# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1445279282 -10800
# Node ID 1063097b22b6351a70c89cc0bb70d243f32192a4
# Parent  97f102a13f3373ed27d1d0d8f78ac9af8d88a0ff
Fixed handling of empty root.

Previously, a configuration with "root" set to an empty string tried test
a character at clcf->root.data[-1].  Additional test added to make sure
this won't happen.

Reported by Markus Linnala, see
http://mailman.nginx.org/pipermail/nginx-devel/2015-August/007210.html.

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -4489,7 +4489,9 @@ ngx_http_core_root(ngx_conf_t *cf, ngx_c
     clcf->alias = alias ? clcf->name.len : 0;
     clcf->root = value[1];
 
-    if (!alias && clcf->root.data[clcf->root.len - 1] == '/') {
+    if (!alias && clcf->root.len > 0
+        && clcf->root.data[clcf->root.len - 1] == '/')
+    {
         clcf->root.len--;
     }