From eefe4db0186940474ee3a5cb37f3d176f7f400c7 Mon Sep 17 00:00:00 2001
From: MarcZX100 <marczxrr@gmail.com>
Date: Mon, 12 Oct 2026 22:56:17 +0000
Subject: [PATCH] fix(libc): return native fopen errors

---
 core/libs/prx/libc/src/FileAndHeap.cpp | 22 ++--------------------
 core/libs/tests/FileStreams.cpp        | 13 +++++++++++++
 2 files changed, 15 insertions(+), 20 deletions(-)

diff --git a/core/libs/prx/libc/src/FileAndHeap.cpp b/core/libs/prx/libc/src/FileAndHeap.cpp
index ef219f06b..1c14681ec 100644
--- a/core/libs/prx/libc/src/FileAndHeap.cpp
+++ b/core/libs/prx/libc/src/FileAndHeap.cpp
@@ -274,29 +274,11 @@ FileStream* APS5_VABI fopen_nid_postfix(const char* filename, const char* mode)
     }
     std::filesystem::path fpath;
     if (const int error = ResolvePathError_nid_no_patch(filename, fpath)) { errno = error; return nullptr; }
-    const auto abs_path = fpath.string();
     std::unique_ptr<std::FILE, int (*)(std::FILE*)> handle(OpenNative(fpath, parsed->native), std::fclose);
     if (!handle) {
         const int error = errno;
-        if (error == ENOENT || (parsed->exclusive && error == EEXIST)) {
-            errno = error;
-            return nullptr;
-        }
-        const auto reason = std::strerror(error);
-        std::error_code ec;
-        std::filesystem::path sibling;
-        for (const auto& entry : std::filesystem::directory_iterator(fpath.parent_path(), ec)) {
-            if (ec) break;
-            if (entry.path().stem() == fpath.stem() && entry.path().extension() != fpath.extension()) {
-                sibling = std::filesystem::absolute(entry.path());
-                break;
-            }
-        }
-        if (!sibling.empty()) {
-            // APS5_LOG_OUT("%s: \"%s\": %s. Sibling: \"%s\"", FOPEN_MSG_NOT_FOUND, abs_path.c_str(), reason, sibling.filename().string().c_str());
-            return nullptr;
-        }
-        throw std::runtime_error(std::string(__func__) + ": " + FOPEN_MSG_OPEN_FAILED + ": \"" + abs_path + "\": " + reason);
+        errno = error;
+        return nullptr;
     }
     // APS5_LOG_OUT("success: \"%s\"", abs_path.c_str());
     if (parsed->append) static_cast<void>(std::fseek(handle.get(), 0, SEEK_END));
diff --git a/core/libs/tests/FileStreams.cpp b/core/libs/tests/FileStreams.cpp
index d0431836b..60a760f1c 100644
--- a/core/libs/tests/FileStreams.cpp
+++ b/core/libs/tests/FileStreams.cpp
@@ -75,6 +75,19 @@ int main(int argc, char** argv) {
     errno = 0;
     Require(fopen_nid_postfix(argv[1], "rb") == nullptr);
     Require(errno == ENOENT);
+#ifdef _WIN32
+    const std::string directoryMode = "rb";
+    constexpr int directoryError = EACCES;
+#else
+    const std::string directoryMode = "wb";
+    constexpr int directoryError = EISDIR;
+#endif
+    const std::string directoryName = std::string(argv[1]) + ".dir";
+    Require(std::filesystem::create_directory(directoryName));
+    errno = 0;
+    Require(fopen_nid_postfix(directoryName.c_str(), directoryMode.c_str()) == nullptr);
+    Require(errno == directoryError);
+    Require(std::filesystem::remove(directoryName));
     const std::u8string unicodeName = u8"セーブé.tmp";
     const std::string guestName(unicodeName.begin(), unicodeName.end());
     const std::filesystem::path hostName(unicodeName);