Get the new Mojo EDK working on POSIX.

Some notes:
-in RawChannel, I'm passing FDs as ints instead of PlatformHandle to make it very clear that this is only used on POSIX

BUG=478251

Review URL: https://codereview.chromium.org/1417773004

Cr-Commit-Position: refs/heads/master@{#356092}

5 files changed, 31 insertions, 5 deletions

diff --git a/mojo/edk/embedder/embedder.cc b/mojo/edk/embedder/embedder.cc
index 91f03d0..fe5202c 100644
--- a/mojo/edk/embedder/embedder.cc
+++ b/mojo/edk/embedder/embedder.cc
@@ -166,7 +166,8 @@ ScopedMessagePipeHandle CreateMessagePipe(
   ScopedMessagePipeHandle rv(
       MessagePipeHandle(internal::g_core->AddDispatcher(dispatcher)));
   CHECK(rv.is_valid());
-  dispatcher->Init(platform_handle.Pass(), nullptr, 0, nullptr, 0);
+  dispatcher->Init(platform_handle.Pass(), nullptr, 0, nullptr, 0, nullptr,
+                   nullptr);
   // TODO(vtl): The |.Pass()| below is only needed due to an MSVS bug; remove it
   // once that's fixed.
   return rv.Pass();
diff --git a/mojo/edk/embedder/embedder_unittest.cc b/mojo/edk/embedder/embedder_unittest.cc
index bbc3f52..f53e440 100644
--- a/mojo/edk/embedder/embedder_unittest.cc
+++ b/mojo/edk/embedder/embedder_unittest.cc
@@ -126,7 +126,7 @@ TEST_F(EmbedderTest, SendReadableMessagePipe) {
   char read_buffer[20000] = {};
   uint32_t num_bytes = static_cast<uint32_t>(sizeof(read_buffer));
   MojoHandle ports[10];
-  uint32_t num_ports;
+  uint32_t num_ports = arraysize(ports);
   ASSERT_EQ(MOJO_RESULT_OK,
             MojoReadMessage(client_mp, read_buffer, &num_bytes, &ports[0],
                             &num_ports, MOJO_READ_MESSAGE_FLAG_NONE));
diff --git a/mojo/edk/embedder/platform_channel_pair_posix.cc b/mojo/edk/embedder/platform_channel_pair_posix.cc
index 8cdac36..eaeac26 100644
--- a/mojo/edk/embedder/platform_channel_pair_posix.cc
+++ b/mojo/edk/embedder/platform_channel_pair_posix.cc
@@ -12,10 +12,15 @@
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/posix/global_descriptors.h"
+#include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "build/build_config.h"
 #include "mojo/edk/embedder/platform_handle.h"
 
+#if !defined(SO_PEEK_OFF)
+#define SO_PEEK_OFF 42
+#endif
+
 namespace mojo {
 namespace edk {
 
@@ -37,7 +42,16 @@ PlatformChannelPair::PlatformChannelPair() {
   // Create the Unix domain socket and set the ends to nonblocking.
   int fds[2];
   // TODO(vtl): Maybe fail gracefully if |socketpair()| fails.
+
   PCHECK(socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0);
+
+  // Store a common id in the SO_PEEK_OFF option (which we don't use since we
+  // don't peak) as a way of determining later if two sockets are connected to
+  // each other.
+  int identifier = base::RandInt(kint32min, kint32max);
+  setsockopt(fds[0], SOL_SOCKET, SO_PEEK_OFF, &identifier, sizeof(identifier));
+  setsockopt(fds[1], SOL_SOCKET, SO_PEEK_OFF, &identifier, sizeof(identifier));
+
   PCHECK(fcntl(fds[0], F_SETFL, O_NONBLOCK) == 0);
   PCHECK(fcntl(fds[1], F_SETFL, O_NONBLOCK) == 0);
 
diff --git a/mojo/edk/embedder/platform_channel_utils_posix.cc b/mojo/edk/embedder/platform_channel_utils_posix.cc
index 4af45e82..c064139 100644
--- a/mojo/edk/embedder/platform_channel_utils_posix.cc
+++ b/mojo/edk/embedder/platform_channel_utils_posix.cc
@@ -12,6 +12,10 @@
 #include "base/posix/eintr_wrapper.h"
 #include "build/build_config.h"
 
+#if !defined(SO_PEEK_OFF)
+#define SO_PEEK_OFF 42
+#endif
+
 namespace mojo {
 namespace edk {
 
@@ -155,10 +159,18 @@ ssize_t PlatformChannelRecvmsg(PlatformHandle h,
   msg.msg_control = cmsg_buf;
   msg.msg_controllen = sizeof(cmsg_buf);
 
+  // We use SO_PEEK_OFF to hold a common identifier between sockets to detect if
+  // they're connected. recvmsg modifies it, so we cache it and set it again
+  // after the call.
+  int id = 0;
+  socklen_t peek_off_size = sizeof(id);
+  getsockopt(h.fd, SOL_SOCKET, SO_PEEK_OFF, &id, &peek_off_size);
   ssize_t result = HANDLE_EINTR(recvmsg(h.fd, &msg, MSG_DONTWAIT));
   if (result < 0)
     return result;
 
+  setsockopt(h.fd, SOL_SOCKET, SO_PEEK_OFF, &id, sizeof(id));
+
   // Success; no control messages.
   if (msg.msg_controllen == 0)
     return result;
diff --git a/mojo/edk/embedder/platform_channel_utils_posix.h b/mojo/edk/embedder/platform_channel_utils_posix.h
index 00e6a16..ad58753 100644
--- a/mojo/edk/embedder/platform_channel_utils_posix.h
+++ b/mojo/edk/embedder/platform_channel_utils_posix.h
@@ -20,9 +20,8 @@ namespace mojo {
 namespace edk {
 
 // The maximum number of handles that can be sent "at once" using
-// |PlatformChannelSendmsgWithHandles()|.
-// TODO(vtl): This number is taken from ipc/ipc_message_attachment_set.h:
-// |IPC::MessageAttachmentSet::kMaxDescriptorsPerMessage|.
+// |PlatformChannelSendmsgWithHandles()|. This must be less than the Linux
+// kernel's SCM_MAX_FD which is 253.
 const size_t kPlatformChannelMaxNumHandles = 128;
 
 // Use these to write to a socket created using |PlatformChannelPair| (or