Linux: Return a failure in ReadProcStats() if the stat file is empty.

base/process_util_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 "base/process_util.h"
 
 #include <dirent.h>
 #include <malloc.h>
 #include <sys/time.h>
 #include <sys/types.h>
@@ skipping 30 matching lines @@
   VM_COMM           = 1,   // Filename of executable, without parentheses.
   VM_STATE          = 2,   // Letter indicating the state of the process.
   VM_PPID           = 3,   // PID of the parent.
   VM_PGRP           = 4,   // Process group id.
   VM_UTIME          = 13,  // Time scheduled in user mode in clock ticks.
   VM_STIME          = 14,  // Time scheduled in kernel mode in clock ticks.
   VM_VSIZE          = 22,  // Virtual memory size in bytes.
   VM_RSS            = 23,  // Resident Set Size in pages.
 };
 
-// Reads /proc/<pid>/stat into |buffer|. Returns true if successful.
+// Reads /proc/<pid>/stat into |buffer|. Returns true if the file can be read
+// and is non-empty.
 bool ReadProcStats(pid_t pid, std::string* buffer) {
   buffer->clear();
   // Synchronously reading files in /proc is safe.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
 
   FilePath stat_file = GetProcPidDir(pid).Append(kStatFile);
   if (!file_util::ReadFileToString(stat_file, buffer)) {
     DLOG(WARNING) << "Failed to get process stats.";
     return false;
   }
-  return true;
+  return !buffer->empty();
 }
 
 // Takes |stats_data| and populates |proc_stats| with the values split by
 // spaces. Taking into account the 2nd field may, in itself, contain spaces.
 // Returns true if successful.
 bool ParseProcStats(const std::string& stats_data,
                     std::vector<std::string>* proc_stats) {
   // The stat file is formatted as:
   // pid (process name) data1 data2 .... dataN
   // Look for the closing paren by scanning backwards, to avoid being fooled by
@@ skipping 745 matching lines @@
     int score_len = static_cast<int>(score_str.length());
     return (score_len == file_util::WriteFile(oom_file,
                                               score_str.c_str(),
                                               score_len));
   }
 
   return false;
 }
 
 }  // namespace base