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 class FilePath;
  13
  14 namespace content {
  15
  16 class ChildProcessHostDelegate;
  17
  18 // This represents a non-browser process. This can include traditional child
  19 // processes like plugins, or an embedder could even use this for long lived
  20 // processes that run independent of the browser process.
  21 class CONTENT_EXPORT ChildProcessHost : public IPC::Sender {
  22  public:
  23   virtual ~ChildProcessHost() {}
  24
  25   // Used to create a child process host. The delegate must outlive this object.
  26   static ChildProcessHost* Create(
  27       ChildProcessHostDelegate* delegate);
  28
  29   // These flags may be passed to GetChildPath in order to alter its behavior,
  30   // causing it to return a child path more suited to a specific task.
  31   enum {
  32     // No special behavior requested.
  33     CHILD_NORMAL = 0,
  34
  35 #if defined(OS_LINUX)
  36     // Indicates that the child execed after forking may be execced from
  37     // /proc/self/exe rather than using the "real" app path. This prevents
  38     // autoupdate from confusing us if it changes the file out from under us.
  39     // You will generally want to set this on Linux, except when there is an
  40     // override to the command line (for example, we're forking a renderer in
  41     // gdb). In this case, you'd use GetChildPath to get the real executable
  42     // file name, and then prepend the GDB command to the command line.
  43     CHILD_ALLOW_SELF = 1 << 0,
  44 #elif defined(OS_MACOSX)
  45
  46     // Requests that the child run in a process that does not have the
  47     // PIE (position-independent executable) bit set, effectively disabling
  48     // ASLR. For process types that need to allocate a large contiguous
  49     // region, ASLR may not leave a large enough "hole" for the purpose. This
  50     // option should be used sparingly, and only when absolutely necessary.
  51     // This option is currently incompatible with CHILD_ALLOW_HEAP_EXECUTION.
  52     CHILD_NO_PIE = 1 << 1,
  53
  54     // Requests that the child run in a process that does not protect the
  55     // heap against execution. Normally, heap pages may be made executable
  56     // with mprotect, so this mode should be used sparingly. It is intended
  57     // for processes that may host plug-ins that expect an executable heap
  58     // without having to call mprotect. This option is currently incompatible
  59     // with CHILD_NO_PIE.
  60     CHILD_ALLOW_HEAP_EXECUTION = 1 << 2,
  61 #endif
  62   };
  63
  64   // Returns the pathname to be used for a child process.  If a subprocess
  65   // pathname was specified on the command line, that will be used.  Otherwise,
  66   // the default child process pathname will be returned.  On most platforms,
  67   // this will be the same as the currently-executing process.
  68   //
  69   // The |flags| argument accepts one or more flags such as CHILD_ALLOW_SELF
  70   // and CHILD_ALLOW_HEAP_EXECUTION as defined above. Pass only CHILD_NORMAL
  71   // if none of these special behaviors are required.
  72   //
  73   // On failure, returns an empty FilePath.
  74   static FilePath GetChildPath(int flags);
  75
  76   // Send the shutdown message to the child process.
  77   // Does not check with the delegate's CanShutdown.
  78   virtual void ForceShutdown() = 0;
  79
  80   // Creates the IPC channel.  Returns the channel id if it succeeded, an
  81   // empty string otherwise
  82   virtual std::string CreateChannel() = 0;
  83
  84   // Returns true iff the IPC channel is currently being opened;
  85   virtual bool IsChannelOpening() = 0;
  86
  87   // Adds an IPC message filter.  A reference will be kept to the filter.
  88   virtual void AddFilter(IPC::ChannelProxy::MessageFilter* filter) = 0;
  89
  90 #if defined(OS_POSIX)
  91   // See IPC::Channel::TakeClientFileDescriptor.
  92   virtual int TakeClientFileDescriptor() = 0;
  93 #endif
  94 };
  95
  96 };  // namespace content
  97
  98 #endif  // CONTENT_PULIC_COMMON_CHILD_PROCESS_HOST_H_