Split the IPC code into ipc/

This splits the ipc code from the common project.  The 'common' project pulls in
all of webkit, the v8 bindings, skia, googleurl, and a number of other projects
which makes it very difficult to deal with especially for external projects
wanting just to use some of Chromium's infrastructure.  This puts the ipc code
into its top-level ipc/ directory with a dependency only on base.  The common
project depends on the new ipc/ipc.gyp:ipc target so that all projects currently
pulling common in to get the IPC code still have it available.  This mostly
follows agl's pre-gyp attempt to do this which was r13062.

Known issues:
- Currently a number of projects depend on chrome/chrome.gyp:common in order to
use the IPC infrastructure.  Rather than fixing all of these dependencies I have
made common depend on ipc/ipc.gyp:ipc and added "ipc" to the include_rules
section of DEPS so that checkdeps.py doesn't complain.  Over time projects that
need IPC should depend on the IPC project themselves and dependencies on common
removed, although I don't think many projects that need IPC will be able to get
away without common currently.
- ipc/ipc_message_macros.h still has #include "chrome/common/..." inside of a
ipc/ should not refer to files in chrome/... now.  I'm not sure how to resolve
this since it's really an IDE bug
- the named pipe name (windows+linux) and the logging event name (all) + env
variable (posix) refer explicitly to 'Chrome' which somewhat hurts the illusion
of ipc/ being an independent library.  I think this should be examined in a
subsequent, much smaller patch.
- I've eliminated the IPC.SendMsgCount counter since it was implemented in a way
to create a dependency from ipc/ to chrome/common/chrome_counters. This is the
same approach that r13062 took.

http://codereview.chromium.org/155905

(Patch from James Robinson)


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21342 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 108 insertions, 0 deletions

diff --git a/ipc/file_descriptor_set_posix.h b/ipc/file_descriptor_set_posix.h
new file mode 100644
index 0000000..c3d26ba8
--- /dev/null
+++ b/ipc/file_descriptor_set_posix.h
@@ -0,0 +1,108 @@
+// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IPC_FILE_DESCRIPTOR_SET_POSIX_H_
+#define IPC_FILE_DESCRIPTOR_SET_POSIX_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/file_descriptor_posix.h"
+#include "base/ref_counted.h"
+
+// -----------------------------------------------------------------------------
+// A FileDescriptorSet is an ordered set of POSIX file descriptors. These are
+// associated with IPC messages so that descriptors can be transmitted over a
+// UNIX domain socket.
+// -----------------------------------------------------------------------------
+class FileDescriptorSet : public base::RefCountedThreadSafe<FileDescriptorSet> {
+ public:
+  FileDescriptorSet();
+  ~FileDescriptorSet();
+
+  // This is the maximum number of descriptors per message. We need to know this
+  // because the control message kernel interface has to be given a buffer which
+  // is large enough to store all the descriptor numbers. Otherwise the kernel
+  // tells us that it truncated the control data and the extra descriptors are
+  // lost.
+  //
+  // In debugging mode, it's a fatal error to try and add more than this number
+  // of descriptors to a FileDescriptorSet.
+  enum {
+    MAX_DESCRIPTORS_PER_MESSAGE = 4,
+  };
+
+  // ---------------------------------------------------------------------------
+  // Interfaces for building during message serialisation...
+
+  // Add a descriptor to the end of the set. Returns false iff the set is full.
+  bool Add(int fd);
+  // Add a descriptor to the end of the set and automatically close it after
+  // transmission. Returns false iff the set is full.
+  bool AddAndAutoClose(int fd);
+
+  // ---------------------------------------------------------------------------
+
+
+  // ---------------------------------------------------------------------------
+  // Interfaces for accessing during message deserialisation...
+
+  // Return the number of descriptors
+  unsigned size() const { return descriptors_.size(); }
+  // Return true if no unconsumed descriptors remain
+  bool empty() const { return descriptors_.empty(); }
+  // Fetch the nth descriptor from the beginning of the set. Code using this
+  // /must/ access the descriptors in order, except that it may wrap from the
+  // end to index 0 again.
+  //
+  // This interface is designed for the deserialising code as it doesn't
+  // support close flags.
+  //   returns: file descriptor, or -1 on error
+  int GetDescriptorAt(unsigned n) const;
+
+  // ---------------------------------------------------------------------------
+
+
+  // ---------------------------------------------------------------------------
+  // Interfaces for transmission...
+
+  // Fill an array with file descriptors without 'consuming' them. CommitAll
+  // must be called after these descriptors have been transmitted.
+  //   buffer: (output) a buffer of, at least, size() integers.
+  void GetDescriptors(int* buffer) const;
+  // This must be called after transmitting the descriptors returned by
+  // GetDescriptors. It marks all the descriptors as consumed and closes those
+  // which are auto-close.
+  void CommitAll();
+
+  // ---------------------------------------------------------------------------
+
+
+  // ---------------------------------------------------------------------------
+  // Interfaces for receiving...
+
+  // Set the contents of the set from the given buffer. This set must be empty
+  // before calling. The auto-close flag is set on all the descriptors so that
+  // unconsumed descriptors are closed on destruction.
+  void SetDescriptors(const int* buffer, unsigned count);
+
+  // ---------------------------------------------------------------------------
+
+ private:
+  // A vector of descriptors and close flags. If this message is sent, then
+  // these descriptors are sent as control data. After sending, any descriptors
+  // with a true flag are closed. If this message has been received, then these
+  // are the descriptors which were received and all close flags are true.
+  std::vector<base::FileDescriptor> descriptors_;
+
+  // This contains the index of the next descriptor which should be consumed.
+  // It's used in a couple of ways. Firstly, at destruction we can check that
+  // all the descriptors have been read (with GetNthDescriptor). Secondly, we
+  // can check that they are read in order.
+  mutable unsigned consumed_descriptor_highwater_;
+
+  DISALLOW_COPY_AND_ASSIGN(FileDescriptorSet);
+};
+
+#endif  // IPC_FILE_DESCRIPTOR_SET_POSIX_H_