[PATCH] pathspec: prevent empty strings as pathspecs

[Emily Xie <emilyxxie@gmail.com>]

For any command that takes a pathspec, passing an empty string will
execute the command on all files in the current directory. This
results in unexpected behavior. For example, git add "" adds all
files to staging, while git rm -rf "" recursively removes all files
from the working tree and index. This patch prevents such cases by
throwing an error message whenever an empty string is detected as a
pathspec.

Signed-off-by: Emily Xie <emilyxxie@gmail.com>
Reported-by: David Turner <novalis@novalis.org>
Mentored-by: Michail Denchev <mdenchev@gmail.com>
Thanks-to: Sarah Sharp <sarah@thesharps.us> and James Sharp <jamey@minilop.net>
---
 pathspec.c     | 6 +++++-
 t/t3600-rm.sh  | 4 ++++
 t/t3700-add.sh | 4 ++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/pathspec.c b/pathspec.c
index c9e9b6c..11901a2 100644
--- a/pathspec.c
+++ b/pathspec.c
@@ -402,8 +402,12 @@ void parse_pathspec(struct pathspec *pathspec,
 	}
 
 	n = 0;
-	while (argv[n])
+	while (argv[n]) {
+		if (*argv[n] == '\0') {
+			die("Empty string is not a valid pathspec.");
+		}
 		n++;
+	}
 
 	pathspec->nr = n;
 	ALLOC_ARRAY(pathspec->items, n);
diff --git a/t/t3600-rm.sh b/t/t3600-rm.sh
index d046d98..1d7dc79 100755
--- a/t/t3600-rm.sh
+++ b/t/t3600-rm.sh
@@ -791,6 +791,10 @@ test_expect_success 'setup for testing rm messages' '
 	git add bar.txt foo.txt
 '
 
+test_expect_success 'rm files with empty string pathspec' '
+  test_must_fail git rm ""
+'
+
 test_expect_success 'rm files with different staged content' '
 	cat >expect <<-\EOF &&
 	error: the following files have staged content different from both the
diff --git a/t/t3700-add.sh b/t/t3700-add.sh
index f14a665..49cb080 100755
--- a/t/t3700-add.sh
+++ b/t/t3700-add.sh
@@ -207,6 +207,10 @@ test_expect_success POSIXPERM,SANITY 'git add should fail atomically upon an unr
 	! ( git ls-files foo1 | grep foo1 )
 '
 
+test_expect_success 'git add empty string as pathspec must fail' '
+  test_must_fail git add ""
+'
+
 rm -f foo2
 
 test_expect_success POSIXPERM,SANITY 'git add --ignore-errors' '
-- 
2.8.4