config: add include directive

It can be useful to split your ~/.gitconfig across multiple
files. For example, you might have a "main" file which is
used on many machines, but a small set of per-machine
tweaks. Or you may want to make some of your config public
(e.g., clever aliases) while keeping other data back (e.g.,
your name or other identifying information). Or you may want
to include a number of config options in some subset of your
repos without copying and pasting (e.g., you want to
reference them from the .git/config of participating repos).

This patch introduces an include directive for config files.
It looks like:

  [include]
    path = /path/to/file

This is syntactically backwards-compatible with existing git
config parsers (i.e., they will see it as another config
entry and ignore it unless you are looking up include.path).

The implementation provides a "git_config_include" callback
which wraps regular config callbacks. Callers can pass it to
git_config_from_file, and it will transparently follow any
include directives, passing all of the discovered options to
the real callback.

Include directives are turned on automatically for "regular"
git config parsing. This includes calls to git_config, as
well as calls to the "git config" program that do not
specify a single file (e.g., using "-f", "--global", etc).
They are not turned on in other cases, including:

  1. Parsing of other config-like files, like .gitmodules.
     There isn't a real need, and I'd rather be conservative
     and avoid unnecessary incompatibility or confusion.

  2. Reading single files via "git config". This is for two
     reasons:

       a. backwards compatibility with scripts looking at
          config-like files.

       b. inspection of a specific file probably means you
	  care about just what's in that file, not a general
          lookup for "do we have this value anywhere at
	  all". If that is not the case, the caller can
	  always specify "--includes".

  3. Writing files via "git config"; we want to treat
     include.* variables as literal items to be copied (or
     modified), and not expand them. So "git config
     --unset-all foo.bar" would operate _only_ on
     .git/config, not any of its included files (just as it
     also does not operate on ~/.gitconfig).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 134 insertions, 0 deletions

diff --git a/t/t1305-config-include.sh b/t/t1305-config-include.sh
new file mode 100755
index 0000000000..4b1cbaa028
--- /dev/null
+++ b/t/t1305-config-include.sh
@@ -0,0 +1,134 @@
+#!/bin/sh
+
+test_description='test config file include directives'
+. ./test-lib.sh
+
+test_expect_success 'include file by absolute path' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = \"$(pwd)/one\"" >.gitconfig &&
+	echo 1 >expect &&
+	git config test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'include file by relative path' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	echo 1 >expect &&
+	git config test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'chained relative paths' '
+	mkdir subdir &&
+	echo "[test]three = 3" >subdir/three &&
+	echo "[include]path = three" >subdir/two &&
+	echo "[include]path = subdir/two" >.gitconfig &&
+	echo 3 >expect &&
+	git config test.three >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'include options can still be examined' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	echo one >expect &&
+	git config include.path >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'listing includes option and expansion' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	cat >expect <<-\EOF &&
+	include.path=one
+	test.one=1
+	EOF
+	git config --list >actual.full &&
+	grep -v ^core actual.full >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'single file lookup does not expand includes by default' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	test_must_fail git config -f .gitconfig test.one &&
+	test_must_fail git config --global test.one &&
+	echo 1 >expect &&
+	git config --includes -f .gitconfig test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'single file list does not expand includes by default' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	echo "include.path=one" >expect &&
+	git config -f .gitconfig --list >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'writing config file does not expand includes' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	git config test.two 2 &&
+	echo 2 >expect &&
+	git config --no-includes test.two >actual &&
+	test_cmp expect actual &&
+	test_must_fail git config --no-includes test.one
+'
+
+test_expect_success 'config modification does not affect includes' '
+	echo "[test]one = 1" >one &&
+	echo "[include]path = one" >.gitconfig &&
+	git config test.one 2 &&
+	echo 1 >expect &&
+	git config -f one test.one >actual &&
+	test_cmp expect actual &&
+	cat >expect <<-\EOF &&
+	1
+	2
+	EOF
+	git config --get-all test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'missing include files are ignored' '
+	cat >.gitconfig <<-\EOF &&
+	[include]path = foo
+	[test]value = yes
+	EOF
+	echo yes >expect &&
+	git config test.value >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'absolute includes from command line work' '
+	echo "[test]one = 1" >one &&
+	echo 1 >expect &&
+	git -c include.path="$PWD/one" config test.one >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'relative includes from command line fail' '
+	echo "[test]one = 1" >one &&
+	test_must_fail git -c include.path=one config test.one
+'
+
+test_expect_success 'include cycles are detected' '
+	cat >.gitconfig <<-\EOF &&
+	[test]value = gitconfig
+	[include]path = cycle
+	EOF
+	cat >cycle <<-\EOF &&
+	[test]value = cycle
+	[include]path = .gitconfig
+	EOF
+	cat >expect <<-\EOF &&
+	gitconfig
+	cycle
+	EOF
+	test_must_fail git config --get-all test.value 2>stderr &&
+	grep "exceeded maximum include depth" stderr
+'
+
+test_done