apply: compute patch->def_name correctly under -p0

Back when "git apply" was written, we made sure that the user can
skip more than the default number of path components (i.e. 1) by
giving "-p<n>", but the logic for doing so was built around the
notion of "we skip N slashes and stop".  This obviously does not
work well when running under -p0 where we do not want to skip any,
but still want to skip SP/HT that separates the pathnames of
preimage and postimage and want to reject absolute pathnames.

Stop using "stop_at_slash()", and instead introduce a new helper
"skip_tree_prefix()" with similar logic but works correctly even for
the -p0 case.

This is an ancient bug, but has been masked for a long time because
most of the patches are text and have other clues to tell us the
name of the preimage and the postimage.

Noticed by Colin McCabe.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 33 insertions, 21 deletions

diff --git a/t/t4103-apply-binary.sh b/t/t4103-apply-binary.sh
index dbbf56cba9..1b420e3b5f 100755
--- a/t/t4103-apply-binary.sh
+++ b/t/t4103-apply-binary.sh
@@ -8,30 +8,28 @@ test_description='git apply handling binary patches
 '
 . ./test-lib.sh
 
-# setup
-
-cat >file1 <<EOF
-A quick brown fox jumps over the lazy dog.
-A tiny little penguin runs around in circles.
-There is a flag with Linux written on it.
-A slow black-and-white panda just sits there,
-munching on his bamboo.
-EOF
-cat file1 >file2
-cat file1 >file4
-
-test_expect_success 'setup' "
+test_expect_success 'setup' '
+	cat >file1 <<-\EOF &&
+	A quick brown fox jumps over the lazy dog.
+	A tiny little penguin runs around in circles.
+	There is a flag with Linux written on it.
+	A slow black-and-white panda just sits there,
+	munching on his bamboo.
+	EOF
+	cat file1 >file2 &&
+	cat file1 >file4 &&
+
 	git update-index --add --remove file1 file2 file4 &&
-	git commit -m 'Initial Version' 2>/dev/null &&
+	git commit -m "Initial Version" 2>/dev/null &&
 
 	git checkout -b binary &&
-	perl -pe 'y/x/\000/' <file1 >file3 &&
+	perl -pe "y/x/\000/" <file1 >file3 &&
 	cat file3 >file4 &&
 	git add file2 &&
-	perl -pe 'y/\000/v/' <file3 >file1 &&
+	perl -pe "y/\000/v/" <file3 >file1 &&
 	rm -f file2 &&
 	git update-index --add --remove file1 file2 file3 file4 &&
-	git commit -m 'Second Version' &&
+	git commit -m "Second Version" &&
 
 	git diff-tree -p master binary >B.diff &&
 	git diff-tree -p -C master binary >C.diff &&
@@ -42,17 +40,25 @@ test_expect_success 'setup' "
 	git diff-tree -p --full-index master binary >B-index.diff &&
 	git diff-tree -p -C --full-index master binary >C-index.diff &&
 
+	git diff-tree -p --binary --no-prefix master binary -- file3 >B0.diff &&
+
 	git init other-repo &&
-	(cd other-repo &&
-	 git fetch .. master &&
-	 git reset --hard FETCH_HEAD
+	(
+		cd other-repo &&
+		git fetch .. master &&
+		git reset --hard FETCH_HEAD
 	)
-"
+'
 
 test_expect_success 'stat binary diff -- should not fail.' \
 	'git checkout master &&
 	 git apply --stat --summary B.diff'
 
+test_expect_success 'stat binary -p0 diff -- should not fail.' '
+	 git checkout master &&
+	 git apply --stat -p0 B0.diff
+'
+
 test_expect_success 'stat binary diff (copy) -- should not fail.' \
 	'git checkout master &&
 	 git apply --stat --summary C.diff'
@@ -143,4 +149,10 @@ test_expect_success 'apply binary diff (copy).' \
 	 git apply --allow-binary-replacement --index CF.diff &&
 	 test -z "$(git diff --name-status binary)"'
 
+test_expect_success 'apply binary -p0 diff' '
+	do_reset &&
+	git apply -p0 --index B0.diff &&
+	test -z "$(git diff --name-status binary -- file3)"
+'
+
 test_done