sparse checkout: inhibit empty worktree

The way sparse checkout works, users may empty their worktree
completely, because of non-matching sparse-checkout spec, or empty
spec. I believe this is not desired. This patch makes Git refuse to
produce such worktree.

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

diff --git a/t/t1009-read-tree-sparse-checkout.sh b/t/t1009-read-tree-sparse-checkout.sh
index 2192f5abc7bcf71ce1dc8e5d8351fc745998ede7..62246dbf9546b9ee5ad4dbeb0b34de45a1671ac2 100755 (executable)
--- a/t/t1009-read-tree-sparse-checkout.sh
+++ b/t/t1009-read-tree-sparse-checkout.sh
@@ -55,20 +55,16 @@ test_expect_success 'read-tree --no-sparse-checkout with empty .git/info/sparse-
        test -f sub/added
 '
 
-cat >expected.swt <<EOF
-S init.t
-S sub/added
-EOF
 test_expect_success 'read-tree with empty .git/info/sparse-checkout' '
        git config core.sparsecheckout true &&
        echo > .git/info/sparse-checkout &&
-       git read-tree -m -u HEAD &&
+       test_must_fail git read-tree -m -u HEAD &&
        git ls-files --stage > result &&
        test_cmp expected result &&
        git ls-files -t > result &&
        test_cmp expected.swt result &&
-       test ! -f init.t &&
-       test ! -f sub/added
+       test -f init.t &&
+       test -f sub/added
 '
 
 cat >expected.swt <<EOF

diff --git a/unpack-trees.c b/unpack-trees.c
index 72743b34df0944f94af3280f3071b904bde3bec0..80ae2a0f4f149a130d06d7e8129f1e24a9c23b7f 100644 (file)
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -498,6 +498,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
        }
 
        if (!o->skip_sparse_checkout) {
+               int empty_worktree = 1;
                for (i = 0;i < o->result.cache_nr;i++) {
                        struct cache_entry *ce = o->result.cache[i];
 
@@ -512,8 +513,14 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
                         */
                        if (ce_skip_worktree(ce))
                                ce->ce_flags &= ~(CE_UPDATE | CE_REMOVE);
+                       else
+                               empty_worktree = 0;
 
                }
+               if (o->result.cache_nr && empty_worktree) {
+                       ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
+                       goto done;
+               }
        }
 
        o->src_index = NULL;