[MONGOCRYPT-536] A Toggle for Decimal128 Range Support (#569)

* Conditional Decimal128 range support

The configure-time option MONGOCRYPT_ENABLE_DECIMAL128 can be used to
enable/disable Decimal128 range support. This is enabled by default.

- Wrap Decimal128 code in conditions on whether Decimal128 is available.
- Only supports IntelDFP for now.

Author: vector-of-bool

CMakeLists.txt

@@ -45,7 +45,14 @@ include (GNUInstallDirs)
 
 include (LTO)
 include (ImportBSON)
-include (ImportDFP)
+
+option (MONGOCRYPT_ENABLE_DECIMAL128 "Enable extended support for Decimal128" ON)
+mark_as_advanced (MONGOCRYPT_ENABLE_DECIMAL128)
+set (maybe_dfp_library)
+if (MONGOCRYPT_ENABLE_DECIMAL128)
+   include (ImportDFP)
+   set (maybe_dfp_library mongocrypt::intel_dfp)
+endif ()
 
 if (USE_SHARED_LIBBSON AND ENABLE_BUILD_FOR_PPA)
    message (FATAL_ERROR "PPA build requires static linking to libbson")
@@ -281,7 +288,7 @@ target_link_libraries (
       kms_message_static
       $<BUILD_INTERFACE:mongo::mlib>
    PUBLIC
-      mongocrypt::intel_dfp
+      ${maybe_dfp_library}
       ${CMAKE_DL_LIBS}
    )
 
@@ -339,7 +346,7 @@ target_link_libraries (
       kms_message_static
       $<BUILD_INTERFACE:mongo::mlib>
    PUBLIC
-      mongocrypt::intel_dfp
+      ${maybe_dfp_library}
       ${CMAKE_THREAD_LIBS_INIT}
       ${CMAKE_DL_LIBS}
    )
@@ -358,7 +365,7 @@ if (ENABLE_BUILD_FOR_PPA)
    endif ()
    set (PKG_CONFIG_STATIC_LIBS "${PKG_CONFIG_STATIC_LIBS} -pthread")
 endif ()
-if (MONGOCRYPT_DFP_DIR STREQUAL "USE-SYSTEM")
+if (MONGOCRYPT_DFP_DIR STREQUAL "USE-SYSTEM" AND MONGOCRYPT_ENABLE_DECIMAL128)
    get_property (SYSTEM_DFP_LOC TARGET intel_dfp PROPERTY IMPORTED_LOCATION)
    set (PKG_CONFIG_STATIC_LIBS "${PKG_CONFIG_STATIC_LIBS} ${SYSTEM_DFP_LOC}")
 endif ()
@@ -539,7 +546,7 @@ if ("cxx_relaxed_constexpr" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
       target_link_libraries ("${exe_name}" PRIVATE
          mongocrypt
          mongo::mlib
-         mongocrypt::intel_dfp
+         ${maybe_dfp_library}
          Threads::Threads
          _mongocrypt::libbson_for_static
          )
@@ -634,7 +641,7 @@ if (ENABLE_BUILD_FOR_PPA)
    endif ()
    set (PKG_CONFIG_LIBS "${PKG_CONFIG_LIBS} -pthread")
 endif ()
-if (MONGOCRYPT_DFP_DIR STREQUAL "USE-SYSTEM")
+if (MONGOCRYPT_DFP_DIR STREQUAL "USE-SYSTEM" AND MONGOCRYPT_ENABLE_DECIMAL128)
    get_property (SYSTEM_DFP_LOC TARGET intel_dfp PROPERTY IMPORTED_LOCATION)
    set (PKG_CONFIG_LIBS "${PKG_CONFIG_LIBS} ${SYSTEM_DFP_LOC}")
 endif ()

cmake/ImportDFP.cmake

@@ -64,5 +64,7 @@ elseif (MONGOCRYPT_DFP_DIR STREQUAL "USE-SYSTEM")
    # users during find_package()
    target_link_libraries (_mongocrypt-intel_dfp INTERFACE $<BUILD_INTERFACE:intel_dfp>)
 
+   # Notify in-tree consumers that IntelDFP is available:
+   target_compile_definitions (_mongocrypt-intel_dfp INTERFACE $<BUILD_INTERFACE:MONGOCRYPT_INTELDFP>)
 endif ()
 

cmake/IntelDFP.cmake

@@ -380,6 +380,9 @@ target_include_directories(intel_dfp_obj PUBLIC ${intel_dfp_SOURCE_DIR}/LIBRARY/
 add_library (_mongocrypt_intel_dfp INTERFACE)
 add_library (mongocrypt::intel_dfp ALIAS _mongocrypt_intel_dfp)
 
