[config] warn if server.upload-dirs has non-existent dirs (fixes #2508)

Warn at startup if any dirs in server.upload-dirs do not exist.
Take server.chroot into account, if set.

From: Glenn Strauss <gstrauss@gluelogic.com>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@3125 152afb58-edef-0310-8abb-c4023f1b3aa9

NEWS

@@ -49,6 +49,7 @@ NEWS
   * [buffer] refactor buffer_path_simplify (fixes #2560)
   * validate return values from strtol, strtoul (fixes #2564)
   * [mod_ssi] Add SSI vars SCRIPT_{URI,URL} and REQUEST_SCHEME (fixes #2721)
+  * [config] warn if server.upload-dirs has non-existent dirs (fixes #2508)
 
 - 1.4.39 - 2016-01-02
   * [core] fix memset_s call (fixes #2698)

src/configfile.c

@@ -1288,6 +1288,31 @@ int config_set_defaults(server *srv) {
 		}
 	}
 
+	if (srv->srvconf.upload_tempdirs->used) {
+		buffer * const b = srv->tmp_buf;
+		size_t len;
+		if (!buffer_string_is_empty(srv->srvconf.changeroot)) {
+			buffer_copy_buffer(b, srv->srvconf.changeroot);
+			buffer_append_slash(b);
+		} else {
+			buffer_reset(b);
+		}
+		len = buffer_string_length(b);
+
+		for (i = 0; i < srv->srvconf.upload_tempdirs->used; ++i) {
+			const data_string * const ds = (data_string *)srv->srvconf.upload_tempdirs->data[i];
+			buffer_string_set_length(b, len); /*(truncate)*/
+			buffer_append_string_buffer(b, ds->value);
+			if (-1 == stat(b->ptr, &st1)) {
+				log_error_write(srv, __FILE__, __LINE__, "sb",
+					"server.upload-dirs doesn't exist:", b);
+			} else if (!S_ISDIR(st1.st_mode)) {
+				log_error_write(srv, __FILE__, __LINE__, "sb",
+					"server.upload-dirs isn't a directory:", b);
+			}
+		}
+	}
+
 	if (buffer_string_is_empty(s->document_root)) {
 		log_error_write(srv, __FILE__, __LINE__, "s",
 				"a default document-root has to be set");