1 files changed, 201 insertions, 0 deletions
diff --git a/base/process/process_linux.cc b/base/process/process_linux.cc
new file mode 100644
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--- /dev/null
+++ b/base/process/process_linux.cc
@@ -0,0 +1,201 @@
+// 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/process/process.h"
+
+#include <errno.h>
+#include <sys/resource.h>
+
+#include "base/files/file_util.h"
+#include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_split.h"
+#include "base/strings/stringprintf.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_restrictions.h"
+#include "build/build_config.h"
+
+// Not defined on AIX by default.
+#if defined(OS_AIX)
+#define RLIMIT_NICE 20
+#endif
+
+namespace base {
+
+namespace {
+
+const int kForegroundPriority = 0;
+
+#if defined(OS_CHROMEOS)
+// We are more aggressive in our lowering of background process priority
+// for chromeos as we have much more control over other processes running
+// on the machine.
+//
+// TODO(davemoore) Refactor this by adding support for higher levels to set
+// the foregrounding / backgrounding process so we don't have to keep
+// chrome / chromeos specific logic here.
+const int kBackgroundPriority = 19;
+const char kControlPath[] = "/sys/fs/cgroup/cpu%s/cgroup.procs";
+const char kForeground[] = "/chrome_renderers/foreground";
+const char kBackground[] = "/chrome_renderers/background";
+const char kProcPath[] = "/proc/%d/cgroup";
+
+struct CGroups {
+  // Check for cgroups files. ChromeOS supports these by default. It creates
+  // a cgroup mount in /sys/fs/cgroup and then configures two cpu task groups,
+  // one contains at most a single foreground renderer and the other contains
+  // all background renderers. This allows us to limit the impact of background
+  // renderers on foreground ones to a greater level than simple renicing.
+  bool enabled;
+  base::FilePath foreground_file;
+  base::FilePath background_file;
+
+  CGroups() {
+    foreground_file =
+        base::FilePath(base::StringPrintf(kControlPath, kForeground));
+    background_file =
+        base::FilePath(base::StringPrintf(kControlPath, kBackground));
+    base::FileSystemType foreground_type;
+    base::FileSystemType background_type;
+    enabled =
+        base::GetFileSystemType(foreground_file, &foreground_type) &&
+        base::GetFileSystemType(background_file, &background_type) &&
+        foreground_type == FILE_SYSTEM_CGROUP &&
+        background_type == FILE_SYSTEM_CGROUP;
+  }
+
+  static CGroups& Get() {
+    static auto& groups = *new CGroups;
+    return groups;
+  }
+};
+#else
+const int kBackgroundPriority = 5;
+#endif  // defined(OS_CHROMEOS)
+
+bool CanReraisePriority() {
+  // We won't be able to raise the priority if we don't have the right rlimit.
+  // The limit may be adjusted in /etc/security/limits.conf for PAM systems.
+  struct rlimit rlim;
+  return (getrlimit(RLIMIT_NICE, &rlim) == 0) &&
+         (20 - kForegroundPriority) <= static_cast<int>(rlim.rlim_cur);
+}
+
+}  // namespace
+
+// static
+bool Process::CanBackgroundProcesses() {
+#if defined(OS_CHROMEOS)
+  if (CGroups::Get().enabled)
+    return true;
+#endif  // defined(OS_CHROMEOS)
+
+  static const bool can_reraise_priority = CanReraisePriority();
+  return can_reraise_priority;
+}
+
+bool Process::IsProcessBackgrounded() const {
+  DCHECK(IsValid());
+
+#if defined(OS_CHROMEOS)
+  if (CGroups::Get().enabled) {
+    // Used to allow reading the process priority from proc on thread launch.
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    std::string proc;
+    if (base::ReadFileToString(
+            base::FilePath(StringPrintf(kProcPath, process_)), &proc)) {
+      return IsProcessBackgroundedCGroup(proc);
+    }
+    return false;
+  }
+#endif  // defined(OS_CHROMEOS)
+
+  return GetPriority() == kBackgroundPriority;
+}
+
+bool Process::SetProcessBackgrounded(bool background) {
+  DCHECK(IsValid());
+
+#if defined(OS_CHROMEOS)
+  if (CGroups::Get().enabled) {
+    std::string pid = IntToString(process_);
+    const base::FilePath file = background ? CGroups::Get().background_file
+                                           : CGroups::Get().foreground_file;
+    return base::WriteFile(file, pid.c_str(), pid.size()) > 0;
+  }
+#endif  // defined(OS_CHROMEOS)
+
+  if (!CanBackgroundProcesses())
+    return false;
+
+  int priority = background ? kBackgroundPriority : kForegroundPriority;
+  int result = setpriority(PRIO_PROCESS, process_, priority);
+  DPCHECK(result == 0);
+  return result == 0;
+}
+
+#if defined(OS_CHROMEOS)
+bool IsProcessBackgroundedCGroup(const StringPiece& cgroup_contents) {
+  // The process can be part of multiple control groups, and for each cgroup
+  // hierarchy there's an entry in the file. We look for a control group
+  // named "/chrome_renderers/background" to determine if the process is
+  // backgrounded. crbug.com/548818.
+  std::vector<StringPiece> lines = SplitStringPiece(
+      cgroup_contents, "\n", TRIM_WHITESPACE, SPLIT_WANT_NONEMPTY);
+  for (const auto& line : lines) {
+    std::vector<StringPiece> fields =
+        SplitStringPiece(line, ":", TRIM_WHITESPACE, SPLIT_WANT_ALL);
+    if (fields.size() != 3U) {
+      NOTREACHED();
+      continue;
+    }
+    if (fields[2] == kBackground)
+      return true;
+  }
+
+  return false;
+}
+#endif  // defined(OS_CHROMEOS)
+
+#if defined(OS_CHROMEOS)
+// Reads /proc/<pid>/status and returns the PID in its PID namespace.
+// If the process is not in a PID namespace or /proc/<pid>/status does not
+// report NSpid, kNullProcessId is returned.
+ProcessId Process::GetPidInNamespace() const {
+  std::string status;
+  {
+    // Synchronously reading files in /proc does not hit the disk.
+    ThreadRestrictions::ScopedAllowIO allow_io;
+    FilePath status_file =
+        FilePath("/proc").Append(IntToString(process_)).Append("status");
+    if (!ReadFileToString(status_file, &status)) {
+      return kNullProcessId;
+    }
+  }
+
+  StringPairs pairs;
+  SplitStringIntoKeyValuePairs(status, ':', '\n', &pairs);
+  for (const auto& pair : pairs) {
+    const std::string& key = pair.first;
+    const std::string& value_str = pair.second;
+    if (key == "NSpid") {
+      std::vector<StringPiece> split_value_str = SplitStringPiece(
+          value_str, "\t", TRIM_WHITESPACE, SPLIT_WANT_NONEMPTY);
+      if (split_value_str.size() <= 1) {
+        return kNullProcessId;
+      }
+      int value;
+      // The last value in the list is the PID in the namespace.
+      if (!StringToInt(split_value_str.back(), &value)) {
+        NOTREACHED();
+        return kNullProcessId;
+      }
+      return value;
+    }
+  }
+  return kNullProcessId;
+}
+#endif  // defined(OS_CHROMEOS)
+
+}  // namespace base