From b340bb56044c125a5b8bed939b78a14a9b94bdcc Mon Sep 17 00:00:00 2001
From: Ningyuan Wang <nywang@google.com>
Date: Tue, 4 Apr 2017 16:21:44 -0700
Subject: [PATCH] Allow wificond to dump logs

This adds the dump() function for wificond to dump logs
to provided fd.

Bug: 31336376
Test: compile
Test: manual test, see wificond dump logs in bug report

Change-Id: Ia27cee9c14728095d9843dfc08994ec981283ee3
---
 server.cpp | 30 ++++++++++++++++++++++++++++++
 server.h   |  1 +
 2 files changed, 31 insertions(+)

diff --git a/server.cpp b/server.cpp
index e8c56c6..434b44a 100644
--- a/server.cpp
+++ b/server.cpp
@@ -18,11 +18,15 @@
 
 #include <sstream>
 
+#include <android-base/file.h>
 #include <android-base/logging.h>
+#include <binder/IPCThreadState.h>
+#include <binder/PermissionCache.h>
 
 #include "wificond/net/netlink_utils.h"
 #include "wificond/scanning/scan_utils.h"
 
+using android::base::WriteStringToFd;
 using android::binder::Status;
 using android::sp;
 using android::IBinder;
@@ -35,6 +39,7 @@ using android::wifi_system::HostapdManager;
 using android::wifi_system::InterfaceTool;
 using android::wifi_system::SupplicantManager;
 
+using std::endl;
 using std::placeholders::_1;
 using std::string;
 using std::stringstream;
@@ -44,6 +49,12 @@ using std::vector;
 namespace android {
 namespace wificond {
 
+namespace {
+
+constexpr const char* kPermissionDump = "android.permission.DUMP";
+
+}  // namespace
+
 Server::Server(unique_ptr<InterfaceTool> if_tool,
                unique_ptr<SupplicantManager> supplicant_manager,
                unique_ptr<HostapdManager> hostapd_manager,
@@ -177,6 +188,25 @@ Status Server::GetApInterfaces(vector<sp<IBinder>>* out_ap_interfaces) {
   return binder::Status::ok();
 }
 
+status_t Server::dump(int fd, const Vector<String16>& /*args*/) {
+  if (!PermissionCache::checkCallingPermission(String16(kPermissionDump))) {
+    IPCThreadState* ipc = android::IPCThreadState::self();
+    LOG(ERROR) << "Caller (uid: " << ipc->getCallingUid()
+               << ") is not permitted to dump wificond state";
+    return PERMISSION_DENIED;
+  }
+
+  stringstream ss;
+  ss << "Current wiphy index: " << wiphy_index_ << endl;
+
+  if (!WriteStringToFd(ss.str(), fd)) {
+    PLOG(ERROR) << "Failed to dump state to fd " << fd;
+    return FAILED_TRANSACTION;
+  }
+
+  return OK;
+}
+
 void Server::MarkDownAllInterfaces() {
   uint32_t wiphy_index;
   vector<InterfaceInfo> interfaces;
diff --git a/server.h b/server.h
index a0f5b2c..f4f71d9 100644
--- a/server.h
+++ b/server.h
@@ -81,6 +81,7 @@ class Server : public android::net::wifi::BnWificond {
       std::vector<android::sp<android::IBinder>>* out_client_ifs) override;
   android::binder::Status GetApInterfaces(
       std::vector<android::sp<android::IBinder>>* out_ap_ifs) override;
+  status_t dump(int fd, const Vector<String16>& args) override;
 
   // Call this once on startup.  It ignores all the invariants held
   // in wificond and tries to restore ourselves to a blank state by
-- 
2.11.0