fetch: support fetching from a shallow repository

This patch just put together pieces from the 8 steps patch. We stop at
step 7 and reject refs that require new shallow commits.

Note that, by rejecting refs that require new shallow commits, we
leave dangling objects in the repo, which become "object islands" by
the next "git fetch" of the same source.

If the first fetch our "ours" set is zero and we do practically
nothing at step 7, "ours" is full at the next fetch and we may need to
walk through commits for reachability test. Room for improvement.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 128 insertions, 0 deletions

diff --git a/t/t5537-fetch-shallow.sh b/t/t5537-fetch-shallow.sh
new file mode 100755
index 0000000000..d2110527ef
--- /dev/null
+++ b/t/t5537-fetch-shallow.sh
@@ -0,0 +1,128 @@
+#!/bin/sh
+
+test_description='fetch/clone from a shallow clone'
+
+. ./test-lib.sh
+
+commit() {
+	echo "$1" >tracked &&
+	git add tracked &&
+	git commit -m "$1"
+}
+
+test_expect_success 'setup' '
+	commit 1 &&
+	commit 2 &&
+	commit 3 &&
+	commit 4 &&
+	git config --global transfer.fsckObjects true
+'
+
+test_expect_success 'setup shallow clone' '
+	git clone --no-local --depth=2 .git shallow &&
+	git --git-dir=shallow/.git log --format=%s >actual &&
+	cat <<EOF >expect &&
+4
+3
+EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'clone from shallow clone' '
+	git clone --no-local shallow shallow2 &&
+	(
+	cd shallow2 &&
+	git fsck &&
+	git log --format=%s >actual &&
+	cat <<EOF >expect &&
+4
+3
+EOF
+	test_cmp expect actual
+	)
+'
+
+test_expect_success 'fetch from shallow clone' '
+	(
+	cd shallow &&
+	commit 5
+	) &&
+	(
+	cd shallow2 &&
+	git fetch &&
+	git fsck &&
+	git log --format=%s origin/master >actual &&
+	cat <<EOF >expect &&
+5
+4
+3
+EOF
+	test_cmp expect actual
+	)
+'
+
+test_expect_success 'fetch --depth from shallow clone' '
+	(
+	cd shallow &&
+	commit 6
+	) &&
+	(
+	cd shallow2 &&
+	git fetch --depth=2 &&
+	git fsck &&
+	git log --format=%s origin/master >actual &&
+	cat <<EOF >expect &&
+6
+5
+EOF
+	test_cmp expect actual
+	)
+'
+
+test_expect_success 'fetch something upstream has but hidden by clients shallow boundaries' '
+	# the blob "1" is available in .git but hidden by the
+	# shallow2/.git/shallow and it should be resent
+	! git --git-dir=shallow2/.git cat-file blob `echo 1|git hash-object --stdin` >/dev/null &&
+	echo 1 >1.t &&
+	git add 1.t &&
+	git commit -m add-1-back &&
+	(
+	cd shallow2 &&
+	git fetch ../.git +refs/heads/master:refs/remotes/top/master &&
+	git fsck &&
+	git log --format=%s top/master >actual &&
+	cat <<EOF >expect &&
+add-1-back
+4
+3
+EOF
+	test_cmp expect actual
+	) &&
+	git --git-dir=shallow2/.git cat-file blob `echo 1|git hash-object --stdin` >/dev/null
+
+'
+
+test_expect_success 'fetch that requires changes in .git/shallow is filtered' '
+	(
+	cd shallow &&
+	git checkout --orphan no-shallow &&
+	commit no-shallow
+	) &&
+	git init notshallow &&
+	(
+	cd notshallow &&
+	git fetch ../shallow/.git refs/heads/*:refs/remotes/shallow/*&&
+	git for-each-ref --format="%(refname)" >actual.refs &&
+	cat <<EOF >expect.refs &&
+refs/remotes/shallow/no-shallow
+EOF
+	test_cmp expect.refs actual.refs &&
+	git log --format=%s shallow/no-shallow >actual &&
+	cat <<EOF >expect &&
+no-shallow
+EOF
+	test_cmp expect actual
+	)
+'
+
+test_done