content/public/common/child_process_host.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_PUBLIC_COMMON_CHILD_PROCESS_HOST_H_
   6 #define CONTENT_PUBLIC_COMMON_CHILD_PROCESS_HOST_H_
   7
   8 #include "base/files/scoped_file.h"
   9 #include "build/build_config.h"
  10 #include "content/common/content_export.h"
  11 #include "ipc/ipc_channel_proxy.h"
  12
  13 namespace base {
  14 class FilePath;
  15 }
  16
  17 namespace IPC {
  18 class AttachmentBroker;
  19 class MessageFilter;
  20 }
  21
  22 namespace content {
  23
  24 class ChildProcessHostDelegate;
  25
  26 // This represents a non-browser process. This can include traditional child
  27 // processes like plugins, or an embedder could even use this for long lived
  28 // processes that run independent of the browser process.
  29 class CONTENT_EXPORT ChildProcessHost : public IPC::Sender {
  30  public:
  31   ~ChildProcessHost() override {}
  32
  33   // This is a value never returned as the unique id of any child processes of
  34   // any kind, including the values returned by RenderProcessHost::GetID().
  35   static int kInvalidUniqueID;
  36
  37   // Used to create a child process host. The delegate must outlive this object.
  38   static ChildProcessHost* Create(ChildProcessHostDelegate* delegate);
  39
  40   // These flags may be passed to GetChildPath in order to alter its behavior,
  41   // causing it to return a child path more suited to a specific task.
  42   enum {
  43     // No special behavior requested.
  44     CHILD_NORMAL = 0,
  45
  46 #if defined(OS_LINUX)
  47     // Indicates that the child execed after forking may be execced from
  48     // /proc/self/exe rather than using the "real" app path. This prevents
  49     // autoupdate from confusing us if it changes the file out from under us.
  50     // You will generally want to set this on Linux, except when there is an
  51     // override to the command line (for example, we're forking a renderer in
  52     // gdb). In this case, you'd use GetChildPath to get the real executable
  53     // file name, and then prepend the GDB command to the command line.
  54     CHILD_ALLOW_SELF = 1 << 0,
  55 #elif defined(OS_MACOSX)
  56
  57     // Requests that the child run in a process that does not have the
  58     // PIE (position-independent executable) bit set, effectively disabling
  59     // ASLR. For process types that need to allocate a large contiguous
  60     // region, ASLR may not leave a large enough "hole" for the purpose. This
  61     // option should be used sparingly, and only when absolutely necessary.
  62     // This option is currently incompatible with CHILD_ALLOW_HEAP_EXECUTION.
  63     CHILD_NO_PIE = 1 << 1,
  64
  65     // Requests that the child run in a process that does not protect the
  66     // heap against execution. Normally, heap pages may be made executable
  67     // with mprotect, so this mode should be used sparingly. It is intended
  68     // for processes that may host plugins that expect an executable heap
  69     // without having to call mprotect. This option is currently incompatible
  70     // with CHILD_NO_PIE.
  71     CHILD_ALLOW_HEAP_EXECUTION = 1 << 2,
  72 #endif
  73   };
  74
  75   // Returns the pathname to be used for a child process.  If a subprocess
  76   // pathname was specified on the command line, that will be used.  Otherwise,
  77   // the default child process pathname will be returned.  On most platforms,
  78   // this will be the same as the currently-executing process.
  79   //
  80   // The |flags| argument accepts one or more flags such as CHILD_ALLOW_SELF
  81   // and CHILD_ALLOW_HEAP_EXECUTION as defined above. Pass only CHILD_NORMAL
  82   // if none of these special behaviors are required.
  83   //
  84   // On failure, returns an empty FilePath.
  85   static base::FilePath GetChildPath(int flags);
  86
  87   // Returns an AttachmentBroker used to broker attachments of IPC messages to
  88   // child processes.
  89   static IPC::AttachmentBroker* GetAttachmentBroker();
  90
  91   // Send the shutdown message to the child process.
  92   // Does not check with the delegate's CanShutdown.
  93   virtual void ForceShutdown() = 0;
  94
  95   // Creates the IPC channel.  Returns the channel id if it succeeded, an
  96   // empty string otherwise
  97   virtual std::string CreateChannel() = 0;
  98
  99   // Returns true iff the IPC channel is currently being opened;
 100   virtual bool IsChannelOpening() = 0;
 101
 102   // Adds an IPC message filter.  A reference will be kept to the filter.
 103   virtual void AddFilter(IPC::MessageFilter* filter) = 0;
 104
 105 #if defined(OS_POSIX)
 106   // See IPC::Channel::TakeClientFileDescriptor.
 107   virtual base::ScopedFD TakeClientFileDescriptor() = 0;
 108 #endif
 109 };
 110
 111 };  // namespace content
 112
 113 #endif  // CONTENT_PUBLIC_COMMON_CHILD_PROCESS_HOST_H_