecord folder;
+
             input.read(reinterpret_cast<char*>(&folder.mHash), 8);
             input.read(reinterpret_cast<char*>(&folder.mCount), 4);
             if (mHeader.mVersion == Version_SSE) // SSE
@@ -96,10 +95,13 @@ namespace Bsa
             {
                 input.read(reinterpret_cast<char*>(&folder.mOffset), 4);
             }
-        }
 
-        if (input.bad())
-            fail("Failed to read compressed BSA folder records: input error");
+            if (input.fail())
+                fail(std::format(
+                    "Failed to read compressed BSA folder record: {}", std::generic_category().message(errno)));
+
+            folders.emplace_back(std::move(folder), std::vector<FileRecord>());
+        }
 
         // file record blocks
         if ((mHeader.mFlags & ArchiveFlag_FolderNames) == 0)
@@ -126,20 +128,29 @@ namespace Bsa
                 mHeader.mFolderNamesLength -= size;
             }
 
-            filelist.resize(folder.mCount);
-            for (auto& file : filelist)
+            filelist.reserve(folder.mCount);
+
+            for (std::uint32_t i = 0; i < folder.mCount; ++i)
             {
+                FileRecord file;
+
                 input.read(reinterpret_cast<char*>(&file.mHash), 8);
                 input.read(reinterpret_cast<char*>(&file.mSize), 4);
                 input.read(reinterpret_cast<char*>(&file.mOffset), 4);
+
+                if (input.fail())
+                    fail(std::format("Failed to read compressed BSA folder file record: {}",
+                        std::generic_category().message(errno)));
+
+                filelist.push_back(std::move(file));
             }
         }
 
         if (mHeader.mFolderNamesLength != 0)
             input.ignore(mHeader.mFolderNamesLength);
 
-        if (input.bad())
-            fail("Failed to read compressed BSA file records: input error");
+        if (input.fail())
+            fail(std::format("Failed to read compressed BSA file records: {}", std::generic_category().message(errno)));
 
         if ((mHeader.mFlags & ArchiveFlag_FileNames) != 0)
         {
@@ -168,36 +179,42 @@ namespace Bsa
         if (mHeader.mFileNamesLength != 0)
             input.ignore(mHeader.mFileNamesLength);
 
-        if (input.bad())
-            fail("Failed to read compressed BSA filenames: input error");
+        if (input.fail())
+            fail(std::format("Failed to read compressed BSA filenames: {}", std::generic_category().message(errno)));
 
         for (auto& [folder, filelist] : folders)
         {
             std::map<std::uint64_t, FileRecord> fileMap;
-            for (const auto& file : filelist)
+
+            for (auto& file : filelist)
                 fileMap[file.mHash] = std::move(file);
-            auto& folderMap = mFolders[folder.mHash];
-            folderMap = FolderRecord{ folder.mCount, folder.mOffset, std::move(fileMap) };
-            for (auto& [hash, fileRec] : folderMap.mFiles)
-            {
-                FileStruct fileStruct{};
-                fileStruct.fileSize = fileRec.mSize & (~FileSizeFlag_Compression);
-                fileStruct.offset = fileRec.mOffset;
-                fileStruct.setNameInfos(0, &fileRec.mName);
-                mFiles.emplace_back(fileStruct);
-            }
+
+            mFolders[folder.mHash] = FolderRecord{ folder.mCount, folder.mOffset, folder.mName, std::move(fileMap) };
         }
 
-        mIsLoaded = true;
+        for (auto& [folderHash, folderRecord] : mFolders)
+        {
+            for (auto& [fileHash, fileRecord] : folderRecord.mFiles)
+            {
+                FileStruct fileStruct{};
+                fileStruct.mFileSize = fileRecord.mSize & (~FileSizeFlag_Compression);
+                fileStruct.mOffset = fileRecord.mOffset;
+                fileStruct.mNameOffset = 0;
+                fileStruct.mNameSize
+                    = fileRecord.mName.empty() ? 0 : static_cast<uint32_t>(fileRecord.mName.size() - 1);
+                fileStruct.mNamesBuffer = &fileRecord.mName;
+                mFiles.push_back(fileStruct);
+            }
+        }
     }
 
