Subject: [PATCH] pathspec: adjust prefixlen after striping trailing slash

From: Nguyễn Thái Ngọc Duy <[email-masked]>
Date: Sat, 18 Apr 2015 08:19:06 +0700

A path(spec) from git perspective consists of two parts, the prefix,
and the rest. The prefix covers the part of `pwd` after expanding ".."
components. The split is to support case-insensitive match in a sane
way (see 93d9353, especially the big comment block added in dir.c).

Normally the prefix is found after prefix_path_gently() and that will
be it. Unfortunately the *STRIP_SUBMODULE* flags can strip the
trailing slash (see 2ce53f9 for the reason) and cut into this prefix
part. In the test, the prefix is "submodule/", but the final path is
just "submodule". We need to readjust prefix info when this happens.

The assert() that catches this is turned to die() to make sure it's
always active. prefix_pathspec() is not in any critical path to be a
performance concern because of this change.

93d9353 (parse_pathspec: accept :(icase)path syntax - 2013-07-14)
2ce53f9 (git add: do not add files from a submodule - 2009-01-02)

Noticed-by: djanos_ (via irc)
Helped-by: Dennis Kaarsemaker <[email-masked]>
Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
---
 On Fri, Apr 17, 2015 at 2:27 AM, Jens Lehmann <[email-masked]> wrote:
 > The problem seems to be that "subrepo" is still registered as a
 > submodule in the index. But we should see a proper error message
 > instead of an assert in that case ... CCed Duy who knows much
 > more about pathspec.c than me.

 This deals with the bug in pathspec code. I leave it to you to decide
 how git-add should do when a submodule is registered in index, but
 it's no longer a submodule in worktree. Yeah maybe it should error
 out.

 pathspec.c                    | 18 +++++++++++++++---
 t/t3703-add-magic-pathspec.sh |  8 ++++++++
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/pathspec.c b/pathspec.c
index 9304ee3..aa5e2c7 100644
--- a/pathspec.c
+++ b/pathspec.c
@@ -262,7 +262,6 @@ static unsigned prefix_pathspec(struct pathspec_item *item,
 	} else
 		item->original = elt;
 	item->len = strlen(item->match);
-	item->prefix = prefixlen;
 
 	if ((flags & PATHSPEC_STRIP_SUBMODULE_SLASH_CHEAP) &&
 	    (item->len >= 1 && item->match[item->len - 1] == '/') &&
@@ -292,6 +291,15 @@ static unsigned prefix_pathspec(struct pathspec_item *item,
 				     elt, ce_len, ce->name);
 		}
 
+	/*
+	 * Adjust prefixlen if the above trailing slash stripping cuts
+	 * into the prefix part
+	 */
+	if ((flags & (PATHSPEC_STRIP_SUBMODULE_SLASH_CHEAP |
+		      PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE)) &&
+	    prefixlen > item->len)
+		prefixlen = item->len;
+
 	if (magic & PATHSPEC_LITERAL)
 		item->nowildcard_len = item->len;
 	else {
@@ -299,6 +307,7 @@ static unsigned prefix_pathspec(struct pathspec_item *item,
 		if (item->nowildcard_len < prefixlen)
 			item->nowildcard_len = prefixlen;
 	}
+	item->prefix = prefixlen;
 	item->flags = 0;
 	if (magic & PATHSPEC_GLOB) {
 		/*
@@ -313,8 +322,11 @@ static unsigned prefix_pathspec(struct pathspec_item *item,
 	}
 
 	/* sanity checks, pathspec matchers assume these are sane */
-	assert(item->nowildcard_len <= item->len &&
-	       item->prefix         <= item->len);
+	if (!(item->nowildcard_len <= item->len &&
+	      item->prefix         <= item->len))
+		die("BUG: item->nowildcard_len (%d) or item->prefix (%d)"
+		    " is longer than item->len (%d)",
+		    item->nowildcard_len, item->prefix, item->len);
 	return magic;
 }
 
diff --git a/t/t3703-add-magic-pathspec.sh b/t/t3703-add-magic-pathspec.sh
index 5115de7..cced8c4 100755
--- a/t/t3703-add-magic-pathspec.sh
+++ b/t/t3703-add-magic-pathspec.sh
@@ -55,4 +55,12 @@ test_expect_success COLON_DIR 'a file with the same (short) magic name exists' '
 	git add -n "./:/bar"
 '
 
+test_expect_success 'prefix is updated after trailing slash is stripped' '
+	git init submodule &&
+	( cd submodule && test_commit test ) &&
+	git add submodule &&
+	mv submodule/.git submodule/dotgit &&
+	( cd submodule && git add . )
+'
+
 test_done
-- 
2.3.0.rc1.137.g477eb31