diff --git a/adb/adb.cpp b/adb/adb.cpp
index 6a0540c..2e59634 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -835,6 +835,14 @@
     return 0;
 }
 
+#if ADB_HOST
+static int SendOkay(int fd, const std::string& s) {
+    SendOkay(fd);
+    SendProtocolString(fd, s);
+    return 0;
+}
+#endif
+
 int handle_host_request(const char* service, TransportType type,
                         const char* serial, int reply_fd, asocket* s) {
     if (strcmp(service, "kill") == 0) {
@@ -845,7 +853,6 @@
     }
 
 #if ADB_HOST
-    atransport *transport = NULL;
     // "transport:" is used for switching transport with a specified serial number
     // "transport-usb:" is used for switching transport to the only USB transport
     // "transport-local:" is used for switching transport to the only local transport
@@ -864,11 +871,10 @@
             serial = service;
         }
 
-        std::string error_msg = "unknown failure";
-        transport = acquire_one_transport(kCsAny, type, serial, &error_msg);
-
-        if (transport) {
-            s->transport = transport;
+        std::string error_msg;
+        atransport* t = acquire_one_transport(kCsAny, type, serial, &error_msg);
+        if (t != nullptr) {
+            s->transport = t;
             SendOkay(reply_fd);
         } else {
             SendFail(reply_fd, error_msg);
@@ -883,9 +889,7 @@
             D("Getting device list...\n");
             std::string device_list = list_transports(long_listing);
             D("Sending device list...\n");
-            SendOkay(reply_fd);
-            SendProtocolString(reply_fd, device_list);
-            return 0;
+            return SendOkay(reply_fd, device_list);
         }
         return 1;
     }
@@ -905,8 +909,7 @@
                 snprintf(hostbuf, sizeof(hostbuf) - 1, "%s:5555", serial);
                 serial = hostbuf;
             }
-            atransport *t = find_transport(serial);
-
+            atransport* t = find_transport(serial);
             if (t) {
                 unregister_transport(t);
             } else {
@@ -914,52 +917,38 @@
             }
         }
 
-        SendOkay(reply_fd);
-        SendProtocolString(reply_fd, buffer);
-        return 0;
+        return SendOkay(reply_fd, buffer);
     }
 
     // returns our value for ADB_SERVER_VERSION
     if (!strcmp(service, "version")) {
-        SendOkay(reply_fd);
-        SendProtocolString(reply_fd, android::base::StringPrintf("%04x", ADB_SERVER_VERSION));
-        return 0;
+        return SendOkay(reply_fd, android::base::StringPrintf("%04x", ADB_SERVER_VERSION));
     }
 
-    if(!strncmp(service,"get-serialno",strlen("get-serialno"))) {
-        const char *out = "unknown";
-        transport = acquire_one_transport(kCsAny, type, serial, NULL);
-        if (transport && transport->serial) {
-            out = transport->serial;
-        }
-        SendOkay(reply_fd);
-        SendProtocolString(reply_fd, out);
-        return 0;
+    // These always report "unknown" rather than the actual error, for scripts.
+    if (!strcmp(service, "get-serialno")) {
+        std::string ignored;
+        atransport* t = acquire_one_transport(kCsAny, type, serial, &ignored);
+        return SendOkay(reply_fd, (t && t->serial) ? t->serial : "unknown");
     }
-    if(!strncmp(service,"get-devpath",strlen("get-devpath"))) {
-        const char *out = "unknown";
-        transport = acquire_one_transport(kCsAny, type, serial, NULL);
-        if (transport && transport->devpath) {
-            out = transport->devpath;
-        }
-        SendOkay(reply_fd);
-        SendProtocolString(reply_fd, out);
-        return 0;
+    if (!strcmp(service, "get-devpath")) {
+        std::string ignored;
+        atransport* t = acquire_one_transport(kCsAny, type, serial, &ignored);
+        return SendOkay(reply_fd, (t && t->devpath) ? t->devpath : "unknown");
     }
+    if (!strcmp(service, "get-state")) {
+        std::string ignored;
+        atransport* t = acquire_one_transport(kCsAny, type, serial, &ignored);
+        return SendOkay(reply_fd, t ? t->connection_state_name() : "unknown");
+    }
+
     // indicates a new emulator instance has started
-    if (!strncmp(service,"emulator:",9)) {
+    if (!strncmp(service, "emulator:", 9)) {
         int  port = atoi(service+9);
         local_connect(port);
         /* we don't even need to send a reply */
         return 0;
     }
-
-    if(!strncmp(service,"get-state",strlen("get-state"))) {
-        transport = acquire_one_transport(kCsAny, type, serial, NULL);
-        SendOkay(reply_fd);
-        SendProtocolString(reply_fd, transport->connection_state_name());
-        return 0;
-    }
 #endif // ADB_HOST
 
