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 <stddef.h>
   9
  10 #include <string>
  11
  12 #include "base/containers/small_map.h"
  13 #include "base/files/scoped_file.h"
  14 #include "base/memory/scoped_vector.h"
  15 #include "base/posix/global_descriptors.h"
  16 #include "base/process/kill.h"
  17 #include "base/process/process.h"
  18
  19 class Pickle;
  20 class PickleIterator;
  21
  22 namespace content {
  23
  24 class ZygoteForkDelegate;
  25
  26 // This is the object which implements the zygote. The ZygoteMain function,
  27 // which is called from ChromeMain, simply constructs one of these objects and
  28 // runs it.
  29 class Zygote {
  30  public:
  31   Zygote(int sandbox_flags, ScopedVector<ZygoteForkDelegate> helpers,
  32          const std::vector<base::ProcessHandle>& extra_children,
  33          const std::vector<int>& extra_fds);
  34   ~Zygote();
  35
  36   bool ProcessRequests();
  37
  38  private:
  39   struct ZygoteProcessInfo {
  40     // Pid from inside the Zygote's PID namespace.
  41     base::ProcessHandle internal_pid;
  42     // Keeps track of which fork delegate helper the process was started from.
  43     ZygoteForkDelegate* started_from_helper;
  44   };
  45   typedef base::SmallMap< std::map<base::ProcessHandle, ZygoteProcessInfo> >
  46       ZygoteProcessMap;
  47
  48   // Retrieve a ZygoteProcessInfo from the process_info_map_.
  49   // Returns true and write to process_info if |pid| can be found, return
  50   // false otherwise.
  51   bool GetProcessInfo(base::ProcessHandle pid,
  52                       ZygoteProcessInfo* process_info);
  53
  54   // Returns true if the SUID sandbox is active.
  55   bool UsingSUIDSandbox() const;
  56
  57   // ---------------------------------------------------------------------------
  58   // Requests from the browser...
  59
  60   // Read and process a request from the browser. Returns true if we are in a
  61   // new process and thus need to unwind back into ChromeMain.
  62   bool HandleRequestFromBrowser(int fd);
  63
  64   void HandleReapRequest(int fd, PickleIterator iter);
  65
  66   // Get the termination status of |real_pid|. |real_pid| is the PID as it
  67   // appears outside of the sandbox.
  68   // Return true if it managed to get the termination status and return the
  69   // status in |status| and the exit code in |exit_code|.
  70   bool GetTerminationStatus(base::ProcessHandle real_pid, bool known_dead,
  71                             base::TerminationStatus* status,
  72                             int* exit_code);
  73
  74   void HandleGetTerminationStatus(int fd,
  75                                   PickleIterator iter);
  76
  77   // This is equivalent to fork(), except that, when using the SUID sandbox, it
  78   // returns the real PID of the child process as it appears outside the
  79   // sandbox, rather than returning the PID inside the sandbox.  The child's
  80   // real PID is determined by having it call content::SendZygoteChildPing(int)
  81   // using the |pid_oracle| descriptor.
  82   // Finally, when using a ZygoteForkDelegate helper, |uma_name|, |uma_sample|,
  83   // and |uma_boundary_value| may be set if the helper wants to make a UMA
  84   // report via UMA_HISTOGRAM_ENUMERATION.
  85   int ForkWithRealPid(const std::string& process_type,
  86                       const base::GlobalDescriptors::Mapping& fd_mapping,
  87                       const std::string& channel_id,
  88                       base::ScopedFD pid_oracle,
  89                       std::string* uma_name,
  90                       int* uma_sample,
  91                       int* uma_boundary_value);
  92
  93   // Unpacks process type and arguments from |iter| and forks a new process.
  94   // Returns -1 on error, otherwise returns twice, returning 0 to the child
  95   // process and the child process ID to the parent process, like fork().
  96   base::ProcessId ReadArgsAndFork(PickleIterator iter,
  97                                   ScopedVector<base::ScopedFD> fds,
  98                                   std::string* uma_name,
  99                                   int* uma_sample,
 100                                   int* uma_boundary_value);
 101
 102   // Handle a 'fork' request from the browser: this means that the browser
 103   // wishes to start a new renderer. Returns true if we are in a new process,
 104   // otherwise writes the child_pid back to the browser via |fd|. Writes a
 105   // child_pid of -1 on error.
 106   bool HandleForkRequest(int fd,
 107                          PickleIterator iter,
 108                          ScopedVector<base::ScopedFD> fds);
 109
 110   bool HandleGetSandboxStatus(int fd,
 111                               PickleIterator iter);
 112
 113   // The Zygote needs to keep some information about each process. Most
 114   // notably what the PID of the process is inside the PID namespace of
 115   // the Zygote and whether or not a process was started by the
 116   // ZygoteForkDelegate helper.
 117   ZygoteProcessMap process_info_map_;
 118
 119   const int sandbox_flags_;
 120   ScopedVector<ZygoteForkDelegate> helpers_;
 121
 122   // Count of how many fork delegates for which we've invoked InitialUMA().
 123   size_t initial_uma_index_;
 124
 125   // This vector contains the PIDs of any child processes which have been
 126   // created prior to the construction of the Zygote object, and must be reaped
 127   // before the Zygote exits. The Zygote will perform a blocking wait on these
 128   // children, so they must be guaranteed to be exiting by the time the Zygote
 129   // exits.
 130   std::vector<base::ProcessHandle> extra_children_;
 131
 132   // This vector contains the FDs that must be closed before reaping the extra
 133   // children.
 134   std::vector<int> extra_fds_;
 135 };
 136
 137 }  // namespace content
 138
 139 #endif  // CONTENT_ZYGOTE_ZYGOTE_H_