[Base/Kernel] Add and use truncating null-terminating string copying

src/xenia/base/string_util.h

@@ -10,11 +10,15 @@
 #ifndef XENIA_BASE_STRING_UTIL_H_
 #define XENIA_BASE_STRING_UTIL_H_
 
+#include <algorithm>
 #include <charconv>
+#include <cstddef>
+#include <cstring>
 #include <string>
 
 #include "third_party/fmt/include/fmt/format.h"
 #include "xenia/base/assert.h"
+#include "xenia/base/memory.h"
 #include "xenia/base/platform.h"
 #include "xenia/base/string.h"
 #include "xenia/base/vec128.h"
@@ -30,6 +34,40 @@
 namespace xe {
 namespace string_util {
 
+inline size_t copy_truncating(char* dest, const std::string_view source,
+                              size_t dest_buffer_count) {
+  if (!dest_buffer_count) {
+    return 0;
+  }
+  size_t chars_copied = std::min(source.size(), dest_buffer_count - size_t(1));
+  std::memcpy(dest, source.data(), chars_copied);
+  dest[chars_copied] = '\0';
+  return chars_copied;
+}
+
+inline size_t copy_truncating(char16_t* dest, const std::u16string_view source,
+                              size_t dest_buffer_count) {
+  if (!dest_buffer_count) {
+    return 0;
+  }
+  size_t chars_copied = std::min(source.size(), dest_buffer_count - size_t(1));
+  std::memcpy(dest, source.data(), chars_copied * sizeof(char16_t));
+  dest[chars_copied] = u'\0';
+  return chars_copied;
+}
+
+inline size_t copy_and_swap_truncating(char16_t* dest,
+                                       const std::u16string_view source,
+                                       size_t dest_buffer_count) {
+  if (!dest_buffer_count) {
+    return 0;
+  }
+  size_t chars_copied = std::min(source.size(), dest_buffer_count - size_t(1));
+  xe::copy_and_swap(dest, source.data(), chars_copied);
+  dest[chars_copied] = u'\0';
+  return chars_copied;
+}
+
 inline std::string to_hex_string(uint32_t value) {
   return fmt::format("{:08X}", value);
 }

src/xenia/kernel/xam/xam_content.cc

@@ -8,6 +8,7 @@
  */
 
 #include "xenia/base/logging.h"
+#include "xenia/base/math.h"
 #include "xenia/kernel/kernel_state.h"
 #include "xenia/kernel/util/shim_utils.h"
 #include "xenia/kernel/xam/xam_private.h"
@@ -223,7 +224,8 @@ dword_result_t XamContentCreateDeviceEnumerator(dword_t content_type,
     xe::store_and_swap(&dev->device_type, dummy_device_info_.device_type);
     xe::store_and_swap(&dev->total_bytes, dummy_device_info_.total_bytes);
     xe::store_and_swap(&dev->free_bytes, dummy_device_info_.free_bytes);
-    xe::copy_and_swap(dev->name, dummy_device_info_.name, 28);
+    xe::copy_and_swap(dev->name, dummy_device_info_.name,
+                      xe::countof(dev->name));
   }
 
   *handle_out = e->handle();

src/xenia/kernel/xam/xam_info.cc

@@ -8,6 +8,7 @@
  */
 
 #include "xenia/base/logging.h"
+#include "xenia/base/string_util.h"
 #include "xenia/kernel/kernel_state.h"
 #include "xenia/kernel/user_module.h"
 #include "xenia/kernel/util/shim_utils.h"
@@ -74,15 +75,15 @@ static SYSTEMTIME xeGetLocalSystemTime(uint64_t filetime) {
 
 void XamFormatDateString(dword_t unk, qword_t filetime, lpvoid_t output_buffer,
                          dword_t output_count) {
-  std::memset(output_buffer, 0, output_count * 2);
+  std::memset(output_buffer, 0, output_count * sizeof(char16_t));
 
 // TODO: implement this for other platforms
 #if XE_PLATFORM_WIN32
   auto st = xeGetLocalSystemTime(filetime);
   // TODO: format this depending on users locale?
   auto str = fmt::format(u"{:02d}/{:02d}/{}", st.wMonth, st.wDay, st.wYear);
-  auto copy_length = std::min(size_t(output_count), str.size()) * 2;
+  xe::string_util::copy_and_swap_truncating(output_buffer.as<char16_t*>(), str,
-  xe::copy_and_swap(output_buffer.as<char16_t*>(), str.c_str(), copy_length);
+                                            output_count);
 #else
   assert_always();
 #endif
@@ -91,15 +92,15 @@ DECLARE_XAM_EXPORT1(XamFormatDateString, kNone, kImplemented);
 
 void XamFormatTimeString(dword_t unk, qword_t filetime, lpvoid_t output_buffer,
                          dword_t output_count) {
-  std::memset(output_buffer, 0, output_count * 2);
+  std::memset(output_buffer, 0, output_count * sizeof(char16_t));
 
