interpret_branch_name: find all possible @-marks

When we parse a string like "foo@{upstream}", we look for
the first "@"-sign, and check to see if it is an upstream
mark. However, since branch names can contain an @, we may
also see "@foo@{upstream}". In this case, we check only the
first @, and ignore the second. As a result, we do not find
the upstream.

We can solve this by iterating through all @-marks in the
string, and seeing if any is a legitimate upstream or
empty-at mark.

Another strategy would be to parse from the right-hand side
of the string. However, that does not work for the
"empty_at" case, which allows "@@{upstream}". We need to
find the left-most one in this case (and we then recurse as
"HEAD@{upstream}").

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sha1_name.c

@@ -1126,6 +1126,7 @@ static int interpret_upstream_mark(const char *name, int namelen,
 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
 {
 	char *at;
+	const char *start;
 	int len = interpret_nth_prior_checkout(name, namelen, buf);
 
 	if (!namelen)
@@ -1140,17 +1141,18 @@ int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
 			return reinterpret(name, namelen, len, buf);
 	}
 
-	at = memchr(name, '@', namelen);
-	if (!at)
-		return -1;
+	for (start = name;
+	     (at = memchr(start, '@', namelen - (start - name)));
+	     start = at + 1) {
 
-	len = interpret_empty_at(name, namelen, at - name, buf);
-	if (len > 0)
-		return reinterpret(name, namelen, len, buf);
+		len = interpret_empty_at(name, namelen, at - name, buf);
+		if (len > 0)
+			return reinterpret(name, namelen, len, buf);
 
-	len = interpret_upstream_mark(name, namelen, at - name, buf);
-	if (len > 0)
-		return len;
+		len = interpret_upstream_mark(name, namelen, at - name, buf);
+		if (len > 0)
+			return len;
+	}
 
 	return -1;
 }

t/t1507-rev-parse-upstream.sh

@@ -17,6 +17,9 @@ test_expect_success 'setup' '
 	 test_commit 4 &&
 	 git branch --track my-side origin/side &&
 	 git branch --track local-master master &&
+	 git branch --track fun@ny origin/side &&
+	 git branch --track @funny origin/side &&
+	 git branch --track funny@ origin/side &&
 	 git remote add -t master master-only .. &&
 	 git fetch master-only &&
 	 git branch bad-upstream &&
@@ -54,6 +57,24 @@ test_expect_success 'my-side@{upstream} resolves to correct full name' '
 	test refs/remotes/origin/side = "$(full_name my-side@{u})"
 '
 
+test_expect_success 'upstream of branch with @ in middle' '
+	full_name fun@ny@{u} >actual &&
+	echo refs/remotes/origin/side >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'upstream of branch with @ at start' '
+	full_name @funny@{u} >actual &&
+	echo refs/remotes/origin/side >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'upstream of branch with @ at end' '
+	full_name funny@@{u} >actual &&
+	echo refs/remotes/origin/side >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'refs/heads/my-side@{upstream} does not resolve to my-side{upstream}' '
 	test_must_fail full_name refs/heads/my-side@{upstream}
 '