From 286cf28ec7e397432bcd9fa04a0e7d25d071a78f Mon Sep 17 00:00:00 2001
From: thuanquang <60096168+thuanquang@users.noreply.github.com>
Date: Mon, 12 Oct 2026 23:17:12 +0700
Subject: [PATCH] fix(relinker): reject a directory as the executable output
 path

An existing directory, or a path ending in a separator, was only
rejected when the executable was written, after the converted modules
had already been written to app0/ beside or inside it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 core/relinker/main.cpp                        |  2 ++
 .../relinker/tests/test_input_preservation.py | 21 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/core/relinker/main.cpp b/core/relinker/main.cpp
index 95652550c..cf63c3296 100644
--- a/core/relinker/main.cpp
+++ b/core/relinker/main.cpp
@@ -91,6 +91,8 @@ int Run(const int argc, char* argv[]) {
 
         if (std::filesystem::exists(Io::NativePath(args.inputPath)) && std::filesystem::exists(Io::NativePath(args.outputPath)) && std::filesystem::equivalent(Io::NativePath(args.inputPath), Io::NativePath(args.outputPath)))
             throw Domain::RelinkerException("Executable output would overwrite the input executable");
+        if (Io::NativePath(args.outputPath).filename().empty() || std::filesystem::is_directory(Io::NativePath(args.outputPath)))
+            throw Domain::RelinkerException("Executable output is a directory: " + args.outputPath);
         const std::string absPath = Io::Utf8Path(std::filesystem::absolute(Io::NativePath(args.outputPath)));
 
         struct ExtraExecutable {
diff --git a/core/relinker/relinker/tests/test_input_preservation.py b/core/relinker/relinker/tests/test_input_preservation.py
index 3ec4114b3..10e7c5117 100644
--- a/core/relinker/relinker/tests/test_input_preservation.py
+++ b/core/relinker/relinker/tests/test_input_preservation.py
@@ -142,6 +142,26 @@ def check_registry_after_failed_patch(relinker, work):
     assert not (case / "app0").exists()
 
 
+def check_output_directory(relinker, work):
+    for windows in (False, True):
+        for existing in (False, True):
+            case = work / f"output-directory-{windows}-{existing}"
+            (case / "sce_module").mkdir(parents=True)
+            (case / "sce_module" / "sample.prx").write_bytes(guest_fixture(PLAIN_SITE))
+            source = case / "input.elf"
+            source.write_bytes(main_fixture())
+            target = case / "output"
+            if existing:
+                target.mkdir()
+            output = str(target) if existing else str(target) + os.sep
+            options = ["--windows"] if windows else []
+            result = subprocess.run([str(relinker), *options, str(source), output], cwd=case,
+                                    capture_output=True, text=True, timeout=20)
+            assert result.returncode == 2 and "Executable output is a directory" in result.stderr, (result.stdout, result.stderr)
+            assert not (case / "app0").exists() and not (target / "app0").exists()
+            assert target.exists() == existing
+
+
 def check_desktop_inputs(relinker, work):
     for desktop in (False, True):
         for bundled in (False, True):
@@ -204,6 +224,7 @@ def main():
         check_diagnostic_inputs(relinker, work)
         check_desktop_inputs(relinker, work)
         check_registry_after_failed_patch(relinker, work)
+        check_output_directory(relinker, work)
         for windows in (False, True):
             options = ["--windows"] if windows else []
             check_registry_inputs(relinker, work, windows)