Clean up logging of device id

It helps in debugging and scanning logs if the device id is
human readable.

Bug: 299108238
Change-Id: Ib358b71514b2ddcc61bc6239ff802d87dad7d3ef

libwvdrmengine/oemcrypto/test/oemcrypto_basic_test.cpp

@@ -120,15 +120,39 @@ const char* HDCPCapabilityAsString(OEMCrypto_HDCP_Capability value) {
 // Return a printable string from data. If all the characters are printable,
 // then just use the string. Otherwise, convert to hex.
 std::string MaybeHex(const uint8_t* data, size_t length) {
-  for (size_t i = 0; i < length; i++) {
+  // Check for a early null termination. This is common for the device
+  // id in a keybox, which is padded with 0s.
+  const size_t c_len = strnlen(reinterpret_cast<const char*>(data), length);
+  // If there is any nonzero after the first zero, then just use hex.
+  for (size_t i = c_len; i < length; i++) {
+    if (data[i] != 0) return "0x" + wvutil::HexEncode(data, length);
+  }
+  for (size_t i = 0; i < c_len; i++) {
     if (!isprint(data[i])) return "0x" + wvutil::HexEncode(data, length);
   }
-  return std::string(reinterpret_cast<const char*>(data), length);
+  return std::string(reinterpret_cast<const char*>(data), c_len);
 }
+
 std::string MaybeHex(const std::vector<uint8_t>& data) {
   return MaybeHex(data.data(), data.size());
 }
 
+// Get the Device's ID and return it in a printable format.
+std::string GetDeviceId() {
+  OEMCryptoResult sts;
+  std::vector<uint8_t> dev_id(128, 0);
+  size_t dev_id_len = dev_id.size();
+  sts = OEMCrypto_GetDeviceID(dev_id.data(), &dev_id_len);
+  if (sts == OEMCrypto_ERROR_SHORT_BUFFER) {
+    if (dev_id_len <= 0) return "NO DEVICE ID";
+    dev_id.resize(dev_id_len);
+    sts = OEMCrypto_GetDeviceID(dev_id.data(), &dev_id_len);
+  }
+  if (sts != OEMCrypto_SUCCESS) return "NO DEVICE ID";
+  dev_id.resize(dev_id_len);
+  return MaybeHex(dev_id);
+}
+
 /// @addtogroup basic
 /// @{
 
@@ -175,6 +199,9 @@ TEST_F(OEMCryptoClientTest, VersionNumber) {
   uint32_t minor_version = OEMCrypto_MinorAPIVersion();
   cout << "             OEMCrypto API version is " << version << "."
        << minor_version << endl;
+  cout << "             OEMCrypto Device ID is '" << GetDeviceId() << "'"
+       << endl;
+
   if (OEMCrypto_SupportsUsageTable()) {
     cout << "             OEMCrypto supports usage tables" << endl;
   } else {

libwvdrmengine/oemcrypto/test/oemcrypto_cast_test.h

@@ -19,9 +19,6 @@ namespace wvoec {
 
 const char* HDCPCapabilityAsString(OEMCrypto_HDCP_Capability value);
 
-std::string MaybeHex(const uint8_t* data, size_t length);
-std::string MaybeHex(const std::vector<uint8_t>& data);
-
 // This test attempts to use alternate algorithms for loaded device certs.
 class OEMCryptoLoadsCertificateAlternates : public OEMCryptoLoadsCertificate {
  protected: