transport_local.cpp - SHIFTPHONES/android_packages_modules_adb - Gitiles

 /*
  * Copyright (C) 2007 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define TRACE_TAG TRACE_TRANSPORT

 #include "sysdeps.h"
 #include "transport.h"

 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>

 #include <base/stringprintf.h>

 #if !ADB_HOST
 #include "cutils/properties.h"
 #endif

 #include "adb.h"
 #include "adb_io.h"

 #if ADB_HOST
 /* we keep a list of opened transports. The atransport struct knows to which
  * local transport it is connected. The list is used to detect when we're
  * trying to connect twice to a given local transport.
  */
 #define  ADB_LOCAL_TRANSPORT_MAX  64

 ADB_MUTEX_DEFINE( local_transports_lock );

 static atransport*  local_transports[ ADB_LOCAL_TRANSPORT_MAX ];
 #endif /* ADB_HOST */

 static int remote_read(apacket *p, atransport *t)
 {
     if(!ReadFdExactly(t->sfd, &p->msg, sizeof(amessage))){
         D("remote local: read terminated (message)\n");
         return -1;
     }

     if(check_header(p)) {
         D("bad header: terminated (data)\n");
         return -1;
     }

     if(!ReadFdExactly(t->sfd, p->data, p->msg.data_length)){
         D("remote local: terminated (data)\n");
         return -1;
     }

     if(check_data(p)) {
         D("bad data: terminated (data)\n");
         return -1;
     }

     return 0;
 }

 static int remote_write(apacket *p, atransport *t)
 {
     int   length = p->msg.data_length;

     if(!WriteFdExactly(t->sfd, &p->msg, sizeof(amessage) + length)) {
         D("remote local: write terminated\n");
         return -1;
     }

     return 0;
 }


 int local_connect(int port) {
     return local_connect_arbitrary_ports(port-1, port);
 }

 int local_connect_arbitrary_ports(int console_port, int adb_port)
 {
     int  fd = -1;

 #if ADB_HOST
     const char *host = getenv("ADBHOST");
     if (host) {
         fd = socket_network_client(host, adb_port, SOCK_STREAM);
     }
 #endif
     if (fd < 0) {
         fd = socket_loopback_client(adb_port, SOCK_STREAM);
     }

     if (fd >= 0) {
         D("client: connected on remote on fd %d\n", fd);
         close_on_exec(fd);
         disable_tcp_nagle(fd);
         std::string serial = android::base::StringPrintf("emulator-%d", console_port);
         register_socket_transport(fd, serial.c_str(), adb_port, 1);
         return 0;
     }
     return -1;
 }


 static void *client_socket_thread(void *x)
 {
 #if ADB_HOST
     int  port  = DEFAULT_ADB_LOCAL_TRANSPORT_PORT;
     int  count = ADB_LOCAL_TRANSPORT_MAX;

     D("transport: client_socket_thread() starting\n");

     /* try to connect to any number of running emulator instances     */
     /* this is only done when ADB starts up. later, each new emulator */
     /* will send a message to ADB to indicate that is is starting up  */
     for ( ; count > 0; count--, port += 2 ) {
         (void) local_connect(port);
     }
 #endif
     return 0;
 }

 static void *server_socket_thread(void * arg)
 {
     int serverfd, fd;
     struct sockaddr addr;
     socklen_t alen;
     int port = (int) (uintptr_t) arg;

     D("transport: server_socket_thread() starting\n");
     serverfd = -1;
     for(;;) {
         if(serverfd == -1) {
             serverfd = socket_inaddr_any_server(port, SOCK_STREAM);
             if(serverfd < 0) {
                 D("server: cannot bind socket yet: %s\n", strerror(errno));
                 adb_sleep_ms(1000);
                 continue;
             }
             close_on_exec(serverfd);
         }

         alen = sizeof(addr);
         D("server: trying to get new connection from %d\n", port);
         fd = adb_socket_accept(serverfd, &addr, &alen);
         if(fd >= 0) {
             D("server: new connection on fd %d\n", fd);
             close_on_exec(fd);
             disable_tcp_nagle(fd);
             register_socket_transport(fd, "host", port, 1);
         }
     }
     D("transport: server_socket_thread() exiting\n");
     return 0;
 }

