Adds a README

README.md

@@ -0,0 +1,30 @@
+sudo replacement as a static binary
+
+What is this
+------------
+
+This is a simple C program that changes uid and gid to the ones provided on the
+command-line before executing a command. It is meant to replace sudo where it
+is overkill, and can be compiled to a very small static binary that will work
+everywhere.
+
+It accepts numeric uid and gid (like sudo, but unlike su).
+
+Note that it doesn't do any authentication and is not meant to be set-uid; it
+is only a wrapper intended to be run by root.
+
+Why is this needed?
+-------------------
+
+This is needed by the [ReproZip](https://github.com/ViDA-NYU/reprozip) project.
+The reprounzip component builds virtual machines and unpacks the files needed
+to reproduce an experiment, which might mean overwriting system libraries; a
+dynamically linked binary cannot be guaranteed to work after that. Busybox can
+be used as the shell, but a helper to get the uid/gid right is needed; this is
+it.
+
+Reprounzip downloads the static binaries from this project's releases page:
+
+    https://github.com/remram44/static-sudo/releases/download/current/rpzsudo-{arch}
+
+where ̀`{arch}` is one of: `i686`, `x86_64` (`uname -m`).