Merge bitcoin/bitcoin#21817: refactor: Replace &foo[0] with foo.data()

fac30eec42c486ec1bfd696293040a7aa0f04625 refactor: Replace &foo[0] with foo.data() (MarcoFalke)
faece47c4706783e0460ed977390a44630b2d44c refactor: Avoid &foo[0] on C-Style arrays (MarcoFalke)
face9611093377e8502d91f2ff56f9319a56357c refactor: Use only one temporary buffer in CreateObfuscateKey (MarcoFalke)
fa05dddc42770809fdae4d9c35155f8117960019 refactor: Use CPubKey vector constructor where possible (MarcoFalke)
fabb6dfe6e734eadd91448122f2ce8c1612c39a6 script: Replace address-of idiom with vector data() method (Guido Vranken)

Pull request description:

  The main theme of this refactor is to replace `&foo[0]` with `foo.data()`.

  The first commit is taken from #21781 with the rationale:

  * In CSignatureCache::ComputeEntryECDSA, change the way a vector pointer is resolved to prevent invoking undefined behavior if the vector is empty.

  The other commits aim to remove all `&foo[0]`, where `foo` is any kind of byte representation. The rationale:

  * Sometimes alternative code without any raw data pointers is easier to read (refer to the respective commit message for details)
  * If the raw data pointer is needed, `foo.data()` should be preferred, as pointed out in the developer notes. This addresses the instances that have been missed in commit 592404f03f2b734351d734f0c9ca1fdce997321b, and https://github.com/bitcoin/bitcoin/pull/9804

ACKs for top commit:
  laanwj:
    Code review ACK fac30eec42c486ec1bfd696293040a7aa0f04625
  practicalswift:
    cr ACK fac30eec42c486ec1bfd696293040a7aa0f04625: patch looks correct
  promag:
    Code review ACK fac30eec42c486ec1bfd696293040a7aa0f04625.

Tree-SHA512: e7e73146edbc78911a8e8c728b0a1c6b0ed9a88a008e650aa5dbffe72425bd42c76df70199a9cf7e02637448d7593e0eac52fd0f91f59240283e1390ee21bfa5

5 files changed, 25 insertions, 25 deletions

diff --git a/src/test/compress_tests.cpp b/src/test/compress_tests.cpp
index 7b661a0d1d..b7ba46bd30 100644
--- a/src/test/compress_tests.cpp
+++ b/src/test/compress_tests.cpp
@@ -79,7 +79,7 @@ BOOST_AUTO_TEST_CASE(compress_script_to_ckey_id)
     // Check compressed script
     BOOST_CHECK_EQUAL(out.size(), 21U);
     BOOST_CHECK_EQUAL(out[0], 0x00);
-    BOOST_CHECK_EQUAL(memcmp(&out[1], &script[3], 20), 0); // compare the 20 relevant chars of the CKeyId in the script
+    BOOST_CHECK_EQUAL(memcmp(out.data() + 1, script.data() + 3, 20), 0); // compare the 20 relevant chars of the CKeyId in the script
 }
 
 BOOST_AUTO_TEST_CASE(compress_script_to_cscript_id)
@@ -96,7 +96,7 @@ BOOST_AUTO_TEST_CASE(compress_script_to_cscript_id)
     // Check compressed script
     BOOST_CHECK_EQUAL(out.size(), 21U);
     BOOST_CHECK_EQUAL(out[0], 0x01);
-    BOOST_CHECK_EQUAL(memcmp(&out[1], &script[2], 20), 0); // compare the 20 relevant chars of the CScriptId in the script
+    BOOST_CHECK_EQUAL(memcmp(out.data() + 1, script.data() + 2, 20), 0); // compare the 20 relevant chars of the CScriptId in the script
 }
 
 BOOST_AUTO_TEST_CASE(compress_script_to_compressed_pubkey_id)
@@ -113,8 +113,8 @@ BOOST_AUTO_TEST_CASE(compress_script_to_compressed_pubkey_id)
 
     // Check compressed script
     BOOST_CHECK_EQUAL(out.size(), 33U);
-    BOOST_CHECK_EQUAL(memcmp(&out[0], &script[1], 1), 0);
-    BOOST_CHECK_EQUAL(memcmp(&out[1], &script[2], 32), 0); // compare the 32 chars of the compressed CPubKey
+    BOOST_CHECK_EQUAL(memcmp(out.data(), script.data() + 1, 1), 0);
+    BOOST_CHECK_EQUAL(memcmp(out.data() + 1, script.data() + 2, 32), 0); // compare the 32 chars of the compressed CPubKey
 }
 
 BOOST_AUTO_TEST_CASE(compress_script_to_uncompressed_pubkey_id)
@@ -130,7 +130,7 @@ BOOST_AUTO_TEST_CASE(compress_script_to_uncompressed_pubkey_id)
 
     // Check compressed script
     BOOST_CHECK_EQUAL(out.size(), 33U);
-    BOOST_CHECK_EQUAL(memcmp(&out[1], &script[2], 32), 0); // first 32 chars of CPubKey are copied into out[1:]
+    BOOST_CHECK_EQUAL(memcmp(out.data() + 1, script.data() + 2, 32), 0); // first 32 chars of CPubKey are copied into out[1:]
     BOOST_CHECK_EQUAL(out[0], 0x04 | (script[65] & 0x01)); // least significant bit (lsb) of last char of pubkey is mapped into out[0]
 }
 
diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
index 7358b246b6..edec5f0a31 100644
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -33,7 +33,7 @@ static void TestVector(const Hasher &h, const In &in, const Out &out) {
     hash.resize(out.size());
     {
         // Test that writing the whole input string at once works.
-        Hasher(h).Write((unsigned char*)&in[0], in.size()).Finalize(&hash[0]);
+        Hasher(h).Write((const uint8_t*)in.data(), in.size()).Finalize(hash.data());
         BOOST_CHECK(hash == out);
     }
     for (int i=0; i<32; i++) {
@@ -42,15 +42,15 @@ static void TestVector(const Hasher &h, const In &in, const Out &out) {
         size_t pos = 0;
         while (pos < in.size()) {
             size_t len = InsecureRandRange((in.size() - pos + 1) / 2 + 1);
-            hasher.Write((unsigned char*)&in[pos], len);
+            hasher.Write((const uint8_t*)in.data() + pos, len);
             pos += len;
             if (pos > 0 && pos + 2 * out.size() > in.size() && pos < in.size()) {
                 // Test that writing the rest at once to a copy of a hasher works.
-                Hasher(hasher).Write((unsigned char*)&in[pos], in.size() - pos).Finalize(&hash[0]);
+                Hasher(hasher).Write((const uint8_t*)in.data() + pos, in.size() - pos).Finalize(hash.data());
                 BOOST_CHECK(hash == out);
             }
         }
-        hasher.Finalize(&hash[0]);
+        hasher.Finalize(hash.data());
         BOOST_CHECK(hash == out);
     }
 }
diff --git a/src/test/fuzz/util.cpp b/src/test/fuzz/util.cpp
index b8d846a995..7fd7559d72 100644
--- a/src/test/fuzz/util.cpp
+++ b/src/test/fuzz/util.cpp
@@ -273,7 +273,7 @@ CScript ConsumeScript(FuzzedDataProvider& fuzzed_data_provider, const size_t max
     CScript r_script{b.begin(), b.end()};
     if (maybe_p2wsh && fuzzed_data_provider.ConsumeBool()) {
         uint256 script_hash;
-        CSHA256().Write(&r_script[0], r_script.size()).Finalize(script_hash.begin());
+        CSHA256().Write(r_script.data(), r_script.size()).Finalize(script_hash.begin());
         r_script.clear();
         r_script << OP_0 << ToByteVector(script_hash);
     }
diff --git a/src/test/script_standard_tests.cpp b/src/test/script_standard_tests.cpp
index 103a971d98..44fbfa5970 100644
--- a/src/test/script_standard_tests.cpp
+++ b/src/test/script_standard_tests.cpp
@@ -98,7 +98,7 @@ BOOST_AUTO_TEST_CASE(script_standard_Solver_success)
 
     // TxoutType::WITNESS_V0_SCRIPTHASH
     uint256 scriptHash;
-    CSHA256().Write(&redeemScript[0], redeemScript.size())
+    CSHA256().Write(redeemScript.data(), redeemScript.size())
         .Finalize(scriptHash.begin());
 
     s.clear();
@@ -370,7 +370,7 @@ BOOST_AUTO_TEST_CASE(script_standard_GetScriptFor_)
     witnessScript << OP_1 << ToByteVector(pubkeys[0]) << OP_1 << OP_CHECKMULTISIG;
 
     uint256 scriptHash;
-    CSHA256().Write(&witnessScript[0], witnessScript.size())
+    CSHA256().Write(witnessScript.data(), witnessScript.size())
         .Finalize(scriptHash.begin());
 
     expected.clear();
diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp
index 14cfadf75d..171234f745 100644
--- a/src/test/script_tests.cpp
+++ b/src/test/script_tests.cpp
@@ -155,10 +155,10 @@ void DoTest(const CScript& scriptPubKey, const CScript& scriptSig, const CScript
     if (libconsensus_flags == flags) {
         int expectedSuccessCode = expect ? 1 : 0;
         if (flags & bitcoinconsensus_SCRIPT_FLAGS_VERIFY_WITNESS) {
-            BOOST_CHECK_MESSAGE(bitcoinconsensus_verify_script_with_amount(scriptPubKey.data(), scriptPubKey.size(), txCredit.vout[0].nValue, (const unsigned char*)&stream[0], stream.size(), 0, libconsensus_flags, nullptr) == expectedSuccessCode, message);
+            BOOST_CHECK_MESSAGE(bitcoinconsensus_verify_script_with_amount(scriptPubKey.data(), scriptPubKey.size(), txCredit.vout[0].nValue, stream.data(), stream.size(), 0, libconsensus_flags, nullptr) == expectedSuccessCode, message);
         } else {
-            BOOST_CHECK_MESSAGE(bitcoinconsensus_verify_script_with_amount(scriptPubKey.data(), scriptPubKey.size(), 0, (const unsigned char*)&stream[0], stream.size(), 0, libconsensus_flags, nullptr) == expectedSuccessCode, message);
-            BOOST_CHECK_MESSAGE(bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), (const unsigned char*)&stream[0], stream.size(), 0, libconsensus_flags, nullptr) == expectedSuccessCode, message);
+            BOOST_CHECK_MESSAGE(bitcoinconsensus_verify_script_with_amount(scriptPubKey.data(), scriptPubKey.size(), 0, stream.data(), stream.size(), 0, libconsensus_flags, nullptr) == expectedSuccessCode, message);
+            BOOST_CHECK_MESSAGE(bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), stream.data(), stream.size(), 0, libconsensus_flags, nullptr) == expectedSuccessCode, message);
         }
     }
 #endif
@@ -224,7 +224,7 @@ struct KeyData
         pubkey0 = key0.GetPubKey();
         pubkey0H = key0.GetPubKey();
         pubkey0C = key0C.GetPubKey();
-        *const_cast<unsigned char*>(&pubkey0H[0]) = 0x06 | (pubkey0H[64] & 1);
+        *const_cast<unsigned char*>(pubkey0H.data()) = 0x06 | (pubkey0H[64] & 1);
 
         key1.Set(vchKey1, vchKey1 + 32, false);
         key1C.Set(vchKey1, vchKey1 + 32, true);
@@ -290,7 +290,7 @@ public:
         } else if (wm == WitnessMode::SH) {
             witscript = scriptPubKey;
             uint256 hash;
-            CSHA256().Write(&witscript[0], witscript.size()).Finalize(hash.begin());
+            CSHA256().Write(witscript.data(), witscript.size()).Finalize(hash.begin());
             scriptPubKey = CScript() << witnessversion << ToByteVector(hash);
         }
         if (P2SH) {
@@ -774,7 +774,7 @@ BOOST_AUTO_TEST_CASE(script_build)
     {
         CScript witscript = CScript() << ToByteVector(keys.pubkey0);
         uint256 hash;
-        CSHA256().Write(&witscript[0], witscript.size()).Finalize(hash.begin());
+        CSHA256().Write(witscript.data(), witscript.size()).Finalize(hash.begin());
         std::vector<unsigned char> hashBytes = ToByteVector(hash);
         hashBytes.pop_back();
         tests.push_back(TestBuilder(CScript() << OP_0 << hashBytes,
@@ -1520,7 +1520,7 @@ BOOST_AUTO_TEST_CASE(bitcoinconsensus_verify_script_returns_true)
     stream << spendTx;
 