 /* This is relevant only for ADB daemon running inside the emulator. */
 #if !ADB_HOST
 /*
  * Redefine open and write for qemu_pipe.h that contains inlined references
  * to those routines. We will redifine them back after qemu_pipe.h inclusion.
  */
 #undef open
 #undef write
 #define open    adb_open
 #define write   adb_write
 #include <hardware/qemu_pipe.h>
 #undef open
 #undef write
 #define open    ___xxx_open
 #define write   ___xxx_write

 /* A worker thread that monitors host connections, and registers a transport for
  * every new host connection. This thread replaces server_socket_thread on
  * condition that adbd daemon runs inside the emulator, and emulator uses QEMUD
  * pipe to communicate with adbd daemon inside the guest. This is done in order
  * to provide more robust communication channel between ADB host and guest. The
  * main issue with server_socket_thread approach is that it runs on top of TCP,
  * and thus is sensitive to network disruptions. For instance, the
  * ConnectionManager may decide to reset all network connections, in which case
  * the connection between ADB host and guest will be lost. To make ADB traffic
  * independent from the network, we use here 'adb' QEMUD service to transfer data
  * between the host, and the guest. See external/qemu/android/adb-*.* that
  * implements the emulator's side of the protocol. Another advantage of using
  * QEMUD approach is that ADB will be up much sooner, since it doesn't depend
  * anymore on network being set up.
  * The guest side of the protocol contains the following phases:
  * - Connect with adb QEMUD service. In this phase a handle to 'adb' QEMUD service
  *   is opened, and it becomes clear whether or not emulator supports that
  *   protocol.
  * - Wait for the ADB host to create connection with the guest. This is done by
  *   sending an 'accept' request to the adb QEMUD service, and waiting on
  *   response.
  * - When new ADB host connection is accepted, the connection with adb QEMUD
  *   service is registered as the transport, and a 'start' request is sent to the
  *   adb QEMUD service, indicating that the guest is ready to receive messages.
  *   Note that the guest will ignore messages sent down from the emulator before
  *   the transport registration is completed. That's why we need to send the
  *   'start' request after the transport is registered.
  */
 static void *qemu_socket_thread(void * arg)
 {
 /* 'accept' request to the adb QEMUD service. */
 static const char _accept_req[] = "accept";
 /* 'start' request to the adb QEMUD service. */
 static const char _start_req[]  = "start";
 /* 'ok' reply from the adb QEMUD service. */
 static const char _ok_resp[]    = "ok";

     const int port = (int) (uintptr_t) arg;
     int res, fd;
     char tmp[256];
     char con_name[32];

     D("transport: qemu_socket_thread() starting\n");

     /* adb QEMUD service connection request. */
     snprintf(con_name, sizeof(con_name), "qemud:adb:%d", port);

     /* Connect to the adb QEMUD service. */
     fd = qemu_pipe_open(con_name);
     if (fd < 0) {
         /* This could be an older version of the emulator, that doesn't
          * implement adb QEMUD service. Fall back to the old TCP way. */
         D("adb service is not available. Falling back to TCP socket.\n");
         adb_thread_create(server_socket_thread, arg);
         return 0;
     }

     for(;;) {
         /*
          * Wait till the host creates a new connection.
          */

         /* Send the 'accept' request. */
         res = adb_write(fd, _accept_req, strlen(_accept_req));
         if ((size_t)res == strlen(_accept_req)) {
             /* Wait for the response. In the response we expect 'ok' on success,
              * or 'ko' on failure. */
             res = adb_read(fd, tmp, sizeof(tmp));
             if (res != 2 || memcmp(tmp, _ok_resp, 2)) {
                 D("Accepting ADB host connection has failed.\n");
                 adb_close(fd);
             } else {
                 /* Host is connected. Register the transport, and start the
                  * exchange. */
                 register_socket_transport(fd, "host", port, 1);
                 adb_write(fd, _start_req, strlen(_start_req));
             }

