Use 0 to represent unexpired license in OnExpirationUpdate

Also fix a missing change for
"playback duration should override license duration".

Merged from Widevine CDM repo:
https://widevine-internal-review.googlesource.com/#/c/14435/

Bug: 21393975
Change-Id: Ibfcf3ae4c13db8944ea285bcc79b6312ea621e1b

libwvdrmengine/cdm/core/include/policy_engine.h

@@ -66,13 +66,6 @@ class PolicyEngine {
 
   virtual const LicenseIdentification& license_id() { return license_id_; }
 
-  bool IsLicenseDurationExpired(int64_t current_time) {
-    return GetLicenseExpiryTime() <= current_time;
-  }
-  bool IsPlaybackDurationExpired(int64_t current_time) {
-    return GetPlaybackExpiryTime() <= current_time;
-  }
-
   bool GetSecondsSinceStarted(int64_t* seconds_since_started);
   bool GetSecondsSinceLastPlayed(int64_t* seconds_since_started);
 
@@ -85,6 +78,8 @@ class PolicyEngine {
   bool IsLicenseForFuture() { return license_state_ == kLicenseStatePending; }
   bool IsPlaybackStarted() { return playback_start_time_ > 0; }
 
+  bool IsLicenseOrPlaybackDurationExpired(int64_t current_time);
+
  private:
   friend class PolicyEngineTest;
 
@@ -139,6 +134,7 @@ class PolicyEngine {
   int64_t playback_start_time_;
   int64_t last_playback_time_;
   int64_t last_expiry_time_;
+  bool last_expiry_time_set_;
 
   // This is used as a reference point for policy management. This value
   // represents an offset from license_start_time_. This is used to

libwvdrmengine/cdm/core/include/wv_cdm_constants.h

@@ -3,8 +3,6 @@
 #ifndef WVCDM_CORE_WV_CDM_CONSTANTS_H_
 #define WVCDM_CORE_WV_CDM_CONSTANTS_H_
 
-#include <limits.h>
-
 #include <string>
 
 namespace wvcdm {
@@ -16,7 +14,9 @@ static const size_t KEY_SIZE = 16;
 static const size_t MAC_KEY_SIZE = 32;
 static const size_t KEYBOX_KEY_DATA_SIZE = 72;
 
-static const int64_t NEVER_EXPIRES = LLONG_MAX;
+// Use 0 to represent never expired license as specified in EME spec
+// (NaN in JS translates to 0 in unix timestamp).
+static const int64_t NEVER_EXPIRES = 0;
 
 static const char SESSION_ID_PREFIX[] = "sid";
 static const char KEY_SET_ID_PREFIX[] = "ksid";

libwvdrmengine/cdm/core/include/wv_cdm_event_listener.h

@@ -17,6 +17,8 @@ class WvCdmEventListener {
   virtual void OnSessionKeysChange(const CdmSessionId& session_id,
                                    const CdmKeyStatusMap& keys_status,
                                    bool has_new_usable_key) = 0;
+  // Note that a |new_expiry_time_seconds| of 0 represents never expired
+  // license.
   virtual void OnExpirationUpdate(const CdmSessionId& session_id,
                                   int64_t new_expiry_time_seconds) = 0;
 

libwvdrmengine/cdm/core/src/cdm_session.cpp

@@ -348,8 +348,7 @@ CdmResponseType CdmSession::Decrypt(const CdmDecryptionParameters& params) {
   } else {
     Clock clock;
     int64_t current_time = clock.GetCurrentTime();
-    if (policy_engine_->IsLicenseDurationExpired(current_time) ||
-        policy_engine_->IsPlaybackDurationExpired(current_time)) {
+    if (policy_engine_->IsLicenseOrPlaybackDurationExpired(current_time)) {
       return NEED_KEY;
     }
   }

libwvdrmengine/cdm/core/src/policy_engine.cpp

@@ -27,6 +27,7 @@ PolicyEngine::PolicyEngine(CdmSessionId session_id,
       playback_start_time_(0),
       last_playback_time_(0),
       last_expiry_time_(0),
+      last_expiry_time_set_(false),
       next_renewal_time_(0),
       policy_max_duration_seconds_(0),
       session_id_(session_id),
@@ -49,8 +50,7 @@ void PolicyEngine::OnTimerEvent() {
   int64_t current_time = clock_->GetCurrentTime();
 
