Add from_base32 presto function

velox/common/encode/Base32.cpp

@@ -182,4 +182,119 @@ template <class T>
   }
 }
 
+size_t Base32::calculateDecodedSize(const char* data, size_t& size) {
+  if (size == 0) {
+    return 0;
+  }
+
+  // Check if the input data is padded
+  if (isPadded(data, size)) {
+    /// If padded, ensure that the string length is a multiple of the encoded
+    /// block size.
+    if (size % kEncodedBlockByteSize != 0) {
+      VELOX_USER_FAIL(
+          "Base32::decode() - invalid input string: "
+          "string length is not a multiple of 8.");
+    }
+
+    auto needed = (size * kBinaryBlockByteSize) / kEncodedBlockByteSize;
+    auto padding = numPadding(data, size);
+    size -= padding;
+
+    // Adjust the needed size by deducting the bytes corresponding to the
+    // padding from the calculated size.
+    return needed -
+        ((padding * kBinaryBlockByteSize) + (kEncodedBlockByteSize - 1)) /
+        kEncodedBlockByteSize;
+  } else {
+    // If not padded, calculate extra bytes, if any.
+    auto extra = size % kEncodedBlockByteSize;
+    auto needed = (size / kEncodedBlockByteSize) * kBinaryBlockByteSize;
+
+    // Adjust the needed size for extra bytes, if present.
+    if (extra) {
+      if ((extra == 6) || (extra == 3) || (extra == 1)) {
+        VELOX_USER_FAIL(
+            "Base32::decode() - invalid input string: "
+            "string length cannot be 6, 3 or 1 more than a multiple of 8.");
+      }
+      needed += (extra * kBinaryBlockByteSize) / kEncodedBlockByteSize;
+    }
+
+    return needed;
+  }
+}
+
+size_t
+Base32::decode(const char* src, size_t src_len, char* dst, size_t dst_len) {
+  return decodeImpl(src, src_len, dst, dst_len, kBase32ReverseIndexTable);
+}
+
+size_t Base32::decodeImpl(
+    const char* src,
+    size_t src_len,
+    char* dst,
+    size_t dst_len,
+    const ReverseIndex& reverse_lookup) {
+  if (!src_len) {
+    return 0;
+  }
+
+  auto needed = calculateDecodedSize(src, src_len);
+  if (dst_len < needed) {
+    VELOX_USER_FAIL(
+        "Base32::decode() - invalid output string: "
+        "output string is too small.");
+  }
+
+  // Handle full groups of 8 characters.
+  for (; src_len > 8; src_len -= 8, src += 8, dst += 5) {
+    /// Each character of the 8 bytes encode 5 bits of the original, grab each
+    /// with the appropriate shifts to rebuild the original and then split that
+    /// back into the original 8 bit bytes.
+    uint64_t last =
+        (uint64_t(baseReverseLookup(kBase, src[0], reverse_lookup)) << 35) |
+        (uint64_t(baseReverseLookup(kBase, src[1], reverse_lookup)) << 30) |
+        (baseReverseLookup(kBase, src[2], reverse_lookup) << 25) |
+        (baseReverseLookup(kBase, src[3], reverse_lookup) << 20) |
+        (baseReverseLookup(kBase, src[4], reverse_lookup) << 15) |
+        (baseReverseLookup(kBase, src[5], reverse_lookup) << 10) |
+        (baseReverseLookup(kBase, src[6], reverse_lookup) << 5) |
+        baseReverseLookup(kBase, src[7], reverse_lookup);
+    dst[0] = (last >> 32) & 0xff;
+    dst[1] = (last >> 24) & 0xff;
+    dst[2] = (last >> 16) & 0xff;
+    dst[3] = (last >> 8) & 0xff;
+    dst[4] = last & 0xff;
+  }
+
+  /// Handle the last 2, 4, 5, 7 or 8 characters.  This is similar to the above,
+  /// but the last characters may or may not exist.
+  DCHECK(src_len >= 2);
+  uint64_t last =
+      (uint64_t(baseReverseLookup(kBase, src[0], reverse_lookup)) << 35) |
+      (uint64_t(baseReverseLookup(kBase, src[1], reverse_lookup)) << 30);
+  dst[0] = (last >> 32) & 0xff;
+  if (src_len > 2) {
+    last |= baseReverseLookup(kBase, src[2], reverse_lookup) << 25;
+    last |= baseReverseLookup(kBase, src[3], reverse_lookup) << 20;
+    dst[1] = (last >> 24) & 0xff;
+    if (src_len > 4) {
+      last |= baseReverseLookup(kBase, src[4], reverse_lookup) << 15;
+      dst[2] = (last >> 16) & 0xff;
+      if (src_len > 5) {
+        last |= baseReverseLookup(kBase, src[5], reverse_lookup) << 10;
+        last |= baseReverseLookup(kBase, src[6], reverse_lookup) << 5;
+        dst[3] = (last >> 8) & 0xff;
+        if (src_len > 7) {
+          last |= baseReverseLookup(kBase, src[7], reverse_lookup);
+          dst[4] = last & 0xff;
+        }
+      }
+    }
+  }
+
+  return needed;
+}
+
 } // namespace facebook::velox::encoding