             /* Prepare for accepting of the next ADB host connection. */
             fd = qemu_pipe_open(con_name);
             if (fd < 0) {
                 D("adb service become unavailable.\n");
                 return 0;
             }
         } else {
             D("Unable to send the '%s' request to ADB service.\n", _accept_req);
             return 0;
         }
     }
     D("transport: qemu_socket_thread() exiting\n");
     return 0;
 }
 #endif  // !ADB_HOST

 void local_init(int port)
 {
     void* (*func)(void *);

     if(HOST) {
         func = client_socket_thread;
     } else {
 #if ADB_HOST
         func = server_socket_thread;
 #else
         /* For the adbd daemon in the system image we need to distinguish
          * between the device, and the emulator. */
         char is_qemu[PROPERTY_VALUE_MAX];
         property_get("ro.kernel.qemu", is_qemu, "");
         if (!strcmp(is_qemu, "1")) {
             /* Running inside the emulator: use QEMUD pipe as the transport. */
             func = qemu_socket_thread;
         } else {
             /* Running inside the device: use TCP socket as the transport. */
             func = server_socket_thread;
         }
 #endif // !ADB_HOST
     }

     D("transport: local %s init\n", HOST ? "client" : "server");

     if (!adb_thread_create(func, (void *) (uintptr_t) port)) {
         fatal_errno("cannot create local socket %s thread", HOST ? "client" : "server");
     }
 }

 static void remote_kick(atransport *t)
 {
     int fd = t->sfd;
     t->sfd = -1;
     adb_shutdown(fd);
     adb_close(fd);

 #if ADB_HOST
     if(HOST) {
         int  nn;
         adb_mutex_lock( &local_transports_lock );
         for (nn = 0; nn < ADB_LOCAL_TRANSPORT_MAX; nn++) {
             if (local_transports[nn] == t) {
                 local_transports[nn] = NULL;
                 break;
             }
         }
         adb_mutex_unlock( &local_transports_lock );
     }
 #endif
 }

 static void remote_close(atransport *t)
 {
     adb_close(t->fd);
 }


 #if ADB_HOST
 /* Only call this function if you already hold local_transports_lock. */
 atransport* find_emulator_transport_by_adb_port_locked(int adb_port)
 {
     int i;
     for (i = 0; i < ADB_LOCAL_TRANSPORT_MAX; i++) {
         if (local_transports[i] && local_transports[i]->adb_port == adb_port) {
             return local_transports[i];
         }
     }
     return NULL;
 }

 atransport* find_emulator_transport_by_adb_port(int adb_port)
 {
     adb_mutex_lock( &local_transports_lock );
     atransport* result = find_emulator_transport_by_adb_port_locked(adb_port);
     adb_mutex_unlock( &local_transports_lock );
     return result;
 }

 /* Only call this function if you already hold local_transports_lock. */
 int get_available_local_transport_index_locked()
 {
     int i;
     for (i = 0; i < ADB_LOCAL_TRANSPORT_MAX; i++) {
         if (local_transports[i] == NULL) {
             return i;
         }
     }
     return -1;
 }

 int get_available_local_transport_index()
 {
     adb_mutex_lock( &local_transports_lock );
     int result = get_available_local_transport_index_locked();
     adb_mutex_unlock( &local_transports_lock );
     return result;
 }
 #endif

 int init_socket_transport(atransport *t, int s, int adb_port, int local)
 {
     int  fail = 0;

     t->kick = remote_kick;
     t->close = remote_close;
     t->read_from_remote = remote_read;
     t->write_to_remote = remote_write;
     t->sfd = s;
     t->sync_token = 1;
     t->connection_state = CS_OFFLINE;
     t->type = kTransportLocal;
     t->adb_port = 0;

 #if ADB_HOST
     if (HOST && local) {
         adb_mutex_lock( &local_transports_lock );
         {
             t->adb_port = adb_port;
             atransport* existing_transport =
                     find_emulator_transport_by_adb_port_locked(adb_port);
             int index = get_available_local_transport_index_locked();
             if (existing_transport != NULL) {
                 D("local transport for port %d already registered (%p)?\n",
                 adb_port, existing_transport);
                 fail = -1;
             } else if (index < 0) {
                 // Too many emulators.
                 D("cannot register more emulators. Maximum is %d\n",
                         ADB_LOCAL_TRANSPORT_MAX);
                 fail = -1;
             } else {
                 local_transports[index] = t;
             }
        }
        adb_mutex_unlock( &local_transports_lock );
     }
 #endif
     return fail;
 }
	/*
	* Copyright (C) 2007 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define TRACE_TAG TRACE_TRANSPORT

