Rewrite NIO Pipe to use socketpair(2).

Our Pipe originally used socket(2) to create AF_INET/AF_INET6
sockets. This was clearly a bad idea.

I rewrote it to use socketpair(2) and AF_UNIX, but this was
before the big "expose POSIX" rewrite, so it required a bunch
of hacks in the native code, so I went with pipe(2) instead.

The trouble with pipe(2) is that we end up using FileChannel
to implement the Pipe.SinkChannel and Pipe.SourceChannel, but
the kernel won't wake a read(2) on a pipe if another thread
calls close(2) on it, so we started failing interrupt tests.

This (final?) rewrite is hopefully the best of all worlds:
we don't have any INTERNET permission needs, the code is as
simple as the pipe(2) code, and interruption works.

Bug: 7084342
Bug: 2735373
Bug: http://code.google.com/p/android/issues/detail?id=9431

(cherry picked from commit 3218082325b6b8713a8ac15731482e3da86a7df9)

Change-Id: Ib92cdf8c818f6bba1f00e191f1b624ce9e693754

8 files changed, 47 insertions, 29 deletions

diff --git a/luni/src/main/java/java/nio/PipeImpl.java b/luni/src/main/java/java/nio/PipeImpl.java
index 50028f4..d4dde3b 100644
--- a/luni/src/main/java/java/nio/PipeImpl.java
+++ b/luni/src/main/java/java/nio/PipeImpl.java
@@ -19,8 +19,8 @@ package java.nio;
 import java.io.Closeable;
 import java.io.FileDescriptor;
 import java.io.IOException;
-import java.nio.channels.FileChannel;
 import java.nio.channels.Pipe;
+import java.nio.channels.SocketChannel;
 import java.nio.channels.spi.SelectorProvider;
 import libcore.io.ErrnoException;
 import libcore.io.IoUtils;
@@ -34,13 +34,16 @@ final class PipeImpl extends Pipe {
     private final PipeSinkChannel sink;
     private final PipeSourceChannel source;
 
-    public PipeImpl() throws IOException {
+    public PipeImpl(SelectorProvider selectorProvider) throws IOException {
         try {
-            FileDescriptor[] fds = Libcore.os.pipe();
-            // Which fd is used for which channel is important. Unix pipes are only guaranteed to be
-            // unidirectional, and indeed are only unidirectional on Linux.
-            this.sink = new PipeSinkChannel(fds[1]);
-            this.source = new PipeSourceChannel(fds[0]);
+            FileDescriptor fd1 = new FileDescriptor();
+            FileDescriptor fd2 = new FileDescriptor();
+            Libcore.os.socketpair(AF_UNIX, SOCK_STREAM, 0, fd1, fd2);
+
+            // It doesn't matter which file descriptor we use for which end;
+            // they're guaranteed to be indistinguishable.
+            this.sink = new PipeSinkChannel(selectorProvider, fd1);
+            this.source = new PipeSourceChannel(selectorProvider, fd2);
         } catch (ErrnoException errnoException) {
             throw errnoException.rethrowAsIOException();
         }
@@ -54,27 +57,14 @@ final class PipeImpl extends Pipe {
         return source;
     }
 
-    /**
-     * FileChannelImpl doesn't close its fd itself; it calls close on the object it's given.
-     */
-    private static class FdCloser implements Closeable {
-        private final FileDescriptor fd;
-        private FdCloser(FileDescriptor fd) {
-            this.fd = fd;
-        }
-        public void close() throws IOException {
-            IoUtils.close(fd);
-        }
-    }
-
     private class PipeSourceChannel extends Pipe.SourceChannel implements FileDescriptorChannel {
         private final FileDescriptor fd;
-        private final FileChannel channel;
+        private final SocketChannel channel;
 
-        private PipeSourceChannel(FileDescriptor fd) throws IOException {
-            super(SelectorProvider.provider());
+        private PipeSourceChannel(SelectorProvider selectorProvider, FileDescriptor fd) throws IOException {
+            super(selectorProvider);
             this.fd = fd;
-            this.channel = NioUtils.newFileChannel(new FdCloser(fd), fd, O_RDONLY);
+            this.channel = new SocketChannelImpl(selectorProvider, fd);
         }
 
