Fixed ngx_open_cached_file() error handling.

If of.err is 0, it means that there was a memory allocation error
and no further logging and/or processing is needed.  The of.failed
string can be only accessed if of.err is not 0.

src/http/modules/ngx_http_index_module.c

@@ -217,13 +217,13 @@ ngx_http_index_handler(ngx_http_request_t *r)
         if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool)
             != NGX_OK)
         {
-            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, of.err,
-                           "%s \"%s\" failed", of.failed, path.data);
-
             if (of.err == 0) {
                 return NGX_HTTP_INTERNAL_SERVER_ERROR;
             }
 
+            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, of.err,
+                           "%s \"%s\" failed", of.failed, path.data);
+
 #if (NGX_HAVE_OPENAT)
             if (of.err == NGX_EMLINK
                 || of.err == NGX_ELOOP)

src/http/modules/ngx_http_log_module.c

@@ -552,6 +552,11 @@ ngx_http_log_script_write(ngx_http_request_t *r, ngx_http_log_script_t *script,
     if (ngx_open_cached_file(llcf->open_file_cache, &log, &of, r->pool)
         != NGX_OK)
     {
+        if (of.err == 0) {
+            /* simulate successful logging */
+            return len;
+        }
+
         ngx_log_error(NGX_LOG_CRIT, r->connection->log, ngx_errno,
                       "%s \"%s\" failed", of.failed, log.data);
         /* simulate successful logging */

src/http/ngx_http_core_module.c

@@ -1314,6 +1314,11 @@ ngx_http_core_try_files_phase(ngx_http_request_t *r,
         if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool)
             != NGX_OK)
         {
+            if (of.err == 0) {
+                ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
+                return NGX_OK;
+            }
+
             if (of.err != NGX_ENOENT
                 && of.err != NGX_ENOTDIR
                 && of.err != NGX_ENAMETOOLONG)

src/http/ngx_http_script.c

@@ -1513,6 +1513,12 @@ ngx_http_script_file_code(ngx_http_script_engine_t *e)
     if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool)
         != NGX_OK)
     {
+        if (of.err == 0) {
+            e->ip = ngx_http_script_exit;
+            e->status = NGX_HTTP_INTERNAL_SERVER_ERROR;
+            return;
+        }
+
         if (of.err != NGX_ENOENT
             && of.err != NGX_ENOTDIR
             && of.err != NGX_ENAMETOOLONG)

src/stream/ngx_stream_log_module.c

@@ -443,6 +443,11 @@ ngx_stream_log_script_write(ngx_stream_session_t *s,
                              s->connection->pool)
         != NGX_OK)
     {
+        if (of.err == 0) {
+            /* simulate successful logging */
+            return len;
+        }
+
         ngx_log_error(NGX_LOG_CRIT, s->connection->log, ngx_errno,
                       "%s \"%s\" failed", of.failed, log.data);
         /* simulate successful logging */