+# Notify in-tree consumers that IntelDFP is available:
+target_compile_definitions (_mongocrypt_intel_dfp INTERFACE $<BUILD_INTERFACE:MONGOCRYPT_INTELDFP>)
+
 target_sources (_mongocrypt_intel_dfp
     #[[
         For targets *within this build* that link with mongocrypt::intel_dfp,

src/mc-dec128.h

@@ -7,6 +7,16 @@
 #include <mlib/int128.h>
 #include <mlib/endian.h>
 
+// Conditional preprocessor definition set by the usage of an intel_dfp from
+// the ImportDFP.cmake script:
+#ifndef MONGOCRYPT_INTELDFP
+// Notify includers that Decimal128 is not available:
+#define MONGOCRYPT_HAVE_DECIMAL128_SUPPORT 0
+
+#else // With IntelDFP:
+// Tell includers that Decimal128 is okay:
+#define MONGOCRYPT_HAVE_DECIMAL128_SUPPORT 1
+
 // Include the header that declares the DFP functions, which may be macros that
 // expand to renamed symbols:
 #include <bid_conf.h>
@@ -728,4 +738,6 @@ mc_dec128_to_bson_decimal128 (mc_dec128 v)
 
 MLIB_C_LINKAGE_END
 
+#endif /// defined MONGOCRYPT_INTELDFP
+
 #endif // MC_DEC128_H_INCLUDED

src/mc-dec128.test.cpp

@@ -1,5 +1,9 @@
 #include <mc-dec128.h>
 
+#include <cstdio>
+
+#if MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
+
 #include <stdlib.h>
 
 #include <mlib/check.hpp>
@@ -70,3 +74,13 @@ main ()
    mc_dec128 nan = MC_DEC128_POSITIVE_NAN;
    CHECK (mc_dec128_is_nan (nan));
 }
+
+#else
+
+int
+main ()
+{
+   std::puts ("@@ctest-skip@@\n Decimal128 support is not enabled\n");
+}
+
+#endif

src/mc-optional-private.h

@@ -103,6 +103,7 @@ typedef struct {
       .set = true, .value = val \
    }
 
+#if MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 typedef struct {
    bool set;
    mc_dec128 value;
@@ -113,7 +114,7 @@ typedef struct {
    {                                    \
       .set = true, .value = __VA_ARGS__ \
    }
-
+#endif // MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 
 #define OPT_NULLOPT \
    {                \

src/mc-range-edge-generation-private.h

@@ -77,6 +77,7 @@ typedef struct {
 mc_edges_t *
 mc_getEdgesDouble (mc_getEdgesDouble_args_t args, mongocrypt_status_t *status);
 
+#if MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 typedef struct {
    mc_dec128 value;
    size_t sparsity;
@@ -87,6 +88,7 @@ typedef struct {
 mc_edges_t *
 mc_getEdgesDecimal128 (mc_getEdgesDecimal128_args_t args,
                        mongocrypt_status_t *status);
+#endif // MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 
 BSON_STATIC_ASSERT2 (ull_is_u64,
                      sizeof (uint64_t) == sizeof (unsigned long long));

src/mc-range-edge-generation.c

@@ -213,6 +213,7 @@ mc_getEdgesDouble (mc_getEdgesDouble_args_t args, mongocrypt_status_t *status)
    return ret;
 }
 
+#if MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 mc_edges_t *
 mc_getEdgesDecimal128 (mc_getEdgesDecimal128_args_t args,
                        mongocrypt_status_t *status)
@@ -238,3 +239,4 @@ mc_getEdgesDecimal128 (mc_getEdgesDecimal128_args_t args,
    mc_edges_t *ret = mc_edges_new (leaf, args.sparsity, status);
    return ret;
 }
+#endif // MONGOCRYPT_HAVE_DECIMAL128_SUPPORT

src/mc-range-encoding-private.h

@@ -96,6 +96,7 @@ mc_getTypeInfoDouble (mc_getTypeInfoDouble_args_t args,
                       mongocrypt_status_t *status)
    MONGOCRYPT_WARN_UNUSED_RESULT;
 
+#if MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 /**
  * @brief OST-encoding of a Decimal128
  */
@@ -122,5 +123,6 @@ mc_getTypeInfoDecimal128 (mc_getTypeInfoDecimal128_args_t args,
                           mc_OSTType_Decimal128 *out,
                           mongocrypt_status_t *status)
    MONGOCRYPT_WARN_UNUSED_RESULT;
+#endif // MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 
 #endif /* MC_RANGE_ENCODING_PRIVATE_H */

src/mc-range-encoding.c

@@ -314,6 +314,7 @@ mc_getTypeInfoDouble (mc_getTypeInfoDouble_args_t args,
    return true;
 }
 
+#if MONGOCRYPT_HAVE_DECIMAL128_SUPPORT
 /**
  * @brief There is no shipped algorithm for creating a full 128-bit integer from
  * a Decimal128, but it's easy enough to write one of our own.
@@ -615,3 +616,5 @@ mc_getTypeInfoDecimal128 (mc_getTypeInfoDecimal128_args_t args,
 
    return true;
 }
+
+#endif // defined MONGOCRYPT_HAVE_DECIMAL128_SUPPORT