velox/common/encode/Base32.h

@@ -34,13 +34,32 @@ class Base32 {
   /// returned by the calculateEncodedSize().
   static void encode(const char* data, size_t size, char* output);
 
+     /// Returns decoded size for the specified input. Adjusts the 'size' to
+   /// subtract the length of the padding, if exists.
+   static size_t calculateDecodedSize(const char* data, size_t& size);
+
+   /// Decodes the specified number of characters from the 'src' and writes the
+   /// result to the 'dst'. The destination must have enough space, e.g. as
+   /// returned by the calculateDecodedSize().
+   static size_t
+   decode(const char* src, size_t src_len, char* dst, size_t dst_len);
+
  private:
   template <class T>
   static void encodeImpl(
       const T& data,
       const Charset& charset,
       bool include_pad,
       char* out);
+
+         /// Decodes the specified number of base 32 encoded characters from the 'src'
+   /// and writes to 'dst'
+   static size_t decodeImpl(
+       const char* src,
+       size_t src_len,
+       char* dst,
+       size_t dst_len,
+       const ReverseIndex& table);
 };
 
 } // namespace facebook::velox::encoding

velox/common/encode/tests/Base32Test.cpp

@@ -39,4 +39,35 @@ TEST_F(Base32Test, calculateEncodedSizeProperSize) {
   EXPECT_EQ(24, Base32::calculateEncodedSize(11, true));
 }
 
-} // namespace facebook::velox::encoding
+TEST_F(Base32Test, calculateDecodedSizeProperSize) {
+  struct TestCase {
+    std::string encoded;
+    size_t initial_size;
+    int expected_decoded;
+    size_t expected_size;
+  };
+
+  std::vector<TestCase> test_cases = {
+      {"ME======", 8, 1, 2},
+      {"ME", 2, 1, 2},
+      {"MFRA====", 8, 2, 4},
+      {"MFRGG===", 8, 3, 5},
+      {"NBSWY3DPEB3W64TMMQ======", 24, 11, 18},
+      {"NBSWY3DPEB3W64TMMQ", 18, 11, 18}};
+
+  for (const auto& test : test_cases) {
+    size_t encoded_size = test.initial_size;
+    EXPECT_EQ(
+        test.expected_decoded,
+        Base32::calculateDecodedSize(test.encoded.c_str(), encoded_size));
+    EXPECT_EQ(test.expected_size, encoded_size);
+  }
+}
+
+TEST_F(Base32Test, errorWhenDecodedStringPartiallyPadded) {
+  size_t encoded_size = 9;
+  EXPECT_THROW(
+      Base32::calculateDecodedSize("MFRA====", encoded_size), VeloxUserError);
+}
+
+} // namespace facebook::velox::encoding

velox/common/encode/tests/CMakeLists.txt

@@ -12,7 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-add_executable(velox_common_encode_test Base32Test.cpp Base64Test.cpp EncoderUtilsTests.cpp)
+add_executable(velox_common_encode_test Base32Test.cpp Base64Test.cpp
+                                        EncoderUtilsTests.cpp)
 add_test(velox_common_encode_test velox_common_encode_test)
 target_link_libraries(
   velox_common_encode_test

velox/docs/functions/presto/binary.rst

@@ -41,6 +41,28 @@ Binary Functions
 
     Decodes ``bigint`` value from a 64-bit 2’s complement big endian ``binary``.
 
