Merge pull request ClickHouse#89322 from ClickHouse/backport/25.8/89133

Backport ClickHouse#89133 to 25.8: Fix allocation size calculation for baseXXEncode/Decode functions

Author: antonio2368

src/Functions/FunctionBase32Conversion.h

@@ -11,11 +11,10 @@ struct Base32EncodeTraits
     template <typename Col>
     static size_t getBufferSize(Col const & src_column)
     {
-        auto const src_length = src_column.getChars().size();
-        auto const string_count = src_column.size();
+        auto const src_length = src_column.getChars().size() + src_column.size();
         /// Every 5 bytes becomes 8 bytes in base32
         /// Add padding for incomplete blocks and round up
-        return (src_length + 4) / 5 * 8 * string_count;
+        return (src_length + 4) / 5 * 8;
     }
 
     static size_t perform(std::string_view src, UInt8 * dst)
@@ -29,10 +28,10 @@ struct Base32DecodeTraits
     template <typename Col>
     static size_t getBufferSize(Col const & src_column)
     {
-        auto const string_length = src_column.byteSize();
-        auto const string_count = src_column.size();
+        /// This function can be used for FixedString columns so we need to take into account NULL terminator
+        auto const string_length = src_column.getChars().size() + src_column.size();
         /// decoded size is at most length of encoded (every 8 bytes becomes at most 5 bytes)
-        return (string_length * 5 + 7) / 8 * string_count;
+        return (string_length * 5 + 7) / 8;
     }
 
     static std::optional<size_t> perform(std::string_view src, UInt8 * dst)

src/Functions/FunctionBase58Conversion.h

@@ -29,10 +29,10 @@ struct Base58DecodeTraits
     template <typename Col>
     static size_t getBufferSize(Col const & src_column)
     {
-        auto const string_length = src_column.byteSize();
-        auto const string_count = src_column.size();
+        /// This function can be used for FixedString columns so we need to take into account NULL terminator
+        auto const string_length = src_column.getChars().size() + src_column.size();
         /// decoded size is at most length of encoded (every 8 bytes becomes at most 6 bytes)
-        return (string_length * 6 + 7) / 8 * string_count;
+        return (string_length * 6 + 7) / 8;
     }
 
     static std::optional<size_t> perform(std::string_view src, UInt8 * dst)

tests/queries/0_stateless/03702_encode_decode_memory_usage.reference

@@ -0,0 +1,5 @@
+-- Tags: no-fasttest
+
+SELECT base32Decode(s) FROM (SELECT base32Encode(randomString(100)) AS s FROM numbers(100000)) FORMAT Null;
+SELECT base58Decode(s) FROM (SELECT base58Encode(randomString(100)) AS s FROM numbers(100000)) FORMAT Null;
+SELECT base64Decode(s) FROM (SELECT base64Encode(randomString(100)) AS s FROM numbers(100000)) FORMAT Null;