sys_info_linux: positive return value of MaxSharedMemorySize for 32-bit build on 64-bit host.

base/sys_info_linux.cc

 // Copyright (c) 2011 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/sys_info.h"
 
 #include <limits>
 
 #include "base/files/file_util.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/sys_info_internal.h"
 
 namespace {
 
 int64 AmountOfMemory(int pages_name) {
   long pages = sysconf(pages_name);
   long page_size = sysconf(_SC_PAGESIZE);
   if (pages == -1 || page_size == -1) {
     NOTREACHED();
     return 0;
   }
   return static_cast<int64>(pages) * page_size;
 }
 
 int64 AmountOfPhysicalMemory() {
   return AmountOfMemory(_SC_PHYS_PAGES);
 }
 
-size_t MaxSharedMemorySize() {
+uint64 MaxSharedMemorySize() {
   std::string contents;
   base::ReadFileToString(base::FilePath("/proc/sys/kernel/shmmax"), &contents);
   DCHECK(!contents.empty());
   if (!contents.empty() && contents[contents.length() - 1] == '\n') {
     contents.erase(contents.length() - 1);
   }
 
   uint64 limit;
   if (!base::StringToUint64(contents, &limit)) {
     limit = 0;
   }
-  if (limit > std::numeric_limits<size_t>::max()) {
-    limit = 0;
-  }
   DCHECK_GT(limit, 0u);
-  return static_cast<size_t>(limit);
+  return limit;
 }
 
 base::LazyInstance<
     base::internal::LazySysInfoValue<int64, AmountOfPhysicalMemory> >::Leaky
     g_lazy_physical_memory = LAZY_INSTANCE_INITIALIZER;
 base::LazyInstance<
-    base::internal::LazySysInfoValue<size_t, MaxSharedMemorySize> >::Leaky
+    base::internal::LazySysInfoValue<uint64, MaxSharedMemorySize> >::Leaky
     g_lazy_max_shared_memory = LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
 namespace base {
 
 // static
 int64 SysInfo::AmountOfAvailablePhysicalMemory() {
   return AmountOfMemory(_SC_AVPHYS_PAGES);
 }
 
 // static
 int64 SysInfo::AmountOfPhysicalMemory() {
   return g_lazy_physical_memory.Get().value();
 }
 
 // static
-size_t SysInfo::MaxSharedMemorySize() {
+uint64 SysInfo::MaxSharedMemorySize() {
   return g_lazy_max_shared_memory.Get().value();
 }
 
 // static
 std::string SysInfo::CPUModelName() {
 #if defined(OS_CHROMEOS) && defined(ARCH_CPU_ARMEL)
   const char kCpuModelPrefix[] = "Hardware";
 #else
   const char kCpuModelPrefix[] = "model name";
 #endif
   std::string contents;
   ReadFileToString(FilePath("/proc/cpuinfo"), &contents);
   DCHECK(!contents.empty());
   if (!contents.empty()) {
     std::istringstream iss(contents);
     std::string line;
     while (std::getline(iss, line)) {
       if (line.compare(0, strlen(kCpuModelPrefix), kCpuModelPrefix) == 0) {
         size_t pos = line.find(": ");
         return line.substr(pos + 2);
       }
     }
   }
   return std::string();
 }
 
 }  // namespace base