     bitcoinconsensus_error err;
-    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), (const unsigned char*)&stream[0], stream.size(), nIn, libconsensus_flags, &err);
+    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), stream.data(), stream.size(), nIn, libconsensus_flags, &err);
     BOOST_CHECK_EQUAL(result, 1);
     BOOST_CHECK_EQUAL(err, bitcoinconsensus_ERR_OK);
 }
@@ -1543,7 +1543,7 @@ BOOST_AUTO_TEST_CASE(bitcoinconsensus_verify_script_tx_index_err)
     stream << spendTx;
 
     bitcoinconsensus_error err;
-    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), (const unsigned char*)&stream[0], stream.size(), nIn, libconsensus_flags, &err);
+    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), stream.data(), stream.size(), nIn, libconsensus_flags, &err);
     BOOST_CHECK_EQUAL(result, 0);
     BOOST_CHECK_EQUAL(err, bitcoinconsensus_ERR_TX_INDEX);
 }
@@ -1566,7 +1566,7 @@ BOOST_AUTO_TEST_CASE(bitcoinconsensus_verify_script_tx_size)
     stream << spendTx;
 
     bitcoinconsensus_error err;
-    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), (const unsigned char*)&stream[0], stream.size() * 2, nIn, libconsensus_flags, &err);
+    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), stream.data(), stream.size() * 2, nIn, libconsensus_flags, &err);
     BOOST_CHECK_EQUAL(result, 0);
     BOOST_CHECK_EQUAL(err, bitcoinconsensus_ERR_TX_SIZE_MISMATCH);
 }
@@ -1589,7 +1589,7 @@ BOOST_AUTO_TEST_CASE(bitcoinconsensus_verify_script_tx_serialization)
     stream << 0xffffffff;
 
     bitcoinconsensus_error err;
-    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), (const unsigned char*)&stream[0], stream.size(), nIn, libconsensus_flags, &err);
+    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), stream.data(), stream.size(), nIn, libconsensus_flags, &err);
     BOOST_CHECK_EQUAL(result, 0);
     BOOST_CHECK_EQUAL(err, bitcoinconsensus_ERR_TX_DESERIALIZE);
 }
@@ -1612,7 +1612,7 @@ BOOST_AUTO_TEST_CASE(bitcoinconsensus_verify_script_amount_required_err)
     stream << spendTx;
 
     bitcoinconsensus_error err;
-    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), (const unsigned char*)&stream[0], stream.size(), nIn, libconsensus_flags, &err);
+    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), stream.data(), stream.size(), nIn, libconsensus_flags, &err);
     BOOST_CHECK_EQUAL(result, 0);
     BOOST_CHECK_EQUAL(err, bitcoinconsensus_ERR_AMOUNT_REQUIRED);
 }
@@ -1635,7 +1635,7 @@ BOOST_AUTO_TEST_CASE(bitcoinconsensus_verify_script_invalid_flags)
     stream << spendTx;
 
     bitcoinconsensus_error err;
-    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), (const unsigned char*)&stream[0], stream.size(), nIn, libconsensus_flags, &err);
+    int result = bitcoinconsensus_verify_script(scriptPubKey.data(), scriptPubKey.size(), stream.data(), stream.size(), nIn, libconsensus_flags, &err);
     BOOST_CHECK_EQUAL(result, 0);
     BOOST_CHECK_EQUAL(err, bitcoinconsensus_ERR_INVALID_FLAGS);
 }
@@ -1733,7 +1733,7 @@ BOOST_AUTO_TEST_CASE(script_assets_test)
     size_t length = file.tellg();
     file.seekg(0, std::ios::beg);
     std::string data(length, '\0');
-    file.read(&data[0], data.size());
+    file.read(data.data(), data.size());
     UniValue tests = read_json(data);
     BOOST_CHECK(tests.isArray());
     BOOST_CHECK(tests.size() > 0);