Linux: Allow IO in ProcessMetrics::GetWorkingSetKBytes()....

base/process_util_linux.cc

 // Copyright (c) 2009 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/process_util.h"
 
 #include <ctype.h>
 #include <dirent.h>
 #include <dlfcn.h>
 #include <errno.h>
@@ skipping 301 matching lines @@
 }
 
 // Private and Shared working set sizes are obtained from /proc/<pid>/smaps.
 // When that's not available, use the values from /proc<pid>/statm as a
 // close approximation.
 // See http://www.pixelbeat.org/scripts/ps_mem.py
 bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
   // Synchronously reading files in /proc is safe.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
 
-  FilePath stat_file =
-      FilePath("/proc").Append(base::IntToString(process_)).Append("smaps");
+  FilePath proc_dir = FilePath("/proc").Append(base::IntToString(process_));
   std::string smaps;
   int private_kb = 0;
   int pss_kb = 0;
   bool have_pss = false;
-  if (file_util::ReadFileToString(stat_file, &smaps) && smaps.length() > 0) {
+  bool ret;
+
+  {
+    FilePath smaps_file = proc_dir.Append("smaps");
+    // Synchronously reading files in /proc is safe.
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    ret = file_util::ReadFileToString(smaps_file, &smaps);
+  }
+  if (ret && smaps.length() > 0) {
     const std::string private_prefix = "Private_";
     const std::string pss_prefix = "Pss";
     StringTokenizer tokenizer(smaps, ":\n");
     StringPiece last_key_name;
     ParsingState state = KEY_NAME;
     while (tokenizer.GetNext()) {
       switch (state) {
         case KEY_NAME:
           last_key_name = tokenizer.token_piece();
           state = KEY_VALUE;
@@ skipping 17 matching lines @@
           break;
       }
     }
   } else {
     // Try statm if smaps is empty because of the SUID sandbox.
     // First we need to get the page size though.
     int page_size_kb = sysconf(_SC_PAGE_SIZE) / 1024;
     if (page_size_kb <= 0)
       return false;
 
-    stat_file =
-        FilePath("/proc").Append(base::IntToString(process_)).Append("statm");
     std::string statm;
-    if (!file_util::ReadFileToString(stat_file, &statm) || statm.length() == 0)
+    {
+      FilePath statm_file = proc_dir.Append("statm");
+      // Synchronously reading files in /proc is safe.
+      base::ThreadRestrictions::ScopedAllowIO allow_io;
+      ret = file_util::ReadFileToString(statm_file, &statm);
+    }
+    if (!ret || statm.length() == 0)
       return false;
 
     std::vector<std::string> statm_vec;
     base::SplitString(statm, ' ', &statm_vec);
     if (statm_vec.size() != 7)
       return false;  // Not the format we expect.
 
     int statm1, statm2;
     base::StringToInt(statm_vec[1], &statm1);
     base::StringToInt(statm_vec[2], &statm2);
@@ skipping 316 matching lines @@
 
   if (!file_util::PathExists(oom_adj))
     return false;
 
   std::string score_str = base::IntToString(score);
   return (static_cast<int>(score_str.length()) ==
           file_util::WriteFile(oom_adj, score_str.c_str(), score_str.length()));
 }
 
 }  // namespace base