Squash commits for public release

test/kernel/fs/dup/BUILD.gn

@@ -0,0 +1,8 @@
+import("//build/test/TEMPLATE.gni")
+
+xOS_test("dup") {
+  test_bundle = "kernel/fs/dup"
+  sources = [ "main.c" ]
+  configs = [ "//build/userland:userland_flags" ]
+  deplibs = [ "libc" ]
+}

test/kernel/fs/dup/main.c

@@ -0,0 +1,40 @@
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+int main(int argc, char** argv)
+{
+    int fd = -1;
+    fd = open("/boot/kernel.config", O_RDONLY);
+    if (fd < 0) {
+        TestErr("Can't open kernel.config");
+    }
+
+    int dupfd = dup(fd);
+    if (dupfd < 0) {
+        TestErr("Can't dup file");
+    }
+
+    int err = write(dupfd, "abcd", 5);
+    if (!err) {
+        TestErr("Succesfully write to read only file");
+    }
+
+    stat_t stat;
+    if (fstat(fd, &stat) < 0) {
+        TestErr("Can't read fstat of orig file");
+    }
+
+    stat_t newstat;
+    if (fstat(dupfd, &newstat) < 0) {
+        TestErr("Can't read fstat of dup file");
+    }
+
+    if (memcmp(&stat, &newstat, sizeof(stat_t)) != 0) {
+        TestErr("Different stat info of files");
+    }
+    return 0;
+}