cat-file: introduce the --filters option

The --filters option applies the convert_to_working_tree() filter for
the path when showing the contents of a regular file blob object;
the contents are written out as-is for other types of objects.

This feature comes in handy when a 3rd-party tool wants to work with
the contents of files from past revisions as if they had been checked
out, but without detouring via temporary files.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/t/t8010-cat-file-filters.sh b/t/t8010-cat-file-filters.sh
new file mode 100755
index 0000000..e466634
--- /dev/null
+++ b/t/t8010-cat-file-filters.sh
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+test_description='git cat-file filters support'
+. ./test-lib.sh
+
+test_expect_success 'setup ' '
+	echo "*.txt eol=crlf diff=txt" >.gitattributes &&
+	echo "hello" | append_cr >world.txt &&
+	git add .gitattributes world.txt &&
+	test_tick &&
+	git commit -m "Initial commit"
+'
+
+has_cr () {
+	tr '\015' Q <"$1" | grep Q >/dev/null
+}
+
+test_expect_success 'no filters with `git show`' '
+	git show HEAD:world.txt >actual &&
+	! has_cr actual
+
+'
+
+test_expect_success 'no filters with cat-file' '
+	git cat-file blob HEAD:world.txt >actual &&
+	! has_cr actual
+'
+
+test_expect_success 'cat-file --filters converts to worktree version' '
+	git cat-file --filters HEAD:world.txt >actual &&
+	has_cr actual
+'
+
+test_done