content/zygote/zygote_linux.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_ZYGOTE_ZYGOTE_H_
   6 #define CONTENT_ZYGOTE_ZYGOTE_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/containers/small_map.h"
  12 #include "base/posix/global_descriptors.h"
  13 #include "base/process/kill.h"
  14 #include "base/process/process.h"
  15
  16 class Pickle;
  17 class PickleIterator;
  18
  19 namespace content {
  20
  21 class ZygoteForkDelegate;
  22
  23 // This is the object which implements the zygote. The ZygoteMain function,
  24 // which is called from ChromeMain, simply constructs one of these objects and
  25 // runs it.
  26 class Zygote {
  27  public:
  28   Zygote(int sandbox_flags,
  29          ZygoteForkDelegate* helper);
  30   ~Zygote();
  31
  32   bool ProcessRequests();
  33
  34  private:
  35   struct ZygoteProcessInfo {
  36     // Pid from inside the Zygote's PID namespace.
  37     base::ProcessHandle internal_pid;
  38     // Keeps track of whether or not a process was started from a fork
  39     // delegate helper.
  40     bool started_from_helper;
  41   };
  42   typedef base::SmallMap< std::map<base::ProcessHandle, ZygoteProcessInfo> >
  43       ZygoteProcessMap;
  44
  45   // Retrieve a ZygoteProcessInfo from the process_info_map_.
  46   // Returns true and write to process_info if |pid| can be found, return
  47   // false otherwise.
  48   bool GetProcessInfo(base::ProcessHandle pid,
  49                       ZygoteProcessInfo* process_info);
  50
  51   // Returns true if the SUID sandbox is active.
  52   bool UsingSUIDSandbox() const;
  53
  54   // ---------------------------------------------------------------------------
  55   // Requests from the browser...
  56
  57   // Read and process a request from the browser. Returns true if we are in a
  58   // new process and thus need to unwind back into ChromeMain.
  59   bool HandleRequestFromBrowser(int fd);
  60
  61   void HandleReapRequest(int fd, const Pickle& pickle, PickleIterator iter);
  62
  63   // Get the termination status of |real_pid|. |real_pid| is the PID as it
  64   // appears outside of the sandbox.
  65   // Return true if it managed to get the termination status and return the
  66   // status in |status| and the exit code in |exit_code|.
  67   bool GetTerminationStatus(base::ProcessHandle real_pid, bool known_dead,
  68                             base::TerminationStatus* status,
  69                             int* exit_code);
  70
  71   void HandleGetTerminationStatus(int fd,
  72                                   const Pickle& pickle,
  73                                   PickleIterator iter);
  74
  75   // This is equivalent to fork(), except that, when using the SUID sandbox, it
  76   // returns the real PID of the child process as it appears outside the
  77   // sandbox, rather than returning the PID inside the sandbox. Optionally, it
  78   // fills in uma_name et al with a report the helper wants to make via
  79   // UMA_HISTOGRAM_ENUMERATION.
  80   int ForkWithRealPid(const std::string& process_type,
  81                       const base::GlobalDescriptors::Mapping& fd_mapping,
  82                       const std::string& channel_switch,
  83                       std::string* uma_name,
  84                       int* uma_sample,
  85                       int* uma_boundary_value);
  86
  87   // Unpacks process type and arguments from |pickle| and forks a new process.
  88   // Returns -1 on error, otherwise returns twice, returning 0 to the child
  89   // process and the child process ID to the parent process, like fork().
  90   base::ProcessId ReadArgsAndFork(const Pickle& pickle,
  91                                   PickleIterator iter,
  92                                   std::vector<int>& fds,
  93                                   std::string* uma_name,
  94                                   int* uma_sample,
  95                                   int* uma_boundary_value);
  96
  97   // Handle a 'fork' request from the browser: this means that the browser
  98   // wishes to start a new renderer. Returns true if we are in a new process,
  99   // otherwise writes the child_pid back to the browser via |fd|. Writes a
 100   // child_pid of -1 on error.
 101   bool HandleForkRequest(int fd,
 102                          const Pickle& pickle,
 103                          PickleIterator iter,
 104                          std::vector<int>& fds);
 105
 106   bool HandleGetSandboxStatus(int fd,
 107                               const Pickle& pickle,
 108                               PickleIterator iter);
 109
 110   // The Zygote needs to keep some information about each process. Most
 111   // notably what the PID of the process is inside the PID namespace of
 112   // the Zygote and whether or not a process was started by the
 113   // ZygoteForkDelegate helper.
 114   ZygoteProcessMap process_info_map_;
 115
 116   const int sandbox_flags_;
 117   ZygoteForkDelegate* helper_;
 118
 119   // These might be set by helper_->InitialUMA. They supply a UMA enumeration
 120   // sample we should report on the first fork.
 121   std::string initial_uma_name_;
 122   int initial_uma_sample_;
 123   int initial_uma_boundary_value_;
 124 };
 125
 126 }  // namespace content
 127
 128 #endif  // CONTENT_ZYGOTE_ZYGOTE_H_