Linux: don't try and read shmmax in the sandbox.

base/sys_info_posix.cc

 // Copyright (c) 2008 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 "base/file_util.h"
 #include "base/sys_info.h"
 #include "base/basictypes.h"
 
 #include <errno.h>
 #include <string.h>
 #include <sys/statvfs.h>
 #include <sys/utsname.h>
 #include <unistd.h>
 
 #if defined(OS_MACOSX)
@@ skipping 128 matching lines @@
 int SysInfo::DisplayCount() {
   NOTIMPLEMENTED();
   return 1;
 }
 
 // static
 size_t SysInfo::VMAllocationGranularity() {
   return getpagesize();
 }
 
+#if defined(OS_LINUX)
+// static
+size_t SysInfo::MaxSharedMemorySize() {
+  static size_t limit;
+  static bool limit_valid = false;
+
+  if (!limit_valid) {
+    std::string contents;
+    file_util::ReadFileToString(FilePath("/proc/sys/kernel/shmmax"), &contents);
+    limit = strtoul(contents.c_str(), NULL, 0);
+    limit_valid = true;
+  }
+
+  return limit;
+}
+#endif
+
 }  // namespace base