From d3ccd49eebb573cb37019b0cd25f033c857f24fd Mon Sep 17 00:00:00 2001
From: Tyler Yankee <tyler.yankee@kitware.com>
Date: Fri, 6 Feb 2026 12:09:39 -0500
Subject: [PATCH] cmFileAPI: Use cmJSONState to read client queries

This approach will be more portable.
---
 Source/cmFileAPI.cxx                          | 39 ++++---------------
 Source/cmFileAPI.h                            |  2 -
 .../RunCMake/FileAPI/ClientStateful-check.py  |  2 +-
 3 files changed, 8 insertions(+), 35 deletions(-)

diff --git a/Source/cmFileAPI.cxx b/Source/cmFileAPI.cxx
index ff31855155..6fb9b4b7ac 100644
--- a/Source/cmFileAPI.cxx
+++ b/Source/cmFileAPI.cxx
@@ -24,6 +24,7 @@
 #include "cmFileAPIConfigureLog.h"
 #include "cmFileAPIToolchains.h"
 #include "cmGlobalGenerator.h"
+#include "cmJSONState.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmTimestamp.h"
@@ -54,14 +55,6 @@ cmFileAPI::cmFileAPI(cmake* cm)
     this->UserAPIv1 = cmStrCat(std::move(*cmakeConfigDir), "/api/v1"_s);
   }
 
-  Json::CharReaderBuilder rbuilder;
-  rbuilder["collectComments"] = false;
-  rbuilder["failIfExtra"] = true;
-  rbuilder["rejectDupKeys"] = false;
-  rbuilder["strictRoot"] = true;
-  this->JsonReader =
-    std::unique_ptr<Json::CharReader>(rbuilder.newCharReader());
-
   Json::StreamWriterBuilder wbuilder;
   wbuilder["indentation"] = "\t";
   this->JsonWriter =
@@ -174,37 +167,19 @@ void cmFileAPI::RemoveOldReplyFiles()
 bool cmFileAPI::ReadJsonFile(std::string const& file, Json::Value& value,
                              std::string& error)
 {
-  std::vector<char> content;
-
-  cmsys::ifstream fin;
-  if (!cmSystemTools::FileIsDirectory(file)) {
-    fin.open(file.c_str(), std::ios::binary);
-  }
-  auto finEnd = fin.rdbuf()->pubseekoff(0, std::ios::end);
-  if (finEnd > 0) {
-    size_t finSize = finEnd;
-    try {
-      // Allocate a buffer to read the whole file.
-      content.resize(finSize);
-
-      // Now read the file from the beginning.
-      fin.seekg(0, std::ios::beg);
-      fin.read(content.data(), finSize);
-    } catch (...) {
-      fin.setstate(std::ios::failbit);
-    }
-  }
-  fin.close();
-  if (!fin) {
+  // Verify the file exists.
+  if (!cmSystemTools::FileExists(file) ||
+      cmSystemTools::FileIsDirectory(file)) {
     value = Json::Value();
     error = "failed to read from file";
     return false;
   }
 
   // Parse our buffer as json.
-  if (!this->JsonReader->parse(content.data(), content.data() + content.size(),
-                               &value, &error)) {
+  cmJSONState parseState(file, &value);
+  if (!parseState.errors.empty()) {
     value = Json::Value();
+    error = parseState.GetErrorMessage();
     return false;
   }
 
diff --git a/Source/cmFileAPI.h b/Source/cmFileAPI.h
index 2e2511106e..9aad2ca226 100644
--- a/Source/cmFileAPI.h
+++ b/Source/cmFileAPI.h
@@ -10,7 +10,6 @@
 #include <unordered_set>
 #include <vector>
 
-#include <cm3p/json/reader.h>
 #include <cm3p/json/value.h>
 #include <cm3p/json/writer.h>
 
@@ -169,7 +168,6 @@ private:
   /** Identify the situation in which WriteReplies was called.  */
   IndexFor ReplyIndexFor = IndexFor::Success;
 
-  std::unique_ptr<Json::CharReader> JsonReader;
   std::unique_ptr<Json::StreamWriter> JsonWriter;
 
   bool ReadJsonFile(std::string const& file, Json::Value& value,
diff --git a/Tests/RunCMake/FileAPI/ClientStateful-check.py b/Tests/RunCMake/FileAPI/ClientStateful-check.py
index 28679bbce5..8beffb12da 100644
--- a/Tests/RunCMake/FileAPI/ClientStateful-check.py
+++ b/Tests/RunCMake/FileAPI/ClientStateful-check.py
@@ -105,7 +105,7 @@ def check_query_json_bad_root(q):
     check_error_re(q, "A valid JSON document must be either an array or an object value")
 
 def check_query_json_empty(q):
-    check_error_re(q, "value, object or array expected")
+    check_error_re(q, "A JSON document cannot be empty")
 
 def check_query_json_extra(q):
     if bool(os.environ.get("CMake_JSONCPP_PRE_1_7_5", "")) and is_dict(q) and sorted(q.keys()) == ["responses"]: