SF: Parse, hash, and cache block 0 serial number

More EDID fields are required as a part of migrating to EDID-based
display IDs. This CL parses the device's serial number from bytes 12-15
of block 0 in the EDID blob, hashes it using a stable hash, and serves
it as a part of the Edid struct.

Later, amongst others, this value will be used to fabricate a unique
display ID that is based on the display's EDID.

See:
1. EDID spec: https://glenwing.github.io/docs/VESA-EEDID-A2.pdf
2. https://en.wikipedia.org/wiki/Extended_Display_Identification_Data#Structure,_version_1.4

Flag: com.android.graphics.surfaceflinger.flags.stable_edid_ids
Bug: 378923334
Test: DisplayIdentification_test
Change-Id: I8e5c79f2f51c2fd2085dfaba7f5c45fbc698cbcb

3 files changed, 34 insertions, 3 deletions

diff --git a/libs/ui/DisplayIdentification.cpp b/libs/ui/DisplayIdentification.cpp
index 503f92ff32..5cdaa71627 100644
--- a/libs/ui/DisplayIdentification.cpp
+++ b/libs/ui/DisplayIdentification.cpp
@@ -19,9 +19,12 @@
 
 #include <algorithm>
 #include <cctype>
+#include <cstdint>
 #include <numeric>
 #include <optional>
 #include <span>
+#include <string>
+#include <string_view>
 
 #include <ftl/hash.h>
 #include <log/log.h>
@@ -194,6 +197,21 @@ std::optional<Edid> parseEdid(const DisplayIdentificationData& edid) {
     const uint16_t productId =
             static_cast<uint16_t>(edid[kProductIdOffset] | (edid[kProductIdOffset + 1] << 8));
 
+    //   Bytes 12-15: display serial number, in little-endian (LSB). This field is
+    //   optional and its absence is marked by having all bytes set to 0x00.
+    //   Values do not represent ASCII characters.
+    constexpr size_t kSerialNumberOffset = 12;
+    if (edid.size() < kSerialNumberOffset + sizeof(uint32_t)) {
+        ALOGE("Invalid EDID: block zero S/N is truncated.");
+        return {};
+    }
+    const uint32_t blockZeroSerialNumber = edid[kSerialNumberOffset] +
+            (edid[kSerialNumberOffset + 1] << 8) + (edid[kSerialNumberOffset + 2] << 16) +
+            (edid[kSerialNumberOffset + 3] << 24);
+    const auto hashedBlockZeroSNOpt = blockZeroSerialNumber == 0
+            ? std::nullopt
+            : ftl::stable_hash(std::string_view(std::to_string(blockZeroSerialNumber)));
+
     constexpr size_t kManufactureWeekOffset = 16;
     if (edid.size() < kManufactureWeekOffset + sizeof(uint8_t)) {
         ALOGE("Invalid EDID: manufacture week is truncated.");
@@ -350,6 +368,7 @@ std::optional<Edid> parseEdid(const DisplayIdentificationData& edid) {
     return Edid{
             .manufacturerId = manufacturerId,
             .productId = productId,
+            .hashedBlockZeroSerialNumberOpt = hashedBlockZeroSNOpt,
             .pnpId = *pnpId,
             .modelHash = modelHash,
             .displayName = displayName,
diff --git a/libs/ui/include/ui/DisplayIdentification.h b/libs/ui/include/ui/DisplayIdentification.h
index 3f938d6c96..85e5cee490 100644
--- a/libs/ui/include/ui/DisplayIdentification.h
+++ b/libs/ui/include/ui/DisplayIdentification.h
@@ -69,6 +69,7 @@ struct Cea861ExtensionBlock : ExtensionBlock {
 struct Edid {
     uint16_t manufacturerId;
     uint16_t productId;
+    std::optional<uint64_t> hashedBlockZeroSerialNumberOpt;
     PnpId pnpId;
     uint32_t modelHash;
     std::string_view displayName;
diff --git a/libs/ui/tests/DisplayIdentification_test.cpp b/libs/ui/tests/DisplayIdentification_test.cpp
index cf0e98b0c6..fbbe719be8 100644
--- a/libs/ui/tests/DisplayIdentification_test.cpp
+++ b/libs/ui/tests/DisplayIdentification_test.cpp
@@ -33,7 +33,7 @@ namespace android {
 namespace {
 
 const unsigned char kInternalEdid[] =
-        "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\xa3\x42\x31\x00\x00\x00\x00"
+        "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\xa3\x42\x31\x4e\x61\xbc\x00"
         "\x00\x15\x01\x03\x80\x1a\x10\x78\x0a\xd3\xe5\x95\x5c\x60\x90\x27"
         "\x19\x50\x54\x00\x00\x00\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01"
         "\x01\x01\x01\x01\x01\x01\x9e\x1b\x00\xa0\x50\x20\x12\x30\x10\x30"
@@ -54,7 +54,7 @@ const unsigned char kExternalEdid[] =
 
 // Extended EDID with timing extension.
 const unsigned char kExternalEedid[] =
-        "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\x2d\xfe\x08\x00\x00\x00\x00"
+        "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\x2d\xfe\x08\xb1\x7f\x39\x05"
         "\x29\x15\x01\x03\x80\x10\x09\x78\x0a\xee\x91\xa3\x54\x4c\x99\x26"
         "\x0f\x50\x54\xbd\xef\x80\x71\x4f\x81\xc0\x81\x00\x81\x80\x95\x00"
         "\xa9\xc0\xb3\x00\x01\x01\x02\x3a\x80\x18\x71\x38\x2d\x40\x58\x2c"
@@ -112,7 +112,7 @@ const unsigned char kHisenseTvEdid[] =
         "\x07";
 
 const unsigned char kCtlDisplayEdid[] =
-        "\x00\xff\xff\xff\xff\xff\xff\x00\x0e\x8c\x9d\x24\x00\x00\x00\x00"
+        "\x00\xff\xff\xff\xff\xff\xff\x00\x0e\x8c\x9d\x24\x30\x41\xab\x00"
         "\xff\x17\x01\x04\xa5\x34\x1d\x78\x3a\xa7\x25\xa4\x57\x51\xa0\x26"
         "\x10\x50\x54\xbf\xef\x80\xb3\x00\xa9\x40\x95\x00\x81\x40\x81\x80"
         "\x95\x0f\x71\x4f\x90\x40\x02\x3a\x80\x18\x71\x38\x2d\x40\x58\x2c"
@@ -191,6 +191,8 @@ TEST(DisplayIdentificationTest, parseEdid) {
     EXPECT_EQ(hash("121AT11-801"), 626564263);
     EXPECT_TRUE(edid->displayName.empty());
     EXPECT_EQ(12610, edid->productId);
+    EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+    EXPECT_EQ(ftl::stable_hash("12345678"), edid->hashedBlockZeroSerialNumberOpt.value());
     EXPECT_EQ(21, edid->manufactureOrModelYear);
     EXPECT_EQ(0, edid->manufactureWeek);
     EXPECT_EQ(26, edid->physicalSizeInCm.width);
@@ -209,6 +211,8 @@ TEST(DisplayIdentificationTest, parseEdid) {
     EXPECT_EQ(hash("HP ZR30w"), 918492362);
     EXPECT_EQ("HP ZR30w", edid->displayName);
     EXPECT_EQ(10348, edid->productId);
+    EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+    EXPECT_EQ(ftl::stable_hash("16843009"), edid->hashedBlockZeroSerialNumberOpt.value());
     EXPECT_EQ(22, edid->manufactureOrModelYear);
     EXPECT_EQ(2, edid->manufactureWeek);
     EXPECT_EQ(64, edid->physicalSizeInCm.width);
@@ -227,6 +231,8 @@ TEST(DisplayIdentificationTest, parseEdid) {
     EXPECT_EQ(hash("SAMSUNG"), 1201368132);
     EXPECT_EQ("SAMSUNG", edid->displayName);
     EXPECT_EQ(2302, edid->productId);
+    EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+    EXPECT_EQ(ftl::stable_hash("87654321"), edid->hashedBlockZeroSerialNumberOpt.value());
     EXPECT_EQ(21, edid->manufactureOrModelYear);
     EXPECT_EQ(41, edid->manufactureWeek);
     EXPECT_EQ(16, edid->physicalSizeInCm.width);
@@ -251,6 +257,8 @@ TEST(DisplayIdentificationTest, parseEdid) {
     EXPECT_EQ(hash("Panasonic-TV"), 3876373262);
     EXPECT_EQ("Panasonic-TV", edid->displayName);
     EXPECT_EQ(41622, edid->productId);
+    EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+    EXPECT_EQ(ftl::stable_hash("16843009"), edid->hashedBlockZeroSerialNumberOpt.value());
     EXPECT_EQ(29, edid->manufactureOrModelYear);
     EXPECT_EQ(0, edid->manufactureWeek);
     EXPECT_EQ(128, edid->physicalSizeInCm.width);
@@ -275,6 +283,7 @@ TEST(DisplayIdentificationTest, parseEdid) {
     EXPECT_EQ(hash("Hisense"), 2859844809);
     EXPECT_EQ("Hisense", edid->displayName);
     EXPECT_EQ(0, edid->productId);
+    EXPECT_FALSE(edid->hashedBlockZeroSerialNumberOpt.has_value());
     EXPECT_EQ(29, edid->manufactureOrModelYear);
     EXPECT_EQ(18, edid->manufactureWeek);
     EXPECT_EQ(0, edid->physicalSizeInCm.width);
@@ -299,6 +308,8 @@ TEST(DisplayIdentificationTest, parseEdid) {
     EXPECT_EQ(hash("LP2361"), 1523181158);
     EXPECT_EQ("LP2361", edid->displayName);
     EXPECT_EQ(9373, edid->productId);
+    EXPECT_TRUE(edid->hashedBlockZeroSerialNumberOpt.has_value());
+    EXPECT_EQ(ftl::stable_hash("11223344"), edid->hashedBlockZeroSerialNumberOpt.value());
     EXPECT_EQ(23, edid->manufactureOrModelYear);
     EXPECT_EQ(0xff, edid->manufactureWeek);
     EXPECT_EQ(52, edid->physicalSizeInCm.width);