         @Override protected void implCloseSelectableChannel() throws IOException {
@@ -104,12 +94,12 @@ final class PipeImpl extends Pipe {
 
     private class PipeSinkChannel extends Pipe.SinkChannel implements FileDescriptorChannel {
         private final FileDescriptor fd;
-        private final FileChannel channel;
+        private final SocketChannel channel;
 
-        private PipeSinkChannel(FileDescriptor fd) throws IOException {
-            super(SelectorProvider.provider());
+        private PipeSinkChannel(SelectorProvider selectorProvider, FileDescriptor fd) throws IOException {
+            super(selectorProvider);
             this.fd = fd;
-            this.channel = NioUtils.newFileChannel(new FdCloser(fd), fd, O_WRONLY);
+            this.channel = new SocketChannelImpl(selectorProvider, fd);
         }
 
         @Override protected void implCloseSelectableChannel() throws IOException {
diff --git a/luni/src/main/java/java/nio/SelectorProviderImpl.java b/luni/src/main/java/java/nio/SelectorProviderImpl.java
index 03003fe..b7c34e8 100644
--- a/luni/src/main/java/java/nio/SelectorProviderImpl.java
+++ b/luni/src/main/java/java/nio/SelectorProviderImpl.java
@@ -34,7 +34,7 @@ public final class SelectorProviderImpl extends SelectorProvider {
     }
 
     public Pipe openPipe() throws IOException {
-        return new PipeImpl();
+        return new PipeImpl(this);
     }
 
     public AbstractSelector openSelector() throws IOException {
diff --git a/luni/src/main/java/java/nio/SocketChannelImpl.java b/luni/src/main/java/java/nio/SocketChannelImpl.java
index ff2c157..233daf0 100644
--- a/luni/src/main/java/java/nio/SocketChannelImpl.java
+++ b/luni/src/main/java/java/nio/SocketChannelImpl.java
@@ -103,6 +103,15 @@ class SocketChannelImpl extends SocketChannel implements FileDescriptorChannel {
     }
 
     /*
+     * Constructor for use by Pipe.SinkChannel and Pipe.SourceChannel.
+     */
+    public SocketChannelImpl(SelectorProvider selectorProvider, FileDescriptor existingFd) throws IOException {
+        super(selectorProvider);
+        status = SOCKET_STATUS_CONNECTED;
+        fd = existingFd;
+    }
+
+    /*
      * Getting the internal Socket If we have not the socket, we create a new
      * one.
      */
diff --git a/luni/src/main/java/libcore/io/BlockGuardOs.java b/luni/src/main/java/libcore/io/BlockGuardOs.java
index 61c9765..c61a3cf 100644
--- a/luni/src/main/java/libcore/io/BlockGuardOs.java
+++ b/luni/src/main/java/libcore/io/BlockGuardOs.java
@@ -181,6 +181,12 @@ public class BlockGuardOs extends ForwardingOs {
         return tagSocket(os.socket(domain, type, protocol));
     }
 