     int ret = handle_forward_request(service, type, serial, reply_fd);
diff --git a/adb/services.cpp b/adb/services.cpp
index 2fd75ab..227f22a 100644
--- a/adb/services.cpp
+++ b/adb/services.cpp
@@ -528,7 +528,7 @@
     std::string error_msg = "unknown error";
     atransport* t = acquire_one_transport(sinfo->state, sinfo->transport_type, sinfo->serial,
                                           &error_msg);
-    if (t != 0) {
+    if (t != nullptr) {
         SendOkay(fd);
     } else {
         SendFail(fd, error_msg);
diff --git a/adb/transport.cpp b/adb/transport.cpp
index 379c702..274449b 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -731,12 +731,12 @@
     int ambiguous = 0;
 
 retry:
-    if (error_out) *error_out = android::base::StringPrintf("device '%s' not found", serial);
+    *error_out = serial ? android::base::StringPrintf("device '%s' not found", serial) : "no devices found";
 
     adb_mutex_lock(&transport_lock);
     for (auto t : transport_list) {
         if (t->connection_state == kCsNoPerm) {
-            if (error_out) *error_out = "insufficient permissions for device";
+            *error_out = "insufficient permissions for device";
             continue;
         }
 
@@ -748,7 +748,7 @@
                 qual_match(serial, "model:", t->model, true) ||
                 qual_match(serial, "device:", t->device, false)) {
                 if (result) {
-                    if (error_out) *error_out = "more than one device";
+                    *error_out = "more than one device";
                     ambiguous = 1;
                     result = NULL;
                     break;
@@ -758,7 +758,7 @@
         } else {
             if (type == kTransportUsb && t->type == kTransportUsb) {
                 if (result) {
-                    if (error_out) *error_out = "more than one device";
+                    *error_out = "more than one device";
                     ambiguous = 1;
                     result = NULL;
                     break;
@@ -766,7 +766,7 @@
                 result = t;
             } else if (type == kTransportLocal && t->type == kTransportLocal) {
                 if (result) {
-                    if (error_out) *error_out = "more than one emulator";
+                    *error_out = "more than one emulator";
                     ambiguous = 1;
                     result = NULL;
                     break;
@@ -774,7 +774,7 @@
                 result = t;
             } else if (type == kTransportAny) {
                 if (result) {
-                    if (error_out) *error_out = "more than one device/emulator";
+                    *error_out = "more than one device/emulator";
                     ambiguous = 1;
                     result = NULL;
                     break;
@@ -787,33 +787,31 @@
 
     if (result) {
         if (result->connection_state == kCsUnauthorized) {
-            if (error_out) {
-                *error_out = "device unauthorized.\n";
-                char* ADB_VENDOR_KEYS = getenv("ADB_VENDOR_KEYS");
-                *error_out += "This adbd's $ADB_VENDOR_KEYS is ";
-                *error_out += ADB_VENDOR_KEYS ? ADB_VENDOR_KEYS : "not set";
-                *error_out += "; try 'adb kill-server' if that seems wrong.\n";
-                *error_out += "Otherwise check for a confirmation dialog on your device.";
-            }
+            *error_out = "device unauthorized.\n";
+            char* ADB_VENDOR_KEYS = getenv("ADB_VENDOR_KEYS");
+            *error_out += "This adbd's $ADB_VENDOR_KEYS is ";
+            *error_out += ADB_VENDOR_KEYS ? ADB_VENDOR_KEYS : "not set";
+            *error_out += "; try 'adb kill-server' if that seems wrong.\n";
+            *error_out += "Otherwise check for a confirmation dialog on your device.";
             result = NULL;
         }
 
         /* offline devices are ignored -- they are either being born or dying */
         if (result && result->connection_state == kCsOffline) {
-            if (error_out) *error_out = "device offline";
+            *error_out = "device offline";
             result = NULL;
         }
 
         /* check for required connection state */
         if (result && state != kCsAny && result->connection_state != state) {
-            if (error_out) *error_out = "invalid device state";
+            *error_out = "invalid device state";
             result = NULL;
         }
     }
 
     if (result) {
         /* found one that we can take */
-        if (error_out) *error_out = "success";
+        *error_out = "success";
     } else if (state != kCsAny && (serial || !ambiguous)) {
         adb_sleep_ms(1000);
         goto retry;