pathspec: adjust prefixlen after striping trailing slashnd/pathspec-strip-fix

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

2 files changed, 23 insertions, 3 deletions

diff --git a/pathspec.c b/pathspec.c
index 0be5edbd13..5aea0fbf52 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 5115de7036..cced8c4a5e 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