power loss

frontend/test-support/native-fs.c

@@ -0,0 +1,27 @@
+/* Test-only POSIX primitives missing from Node's filesystem API. A preflight
+ * exists() followed by fs.rename() is not an exclusive rename. */
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#if defined(__linux__)
+#include <sys/syscall.h>
+#endif
+
+int main(int argc, char **argv) {
+    if (argc == 4 && strcmp(argv[1], "rename") == 0) {
+        int result;
+#if defined(__APPLE__)
+        result = renamex_np(argv[2], argv[3], RENAME_EXCL);
+#elif defined(__linux__)
+        result = syscall(SYS_renameat2, AT_FDCWD, argv[2], AT_FDCWD, argv[3], 1 /* RENAME_NOREPLACE */);
+#else
+#error "The real filesystem tests require macOS or Linux"
+#endif
+        if (result != 0) { perror("exclusive rename"); return 1; }
+        return 0;
+    }
+    fprintf(stderr, "usage: native-fs rename FROM TO\n");
+    return 2;
+}