Added OEMCrypto build information validation test.

[ Merge of http://go/wvgerrit/219212 ]

This CL adds a new OEMCrypto test CheckBuildInformation*API17 which
ensures that OEMCrypto_BuildInformation() is generating valid build
information.

Bug: 348498112
Bug: 348497732
Change-Id: I22f9878d8ffa05b2b1b1b6ec28718e231438d4a7
Merged-In: I22f9878d8ffa05b2b1b1b6ec28718e231438d4a7

libwvdrmengine/oemcrypto/test/oemcrypto_basic_test.cpp

@@ -2,11 +2,22 @@
 // source code may only be used and distributed under the Widevine
 // License Agreement.
 //
-
 #include "oemcrypto_basic_test.h"
 
+#include <ctype.h>
+#include <inttypes.h>
+
+#include <algorithm>
+#include <map>
+#include <ostream>
+#include <set>
+#include <string>
+#include <vector>
+
+#include <jsmn.h>
+
+#include "OEMCryptoCENC.h"
 #include "clock.h"
-#include "jsmn.h"
 #include "log.h"
 #include "oemcrypto_corpus_generator_helper.h"
 #include "oemcrypto_resource_test.h"
@@ -316,6 +327,119 @@ TEST_F(OEMCryptoClientTest, CheckNullBuildInformationAPI17) {
   }
 }
 
+// Verifies that OEMCrypto_BuildInformation() is behaving as expected
+// by assigning appropriate values to the build info size.
+TEST_F(OEMCryptoClientTest, CheckBuildInformation_OutputLengthAPI17) {
+  constexpr size_t kZero = 0;
+  constexpr char kNullChar = '\0';
+
+  // Allocating single byte to avoid potential null dereference.
+  std::string build_info(1, kNullChar);
+  size_t build_info_length = 0;
+
+  OEMCryptoResult result =
+      OEMCrypto_BuildInformation(&build_info[0], &build_info_length);
+
+  ASSERT_EQ(result, OEMCrypto_ERROR_SHORT_BUFFER);
+  ASSERT_GT(build_info_length, kZero)
+      << "Signaling ERROR_SHORT_BUFFER should have assigned a length";
+
+  // Force a ERROR_SHORT_BUFFER using a non-zero value.
+  // Note: It is assumed that vendors will provide more than a single
+  // character of info.
+  const size_t second_attempt_length =
+      (build_info_length >= 2) ? build_info_length / 2 : 1;
+  build_info.assign(second_attempt_length, kNullChar);
+  build_info_length = build_info.size();
+
+  result = OEMCrypto_BuildInformation(&build_info[0], &build_info_length);
+  ASSERT_EQ(result, OEMCrypto_ERROR_SHORT_BUFFER)
+      << "second_attempt_length = " << second_attempt_length
+      << ", build_info_length" << build_info_length;
+  // OEM specified build info length should be larger than the
+  // original length if returning ERROR_SHORT_BUFFER.
+  ASSERT_GT(build_info_length, second_attempt_length);
+
+  // Final attempt with a buffer large enough buffer, padding to
+  // ensure the caller truncates.
+  constexpr size_t kBufferPadSize = 42;
+  const size_t expected_length = build_info_length;
+  const size_t final_attempt_length = expected_length + kBufferPadSize;
+  build_info.assign(final_attempt_length, kNullChar);
+  build_info_length = build_info.size();
+
+  result = OEMCrypto_BuildInformation(&build_info[0], &build_info_length);
+
+  ASSERT_EQ(result, OEMCrypto_SUCCESS)
+      << "final_attempt_length = " << final_attempt_length
+      << ", expected_length = " << expected_length
+      << ", build_info_length = " << build_info_length;
+  // Ensure not empty.
+  ASSERT_GT(build_info_length, kZero) << "Build info cannot be empty";
+  // Ensure it was truncated down from the padded length.
+  ASSERT_LT(build_info_length, final_attempt_length)
+      << "Should have truncated from oversized buffer: expected_length = "
+      << expected_length;
+  // Ensure the real length is within the size originally specified.
+  // OK if final length is smaller than estimated length.
+  ASSERT_LE(build_info_length, expected_length);
+}
+
+// Verifies that OEMCrypto_BuildInformation() is behaving as expected
+// by checking the resulting contents.
+// Does not validate whether output if valid JSON for v18.
+TEST_F(OEMCryptoClientTest, CheckBuildInformation_OutputContentAPI17) {
+  constexpr size_t kZero = 0;
+  constexpr char kNullChar = '\0';
+
+  // Allocating single byte to avoid potential null dereference.
+  std::string build_info(1, kNullChar);
+  size_t build_info_length = 0;
+  OEMCryptoResult result =
+      OEMCrypto_BuildInformation(&build_info[0], &build_info_length);
+  ASSERT_EQ(result, OEMCrypto_ERROR_SHORT_BUFFER);
+  ASSERT_GT(build_info_length, kZero)
+      << "Signaling ERROR_SHORT_BUFFER should have assigned a length";
+
+  // Expect successful acquisition of build information.
+  const size_t expected_length = build_info_length;
+  build_info.assign(expected_length, kNullChar);
+  result = OEMCrypto_BuildInformation(&build_info[0], &build_info_length);
+  ASSERT_EQ(result, OEMCrypto_SUCCESS)
+      << "expected_length = " << expected_length
+      << ", build_info_length = " << build_info_length;
+  // Ensure not empty.
+  ASSERT_GT(build_info_length, kZero) << "Build info cannot be empty";
+  // Ensure the real length is within the size originally specified.
+  ASSERT_LE(build_info_length, expected_length)
+      << "Cannot specify success if buffer was too small";
+  build_info.resize(build_info_length);
+
+  // Ensure there isn't a trailing null byte.
+  ASSERT_NE(build_info.back(), kNullChar)
+      << "Build info must not contain trailing null byte";
+
+  // Ensure all build info characters are printable, or a limited
+  // set of white space characters (case of JSON build info).
+  const auto is_valid_build_info_white_space = [](const char& ch) -> bool {
+    constexpr char kSpace = ' ';
+    constexpr char kLineFeed = '\n';
+    constexpr char kTab = '\t';
+    return ch == kLineFeed || ch == kTab || ch == kSpace;
+  };
+  const auto is_valid_build_info_char = [&](const char& ch) -> bool {
+    return ::isprint(ch) || is_valid_build_info_white_space(ch);
+  };
+  ASSERT_TRUE(std::all_of(build_info.begin(), build_info.end(),
+                          is_valid_build_info_char))
+      << "Build info is not printable: " << wvutil::b2a_hex(build_info);
+
+  // Ensure build info isn't just white space.
+  ASSERT_FALSE(std::all_of(build_info.begin(), build_info.end(),
+                           is_valid_build_info_white_space))
+      << "Build info is just white space: " << wvutil::b2a_hex(build_info);
+}
+
 TEST_F(OEMCryptoClientTest, CheckJsonBuildInformationAPI18) {
   if (wvoec::global_features.api_version < 18) {
     GTEST_SKIP() << "Test for versions 18 and up only.";