+.. function:: from_base32(string) -> varbinary
+
+    Decodes a Base32-encoded ``string`` back into its original binary form.
+    This function can handle both padded and non-padded Base32 encoded strings. Partially padded Base32 strings will result in an error.
+
+    Examples
+    --------
+    Query with padded Base32 string:
+    ::
+        SELECT from_base32('JBSWY3DPEBLW64TMMQ======'); -- [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]
+
+    Query with non-padded Base32 string:
+    ::
+        SELECT from_base32('JBSWY3DPEBLW64TMMQ'); -- [72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100]
+
+    Query with partially padded Base32 string:
+    ::
+        SELECT from_base32('JBSWY3DPEBLW64TM=='); -- Error: Base32::decode() - invalid input string: length is not a multiple of 8.
+
+    In the examples above, both fully padded and non-padded Base32 strings ('JBSWY3DPEBLW64TMMQ======' and 'JBSWY3DPEBLW64TMMQ') decode to the binary representation of the text 'Hello World'.
+    The partially padded Base32 string 'JBSWY3DPEBLW64TM==' will lead to a decoding error.
+
 .. function:: from_hex(string) -> varbinary
 
     Decodes binary data from the hex encoded ``string``.

velox/functions/prestosql/BinaryFunctions.h

@@ -340,6 +340,22 @@ struct ToBase64UrlFunction {
   }
 };
 
+template <typename TExec>
+struct FromBase32Function {
+  VELOX_DEFINE_FUNCTION_TYPES(TExec);
+
+  // T can be either arg_type<Varchar> or arg_type<Varbinary>. These are the
+  // same, but hard-coding one of them might be confusing.
+  template <typename T>
+  FOLLY_ALWAYS_INLINE void call(out_type<Varbinary>& result, const T& input) {
+    auto inputSize = input.size();
+    result.resize(
+        encoding::Base32::calculateDecodedSize(input.data(), inputSize));
+    encoding::Base32::decode(
+        input.data(), inputSize, result.data(), result.size());
+  }
+};
+
 template <typename T>
 struct ToBase32Function {
   VELOX_DEFINE_FUNCTION_TYPES(T);

velox/functions/prestosql/registration/BinaryFunctionsRegistration.cpp

@@ -57,6 +57,8 @@ void registerSimpleFunctions(const std::string& prefix) {
       {prefix + "from_base64url"});
   registerFunction<ToBase32Function, Varchar, Varbinary>(
       {prefix + "to_base32"});
+  registerFunction<FromBase32Function, Varbinary, Varchar>(
+      {prefix + "from_base32"});
 
   registerFunction<FromBigEndian32, int32_t, Varbinary>(
       {prefix + "from_big_endian_32"});

velox/functions/prestosql/tests/BinaryFunctionsTest.cpp

@@ -502,6 +502,42 @@ TEST_F(BinaryFunctionsTest, toBase32) {
       toBase32("Hello World from Velox!"));
 }
 
+TEST_F(BinaryFunctionsTest, fromBase32) {
+  const auto fromBase32 = [&](std::optional<std::string> value) {
+    return evaluateOnce<std::string>("from_base32(c0)", value);
+  };
+
+  EXPECT_EQ(std::nullopt, fromBase32(std::nullopt));
+  EXPECT_EQ("", fromBase32(""));
+  EXPECT_EQ("a", fromBase32("ME======"));
+  EXPECT_EQ("ab", fromBase32("MFRA===="));
+  EXPECT_EQ("abc", fromBase32("MFRGG==="));
+  EXPECT_EQ("db2", fromBase32("MRRDE==="));
+  EXPECT_EQ("abcd", fromBase32("MFRGGZA="));
+  EXPECT_EQ("hello world", fromBase32("NBSWY3DPEB3W64TMMQ======"));
+  EXPECT_EQ(
+      "Hello World from Velox!",
+      fromBase32("JBSWY3DPEBLW64TMMQQGM4TPNUQFMZLMN54CC==="));
+
+  // Try encoded strings without padding
+  EXPECT_EQ("a", fromBase32("ME"));
+  EXPECT_EQ("ab", fromBase32("MFRA"));
+  EXPECT_EQ("abc", fromBase32("MFRGG"));
+  EXPECT_EQ("db2", fromBase32("MRRDE"));
+  EXPECT_EQ("abcd", fromBase32("MFRGGZA"));
+  EXPECT_EQ("1234", fromBase32("GEZDGNA"));
+  EXPECT_EQ("abcde", fromBase32("MFRGGZDF"));
+  EXPECT_EQ("abcdef", fromBase32("MFRGGZDFMY"));
+
+  // Check with invaild encoded strings
+  EXPECT_THROW(fromBase32("1="), VeloxUserError);
+  EXPECT_THROW(fromBase32("M1======"), VeloxUserError);
+
+  VELOX_ASSERT_THROW(
+      fromBase32("J1======"),
+      "decode() - invalid input string: invalid characters");
+}
+
 TEST_F(BinaryFunctionsTest, fromBigEndian32) {
   const auto fromBigEndian32 = [&](const std::optional<std::string>& arg) {
     return evaluateOnce<int32_t>("from_big_endian_32(c0)", VARBINARY(), arg);