Add Git hooks that check Rust code format issues

.githooks/post-commit

@@ -0,0 +1,20 @@
+#!/bin/bash
+cd src/libos
+output=$(cargo fmt --all -- --check 2>&1)
+retval=$?
+
+if [[ $retval -eq 0 ]]
+then
+	exit 0
+elif [[ $retval -eq 1 ]]
+then
+	echo "Rust format suggestsions (generated by \`cd src/libos && cargo fmt --all -- --check\`):"
+	echo
+	echo "$output"
+	echo
+	echo "To get rid of the format warnings above, run \`cargo fmt\` before the next commit."
+	exit 1
+else
+	echo "Warning: \`cargo fmt\` is not available."
+	exit 1
+fi

.githooks/pre-push

@@ -0,0 +1,38 @@
+#!/bin/bash
+
+# An example hook script to verify what is about to be pushed.  Called by "git
+# push" after it has checked the remote status, but before anything has been
+# pushed.  If this script exits with a non-zero status nothing will be pushed.
+#
+# This hook is called with the following parameters:
+#
+# $1 -- Name of the remote to which the push is being done
+# $2 -- URL to which the push is being done
+#
+# If pushing without using a named remote those arguments will be equal.
+#
+# Information about the commits which are being pushed is supplied as lines to
+# the standard input in the form:
+#
+#   <local ref> <local sha1> <remote ref> <remote sha1>
+#
+# This sample shows how to prevent push of commits where the log message starts
+# with "WIP" (work in progress).
+
+cd src/libos
+output=$(cargo fmt --all -- --check 2>&1)
+retval=$?
+
+# cargo fmt finds any format issues
+if [[ $retval -eq 1 ]]
+then
+	echo "Rust format suggestsions (generated by \`cd src/libos && cargo fmt --all -- --check\`):"
+	echo
+	echo "$output"
+	echo
+	echo "To get rid of the format warnings above, run \`cargo fmt\` before the next commit."
+	exit 1
+fi
+
+# If cargo fmt finds no format issues or carg fmt is not available on the # platform
+exit 0

Makefile

@@ -1,8 +1,12 @@
-.PHONY: all src test clean
+.PHONY: all submodule githooks src test clean
 
 all: src
 
-submodule:
+githooks:
+	@find .git/hooks -type l -exec rm {} \; && find .githooks -type f -exec ln -sf ../../{} .git/hooks/ \;
+	@echo "Add Git hooks that check Rust code format issues before commits and pushes"
+
+submodule: githooks
 	git submodule init
 	git submodule update
 	cd deps/rust-sgx-sdk && git apply ../rust-sgx-sdk.patch