[PATCH v2 1/2] git-am: emit usage when called w/o arguments and w/o patch on stdin

[Jay Soffian <jaysoffian@gmail.com>]

When git am is called w/o arguments, w/o a patch on stdin and the user hits
ctrl-c, it leaves behind a partially populated $dotest directory. After this
commit, it emits usage when called w/o arguments and w/o a patch on stdin.

Also ensure that $dotest is cleaned up if user manages to interupt mailsplit
while it is processing input, but not if mailsplit exits non-zero due to
error.

Noticed by Sverre Rabbelier

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
---
Change from v1: don't remove $dotest if mailsplit exits non-zero

 git-am.sh |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/git-am.sh b/git-am.sh
index b1c05c9..65285a0 100755
--- a/git-am.sh
+++ b/git-am.sh
@@ -254,10 +254,13 @@ else
 		done
 		shift
 	fi
-	git mailsplit -d"$prec" -o"$dotest" -b -- "$@" > "$dotest/last" ||  {
-		rm -fr "$dotest"
+	test $# = 0 && test -t 0 && usage
+	trap 'rm -fr "$dotest"' 0
+	git mailsplit -d"$prec" -o"$dotest" -b -- "$@" > "$dotest/last" || {
+		trap - 0
 		exit 1
 	}
+	trap - 0
 
 	# -s, -u, -k, --whitespace, -3, -C and -p flags are kept
 	# for the resuming session after a patch failure.
-- 
1.6.1.224.gb56c