adb: clean up handle_host_request.

Previously, we were returning the result of SendOkay/SendFail in a few
places after handling a host request, which is incorrect for two
reasons. First, the return type of SendOkay/SendFail is bool, and
handle_host_request was expected to return 0 on success. Second, we
don't care if the SendOkay fails; if we got to that point, we're done
with the request, regardless of whether we succeeded to report our
result. The result of this was a spurious failure result reported after
the initial result, which was ignored by the adb client.

Test: manually straced adb server
Test: python test_adb.py
Test: python test_device.py
Change-Id: I7d45ba527e1faccbbae5b15e7a0d1557b0a84858
diff --git a/adb/adb.cpp b/adb/adb.cpp
index a8fe736..8e028f4 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -1044,7 +1044,7 @@
     return 0;
 }
 
-int handle_host_request(const char* service, TransportType type, const char* serial,
+bool handle_host_request(const char* service, TransportType type, const char* serial,
                         TransportId transport_id, int reply_fd, asocket* s) {
     if (strcmp(service, "kill") == 0) {
         fprintf(stderr, "adb server killed by remote request\n");
@@ -1070,7 +1070,7 @@
             transport_id = strtoll(service, const_cast<char**>(&service), 10);
             if (*service != '\0') {
                 SendFail(reply_fd, "invalid transport id");
-                return 1;
+                return true;
             }
         } else if (!strncmp(service, "transport-usb", strlen("transport-usb"))) {
             type = kTransportUsb;
@@ -1088,10 +1088,13 @@
         if (t != nullptr) {
             s->transport = t;
             SendOkay(reply_fd);
+
+            // We succesfully handled the device selection, but there's another request coming.
+            return false;
         } else {
             SendFail(reply_fd, error);
+            return true;
         }
-        return 1;
     }
 
     // return a list of all connected devices
@@ -1101,9 +1104,9 @@
             D("Getting device list...");
             std::string device_list = list_transports(long_listing);
             D("Sending device list...");
-            return SendOkay(reply_fd, device_list);
+            SendOkay(reply_fd, device_list);
         }
-        return 1;
+        return true;
     }
 
     if (!strcmp(service, "reconnect-offline")) {
@@ -1119,7 +1122,7 @@
             response.resize(response.size() - 1);
         }
         SendOkay(reply_fd, response);
-        return 0;
+        return true;
     }
 
     if (!strcmp(service, "features")) {
@@ -1130,7 +1133,7 @@
         } else {
             SendFail(reply_fd, error);
         }
-        return 0;
+        return true;
     }
 
     if (!strcmp(service, "host-features")) {
@@ -1141,7 +1144,7 @@
         }
         features.insert(kFeaturePushSync);
         SendOkay(reply_fd, FeatureSetToString(features));
-        return 0;
+        return true;
     }
 
     // remove TCP transport
@@ -1149,7 +1152,8 @@
         const std::string address(service + 11);
         if (address.empty()) {
             kick_all_tcp_devices();
-            return SendOkay(reply_fd, "disconnected everything");
+            SendOkay(reply_fd, "disconnected everything");
+            return true;
         }
 
         std::string serial;
@@ -1157,21 +1161,24 @@
         int port = DEFAULT_ADB_LOCAL_TRANSPORT_PORT;
         std::string error;
         if (!android::base::ParseNetAddress(address, &host, &port, &serial, &error)) {
-            return SendFail(reply_fd, android::base::StringPrintf("couldn't parse '%s': %s",
-                                                                  address.c_str(), error.c_str()));
+            SendFail(reply_fd, android::base::StringPrintf("couldn't parse '%s': %s",
+                                                           address.c_str(), error.c_str()));
+            return true;
         }
         atransport* t = find_transport(serial.c_str());
         if (t == nullptr) {
-            return SendFail(reply_fd, android::base::StringPrintf("no such device '%s'",
-                                                                  serial.c_str()));
+            SendFail(reply_fd, android::base::StringPrintf("no such device '%s'", serial.c_str()));
+            return true;
         }
         kick_transport(t);
-        return SendOkay(reply_fd, android::base::StringPrintf("disconnected %s", address.c_str()));
+        SendOkay(reply_fd, android::base::StringPrintf("disconnected %s", address.c_str()));
+        return true;
     }
 
