Determine wallet file type based on file magic

1 files changed, 26 insertions, 1 deletions

diff --git a/src/wallet/bdb.cpp b/src/wallet/bdb.cpp
index ae3c7ae7bb..85aae0170d 100644
--- a/src/wallet/bdb.cpp
+++ b/src/wallet/bdb.cpp
@@ -813,7 +813,7 @@ bool ExistsBerkeleyDatabase(const fs::path& path)
     fs::path env_directory;
     std::string data_filename;
     SplitWalletPath(path, env_directory, data_filename);
-    return IsBerkeleyBtree(env_directory / data_filename);
+    return IsBDBFile(env_directory / data_filename);
 }
 
 std::unique_ptr<BerkeleyDatabase> MakeBerkeleyDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error)
@@ -839,3 +839,28 @@ std::unique_ptr<BerkeleyDatabase> MakeBerkeleyDatabase(const fs::path& path, con
     status = DatabaseStatus::SUCCESS;
     return db;
 }
+
+bool IsBDBFile(const fs::path& path)
+{
+    if (!fs::exists(path)) return false;
+
+    // A Berkeley DB Btree file has at least 4K.
+    // This check also prevents opening lock files.
+    boost::system::error_code ec;
+    auto size = fs::file_size(path, ec);
+    if (ec) LogPrintf("%s: %s %s\n", __func__, ec.message(), path.string());
+    if (size < 4096) return false;
+
+    fsbridge::ifstream file(path, std::ios::binary);
+    if (!file.is_open()) return false;
+
+    file.seekg(12, std::ios::beg); // Magic bytes start at offset 12
+    uint32_t data = 0;
+    file.read((char*) &data, sizeof(data)); // Read 4 bytes of file to compare against magic
+
+    // Berkeley DB Btree magic bytes, from:
+    //  https://github.com/file/file/blob/5824af38469ec1ca9ac3ffd251e7afe9dc11e227/magic/Magdir/database#L74-L75
+    //  - big endian systems - 00 05 31 62
+    //  - little endian systems - 62 31 05 00
+    return data == 0x00053162 || data == 0x62310500;
+}