[PATCH] attr: allow pattern escape using backslashes

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Patterns in .gitattributes are separated by whitespaces, which makes
it impossible to specify exact spaces in the pattern. '?' can be used
as a workaround, but it matches other characters too. This patch makes
a space following a backslash part of the pattern, not a pattern
separator.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 A similar patch was posted twice (during freeze time iirc). I think
 this is a good change, so I will keep reposting until someone turns
 it down.

 We could use wildmatch for parsing here, which would support patterns
 like "Hello[ ]world". But that's not going to happen until wildmatch
 graduates and somebody brings it up again.

 Documentation/gitattributes.txt | 6 +++---
 attr.c                          | 8 +++++++-
 t/t0003-attributes.sh           | 5 +++++
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index 2698f63..113b1f8 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -20,9 +20,9 @@ Each line in `gitattributes` file is of form:
 
 	pattern	attr1 attr2 ...
 
-That is, a pattern followed by an attributes list,
-separated by whitespaces.  When the pattern matches the
-path in question, the attributes listed on the line are given to
+That is, a pattern followed by an attributes list, separated by
+whitespaces that are not quoted by a backslash. When the pattern matches
+the path in question, the attributes listed on the line are given to
 the path.
 
 Each attribute can be in one of these states for a given path:
diff --git a/attr.c b/attr.c
index 097ae87..776f34e 100644
--- a/attr.c
+++ b/attr.c
@@ -209,7 +209,13 @@ static struct match_attr *parse_attr_line(const char *line, const char *src,
 	if (!*cp || *cp == '#')
 		return NULL;
 	name = cp;
-	namelen = strcspn(name, blank);
+	namelen = 0;
+	while (name[namelen] != '\0' && !strchr(blank, name[namelen])) {
+		if (name[namelen] == '\\' && name[namelen + 1] != '\0')
+			namelen += 2;
+		else
+			namelen++;
+	}
 	if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
 	    !prefixcmp(name, ATTRIBUTE_MACRO_PREFIX)) {
 		if (!macro_ok) {
diff --git a/t/t0003-attributes.sh b/t/t0003-attributes.sh
index 807b8b8..6a5d8ab 100755
--- a/t/t0003-attributes.sh
+++ b/t/t0003-attributes.sh
@@ -24,6 +24,7 @@ test_expect_success 'setup' '
 		echo "offon -test test"
 		echo "no notest"
 		echo "A/e/F test=A/e/F"
+		echo "A\\ b test=space"
 	) >.gitattributes &&
 	(
 		echo "g test=a/g" &&
@@ -196,6 +197,10 @@ test_expect_success 'root subdir attribute test' '
 	attr_check subdir/a/i unspecified
 '
 
+test_expect_success 'quoting in pattern' '
+	attr_check "A b" space
+'
+
 test_expect_success 'negative patterns' '
 	echo "!f test=bar" >.gitattributes &&
 	test_must_fail git check-attr test -- f
-- 
1.8.0.rc2.23.g1fb49df