scripts: add kcargo.sh

kcargo runs the Rust cargo for Shodan outside the normal build
process. This is useful for doing things like

kcargo fmt
kcargo tree
kcargo clippy

Change-Id: If279cf55caaf661d46c92d7e62f9ef869bbaa0ae

kcargo.sh

diff --git a/kcargo.sh b/kcargo.sh
new file mode 100755
index 0000000..6ed12ac
--- /dev/null
+++ b/kcargo.sh
@@ -0,0 +1,34 @@
+#! /bin/bash
+
+# Script for running Shodan cargo outside the build; useful
+# for doing things like kcargo tree or kcargo clippy.
+
+if [[ -z "${ROOTDIR}" ]]; then
+    echo "Source build/setup.sh first"
+    exit 1
+fi
+
+# HACK: sel4-config needs a path to the kernel build which could be
+#   in debug or release
+export SEL4_OUT_DIR="$ROOTDIR/out/kata/riscv32-unknown-elf/debug/kernel/"
+if [[ ! -d "${SEL4_OUT_DIR}/gen_config" ]]; then
+    echo "No kernel build found at ${SEL4_OUT_DIR}; build a kernel first"
+    exit 2
+fi
+
+CARGO="${CARGO_HOME}/bin/cargo +${KATA_RUST_VERSION}"
+CARGO_TARGET="--target riscv32imac-unknown-none-elf"
+CARGO_OPTS='-Z unstable-options -Z avoid-dev-deps'
+
+export RUSTFLAGS='-Z tls-model=local-exec'
+
+cmd=${1:-build}
+case "$1" in
+fmt)
+      ${CARGO} $*;;
+""|-*)
+      # TODO(sleffler): maybe set --target-dir to avoid polluting the src tree
+      ${CARGO} build ${CARGO_OPTS} ${CARGO_TARGET};;
+*)
+      ${CARGO} $* ${CARGO_OPTS} ${CARGO_TARGET};;
+esac