SECCOMP-BPF: Refactor the BPF sandbox API to use fewer "static" fields and methods.

sandbox/linux/seccomp-bpf/util.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 97 matching lines @@
     return false;
   }
   va_start(ap, len);
   for (int *fd, i = 0; (fd = va_arg(ap, int *)) != NULL; ++i) {
     *fd = (reinterpret_cast<int *>(CMSG_DATA(cmsg)))[i];
   }
   va_end(ap);
   return true;
 }
 
-void Util::CloseAllBut(int fd, ...) {
-  int proc_fd;
+void Util::CloseAllBut(int proc_fd, int fd, ...) {
   int fdir;
-  if ((proc_fd = Sandbox::proc_fd()) < 0 ||
+  if (proc_fd < 0) {
+    proc_fd = open("/proc/", O_RDONLY|O_DIRECTORY);

[jln (very slow on Chromium), 2013/02/20 01:35:49]

It really scares me to do that. We absolutely don't want to keep an open fd to
/proc.

It looks like this whole function could be deleted anyways and is not used by
demo.cc  ?

If you really want to do that, please use a ScopedFD to make sure it gets closed
before we return.

+  }
+  if (proc_fd < 0 ||
       (fdir = openat(proc_fd, "self/fd", O_RDONLY|O_DIRECTORY)) < 0) {
     SANDBOX_DIE("Cannot access \"/proc/self/fd\"");
   }
   int dev_null = open("/dev/null", O_RDWR);
   DIR *dir = fdopendir(fdir);
   struct dirent de, *res;
   while (!readdir_r(dir, &de, &res) && res) {
     if (res->d_name[0] < '0') {
       continue;
     }
@@ skipping 23 matching lines @@
     }
   }
   closedir(dir);
   if (dev_null >= 0) {
     if (HANDLE_EINTR(close(dev_null))) { }
   }
   return;
 }
 
 }  // namespace