From 880be434a9ec197100fe5c6f0b299353d13b916b Mon Sep 17 00:00:00 2001
From: David Pursell <dpursell@google.com>
Date: Fri, 4 Sep 2015 16:40:30 -0700
Subject: [PATCH] adb: `features` passes transport features.

`adb features` previously returned a list of host features which was
not terribly useful. This CL changes functionality to return the
transport features instead using the standard targeting args:
  $ adb features  # default target.
  $ adb -e features
  $ adb -s 123456 features

Also adds a "check-feature" service which is currently unused but will
allow the adb client to easily check for a specific feature.

Bug: http://b/23824036
Change-Id: Ibc0c420c75f73d363f3bba7705af616ba2059348
---
 adb/adb.cpp         | 24 +++++++++++++++++++++---
 adb/commandline.cpp |  2 +-
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/adb/adb.cpp b/adb/adb.cpp
index 14df8a152..dcb6424ec 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -1132,9 +1132,27 @@ int handle_host_request(const char* service, TransportType type,
     }
 
     if (!strcmp(service, "features")) {
-        SendOkay(reply_fd);
-        SendProtocolString(
-            reply_fd, android::base::Join(supported_features(), '\n'));
+        std::string error_msg;
+        atransport* t = acquire_one_transport(kCsAny, type, serial, &error_msg);
+        if (t != nullptr) {
+            SendOkay(reply_fd, android::base::Join(t->features(), '\n'));
+        } else {
+            SendFail(reply_fd, error_msg);
+        }
+        return 0;
+    }
+
+    if (!strncmp(service, "check-feature:", strlen("check-feature:"))) {
+        std::string error_msg;
+        atransport* t = acquire_one_transport(kCsAny, type, serial, &error_msg);
+        if (t && t->CanUseFeature(service + strlen("check-feature:"))) {
+            // We could potentially extend this to reply with the feature
+            // version if that becomes necessary.
+            SendOkay(reply_fd, "1");
+        } else {
+            // Empty response means unsupported feature.
+            SendOkay(reply_fd, "");
+        }
         return 0;
     }
 
diff --git a/adb/commandline.cpp b/adb/commandline.cpp
index 86f926343..4fe0c2588 100644
--- a/adb/commandline.cpp
+++ b/adb/commandline.cpp
@@ -1444,7 +1444,7 @@ int adb_commandline(int argc, const char **argv) {
         return 0;
     }
     else if (!strcmp(argv[0], "features")) {
-        return adb_query_command("host:features");
+        return adb_query_command(format_host_command("features", transport_type, serial));
     }
 
     usage();