     // Returns our value for ADB_SERVER_VERSION.
     if (!strcmp(service, "version")) {
-        return SendOkay(reply_fd, android::base::StringPrintf("%04x", ADB_SERVER_VERSION));
+        SendOkay(reply_fd, android::base::StringPrintf("%04x", ADB_SERVER_VERSION));
+        return true;
     }
 
     // These always report "unknown" rather than the actual error, for scripts.
@@ -1179,28 +1186,31 @@
         std::string error;
         atransport* t = acquire_one_transport(type, serial, transport_id, nullptr, &error);
         if (t) {
-            return SendOkay(reply_fd, !t->serial.empty() ? t->serial : "unknown");
+            SendOkay(reply_fd, !t->serial.empty() ? t->serial : "unknown");
         } else {
-            return SendFail(reply_fd, error);
+            SendFail(reply_fd, error);
         }
+        return true;
     }
     if (!strcmp(service, "get-devpath")) {
         std::string error;
         atransport* t = acquire_one_transport(type, serial, transport_id, nullptr, &error);
         if (t) {
-            return SendOkay(reply_fd, !t->devpath.empty() ? t->devpath : "unknown");
+            SendOkay(reply_fd, !t->devpath.empty() ? t->devpath : "unknown");
         } else {
-            return SendFail(reply_fd, error);
+            SendFail(reply_fd, error);
         }
+        return true;
     }
     if (!strcmp(service, "get-state")) {
         std::string error;
         atransport* t = acquire_one_transport(type, serial, transport_id, nullptr, &error);
         if (t) {
-            return SendOkay(reply_fd, t->connection_state_name());
+            SendOkay(reply_fd, t->connection_state_name());
         } else {
-            return SendFail(reply_fd, error);
+            SendFail(reply_fd, error);
         }
+        return true;
     }
 
     // Indicates a new emulator instance has started.
@@ -1208,7 +1218,7 @@
         int  port = atoi(service+9);
         local_connect(port);
         /* we don't even need to send a reply */
-        return 0;
+        return true;
     }
 
     if (!strcmp(service, "reconnect")) {
@@ -1219,7 +1229,8 @@
             response =
                 "reconnecting " + t->serial_name() + " [" + t->connection_state_name() + "]\n";
         }
-        return SendOkay(reply_fd, response);
+        SendOkay(reply_fd, response);
+        return true;
     }
 
     if (handle_forward_request(service,
@@ -1228,10 +1239,10 @@
                                                                 error);
                                },
                                reply_fd)) {
-        return 0;
+        return true;
     }
 
-    return -1;
+    return false;
 }
 
 static auto& init_mutex = *new std::mutex();
diff --git a/adb/adb.h b/adb/adb.h
index e6af780..f434e2d 100644
--- a/adb/adb.h
+++ b/adb/adb.h
@@ -210,8 +210,8 @@
 #define USB_FFS_ADB_IN USB_FFS_ADB_EP(ep2)
 #endif
 
-int handle_host_request(const char* service, TransportType type, const char* serial,
-                        TransportId transport_id, int reply_fd, asocket* s);
+bool handle_host_request(const char* service, TransportType type, const char* serial,
+                         TransportId transport_id, int reply_fd, asocket* s);
 
 void handle_online(atransport* t);
 void handle_offline(atransport* t);
diff --git a/adb/sockets.cpp b/adb/sockets.cpp
index 69b5180..1534792 100644
--- a/adb/sockets.cpp
+++ b/adb/sockets.cpp
@@ -685,13 +685,9 @@
     if (service) {
         asocket* s2;
 
-        /* some requests are handled immediately -- in that
-        ** case the handle_host_request() routine has sent
-        ** the OKAY or FAIL message and all we have to do
-        ** is clean up.
-        */
-        if (handle_host_request(service, type, serial, transport_id, s->peer->fd, s) == 0) {
-            /* XXX fail message? */
+        // Some requests are handled immediately -- in that case the handle_host_request() routine
+        // has sent the OKAY or FAIL message and all we have to do is clean up.
+        if (handle_host_request(service, type, serial, transport_id, s->peer->fd, s)) {
             D("SS(%d): handled host service '%s'", s->id, service);
             goto fail;
         }