	#include "sysdeps.h"
	#include "transport.h"

	#include <errno.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/types.h>

	#include <base/stringprintf.h>

	#if !ADB_HOST
	#include "cutils/properties.h"
	#endif

	#include "adb.h"
	#include "adb_io.h"

	#if ADB_HOST
	/* we keep a list of opened transports. The atransport struct knows to which
	* local transport it is connected. The list is used to detect when we're
	* trying to connect twice to a given local transport.
	*/
	#define ADB_LOCAL_TRANSPORT_MAX 64

	ADB_MUTEX_DEFINE( local_transports_lock );

	static atransport* local_transports[ ADB_LOCAL_TRANSPORT_MAX ];
	#endif /* ADB_HOST */

	static int remote_read(apacket p, atransport t)
	{
	if(!ReadFdExactly(t->sfd, &p->msg, sizeof(amessage))){
	D("remote local: read terminated (message)\n");
	return -1;
	}

	if(check_header(p)) {
	D("bad header: terminated (data)\n");
	return -1;
	}

	if(!ReadFdExactly(t->sfd, p->data, p->msg.data_length)){
	D("remote local: terminated (data)\n");
	return -1;
	}

	if(check_data(p)) {
	D("bad data: terminated (data)\n");
	return -1;
	}

	return 0;
	}

	static int remote_write(apacket p, atransport t)
	{
	int length = p->msg.data_length;

	if(!WriteFdExactly(t->sfd, &p->msg, sizeof(amessage) + length)) {
	D("remote local: write terminated\n");
	return -1;
	}

	return 0;
	}


	int local_connect(int port) {
	return local_connect_arbitrary_ports(port-1, port);
	}

	int local_connect_arbitrary_ports(int console_port, int adb_port)
	{
	int fd = -1;

	#if ADB_HOST
	const char *host = getenv("ADBHOST");
	if (host) {
	fd = socket_network_client(host, adb_port, SOCK_STREAM);
	}
	#endif
	if (fd < 0) {
	fd = socket_loopback_client(adb_port, SOCK_STREAM);
	}

	if (fd >= 0) {
	D("client: connected on remote on fd %d\n", fd);
	close_on_exec(fd);
	disable_tcp_nagle(fd);
	std::string serial = android::base::StringPrintf("emulator-%d", console_port);
	register_socket_transport(fd, serial.c_str(), adb_port, 1);
	return 0;
	}
	return -1;
	}


	static void client_socket_thread(void x)
	{
	#if ADB_HOST
	int port = DEFAULT_ADB_LOCAL_TRANSPORT_PORT;
	int count = ADB_LOCAL_TRANSPORT_MAX;

	D("transport: client_socket_thread() starting\n");

	/* try to connect to any number of running emulator instances */
	/* this is only done when ADB starts up. later, each new emulator */
	/* will send a message to ADB to indicate that is is starting up */
	for ( ; count > 0; count--, port += 2 ) {
	(void) local_connect(port);
	}
	#endif
	return 0;
	}

	static void server_socket_thread(void arg)
	{
	int serverfd, fd;
	struct sockaddr addr;
	socklen_t alen;
	int port = (int) (uintptr_t) arg;

	D("transport: server_socket_thread() starting\n");
	serverfd = -1;
	for(;;) {
	if(serverfd == -1) {
	serverfd = socket_inaddr_any_server(port, SOCK_STREAM);
	if(serverfd < 0) {
	D("server: cannot bind socket yet: %s\n", strerror(errno));
	adb_sleep_ms(1000);
	continue;
	}
	close_on_exec(serverfd);
	}

	alen = sizeof(addr);
	D("server: trying to get new connection from %d\n", port);
	fd = adb_socket_accept(serverfd, &addr, &alen);
	if(fd >= 0) {
	D("server: new connection on fd %d\n", fd);
	close_on_exec(fd);
	disable_tcp_nagle(fd);
	register_socket_transport(fd, "host", port, 1);
	}
	}
	D("transport: server_socket_thread() exiting\n");
	return 0;
	}

