Generate handin tarballs via git.

Previously, the tarball rule sucked in everything in sight.  This
allows students to better control what gets handed in and code
reviewed.  The rule checks several sanity conditions before creating
the archive.

.gitignore

@@ -8,6 +8,7 @@
 /wget.log
 /slirp.cap
 /qemu.out
+/qemu.log
 /lab?-handin.tar.gz
 /lab?/
 /sol?/

GNUmakefile

@@ -190,8 +190,24 @@ handin: tarball
 	@echo Please visit http://pdos.csail.mit.edu/6.828/submit/
 	@echo and upload lab$(LAB)-handin.tar.gz.  Thanks!
 
-tarball: realclean
-	tar cf - `find . -type f | grep -v '^\.*$$' | grep -v '/CVS/' | grep -v '/\.svn/' | grep -v '/\.git/' | grep -v 'lab[0-9].*\.tar\.gz'` | gzip > lab$(LAB)-handin.tar.gz
+tarball:
+	@if test "$$(git symbolic-ref HEAD)" != refs/heads/lab$(LAB); then \
+		git branch; \
+		read -p "You are not on the lab$(LAB) branch.  Handin the current branch? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+	@if ! git diff-files --quiet || ! git diff-index --quiet --cached HEAD; then \
+		git status; \
+		echo; \
+		echo "You have uncomitted changes.  Please commit or stash them."; \
+		false; \
+	fi
+	@if test -n "`git ls-files -o --exclude-standard`"; then \
+		git status; \
+		read -p "Untracked files will not be handed in.  Continue? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+	git archive --format=tar HEAD | gzip > lab$(LAB)-handin.tar.gz
 
 # For test runs
 prep-%:

conf/lab.mk

@@ -1,2 +1,2 @@
 LAB=4
-PACKAGEDATE=Tue Nov 1 19:35:08 EDT 2011
+PACKAGEDATE=Wed Nov 2 21:31:50 EDT 2011