From 1d5d4a7663a22b96e135bc7033a988993523c0d4 Mon Sep 17 00:00:00 2001
From: StoneDC <19905433+StoneDC@users.noreply.github.com>
Date: Fri, 30 Oct 2026 20:55:05 +0800
Subject: [PATCH] test(libc): bound UTF-16 memory searches including zero units

---
 core/libs/prx/libc/CMakeLists.txt        | 10 +++
 core/libs/tests/GuestWmemchrBoundary.cpp | 85 ++++++++++++++++++++++++
 2 files changed, 95 insertions(+)
 create mode 100644 core/libs/tests/GuestWmemchrBoundary.cpp

diff --git a/core/libs/prx/libc/CMakeLists.txt b/core/libs/prx/libc/CMakeLists.txt
index 176bc416d1e..95a8609c729 100644
--- a/core/libs/prx/libc/CMakeLists.txt
+++ b/core/libs/prx/libc/CMakeLists.txt
@@ -1051,6 +1051,16 @@ if(BUILD_TESTING)
         set_tests_properties(guest_search PROPERTIES ENVIRONMENT_MODIFICATION
             "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
     endif()
+    add_test_executable(guest_wmemchr_boundary_tests ${LIBS_INCLUDE_DIR}/tests/GuestWmemchrBoundary.cpp)
+    target_include_directories(guest_wmemchr_boundary_tests PRIVATE ${LIBS_INCLUDE_DIR})
+    target_link_libraries(guest_wmemchr_boundary_tests PRIVATE libc)
+    configure_windows_unwind(guest_wmemchr_boundary_tests)
+    add_test(NAME guest_wmemchr_boundary COMMAND guest_wmemchr_boundary_tests)
+    set_tests_properties(guest_wmemchr_boundary PROPERTIES TIMEOUT 20)
+    if(WIN32)
+        set_tests_properties(guest_wmemchr_boundary PROPERTIES ENVIRONMENT_MODIFICATION
+            "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
+    endif()
     add_test_executable(guest_demangle_tests ${LIBS_INCLUDE_DIR}/tests/GuestDemangle.cpp)
     target_include_directories(guest_demangle_tests PRIVATE ${LIBS_INCLUDE_DIR})
     target_link_libraries(guest_demangle_tests PRIVATE libc)
diff --git a/core/libs/tests/GuestWmemchrBoundary.cpp b/core/libs/tests/GuestWmemchrBoundary.cpp
new file mode 100644
index 00000000000..889e7123729
--- /dev/null
+++ b/core/libs/tests/GuestWmemchrBoundary.cpp
@@ -0,0 +1,85 @@
+#include "prx/libc/include/Api.hpp"
+#include <algorithm>
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <string>
+#include <vector>
+
+static void Require(bool condition) {
+    if (!condition) {
+        std::fputs("GuestWmemchrBoundary check failed\n", stderr);
+        std::abort();
+    }
+}
+
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <sys/mman.h>
+#include <unistd.h>
+#endif
+
+class Buffer {
+    unsigned char* allocation;
+    std::size_t page;
+public:
+    Buffer() {
+#ifdef _WIN32
+        SYSTEM_INFO info{};
+        GetSystemInfo(&info);
+        page = info.dwPageSize;
+        allocation = static_cast<unsigned char*>(VirtualAlloc(nullptr, page * 3, MEM_RESERVE | MEM_COMMIT, PAGE_NOACCESS));
+        Require(allocation != nullptr);
+        DWORD previous;
+        Require(VirtualProtect(allocation + page, page, PAGE_READWRITE, &previous) != 0);
+#else
+        const long size = sysconf(_SC_PAGESIZE);
+        Require(size > 0);
+        page = static_cast<std::size_t>(size);
+        allocation = static_cast<unsigned char*>(mmap(nullptr, page * 3, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
+        Require(allocation != MAP_FAILED);
+        Require(mprotect(allocation + page, page, PROT_READ | PROT_WRITE) == 0);
+#endif
+        std::memset(allocation + page, 0xa5, page);
+    }
+    ~Buffer() {
+#ifdef _WIN32
+        Require(VirtualFree(allocation, 0, MEM_RELEASE) != 0);
+#else
+        Require(munmap(allocation, page * 3) == 0);
+#endif
+    }
+    Buffer(const Buffer&) = delete;
+    Buffer& operator=(const Buffer&) = delete;
+    template<class T = unsigned char>
+    T* At(std::size_t count) {
+        Require(count <= (page - 32) / sizeof(T));
+        return reinterpret_cast<T*>(allocation + page * 2 - (std::max)(count, std::size_t{1}) * sizeof(T));
+    }
+};
+
+template<class T>
+static void Prefix(const T* data) {
+    for (int index = 1; index <= 8; ++index) Require(data[-index] == static_cast<T>(sizeof(T) == 1 ? 0xa5 : 0xa5a5));
+}
+
+int main() {
+    Buffer input;
+    const std::array<char16_t, 7> values{0, 1, 0xff, 0x100, 0x8000, 0xd800, 0xffff};
+    for (std::size_t length = 0; length <= 192; ++length) {
+        auto* source = input.At<char16_t>(length);
+        const auto extent = (std::max)(length, std::size_t{1});
+        for (std::size_t i = 0; i < extent; ++i) source[i] = values[(i + length) % values.size()];
+        const std::vector<char16_t> saved(source, source + extent);
+        for (char16_t target : {0, 1, 0xff, 0x100, 0x8000, 0xd800, 0xdc00, 0xffff}) {
+            const auto found = std::find(saved.begin(), saved.begin() + length, target);
+            const auto* expected = found == saved.begin() + length ? nullptr : source + (found - saved.begin());
+            Require(wmemchr_nid_postfix(source, target, length) == expected);
+            Require(std::equal(saved.begin(), saved.end(), source));
+        }
+    }
+}