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