   // License expiration trumps all.
-  if ((IsPlaybackDurationExpired(current_time) ||
-      (IsLicenseDurationExpired(current_time) && !IsPlaybackStarted())) &&
+  if (IsLicenseOrPlaybackDurationExpired(current_time) &&
       license_state_ != kLicenseStateExpired) {
     license_state_ = kLicenseStateExpired;
     NotifyKeysChange(kKeyStatusExpired);
@@ -164,8 +164,7 @@ void PolicyEngine::UpdateLicense(const License& license) {
   }
 
   int64_t current_time = clock_->GetCurrentTime();
-  if (!policy_.can_play() || IsPlaybackDurationExpired(current_time) ||
-      (IsLicenseDurationExpired(current_time) && !IsPlaybackStarted())) {
+  if (!policy_.can_play() || IsLicenseOrPlaybackDurationExpired(current_time)) {
     license_state_ = kLicenseStateExpired;
     NotifyKeysChange(kKeyStatusExpired);
     return;
@@ -274,6 +273,12 @@ void PolicyEngine::UpdateRenewalRequest(int64_t current_time) {
   next_renewal_time_ = current_time + policy_.renewal_retry_interval_seconds();
 }
 
+bool PolicyEngine::IsLicenseOrPlaybackDurationExpired(int64_t current_time) {
+  int64_t expiry_time =
+      IsPlaybackStarted() ? GetPlaybackExpiryTime() : GetLicenseExpiryTime();
+  return (expiry_time == NEVER_EXPIRES) ? false : (expiry_time <= current_time);
+}
+
 // For the policy time fields checked in the following methods, a value of 0
 // indicates that there is no limit to the duration. These methods
 // will always return false if the value is 0.
@@ -290,16 +295,21 @@ int64_t PolicyEngine::GetPlaybackExpiryTime() {
 }
 
 int64_t PolicyEngine::GetLicenseDurationRemaining(int64_t current_time) {
-  if (policy_max_duration_seconds_ == 0) return LLONG_MAX;
   int64_t license_expiry_time = GetLicenseExpiryTime();
+  if (license_expiry_time == NEVER_EXPIRES) return LLONG_MAX;
   if (license_expiry_time < current_time) return 0;
   return std::min(license_expiry_time - current_time,
                   policy_max_duration_seconds_);
 }
 
 int64_t PolicyEngine::GetPlaybackDurationRemaining(int64_t current_time) {
-  if (policy_.playback_duration_seconds() == 0) return LLONG_MAX;
   int64_t playback_expiry_time = GetPlaybackExpiryTime();
+  if (playback_expiry_time == NEVER_EXPIRES) {
+    return (policy_.playback_duration_seconds() != 0)
+               ? policy_.playback_duration_seconds()
+               : LLONG_MAX;
+  }
+
   if (playback_expiry_time < current_time) return 0;
   return std::min(playback_expiry_time - current_time,
                   policy_.playback_duration_seconds());
@@ -348,14 +358,14 @@ void PolicyEngine::NotifyKeysChange(CdmKeyStatus new_status) {
 }
 
 void PolicyEngine::NotifyExpirationUpdate() {
-  int64_t expiry_time = IsPlaybackStarted() ? GetPlaybackExpiryTime()
-                                            : std::min(GetLicenseExpiryTime(),
-                                                       GetPlaybackExpiryTime());
-  if (expiry_time != last_expiry_time_) {
+  int64_t expiry_time =
+      IsPlaybackStarted() ? GetPlaybackExpiryTime() : GetLicenseExpiryTime();
+  if (!last_expiry_time_set_ || expiry_time != last_expiry_time_) {
     last_expiry_time_ = expiry_time;
     if (event_listener_)
       event_listener_->OnExpirationUpdate(session_id_, expiry_time);
   }
+  last_expiry_time_set_ = true;
 }
 
 void PolicyEngine::set_clock(Clock* clock) { clock_.reset(clock); }