Only use stdio.h to read stdin, avoid using C++ I/O libraries

CLI/Analyze.cpp

@@ -6,9 +6,6 @@
 #include "Luau/TypeAttach.h"
 #include "Luau/Transpiler.h"
 
-#include <iterator>
-#include <iostream>
-
 #include "FileUtils.h"
 
 LUAU_FASTFLAG(DebugLuauTimeTracing)
@@ -124,22 +121,25 @@ struct CliFileResolver : Luau::FileResolver
 {
     std::optional<Luau::SourceCode> readSource(const Luau::ModuleName& name) override
     {
+        Luau::SourceCode::Type sourceType;
+        std::optional<std::string> source = std::nullopt;
+
         // If the module name is "-", then read source from stdin
         if (name == "-")
         {
-            std::cin >> std::noskipws; // Do not skip whitespace when reading from stdin
-            std::string source {std::istreambuf_iterator<char>(std::cin), std::istreambuf_iterator<char>()};
-            if (source.empty())
-                return std::nullopt;
-
-            return Luau::SourceCode{source, Luau::SourceCode::Script};
+            source = readStdin();
+            sourceType = Luau::SourceCode::Script;
+        }
+        else
+        {
+            source = readFile(name);
+            sourceType = Luau::SourceCode::Module;
         }
 
-        std::optional<std::string> source = readFile(name);
         if (!source)
             return std::nullopt;
 
-        return Luau::SourceCode{*source, Luau::SourceCode::Module};
+        return Luau::SourceCode{*source, sourceType};
     }
 
     std::optional<Luau::ModuleInfo> resolveModule(const Luau::ModuleInfo* context, Luau::AstExpr* node) override

CLI/FileUtils.cpp

@@ -15,6 +15,8 @@
 
 #include <string.h>
 
+#define READ_BUFFER_SIZE 4096
+
 #ifdef _WIN32
 static std::wstring fromUtf8(const std::string& path)
 {
@@ -74,6 +76,20 @@ std::optional<std::string> readFile(const std::string& name)
     return result;
 }
 
+std::optional<std::string> readStdin() {
+    std::string result;
+    char buffer[READ_BUFFER_SIZE] = { };
+
+    while (fgets(buffer, READ_BUFFER_SIZE, stdin) != nullptr)
+        result.append(buffer);
+
+    // If eof was not reached for stdin, then a read error occurred
+    if (!feof(stdin))
+        return std::nullopt;
+
+    return result;
+}
+
 template<typename Ch>
 static void joinPaths(std::basic_string<Ch>& str, const Ch* lhs, const Ch* rhs)
 {

CLI/FileUtils.h

@@ -7,6 +7,7 @@
 #include <vector>
 
 std::optional<std::string> readFile(const std::string& name);
+std::optional<std::string> readStdin();
 
 bool isDirectory(const std::string& path);
 bool traverseDirectory(const std::string& path, const std::function<void(const std::string& name)>& callback);