Handle special characters in JSON model dump.

src/common/common.cc

@@ -1,16 +1,17 @@
-/*!
- * Copyright 2015-2019 by Contributors
- * \file common.cc
- * \brief Enable all kinds of global variables in common.
+/**
+ * Copyright 2015-2023 by Contributors
  */
-#include <dmlc/thread_local.h>
-#include <xgboost/logging.h>
-
 #include "common.h"
-#include "./random.h"
 
-namespace xgboost {
-namespace common {
+#include <dmlc/thread_local.h>  // for ThreadLocalStore
+
+#include <cstdint>  // for uint8_t
+#include <cstdio>   // for snprintf, size_t
+#include <string>   // for string
+
+#include "./random.h"  // for GlobalRandomEngine, GlobalRandom
+
+namespace xgboost::common {
 /*! \brief thread local entry for random. */
 struct RandomThreadLocalEntry {
   /*! \brief the random engine instance. */
@@ -19,15 +20,43 @@ struct RandomThreadLocalEntry {
 
 using RandomThreadLocalStore = dmlc::ThreadLocalStore<RandomThreadLocalEntry>;
 
-GlobalRandomEngine& GlobalRandom() {
-  return RandomThreadLocalStore::Get()->engine;
+GlobalRandomEngine &GlobalRandom() { return RandomThreadLocalStore::Get()->engine; }
+
+void EscapeU8(std::string const &string, std::string *p_buffer) {
+  auto &buffer = *p_buffer;
+  for (size_t i = 0; i < string.length(); i++) {
+    const auto ch = string[i];
+    if (ch == '\\') {
+      if (i < string.size() && string[i + 1] == 'u') {
+        buffer += "\\";
+      } else {
+        buffer += "\\\\";
+      }
+    } else if (ch == '"') {
+      buffer += "\\\"";
+    } else if (ch == '\b') {
+      buffer += "\\b";
+    } else if (ch == '\f') {
+      buffer += "\\f";
+    } else if (ch == '\n') {
+      buffer += "\\n";
+    } else if (ch == '\r') {
+      buffer += "\\r";
+    } else if (ch == '\t') {
+      buffer += "\\t";
+    } else if (static_cast<uint8_t>(ch) <= 0x1f) {
+      // Unit separator
+      char buf[8];
+      snprintf(buf, sizeof buf, "\\u%04x", ch);
+      buffer += buf;
+    } else {
+      buffer += ch;
+    }
+  }
 }
 
 #if !defined(XGBOOST_USE_CUDA)
-int AllVisibleGPUs() {
-  return 0;
-}
+int AllVisibleGPUs() { return 0; }
 #endif  // !defined(XGBOOST_USE_CUDA)
 
-}  // namespace common
-}  // namespace xgboost
+}  // namespace xgboost::common

src/common/common.h

@@ -6,20 +6,19 @@
 #ifndef XGBOOST_COMMON_COMMON_H_
 #define XGBOOST_COMMON_COMMON_H_
 
-#include <xgboost/base.h>
-#include <xgboost/logging.h>
-#include <xgboost/span.h>
-
-#include <algorithm>
-#include <exception>
-#include <functional>
-#include <limits>
-#include <numeric>
-#include <sstream>
-#include <string>
-#include <type_traits>
-#include <utility>
-#include <vector>
+#include <algorithm>  // for max
+#include <array>      // for array
+#include <cmath>      // for ceil
+#include <cstddef>    // for size_t
+#include <cstdint>    // for int32_t, int64_t
+#include <sstream>    // for basic_istream, operator<<, istringstream
+#include <string>     // for string, basic_string, getline, char_traits
+#include <tuple>      // for make_tuple
+#include <utility>    // for forward, index_sequence, make_index_sequence
+#include <vector>     // for vector
+
+#include "xgboost/base.h"     // for XGBOOST_DEVICE
+#include "xgboost/logging.h"  // for LOG, LOG_FATAL, LogMessageFatal
 
 #if defined(__CUDACC__)
 #include <thrust/system/cuda/error.h>
@@ -52,8 +51,7 @@ inline cudaError_t ThrowOnCudaError(cudaError_t code, const char *file,
 #endif  // defined(__CUDACC__)
 }  // namespace dh
 
-namespace xgboost {
-namespace common {
+namespace xgboost::common {
 /*!
  * \brief Split a string by delimiter
  * \param s String to be split.
@@ -69,19 +67,13 @@ inline std::vector<std::string> Split(const std::string& s, char delim) {
   return ret;
 }
 
+void EscapeU8(std::string const &string, std::string *p_buffer);
+
 template <typename T>
 XGBOOST_DEVICE T Max(T a, T b) {
   return a < b ? b : a;
 }
 
