[PATCH] pathspec: die on empty strings as pathspec

[Emily Xie <emilyxxie@xxxxxxxxx>]

An empty string as a pathspec element matches all paths.  A buggy
script, however, could accidentally assign an empty string to a
variable that then gets passed to a Git command invocation, e.g.:

  path=... compute a path to be removed in $path ...
        git rm -r "$path"

which would unintentionally remove all paths in the current
directory.

The fix for this issue comprises of two steps. Step 1, which warns
that empty strings as pathspecs will become invalid, has already
been implemented in commit d426430 ("pathspec: warn on empty strings
as pathspec", 2016-06-22).

This patch is step 2. It removes the warning and throws an error
instead.

Signed-off-by: Emily Xie <emilyxxie@xxxxxxxxx>
Reported-by: David Turner <novalis@xxxxxxxxxxx>
---
 pathspec.c     | 10 ++++------
 t/t3600-rm.sh  |  5 ++---
 t/t3700-add.sh |  5 ++---
 3 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/pathspec.c b/pathspec.c
index 50f76ff..65e18b1 100644
--- a/pathspec.c
+++ b/pathspec.c
@@ -605,7 +605,7 @@ void parse_pathspec(struct pathspec *pathspec,
 {
 	struct pathspec_item *item;
 	const char *entry = argv ? *argv : NULL;
-	int i, n, prefixlen, warn_empty_string, nr_exclude = 0;
+	int i, n, prefixlen, nr_exclude = 0;
 
 	memset(pathspec, 0, sizeof(*pathspec));
 
@@ -638,12 +638,10 @@ void parse_pathspec(struct pathspec *pathspec,
 	}
 
 	n = 0;
-	warn_empty_string = 1;
 	while (argv[n]) {
-		if (*argv[n] == '\0' && warn_empty_string) {
-			warning(_("empty strings as pathspecs will be made invalid in upcoming releases. "
-				  "please use . instead if you meant to match all paths"));
-			warn_empty_string = 0;
+		if (*argv[n] == '\0') {
+			die("empty string is not a valid pathspec. "
+				  "please use . instead if you meant to match all paths");
 		}
 		n++;
 	}
diff --git a/t/t3600-rm.sh b/t/t3600-rm.sh
index 5f9913b..c787eac 100755
--- a/t/t3600-rm.sh
+++ b/t/t3600-rm.sh
@@ -858,9 +858,8 @@ test_expect_success 'rm files with two different errors' '
 	test_i18ncmp expect actual
 '
 
-test_expect_success 'rm empty string should invoke warning' '
-	git rm -rf "" 2>output &&
-	test_i18ngrep "warning: empty strings" output
+test_expect_success 'rm empty string should fail' '
+	test_must_fail git rm -rf ""
 '
 
 test_done
diff --git a/t/t3700-add.sh b/t/t3700-add.sh
index f3a4b4a..40a0d2b 100755
--- a/t/t3700-add.sh
+++ b/t/t3700-add.sh
@@ -331,9 +331,8 @@ test_expect_success 'git add --dry-run --ignore-missing of non-existing file out
 	test_i18ncmp expect.err actual.err
 '
 
-test_expect_success 'git add empty string should invoke warning' '
-	git add "" 2>output &&
-	test_i18ngrep "warning: empty strings" output
+test_expect_success 'git add empty string should fail' '
+	test_must_fail git add ""
 '
 
 test_expect_success 'git add --chmod=[+-]x stages correctly' '
-- 
2.8.4