[PATCH] Improve function dir.c:trim_trailing_spaces()

[Pasha Bolokhov <pasha.bolokhov@gmail.com>]

Move backwards from the end of the string (more efficient for
lines which do not have trailing spaces or have just a couple).
Slightly more rare occurrences of 'text  \    ' with a backslash
in between spaces are handled correctly.
Namely, the code in 8ba87adad6 does not reset 'last_space' when
a backslash is encountered and the above line stays intact as
a result
---
How about trailing tabs?

 dir.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/dir.c b/dir.c
index eb6f581..3315eea 100644
--- a/dir.c
+++ b/dir.c
@@ -508,21 +508,18 @@ void clear_exclude_list(struct exclude_list *el)
 
 static void trim_trailing_spaces(char *buf)
 {
-	int i, last_space = -1, nr_spaces, len = strlen(buf);
-	for (i = 0; i < len; i++)
-		if (buf[i] == '\\')
-			i++;
-		else if (buf[i] == ' ') {
-			if (last_space == -1) {
-				last_space = i;
-				nr_spaces = 1;
-			} else
-				nr_spaces++;
-		} else
-			last_space = -1;
-
-	if (last_space != -1 && last_space + nr_spaces == len)
+	int i, last_space, bslash = 0, len = strlen(buf);
+
+	if (len == 0 || buf[len - 1] != ' ')
+		return;
+	for (i = len - 2; i >= 0 && buf[i] == ' '; i--) ;
+	last_space = i + 1;
+	for ( ; i >=0 && buf[i] == '\\'; i--) bslash ^= 1;
+
+	if (!bslash)
 		buf[last_space] = '\0';
+	else if (bslash && last_space < len - 1)
+		buf[last_space + 1] = '\0';
 }
 
 int add_excludes_from_file_to_list(const char *fname,
-- 
1.9.1