-// simple routine to convert any data to string
-template<typename T>
-inline std::string ToString(const T& data) {
-  std::ostringstream os;
-  os << data;
-  return os.str();
-}
-
 template <typename T1, typename T2>
 XGBOOST_DEVICE T1 DivRoundUp(const T1 a, const T2 b) {
   return static_cast<T1>(std::ceil(static_cast<double>(a) / b));
@@ -195,6 +187,5 @@ template <typename Indexable>
 XGBOOST_DEVICE size_t LastOf(size_t group, Indexable const &indptr) {
   return indptr[group + 1] - 1;
 }
-}  // namespace common
-}  // namespace xgboost
+}  // namespace xgboost::common
 #endif  // XGBOOST_COMMON_COMMON_H_

src/common/json.cc

@@ -1,23 +1,29 @@
-/*!
- * Copyright (c) by Contributors 2019-2022
+/**
+ * Copyright 2019-2023, XGBoost Contributors
  */
 #include "xgboost/json.h"
 
-#include <dmlc/endian.h>
-
-#include <cctype>
-#include <cmath>
-#include <cstddef>
-#include <iterator>
-#include <limits>
-#include <sstream>
-
-#include "./math.h"
-#include "charconv.h"
-#include "xgboost/base.h"
-#include "xgboost/json_io.h"
-#include "xgboost/logging.h"
-#include "xgboost/string_view.h"
+#include <array>             // for array
+#include <cctype>            // for isdigit
+#include <cmath>             // for isinf, isnan
+#include <cstdio>            // for EOF
+#include <cstdlib>           // for size_t, strtof
+#include <cstring>           // for memcpy
+#include <initializer_list>  // for initializer_list
+#include <iterator>          // for distance
+#include <limits>            // for numeric_limits
+#include <memory>            // for allocator
+#include <sstream>           // for operator<<, basic_ostream, operator&, ios, stringstream
+#include <system_error>      // for errc
+
+#include "./math.h"                 // for CheckNAN
+#include "charconv.h"               // for to_chars, NumericLimits, from_chars, to_chars_result
+#include "common.h"                 // for EscapeU8
+#include "xgboost/base.h"           // for XGBOOST_EXPECT
+#include "xgboost/intrusive_ptr.h"  // for IntrusivePtr
+#include "xgboost/json_io.h"        // for JsonReader, UBJReader, UBJWriter, JsonWriter, ToBigEn...
+#include "xgboost/logging.h"        // for LOG, LOG_FATAL, LogMessageFatal, LogCheck_NE, CHECK
+#include "xgboost/string_view.h"    // for StringView, operator<<
 
 namespace xgboost {
 
@@ -57,12 +63,12 @@ void JsonWriter::Visit(JsonObject const* obj) {
 }
 
 void JsonWriter::Visit(JsonNumber const* num) {
-  char number[NumericLimits<float>::kToCharsSize];
-  auto res = to_chars(number, number + sizeof(number), num->GetNumber());
+  std::array<char, NumericLimits<float>::kToCharsSize> number;
+  auto res = to_chars(number.data(), number.data() + number.size(), num->GetNumber());
   auto end = res.ptr;
   auto ori_size = stream_->size();
-  stream_->resize(stream_->size() + end - number);
-  std::memcpy(stream_->data() + ori_size, number, end - number);
+  stream_->resize(stream_->size() + end - number.data());
+  std::memcpy(stream_->data() + ori_size, number.data(), end - number.data());
 }
 
 void JsonWriter::Visit(JsonInteger const* num) {
@@ -88,43 +94,15 @@ void JsonWriter::Visit(JsonNull const* ) {
 }
 
 void JsonWriter::Visit(JsonString const* str) {
-  std::string buffer;
-  buffer += '"';
-  auto const& string = str->GetString();
-  for (size_t i = 0; i < string.length(); i++) {
-    const char ch = string[i];
-    if (ch == '\\') {
-      if (i < string.size() && string[i+1] == 'u') {
-        buffer += "\\";
-      } else {
-        buffer += "\\\\";
-      }
-    } else if (ch == '"') {
-      buffer += "\\\"";
-    } else if (ch == '\b') {
-      buffer += "\\b";
-    } else if (ch == '\f') {
-      buffer += "\\f";
-    } else if (ch == '\n') {
-      buffer += "\\n";
-    } else if (ch == '\r') {
-      buffer += "\\r";
-    } else if (ch == '\t') {
-      buffer += "\\t";
-    } else if (static_cast<uint8_t>(ch) <= 0x1f) {
-      // Unit separator
-      char buf[8];
-      snprintf(buf, sizeof buf, "\\u%04x", ch);
-      buffer += buf;
-    } else {
-      buffer += ch;
-    }
-  }
-  buffer += '"';
+    std::string buffer;
+    buffer += '"';
+    auto const& string = str->GetString();
+    common::EscapeU8(string, &buffer);
+    buffer += '"';
 
