ignore: handle escaped trailing whitespace

The gitignore's pattern format specifies that "Trailing spaces
are ignored unless they are quoted with backslash ("\")". We do
not honor this currently and will treat a pattern "foo\ " as if
it was "foo\" only and a pattern "foo\ \ " as "foo\ \".

Fix our code to handle those special cases and add tests to avoid
regressions.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/attr_file.c b/src/attr_file.c
index b2c60f204..40262eca6 100644
--- a/src/attr_file.c
+++ b/src/attr_file.c
@@ -560,13 +560,15 @@ void git_attr_path__free(git_attr_path *info)
  */
 
 /*
- * Determine the length of trailing spaces.
+ * Determine the length of trailing spaces. Escaped spaces do not count as
+ * trailing whitespace.
  */
 static size_t trailing_space_length(const char *p, size_t len)
 {
 	size_t n;
 	for (n = len; n; n--) {
-		if (p[n-1] != ' ' && p[n-1] != '\t')
+		if ((p[n-1] != ' ' && p[n-1] != '\t') ||
+		    (n > 1 && p[n-2] == '\\'))
 			break;
 	}
 	return len - n;