adb: allow selection of a specific transport.

Extend device selection to allow selecting a specific transport via
monotonically increasing identifier (visible in devices -l).

This is useful when using multiple devices (like hikey960...) that
have identical bogus serial numbers like 0123456789ABCDEF.

Bug: http://b/37043226
Test: adb -t {1, 2, 9999999} {get-serialno, shell, features}
Change-Id: I55e5dc5a406a4eeee0012e39b52e8cd232e608a6
diff --git a/transport.cpp b/transport.cpp
index c26252e..91d708f 100644
--- a/transport.cpp
+++ b/transport.cpp
@@ -21,6 +21,7 @@
 
 #include <ctype.h>
 #include <errno.h>
+#include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -36,6 +37,7 @@
 #include <android-base/quick_exit.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
+#include <android-base/thread_annotations.h>
 
 #include "adb.h"
 #include "adb_auth.h"
@@ -46,6 +48,7 @@
 
 static void transport_unref(atransport *t);
 
+// TODO: unordered_map<TransportId, atransport*>
 static auto& transport_list = *new std::list<atransport*>();
 static auto& pending_list = *new std::list<atransport*>();
 
@@ -57,6 +60,11 @@
 const char* const kFeatureLibusb = "libusb";
 const char* const kFeaturePushSync = "push_sync";
 
+TransportId NextTransportId() {
+    static std::atomic<TransportId> next(1);
+    return next++;
+}
+
 static std::string dump_packet(const char* name, const char* func, apacket* p) {
     unsigned command = p->msg.command;
     int len = p->msg.data_length;
@@ -301,6 +309,8 @@
     std::lock_guard<std::recursive_mutex> lock(transport_lock);
     // As kick_transport() can be called from threads without guarantee that t is valid,
     // check if the transport is in transport_list first.
+    //
+    // TODO(jmgao): WTF? Is this actually true?
     if (std::find(transport_list.begin(), transport_list.end(), t) != transport_list.end()) {
         t->Kick();
     }
@@ -638,11 +648,15 @@
     return !*to_test;
 }
 
-atransport* acquire_one_transport(TransportType type, const char* serial, bool* is_ambiguous,
-                                  std::string* error_out, bool accept_any_state) {
+atransport* acquire_one_transport(TransportType type, const char* serial, TransportId transport_id,
+                                  bool* is_ambiguous, std::string* error_out,
+                                  bool accept_any_state) {
     atransport* result = nullptr;
 
-    if (serial) {
+    if (transport_id != 0) {
+        *error_out =
+            android::base::StringPrintf("no device with transport id '%" PRIu64 "'", transport_id);
+    } else if (serial) {
         *error_out = android::base::StringPrintf("device '%s' not found", serial);
     } else if (type == kTransportLocal) {
         *error_out = "no emulators found";
@@ -661,8 +675,12 @@
             continue;
         }
 
-        // Check for matching serial number.
-        if (serial) {
+        if (transport_id) {
+            if (t->id == transport_id) {
+                result = t;
+                break;
+            }
+        } else if (serial) {
             if (t->MatchesTarget(serial)) {
                 if (result) {
                     *error_out = "more than one device";
@@ -889,18 +907,23 @@
 
 #if ADB_HOST
 
+// We use newline as our delimiter, make sure to never output it.
+static std::string sanitize(std::string str, bool alphanumeric) {
+    auto pred = alphanumeric ? [](const char c) { return !isalnum(c); }
+                             : [](const char c) { return c == '\n'; };
+    std::replace_if(str.begin(), str.end(), pred, '_');
+    return str;
+}
+
 static void append_transport_info(std::string* result, const char* key, const char* value,
-                                  bool sanitize) {
+                                  bool alphanumeric) {
     if (value == nullptr || *value == '\0') {
         return;
     }
 
     *result += ' ';
     *result += key;
-
-    for (const char* p = value; *p; ++p) {
-        result->push_back((!sanitize || isalnum(*p)) ? *p : '_');
-    }
+    *result += sanitize(value, alphanumeric);
 }
 
 static void append_transport(const atransport* t, std::string* result, bool long_listing) {
@@ -920,6 +943,11 @@
         append_transport_info(result, "product:", t->product, false);
         append_transport_info(result, "model:", t->model, true);
         append_transport_info(result, "device:", t->device, false);
+
+        // Put id at the end, so that anyone parsing the output here can always find it by scanning
+        // backwards from newlines, even with hypothetical devices named 'transport_id:1'.
+        *result += " transport_id:";
+        *result += std::to_string(t->id);
     }
     *result += '\n';
 }