-  auto s = stream_->size();
-  stream_->resize(s + buffer.size());
-  std::memcpy(stream_->data() + s, buffer.data(), buffer.size());
+    auto s = stream_->size();
+    stream_->resize(s + buffer.size());
+    std::memcpy(stream_->data() + s, buffer.data(), buffer.size());
 }
 
 void JsonWriter::Visit(JsonBoolean const* boolean) {

src/common/numeric.h

@@ -10,6 +10,7 @@
 #include <cstddef>    // for size_t
 #include <cstdint>    // for int32_t
 #include <iterator>   // for iterator_traits
+#include <numeric>    // for accumulate
 #include <vector>
 
 #include "common.h"                      // AssertGPUSupport

src/learner.cc

@@ -797,7 +797,7 @@ class LearnerConfiguration : public Learner {
     bool has_nc {cfg_.find("num_class") != cfg_.cend()};
     // Inject num_class into configuration.
     // FIXME(jiamingy): Remove the duplicated parameter in softmax
-    cfg_["num_class"] = common::ToString(mparam_.num_class);
+    cfg_["num_class"] = std::to_string(mparam_.num_class);
     auto& args = *p_args;
     args = {cfg_.cbegin(), cfg_.cend()};  // renew
     obj_->Configure(args);
@@ -1076,7 +1076,7 @@ class LearnerIO : public LearnerConfiguration {
     mparam_.major_version = std::get<0>(Version::Self());
     mparam_.minor_version = std::get<1>(Version::Self());
 
-    cfg_["num_feature"] = common::ToString(mparam_.num_feature);
+    cfg_["num_feature"] = std::to_string(mparam_.num_feature);
 
     auto n = tparam_.__DICT__();
     cfg_.insert(n.cbegin(), n.cend());

src/tree/tree_model.cc

@@ -398,11 +398,14 @@ class JsonGenerator : public TreeGenerator {
     static std::string const kIndicatorTemplate =
         R"ID( "nodeid": {nid}, "depth": {depth}, "split": "{fname}", "yes": {yes}, "no": {no})ID";
     auto split_index = tree[nid].SplitIndex();
+    auto fname = fmap_.Name(split_index);
+    std::string qfname;  // quoted
+    common::EscapeU8(fname, &qfname);
     auto result = SuperT::Match(
         kIndicatorTemplate,
         {{"{nid}",   std::to_string(nid)},
          {"{depth}", std::to_string(depth)},
-         {"{fname}", fmap_.Name(split_index)},
+         {"{fname}", qfname},
          {"{yes}",   std::to_string(nyes)},
          {"{no}",    std::to_string(tree[nid].DefaultChild())}});
     return result;
@@ -430,12 +433,14 @@ class JsonGenerator : public TreeGenerator {
                             std::string const &template_str, std::string cond,
                             uint32_t depth) const {
     auto split_index = tree[nid].SplitIndex();
+    auto fname = split_index < fmap_.Size() ? fmap_.Name(split_index) : std::to_string(split_index);
+    std::string qfname;  // quoted
+    common::EscapeU8(fname, &qfname);
     std::string const result = SuperT::Match(
         template_str,
         {{"{nid}",     std::to_string(nid)},
          {"{depth}",   std::to_string(depth)},
-         {"{fname}",   split_index < fmap_.Size() ? fmap_.Name(split_index) :
-                                                    std::to_string(split_index)},
+         {"{fname}",   qfname},
          {"{cond}",    cond},
          {"{left}",    std::to_string(tree[nid].LeftChild())},
          {"{right}",   std::to_string(tree[nid].RightChild())},

tests/python/test_basic_models.py

@@ -439,6 +439,26 @@ def validate_model(parameters):
                       'objective': 'multi:softmax'}
         validate_model(parameters)
 
+    def test_special_model_dump_characters(self):
+        params = {"objective": "reg:squarederror", "max_depth": 3}
+        feature_names = ['"feature 0"', "\tfeature\n1", "feature 2"]
+        X, y, w = tm.make_regression(n_samples=128, n_features=3, use_cupy=False)
+        Xy = xgb.DMatrix(X, label=y, feature_names=feature_names)
+        booster = xgb.train(params, Xy, num_boost_round=3)
+        json_dump = booster.get_dump(dump_format="json")
+        assert len(json_dump) == 3
+
+        def validate(obj: dict) -> None:
+            for k, v in obj.items():
+                if k == "split":
+                    assert v in feature_names
+                elif isinstance(v, dict):
+                    validate(v)
+
+        for j_tree in json_dump:
+            loaded = json.loads(j_tree)
+            validate(loaded)
+
     def test_categorical_model_io(self):
         X, y = tm.make_categorical(256, 16, 71, False)
         Xy = xgb.DMatrix(X, y, enable_categorical=True)