fix(nid): report failed library writes

core/libs/nid/src/main.cpp

@@ -19,6 +19,8 @@ void _writeFile(const std::string& path, const std::vector<std::uint8_t>& data)
     std::ofstream f(Nid::Internal::NativePath(path), std::ios::binary);
     if (!f) throw std::runtime_error("cannot write: " + path);
     f.write(reinterpret_cast<const char*>(data.data()), static_cast<std::streamsize>(data.size()));
+    f.close();
+    if (!f) throw std::runtime_error("cannot write: " + path);
 }
 
 }

core/libs/nid/tests/test_native_paths.py

@@ -1,11 +1,17 @@
 import subprocess
+import signal
 import sys
 import tempfile
 import unittest
 from pathlib import Path
 
 from test_macho_nids import build_dylib, exports_of, nid
 
+try:
+    import resource
+except ImportError:
+    resource = None
+
 PATCHER = Path(sys.argv.pop(1)).resolve()
 
 
@@ -51,6 +57,27 @@ def test_missing_unicode_input_does_not_modify_another_file(self):
             self.assertFalse(missing.exists())
             self.assertEqual(existing.read_bytes(), b"unchanged")
 
+    @unittest.skipUnless(resource is not None and hasattr(signal, "SIGXFSZ"), "requires POSIX file size limits")
+    def test_failed_file_write_is_reported_without_success(self):
+        for limit in (0, 1024):
+            with self.subTest(limit=limit), tempfile.TemporaryDirectory() as temporary:
+                file = Path(temporary) / "library.prx"
+                original = build_dylib([("_puts_nid_postfix", 0, 0x100)], [])
+                file.write_bytes(original)
+
+                def restrict_output():
+                    signal.signal(signal.SIGXFSZ, signal.SIG_IGN)
+                    resource.setrlimit(resource.RLIMIT_FSIZE, (limit, limit))
+
+                result = subprocess.run([str(PATCHER), "libtest", str(file)], capture_output=True,
+                                        encoding="utf-8", errors="replace", timeout=10,
+                                        preexec_fn=restrict_output)
+                self.assertEqual(file.stat().st_size, limit)
+                self.assertEqual(result.returncode, 2, result.stdout + result.stderr)
+                self.assertIn("cannot write", result.stderr)
+                self.assertIn(str(file), result.stderr)
+                self.assertNotIn("OK:", result.stdout)
+
 
 if __name__ == "__main__":
     unittest.main()