From c823cf6594c2ed8f69c84cabb9ed307496a55eff Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Thu, 9 May 2019 20:41:33 -0400
Subject: [PATCH] service/set: Correct and simplify behavior related to copying
 language codes

This corrects cases where it was possible to write more entries into the
write buffer than were requested. Now, we check the size of the buffer
before actually writing into them.

We were also returning the wrong value for
GetAvailableLanguageCodeCount2(). This was previously returning 64, but
only 17 should have been returned. 64 entries is the size of the static
array used in MakeLanguageCode() within the service binary itself, but
isn't the actual total number of language codes present.
---
 src/core/hle/service/set/set.cpp | 60 +++++++++++++-------------------
 1 file changed, 24 insertions(+), 36 deletions(-)

diff --git a/src/core/hle/service/set/set.cpp b/src/core/hle/service/set/set.cpp
index 4ecb6bcef3..298d850110 100644
--- a/src/core/hle/service/set/set.cpp
+++ b/src/core/hle/service/set/set.cpp
@@ -2,16 +2,15 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <algorithm>
 #include <chrono>
 #include "common/logging/log.h"
 #include "core/hle/ipc_helpers.h"
-#include "core/hle/kernel/client_port.h"
-#include "core/hle/kernel/client_session.h"
 #include "core/hle/service/set/set.h"
 #include "core/settings.h"
 
 namespace Service::Set {
-
+namespace {
 constexpr std::array<LanguageCode, 17> available_language_codes = {{
     LanguageCode::JA,
     LanguageCode::EN_US,
@@ -32,41 +31,35 @@ constexpr std::array<LanguageCode, 17> available_language_codes = {{
     LanguageCode::ZH_HANT,
 }};
 
-constexpr std::size_t pre4_0_0_max_entries = 0xF;
-constexpr std::size_t post4_0_0_max_entries = 0x40;
+constexpr std::size_t pre4_0_0_max_entries = 15;
+constexpr std::size_t post4_0_0_max_entries = 17;
 
 constexpr ResultCode ERR_INVALID_LANGUAGE{ErrorModule::Settings, 625};
 
+void PushResponseLanguageCode(Kernel::HLERequestContext& ctx, std::size_t num_language_codes) {
+    IPC::ResponseBuilder rb{ctx, 3};
+    rb.Push(RESULT_SUCCESS);
+    rb.Push(static_cast<u32>(num_language_codes));
+}
+
+void GetAvailableLanguageCodesImpl(Kernel::HLERequestContext& ctx, std::size_t max_size) {
+    const std::size_t requested_amount = ctx.GetWriteBufferSize() / sizeof(LanguageCode);
+    const std::size_t copy_amount = std::min(requested_amount, max_size);
+    const std::size_t copy_size = copy_amount * sizeof(LanguageCode);
+
+    ctx.WriteBuffer(available_language_codes.data(), copy_size);
+    PushResponseLanguageCode(ctx, copy_amount);
+}
+} // Anonymous namespace
+
 LanguageCode GetLanguageCodeFromIndex(std::size_t index) {
     return available_language_codes.at(index);
 }
 
-template <std::size_t size>
-static std::array<LanguageCode, size> MakeLanguageCodeSubset() {
-    std::array<LanguageCode, size> arr;
-    std::copy_n(available_language_codes.begin(), size, arr.begin());
-    return arr;
-}
-
-static void PushResponseLanguageCode(Kernel::HLERequestContext& ctx, std::size_t max_size) {
-    IPC::ResponseBuilder rb{ctx, 3};
-    rb.Push(RESULT_SUCCESS);
-    if (available_language_codes.size() > max_size) {
-        rb.Push(static_cast<u32>(max_size));
-    } else {
-        rb.Push(static_cast<u32>(available_language_codes.size()));
-    }
-}
-
 void SET::GetAvailableLanguageCodes(Kernel::HLERequestContext& ctx) {
     LOG_DEBUG(Service_SET, "called");
 
-    if (available_language_codes.size() > pre4_0_0_max_entries) {
-        ctx.WriteBuffer(MakeLanguageCodeSubset<pre4_0_0_max_entries>());
-    } else {
-        ctx.WriteBuffer(available_language_codes);
-    }
-    PushResponseLanguageCode(ctx, pre4_0_0_max_entries);
+    GetAvailableLanguageCodesImpl(ctx, pre4_0_0_max_entries);
 }
 
 void SET::MakeLanguageCode(Kernel::HLERequestContext& ctx) {
@@ -87,12 +80,7 @@ void SET::MakeLanguageCode(Kernel::HLERequestContext& ctx) {
 void SET::GetAvailableLanguageCodes2(Kernel::HLERequestContext& ctx) {
     LOG_DEBUG(Service_SET, "called");
 
-    if (available_language_codes.size() > post4_0_0_max_entries) {
-        ctx.WriteBuffer(MakeLanguageCodeSubset<post4_0_0_max_entries>());
-    } else {
-        ctx.WriteBuffer(available_language_codes);
-    }
-    PushResponseLanguageCode(ctx, post4_0_0_max_entries);
+    GetAvailableLanguageCodesImpl(ctx, post4_0_0_max_entries);
 }
 
 void SET::GetAvailableLanguageCodeCount(Kernel::HLERequestContext& ctx) {
@@ -102,9 +90,9 @@ void SET::GetAvailableLanguageCodeCount(Kernel::HLERequestContext& ctx) {
 }
 
 void SET::GetAvailableLanguageCodeCount2(Kernel::HLERequestContext& ctx) {
-    PushResponseLanguageCode(ctx, post4_0_0_max_entries);
-
     LOG_DEBUG(Service_SET, "called");
+
+    PushResponseLanguageCode(ctx, post4_0_0_max_entries);
 }
 
 void SET::GetLanguageCode(Kernel::HLERequestContext& ctx) {