[PATCH libXau] Avoid out of boundary read access

[Tobias Stoeckmann]

If the environment variable HOME is empty, XauFileName triggers an
out of boundary read access (name[1]). If HOME consists of a single
character relative path, the output becomes unexpected, because
"HOME=a" leads to "a.Xauthority" instead of "a/.Xauthority". Granted,
a relative HOME path leads to trouble in general, the code should
properly return "a/.Xauthority" nonetheless.

Signed-off-by: Tobias Stoeckmann <tobias at stoeckmann.org>
---
 AuFileName.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/AuFileName.c b/AuFileName.c
index 37c8b62..2946c80 100644
--- a/AuFileName.c
+++ b/AuFileName.c
@@ -85,6 +85,6 @@ XauFileName (void)
 	bsize = size;
     }
     snprintf (buf, bsize, "%s%s", name,
-              slashDotXauthority + (name[1] == '\0' ? 1 : 0));
+              slashDotXauthority + (name[0] == '/' && name[1] == '\0' ? 1 : 0));
     return buf;
 }
-- 
2.14.2