am: don't infloop for an empty input file

git-am.sh's check_patch_format function would attempt to preview
the patch to guess its format, but would go into an infinite loop
when the patch file happened to be empty.  The solution: exit the
loop when "read" fails, not when the line var, "$l1" becomes empty.

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-am.sh b/git-am.sh
index 1c13b1399185506dd11750fe7e8c1b989a0f3d0c..f43a75b04bf692b9ff6acaae0f6bbe51369aa399 100755 (executable)
--- a/git-am.sh
+++ b/git-am.sh
@@ -201,7 +201,7 @@ check_patch_format () {
                l1=
                while test -z "$l1"
                do
-                       read l1
+                       read l1 || break
                done
                read l2
                read l3

diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index d7d9ccc1c8c31ef3b2d4763532344d0637a18b5c..03eee07ffb3bcbcac3090eeb3a58e5dcbb66307f 100755 (executable)
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -495,4 +495,14 @@ test_expect_success 'am -q is quiet' '
        ! test -s output.out
 '
 
+test_expect_success 'am empty-file does not infloop' '
+       rm -fr .git/rebase-apply &&
+       git reset --hard &&
+       touch empty-file &&
+       test_tick &&
+       { git am empty-file > actual 2>&1 && false || :; } &&
+       echo Patch format detection failed. >expected &&
+       test_cmp expected actual
+'
+
 test_done