	/* This is relevant only for ADB daemon running inside the emulator. */
	#if !ADB_HOST
	/*
	* Redefine open and write for qemu_pipe.h that contains inlined references
	* to those routines. We will redifine them back after qemu_pipe.h inclusion.
	*/
	#undef open
	#undef write
	#define open adb_open
	#define write adb_write
	#include <hardware/qemu_pipe.h>
	#undef open
	#undef write
	#define open ___xxx_open
	#define write ___xxx_write

	/* A worker thread that monitors host connections, and registers a transport for
	* every new host connection. This thread replaces server_socket_thread on
	* condition that adbd daemon runs inside the emulator, and emulator uses QEMUD
	* pipe to communicate with adbd daemon inside the guest. This is done in order
	* to provide more robust communication channel between ADB host and guest. The
	* main issue with server_socket_thread approach is that it runs on top of TCP,
	* and thus is sensitive to network disruptions. For instance, the
	* ConnectionManager may decide to reset all network connections, in which case
	* the connection between ADB host and guest will be lost. To make ADB traffic
	* independent from the network, we use here 'adb' QEMUD service to transfer data
	* between the host, and the guest. See external/qemu/android/adb-. that
	* implements the emulator's side of the protocol. Another advantage of using
	* QEMUD approach is that ADB will be up much sooner, since it doesn't depend
	* anymore on network being set up.
	* The guest side of the protocol contains the following phases:
	* - Connect with adb QEMUD service. In this phase a handle to 'adb' QEMUD service
	* is opened, and it becomes clear whether or not emulator supports that
	* protocol.
	* - Wait for the ADB host to create connection with the guest. This is done by
	* sending an 'accept' request to the adb QEMUD service, and waiting on
	* response.
	* - When new ADB host connection is accepted, the connection with adb QEMUD
	* service is registered as the transport, and a 'start' request is sent to the
	* adb QEMUD service, indicating that the guest is ready to receive messages.
	* Note that the guest will ignore messages sent down from the emulator before
	* the transport registration is completed. That's why we need to send the
	* 'start' request after the transport is registered.
	*/
	static void qemu_socket_thread(void arg)
	{
	/* 'accept' request to the adb QEMUD service. */
	static const char _accept_req[] = "accept";
	/* 'start' request to the adb QEMUD service. */
	static const char _start_req[] = "start";
	/* 'ok' reply from the adb QEMUD service. */
	static const char _ok_resp[] = "ok";

	const int port = (int) (uintptr_t) arg;
	int res, fd;
	char tmp[256];
	char con_name[32];

	D("transport: qemu_socket_thread() starting\n");

	/* adb QEMUD service connection request. */
	snprintf(con_name, sizeof(con_name), "qemud:adb:%d", port);

	/* Connect to the adb QEMUD service. */
	fd = qemu_pipe_open(con_name);
	if (fd < 0) {
	/* This could be an older version of the emulator, that doesn't
	* implement adb QEMUD service. Fall back to the old TCP way. */
	D("adb service is not available. Falling back to TCP socket.\n");
	adb_thread_create(server_socket_thread, arg);
	return 0;
	}

	for(;;) {
	/*
	* Wait till the host creates a new connection.
	*/

	/* Send the 'accept' request. */
	res = adb_write(fd, _accept_req, strlen(_accept_req));
	if ((size_t)res == strlen(_accept_req)) {
	/* Wait for the response. In the response we expect 'ok' on success,
	* or 'ko' on failure. */
	res = adb_read(fd, tmp, sizeof(tmp));
	if (res != 2 \|\| memcmp(tmp, _ok_resp, 2)) {
	D("Accepting ADB host connection has failed.\n");
	adb_close(fd);
	} else {
	/* Host is connected. Register the transport, and start the
	* exchange. */
	register_socket_transport(fd, "host", port, 1);
	adb_write(fd, _start_req, strlen(_start_req));
	}

