[PATCH v2] added git-config support for diff.relative setting

[Kelson <kelson@shysecurity.com>]

By default, git-diff shows changes and pathnames relative to the 
repository root. Setting the diff.relative config option to "true" shows 
pathnames relative to the current directory and excludes changes outside 
this directory.

Signed-off-by: Brandon Phillips <kelson@shysecurity.com>
---
  Documentation/diff-config.txt |  6 ++++++
  diff.c                        |  8 ++++++++
  t/t4045-diff-relative.sh      | 21 +++++++++++++++++++++
  3 files changed, 35 insertions(+)

diff --git a/Documentation/diff-config.txt b/Documentation/diff-config.txt
index b001779..10f183f 100644
--- a/Documentation/diff-config.txt
+++ b/Documentation/diff-config.txt
@@ -182,3 +182,9 @@ diff.algorithm::
  	low-occurrence common elements".
  --
  +
+
+diff.relative::
+	By default, linkgit:git-diff[1] shows changes and pathnames
+	relative to the repository root. Setting this variable to
+	`true` shows pathnames relative to the current directory and
+	excludes changes outside this directory.
diff --git a/diff.c b/diff.c
index d1bd534..03697a9 100644
--- a/diff.c
+++ b/diff.c
@@ -223,6 +223,14 @@ int git_diff_ui_config(const char *var, const char 
*value, void *cb)
  		return 0;
  	}

+	if (!strcmp(var, "diff.relative")) {
+		if (git_config_bool(var, value))
+			DIFF_OPT_SET(&default_diff_options, RELATIVE_NAME);
+		else
+			DIFF_OPT_CLR(&default_diff_options, RELATIVE_NAME);
+		return 0;
+	}
+
  	if (git_color_config(var, value, cb) < 0)
  		return -1;

diff --git a/t/t4045-diff-relative.sh b/t/t4045-diff-relative.sh
index 3950f50..8c8fe0b 100755
--- a/t/t4045-diff-relative.sh
+++ b/t/t4045-diff-relative.sh
@@ -29,6 +29,23 @@ test_expect_success "-p $*" "
  "
  }

+check_config() {
+expect=$1; shift
+cat >expected <<EOF
+diff --git a/$expect b/$expect
+new file mode 100644
+index 0000000..25c05ef
+--- /dev/null
++++ b/$expect
+@@ -0,0 +1 @@
++other content
+EOF
+test_expect_success "git-config diff.relative=true in $1" "
+	(cd $1; git -c diff.relative=true diff -p HEAD^ >../actual) &&
+	test_cmp expected actual
+"
+}
+
  check_numstat() {
  expect=$1; shift
  cat >expected <<EOF
@@ -69,5 +86,9 @@ for type in diff numstat stat raw; do
  	check_$type file2 --relative=subdir
  	check_$type dir/file2 --relative=sub
  done
+for type in config; do
+	check_$type file2 subdir/
+	check_$type file2 subdir
+done

  test_done
-- 
1.9.1