 // TODO: implement this for other platforms
 #if XE_PLATFORM_WIN32
   auto st = xeGetLocalSystemTime(filetime);
   // TODO: format this depending on users locale?
   auto str = fmt::format(u"{:02d}:{:02d}", st.wHour, st.wMinute);
-  auto copy_count = std::min(size_t(output_count), str.size());
+  xe::string_util::copy_and_swap_truncating(output_buffer.as<char16_t*>(), str,
-  xe::copy_and_swap(output_buffer.as<char16_t*>(), str.c_str(), copy_count);
+                                            output_count);
 #else
   assert_always();
 #endif
@@ -113,7 +114,7 @@ dword_result_t keXamBuildResourceLocator(uint64_t module,
                                          uint32_t buffer_count) {
   std::u16string path;
   if (!module) {
-    path = fmt::format(u"file://media:/{0}.xzp#{0}", container, resource);
+    path = fmt::format(u"file://media:/{}.xzp#{}", container, resource);
     XELOGD(
         "XamBuildResourceLocator({0}) returning locator to local file {0}.xzp",
         xe::to_utf8(container));
@@ -121,8 +122,8 @@ dword_result_t keXamBuildResourceLocator(uint64_t module,
     path = fmt::format(u"section://{:X},{}#{}", (uint32_t)module, container,
                        resource);
   }
-  auto copy_count = std::min(size_t(buffer_count), path.size());
+  xe::string_util::copy_and_swap_truncating(buffer_ptr.as<char16_t*>(), path,
-  xe::copy_and_swap(buffer_ptr.as<char16_t*>(), path.c_str(), copy_count);
+                                            buffer_count);
   return 0;
 }
 

src/xenia/kernel/xam/xam_ui.cc

@@ -9,6 +9,7 @@
 
 #include "third_party/imgui/imgui.h"
 #include "xenia/base/logging.h"
+#include "xenia/base/string_util.h"
 #include "xenia/emulator.h"
 #include "xenia/kernel/kernel_flags.h"
 #include "xenia/kernel/kernel_state.h"
@@ -188,8 +189,8 @@ class KeyboardInputDialog : public xe::ui::ImGuiDialog {
       *out_text_ = default_text;
     }
     text_buffer_.resize(max_length);
-    std::strncpy(text_buffer_.data(), default_text_.c_str(),
+    xe::string_util::copy_truncating(text_buffer_.data(), default_text_,
-                 std::min(text_buffer_.size() - 1, default_text_.size()));
+                                     text_buffer_.size());
   }
 
   void OnDraw(ImGuiIO& io) override {

src/xenia/kernel/xam/xam_user.cc

@@ -10,6 +10,8 @@
 #include <cstring>
 
 #include "xenia/base/logging.h"
+#include "xenia/base/math.h"
+#include "xenia/base/string_util.h"
 #include "xenia/kernel/kernel_state.h"
 #include "xenia/kernel/util/shim_utils.h"
 #include "xenia/kernel/xam/xam_private.h"
@@ -91,7 +93,8 @@ X_HRESULT_result_t XamUserGetSigninInfo(dword_t user_index, dword_t flags,
   const auto& user_profile = kernel_state()->user_profile();
   info->xuid = user_profile->xuid();
   info->signin_state = user_profile->signin_state();
-  std::strncpy(info->name, user_profile->name().data(), 15);
+  xe::string_util::copy_truncating(info->name, user_profile->name(),
+                                   xe::countof(info->name));
   return X_E_SUCCESS;
 }
 DECLARE_XAM_EXPORT1(XamUserGetSigninInfo, kUserProfiles, kImplemented);
@@ -110,10 +113,8 @@ dword_result_t XamUserGetName(dword_t user_index, lpstring_t buffer,
   const auto& user_name = user_profile->name();
 
   // Real XAM will only copy a maximum of 15 characters out.
-  size_t copy_length = std::min(
+  xe::string_util::copy_truncating(buffer, user_name,
-      {size_t(15), user_name.size(), static_cast<size_t>(buffer_len) - 1});
+                                   std::min(buffer_len.value(), uint32_t(15)));
-  std::memcpy(buffer, user_name.data(), copy_length);
-  buffer[copy_length] = '\0';
   return X_ERROR_SUCCESS;
 }
 DECLARE_XAM_EXPORT1(XamUserGetName, kUserProfiles, kImplemented);