[PATCH maint-1.7.6] fast-import: don't allow 'ls' of path with empty components

[Jonathan Nieder <jrnieder@gmail.com>]

As the fast-import manual explains:

	The value of <path> must be in canonical form. That is it must
	not:
	. contain an empty directory component (e.g. foo//bar is invalid),
	. end with a directory separator (e.g. foo/ is invalid),
	. start with a directory separator (e.g. /foo is invalid),

Unfortunately the "ls" command accepts these invalid syntaxes and
responds by declaring that the indicated path is missing.  This is too
subtle and causes importers to silently misbehave; better to error out
so the operator knows what's happening.

The C, R, and M commands already error out for such paths.

Based on initial analysis by David Barr.

Reported-by: Andrew Sayers <andrew-git@pileofstuff.org>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
Also against on 8dc6a373d (fast-import: add 'ls' command, 2010-12-02).

 fast-import.c          |    2 ++
 t/t9300-fast-import.sh |   39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/fast-import.c b/fast-import.c
index fff285cd..47f61f3c 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1640,6 +1640,8 @@ static int tree_content_get(
 		n = slash1 - p;
 	else
 		n = strlen(p);
+	if (!n)
+		die("Empty path component found in input");
 
 	if (!root->tree)
 		load_tree(root);
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 6b1ba6c8..2cd0f061 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -1088,6 +1088,45 @@ test_expect_success \
 	INPUT_END'
 
+test_expect_success \
+	'N: reject foo/ syntax in copy source' \
+	'test_must_fail git fast-import <<-INPUT_END
+	commit refs/heads/N5C
+	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+	data <<COMMIT
+	copy with invalid syntax
+	COMMIT
+
+	from refs/heads/branch^0
+	C file2/ file3
+	INPUT_END'
+
+test_expect_success \
+	'N: reject foo/ syntax in rename source' \
+	'test_must_fail git fast-import <<-INPUT_END
+	commit refs/heads/N5D
+	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+	data <<COMMIT
+	rename with invalid syntax
+	COMMIT
+
+	from refs/heads/branch^0
+	R file2/ file3
+	INPUT_END'
+
+test_expect_success \
+	'N: reject foo/ syntax in ls argument' \
+	'test_must_fail git fast-import <<-INPUT_END
+	commit refs/heads/N5E
+	committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+	data <<COMMIT
+	copy with invalid syntax
+	COMMIT
+
+	from refs/heads/branch^0
+	ls "file2/"
+	INPUT_END'
+
 test_expect_success \
 	'N: copy to root by id and modify' \
 	'echo "hello, world" >expect.foo &&
 	 echo hello >expect.bar &&
-- 
1.7.9.2