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: ~ChildProcessHost()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_ 108