-    CompressedBSAFile::FileRecord CompressedBSAFile::getFileRecord(const std::string& str) const
+    CompressedBSAFile::FileRecord CompressedBSAFile::getFileRecord(std::string_view str) const
     {
         for (const auto c : str)
         {
             if (((static_cast<unsigned>(c) >> 7U) & 1U) != 0U)
             {
-                fail("File record " + str + " contains unicode characters, refusing to load.");
+                fail(std::format("File record {} contains unicode characters, refusing to load.", str));
             }
         }
 
@@ -207,7 +224,7 @@ namespace Bsa
         // Force-convert the path into something UNIX can handle first
         // to make sure std::filesystem::path doesn't think the entire path is the filename on Linux
         // and subsequently purge it to determine the file folder.
-        std::string path = str;
+        std::string path(str);
         std::replace(path.begin(), path.end(), '\\', '/');
 #endif
 
diff --git a/components/bsa/compressedbsafile.hpp b/components/bsa/compressedbsafile.hpp
index 1e359ea3fe..6eae44cec1 100644
--- a/components/bsa/compressedbsafile.hpp
+++ b/components/bsa/compressedbsafile.hpp
@@ -36,7 +36,7 @@ namespace Bsa
 {
     class CompressedBSAFile : private BSAFile
     {
-    private:
+    public:
         enum ArchiveFlags
         {
             ArchiveFlag_FolderNames = 0x0001,
@@ -89,8 +89,6 @@ namespace Bsa
             std::uint32_t mFileFlags;
         };
 
-        Header mHeader;
-
         struct FileRecord
         {
             std::uint64_t mHash;
@@ -103,12 +101,15 @@ namespace Bsa
         {
             std::uint32_t mCount;
             std::int64_t mOffset;
+            std::string mName;
             std::map<std::uint64_t, FileRecord> mFiles;
         };
 
+    private:
+        Header mHeader;
         std::map<std::uint64_t, FolderRecord> mFolders;
 
-        FileRecord getFileRecord(const std::string& str) const;
+        FileRecord getFileRecord(std::string_view str) const;
 
         /// \brief Normalizes given filename or folder and generates format-compatible hash.
         static std::uint64_t generateHash(const std::filesystem::path& stem, std::string extension);
@@ -124,7 +125,7 @@ namespace Bsa
         virtual ~CompressedBSAFile() = default;
 
         /// Read header information from the input source
-        void readHeader() override;
+        void readHeader(std::istream& input) override;
 
         Files::IStreamPtr getFile(const char* filePath);
         Files::IStreamPtr getFile(const FileStruct* fileStruct);
diff --git a/components/files/utils.hpp b/components/files/utils.hpp
new file mode 100644
index 0000000000..732a7d39cd
--- /dev/null
+++ b/components/files/utils.hpp
@@ -0,0 +1,38 @@
+#ifndef COMPONENTS_FILES_UTILS_H
+#define COMPONENTS_FILES_UTILS_H
+
+#include <cerrno>
+#include <format>
+#include <istream>
+#include <stdexcept>
+#include <system_error>
+
+namespace Files
+{
+    inline std::streamsize getStreamSizeLeft(std::istream& stream)
+    {
+        const auto begin = stream.tellg();
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to get current file position: {}", std::generic_category().message(errno)));
+
+        stream.seekg(0, std::ios_base::end);
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to seek end file position: {}", std::generic_category().message(errno)));
+
+        const auto end = stream.tellg();
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to get current file position: {}", std::generic_category().message(errno)));
+
+        stream.seekg(begin);
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to seek original file position: {}", std::generic_category().message(errno)));
+
+        return end - begin;
+    }
+}
+
+#endif