AsanCoverage: make the filenames of zygote/gpu coverage files more unique.

content/zygote/zygote_main_linux.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 "content/zygote/zygote_main.h"
 
 #include <dlfcn.h>
 #include <fcntl.h>
 #include <pthread.h>
 #include <string.h>
@@ skipping 478 matching lines @@
 bool ZygoteMain(const MainFunctionParams& params,
                 ScopedVector<ZygoteForkDelegate> fork_delegates) {
   g_am_zygote_or_renderer = true;
   sandbox::InitLibcUrandomOverrides();
 
   base::Closure *post_fork_parent_callback = NULL;
 
   LinuxSandbox* linux_sandbox = LinuxSandbox::GetInstance();
 
 #if defined(ADDRESS_SANITIZER)
-  base::ScopedFD sancov_file_fd(__sanitizer_maybe_open_cov_file("zygote"));
+  std::stringstream ss;

[jln (very slow on Chromium), 2014/06/03 21:43:40]

please do:

const std::string sancov_file_name = "zygote." +
base::Uint64ToString(base::RandUint64());

instead.

[earthdok, 2014/06/03 21:49:27]

Done.

+  ss << "zygote." << base::RandUint64();
+  std::string sancov_file_name = ss.str();
+  base::ScopedFD sancov_file_fd(
+      __sanitizer_maybe_open_cov_file(sancov_file_name.c_str()));
   int sancov_socket_fds[2] = {-1, -1};
   CreateSanitizerCoverageSocketPair(sancov_socket_fds);
   linux_sandbox->sanitizer_args()->coverage_sandboxed = 1;
   linux_sandbox->sanitizer_args()->coverage_fd = sancov_socket_fds[1];
   linux_sandbox->sanitizer_args()->coverage_max_block_size =
       kSanitizerMaxMessageLength;
   // Zygote termination will block until the helper process exits, which will
   // not happen until the write end of the socket is closed everywhere. Make
   // sure the init process does not hold on to it.
   base::Closure close_sancov_socket_fds =
@@ skipping 49 matching lines @@
   bool setuid_sandbox_engaged = sandbox_flags & kSandboxLinuxSUID;
   CHECK_EQ(must_enable_setuid_sandbox, setuid_sandbox_engaged);
 
   Zygote zygote(sandbox_flags, fork_delegates.Pass(), extra_children,
                 extra_fds);
   // This function call can return multiple times, once per fork().
   return zygote.ProcessRequests();
 }
 
 }  // namespace content