add smaller-than-gnu "hello world" package

overlay.nix

@@ -49,7 +49,6 @@ extraPkgs // {
 
   # openssl is reqired by ntp
 
-
   rsyncSmall = prev.rsync.overrideAttrs(o: {
     configureFlags = o.configureFlags ++ [
       "--disable-openssl"

pkgs/default.nix

@@ -44,4 +44,6 @@
   swconfig = callPackage ./swconfig {};
 
   openwrt = callPackage ./openwrt {};
+
+  hi = callPackage ./hi {};
 }

pkgs/hi/default.nix

@@ -0,0 +1,27 @@
+# A "hello world" program that's smaller than the GNU
+# one. Used for testing the toolchain/linker behaviour.
+{
+  runCommandCC
+}:
+let code = ''
+  #include <stdio.h>
+  int main()
+  {
+    printf("hello world\n");
+    return 0;
+  }
+'';
+in runCommandCC "hello" {
+  name = "hi";
+  inherit code;
+  executable = true;
+  # hardeningDisable = ["all"];
+  passAsFile = ["code"];
+  preferLocalBuild = true;
+  allowSubstitutes = false;
+} ''
+  n=$out/bin/$name
+  mkdir -p "$(dirname "$n")"
+  mv "$codePath" code.c
+  $CC -x c code.c -o "$n"
+''