	/* Prepare for accepting of the next ADB host connection. */
	fd = qemu_pipe_open(con_name);
	if (fd < 0) {
	D("adb service become unavailable.\n");
	return 0;
	}
	} else {
	D("Unable to send the '%s' request to ADB service.\n", _accept_req);
	return 0;
	}
	}
	D("transport: qemu_socket_thread() exiting\n");
	return 0;
	}
	#endif // !ADB_HOST

	void local_init(int port)
	{
	void* (func)(void );

	if(HOST) {
	func = client_socket_thread;
	} else {
	#if ADB_HOST
	func = server_socket_thread;
	#else
	/* For the adbd daemon in the system image we need to distinguish
	* between the device, and the emulator. */
	char is_qemu[PROPERTY_VALUE_MAX];
	property_get("ro.kernel.qemu", is_qemu, "");
	if (!strcmp(is_qemu, "1")) {
	/* Running inside the emulator: use QEMUD pipe as the transport. */
	func = qemu_socket_thread;
	} else {
	/* Running inside the device: use TCP socket as the transport. */
	func = server_socket_thread;
	}
	#endif // !ADB_HOST
	}

	D("transport: local %s init\n", HOST ? "client" : "server");

	if (!adb_thread_create(func, (void *) (uintptr_t) port)) {
	fatal_errno("cannot create local socket %s thread", HOST ? "client" : "server");
	}
	}

	static void remote_kick(atransport *t)
	{
	int fd = t->sfd;
	t->sfd = -1;
	adb_shutdown(fd);
	adb_close(fd);

	#if ADB_HOST
	if(HOST) {
	int nn;
	adb_mutex_lock( &local_transports_lock );
	for (nn = 0; nn < ADB_LOCAL_TRANSPORT_MAX; nn++) {
	if (local_transports[nn] == t) {
	local_transports[nn] = NULL;
	break;
	}
	}
	adb_mutex_unlock( &local_transports_lock );
	}
	#endif
	}

	static void remote_close(atransport *t)
	{
	adb_close(t->fd);
	}


	#if ADB_HOST
	/* Only call this function if you already hold local_transports_lock. */
	atransport* find_emulator_transport_by_adb_port_locked(int adb_port)
	{
	int i;
	for (i = 0; i < ADB_LOCAL_TRANSPORT_MAX; i++) {
	if (local_transports[i] && local_transports[i]->adb_port == adb_port) {
	return local_transports[i];
	}
	}
	return NULL;
	}

	atransport* find_emulator_transport_by_adb_port(int adb_port)
	{
	adb_mutex_lock( &local_transports_lock );
	atransport* result = find_emulator_transport_by_adb_port_locked(adb_port);
	adb_mutex_unlock( &local_transports_lock );
	return result;
	}

	/* Only call this function if you already hold local_transports_lock. */
	int get_available_local_transport_index_locked()
	{
	int i;
	for (i = 0; i < ADB_LOCAL_TRANSPORT_MAX; i++) {
	if (local_transports[i] == NULL) {
	return i;
	}
	}
	return -1;
	}

	int get_available_local_transport_index()
	{
	adb_mutex_lock( &local_transports_lock );
	int result = get_available_local_transport_index_locked();
	adb_mutex_unlock( &local_transports_lock );
	return result;
	}
	#endif

	int init_socket_transport(atransport *t, int s, int adb_port, int local)
	{
	int fail = 0;

	t->kick = remote_kick;
	t->close = remote_close;
	t->read_from_remote = remote_read;
	t->write_to_remote = remote_write;
	t->sfd = s;
	t->sync_token = 1;
	t->connection_state = CS_OFFLINE;
	t->type = kTransportLocal;
	t->adb_port = 0;

	#if ADB_HOST
	if (HOST && local) {
	adb_mutex_lock( &local_transports_lock );
	{
	t->adb_port = adb_port;
	atransport* existing_transport =
	find_emulator_transport_by_adb_port_locked(adb_port);
	int index = get_available_local_transport_index_locked();
	if (existing_transport != NULL) {
	D("local transport for port %d already registered (%p)?\n",
	adb_port, existing_transport);
	fail = -1;
	} else if (index < 0) {
	// Too many emulators.
	D("cannot register more emulators. Maximum is %d\n",
	ADB_LOCAL_TRANSPORT_MAX);
	fail = -1;
	} else {
	local_transports[index] = t;
	}
	}
	adb_mutex_unlock( &local_transports_lock );
	}
	#endif
	return fail;
	}