Merge branch 'jk/diffcore-rename-duplicate' into maint

A corrupt input to "git diff -M" can cause us to segfault.

* jk/diffcore-rename-duplicate:
  diffcore-rename: avoid processing duplicate destinations
  diffcore-rename: split locate_rename_dst into two functions

1 files changed, 79 insertions, 0 deletions

diff --git a/t/t4058-diff-duplicates.sh b/t/t4058-diff-duplicates.sh
new file mode 100755
index 0000000000..0a23242cb6
--- /dev/null
+++ b/t/t4058-diff-duplicates.sh
@@ -0,0 +1,79 @@
+#!/bin/sh
+
+test_description='test tree diff when trees have duplicate entries'
+. ./test-lib.sh
+
+# make_tree_entry <mode> <mode> <sha1>
+#
+# We have to rely on perl here because not all printfs understand
+# hex escapes (only octal), and xxd is not portable.
+make_tree_entry () {
+	printf '%s %s\0' "$1" "$2" &&
+	perl -e 'print chr(hex($_)) for ($ARGV[0] =~ /../g)' "$3"
+}
+
+# Like git-mktree, but without all of the pesky sanity checking.
+# Arguments come in groups of three, each group specifying a single
+# tree entry (see make_tree_entry above).
+make_tree () {
+	while test $# -gt 2; do
+		make_tree_entry "$1" "$2" "$3"
+		shift; shift; shift
+	done |
+	git hash-object -w -t tree --stdin
+}
+
+# this is kind of a convoluted setup, but matches
+# a real-world case. Each tree contains four entries
+# for the given path, one with one sha1, and three with
+# the other. The first tree has them split across
+# two subtrees (which are themselves duplicate entries in
+# the root tree), and the second has them all in a single subtree.
+test_expect_success 'create trees with duplicate entries' '
+	blob_one=$(echo one | git hash-object -w --stdin) &&
+	blob_two=$(echo two | git hash-object -w --stdin) &&
+	inner_one_a=$(make_tree \
+		100644 inner $blob_one
+	) &&
+	inner_one_b=$(make_tree \
+		100644 inner $blob_two \
+		100644 inner $blob_two \
+		100644 inner $blob_two
+	) &&
+	outer_one=$(make_tree \
+		040000 outer $inner_one_a \
+		040000 outer $inner_one_b
+	) &&
+	inner_two=$(make_tree \
+		100644 inner $blob_one \
+		100644 inner $blob_two \
+		100644 inner $blob_two \
+		100644 inner $blob_two
+	) &&
+	outer_two=$(make_tree \
+		040000 outer $inner_two
+	) &&
+	git tag one $outer_one &&
+	git tag two $outer_two
+'
+
+test_expect_success 'diff-tree between trees' '
+	{
+		printf ":000000 100644 $_z40 $blob_two A\touter/inner\n" &&
+		printf ":000000 100644 $_z40 $blob_two A\touter/inner\n" &&
+		printf ":000000 100644 $_z40 $blob_two A\touter/inner\n" &&
+		printf ":100644 000000 $blob_two $_z40 D\touter/inner\n" &&
+		printf ":100644 000000 $blob_two $_z40 D\touter/inner\n" &&
+		printf ":100644 000000 $blob_two $_z40 D\touter/inner\n"
+	} >expect &&
+	git diff-tree -r --no-abbrev one two >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'diff-tree with renames' '
+	# same expectation as above, since we disable rename detection
+	git diff-tree -M -r --no-abbrev one two >actual &&
+	test_cmp expect actual
+'
+
+test_done