+    @Override public void socketpair(int domain, int type, int protocol, FileDescriptor fd1, FileDescriptor fd2) throws ErrnoException {
+        os.socketpair(domain, type, protocol, fd1, fd2);
+        tagSocket(fd1);
+        tagSocket(fd2);
+    }
+
     @Override public int write(FileDescriptor fd, ByteBuffer buffer) throws ErrnoException {
         BlockGuard.getThreadPolicy().onWriteToDisk();
         return os.write(fd, buffer);
diff --git a/luni/src/main/java/libcore/io/ForwardingOs.java b/luni/src/main/java/libcore/io/ForwardingOs.java
index 719c5f0..ee26d04 100644
--- a/luni/src/main/java/libcore/io/ForwardingOs.java
+++ b/luni/src/main/java/libcore/io/ForwardingOs.java
@@ -121,6 +121,7 @@ public class ForwardingOs implements Os {
     public void setuid(int uid) throws ErrnoException { os.setuid(uid); }
     public void shutdown(FileDescriptor fd, int how) throws ErrnoException { os.shutdown(fd, how); }
     public FileDescriptor socket(int domain, int type, int protocol) throws ErrnoException { return os.socket(domain, type, protocol); }
+    public void socketpair(int domain, int type, int protocol, FileDescriptor fd1, FileDescriptor fd2) throws ErrnoException { os.socketpair(domain, type, protocol, fd1, fd2); }
     public StructStat stat(String path) throws ErrnoException { return os.stat(path); }
     public StructStatFs statfs(String path) throws ErrnoException { return os.statfs(path); }
     public String strerror(int errno) { return os.strerror(errno); }
diff --git a/luni/src/main/java/libcore/io/Os.java b/luni/src/main/java/libcore/io/Os.java
index 55588d8..1f42497 100644
--- a/luni/src/main/java/libcore/io/Os.java
+++ b/luni/src/main/java/libcore/io/Os.java
@@ -114,6 +114,7 @@ public interface Os {
     public void setuid(int uid) throws ErrnoException;
     public void shutdown(FileDescriptor fd, int how) throws ErrnoException;
     public FileDescriptor socket(int domain, int type, int protocol) throws ErrnoException;
+    public void socketpair(int domain, int type, int protocol, FileDescriptor fd1, FileDescriptor fd2) throws ErrnoException;
     public StructStat stat(String path) throws ErrnoException;
     /* TODO: replace statfs with statvfs. */
     public StructStatFs statfs(String path) throws ErrnoException;
diff --git a/luni/src/main/java/libcore/io/Posix.java b/luni/src/main/java/libcore/io/Posix.java
index ad01bcf..2fb187e 100644
--- a/luni/src/main/java/libcore/io/Posix.java
+++ b/luni/src/main/java/libcore/io/Posix.java
@@ -165,6 +165,7 @@ public final class Posix implements Os {
     public native void setuid(int uid) throws ErrnoException;
     public native void shutdown(FileDescriptor fd, int how) throws ErrnoException;
     public native FileDescriptor socket(int domain, int type, int protocol) throws ErrnoException;
+    public native void socketpair(int domain, int type, int protocol, FileDescriptor fd1, FileDescriptor fd2) throws ErrnoException;
     public native StructStat stat(String path) throws ErrnoException;
     public native StructStatFs statfs(String path) throws ErrnoException;
     public native String strerror(int errno);
diff --git a/luni/src/main/native/libcore_io_Posix.cpp b/luni/src/main/native/libcore_io_Posix.cpp
index dd9b87f..acb3dc2 100644
--- a/luni/src/main/native/libcore_io_Posix.cpp
+++ b/luni/src/main/native/libcore_io_Posix.cpp
@@ -1168,6 +1168,15 @@ static jobject Posix_socket(JNIEnv* env, jobject, jint domain, jint type, jint p
     return fd != -1 ? jniCreateFileDescriptor(env, fd) : NULL;
 }
 
+static void Posix_socketpair(JNIEnv* env, jobject, jint domain, jint type, jint protocol, jobject javaFd1, jobject javaFd2) {
+    int fds[2];
+    int rc = throwIfMinusOne(env, "socketpair", TEMP_FAILURE_RETRY(socketpair(domain, type, protocol, fds)));
+    if (rc != -1) {
+        jniSetFileDescriptorOfFD(env, javaFd1, fds[0]);
+        jniSetFileDescriptorOfFD(env, javaFd2, fds[1]);
+    }
+}
+
 static jobject Posix_stat(JNIEnv* env, jobject, jstring javaPath) {
     return doStat(env, javaPath, false);
 }
@@ -1341,6 +1350,7 @@ static JNINativeMethod gMethods[] = {
     NATIVE_METHOD(Posix, setuid, "(I)V"),
     NATIVE_METHOD(Posix, shutdown, "(Ljava/io/FileDescriptor;I)V"),
     NATIVE_METHOD(Posix, socket, "(III)Ljava/io/FileDescriptor;"),
+    NATIVE_METHOD(Posix, socketpair, "(IIILjava/io/FileDescriptor;Ljava/io/FileDescriptor;)V"),
     NATIVE_METHOD(Posix, stat, "(Ljava/lang/String;)Llibcore/io/StructStat;"),
     NATIVE_METHOD(Posix, statfs, "(Ljava/lang/String;)Llibcore/io/StructStatFs;"),
     NATIVE_METHOD(Posix, strerror, "(I)Ljava/lang/String;"),