feat: add isAccountWritable and isAccountSigner to MessageV0 (#27808)

Author: jstarry

web3.js/src/message/legacy.ts

@@ -130,14 +130,18 @@ export class Message {
   }
 
   isAccountWritable(index: number): boolean {
-    return (
-      index <
-        this.header.numRequiredSignatures -
-          this.header.numReadonlySignedAccounts ||
-      (index >= this.header.numRequiredSignatures &&
-        index <
-          this.accountKeys.length - this.header.numReadonlyUnsignedAccounts)
-    );
+    const numSignedAccounts = this.header.numRequiredSignatures;
+    if (index >= this.header.numRequiredSignatures) {
+      const unsignedAccountIndex = index - numSignedAccounts;
+      const numUnsignedAccounts = this.accountKeys.length - numSignedAccounts;
+      const numWritableUnsignedAccounts =
+        numUnsignedAccounts - this.header.numReadonlyUnsignedAccounts;
+      return unsignedAccountIndex < numWritableUnsignedAccounts;
+    } else {
+      const numWritableSignedAccounts =
+        numSignedAccounts - this.header.numReadonlySignedAccounts;
+      return index < numWritableSignedAccounts;
+    }
   }
 
   isProgramId(index: number): boolean {

web3.js/src/message/v0.ts

@@ -103,6 +103,33 @@ export class MessageV0 {
     );
   }
 
+  isAccountSigner(index: number): boolean {
+    return index < this.header.numRequiredSignatures;
+  }
+
+  isAccountWritable(index: number): boolean {
+    const numSignedAccounts = this.header.numRequiredSignatures;
+    const numStaticAccountKeys = this.staticAccountKeys.length;
+    if (index >= numStaticAccountKeys) {
+      const lookupAccountKeysIndex = index - numStaticAccountKeys;
+      const numWritableLookupAccountKeys = this.addressTableLookups.reduce(
+        (count, lookup) => count + lookup.writableIndexes.length,
+        0,
+      );
+      return lookupAccountKeysIndex < numWritableLookupAccountKeys;
+    } else if (index >= this.header.numRequiredSignatures) {
+      const unsignedAccountIndex = index - numSignedAccounts;
+      const numUnsignedAccounts = numStaticAccountKeys - numSignedAccounts;
+      const numWritableUnsignedAccounts =
+        numUnsignedAccounts - this.header.numReadonlyUnsignedAccounts;
+      return unsignedAccountIndex < numWritableUnsignedAccounts;
+    } else {
+      const numWritableSignedAccounts =
+        numSignedAccounts - this.header.numReadonlySignedAccounts;
+      return index < numWritableSignedAccounts;
+    }
+  }
+
   resolveAddressTableLookups(
     addressLookupTableAccounts: AddressLookupTableAccount[],
   ): AccountKeysFromLookups {

web3.js/test/message-tests/legacy.test.ts

@@ -88,4 +88,56 @@ describe('Message', () => {
     expect(message.instructions.length).to.eq(0);
     expect(message.recentBlockhash).to.eq(recentBlockhash);
   });
+
+  it('isAccountWritable', () => {
+    const accountKeys = [
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+    ];
+
+    const recentBlockhash = bs58.encode(sha256('test'));
+    const message = new Message({
+      header: {
+        numRequiredSignatures: 2,
+        numReadonlySignedAccounts: 1,
+        numReadonlyUnsignedAccounts: 1,
+      },
+      recentBlockhash,
+      accountKeys,
+      instructions: [],
+    });
+
+    expect(message.isAccountWritable(0)).to.be.true;
+    expect(message.isAccountWritable(1)).to.be.false;
+    expect(message.isAccountWritable(2)).to.be.true;
+    expect(message.isAccountWritable(3)).to.be.false;
+  });
+
+  it('isAccountSigner', () => {
+    const accountKeys = [
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+    ];
+
+    const recentBlockhash = bs58.encode(sha256('test'));
+    const message = new Message({
+      header: {
+        numRequiredSignatures: 2,
+        numReadonlySignedAccounts: 1,
+        numReadonlyUnsignedAccounts: 1,
+      },
+      recentBlockhash,
+      accountKeys,
+      instructions: [],
+    });
+
+    expect(message.isAccountSigner(0)).to.be.true;
+    expect(message.isAccountSigner(1)).to.be.true;
+    expect(message.isAccountSigner(2)).to.be.false;
+    expect(message.isAccountSigner(3)).to.be.false;
+  });
 });

web3.js/test/message-tests/v0.test.ts

@@ -298,4 +298,87 @@ describe('MessageV0', () => {
       'Expected versioned message with version 0 but found version 1',
     );
   });
+
+  it('isAccountWritable', () => {
+    const staticAccountKeys = [
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+    ];
+
+    const recentBlockhash = bs58.encode(sha256('test'));
+    const message = new MessageV0({
+      header: {
+        numRequiredSignatures: 2,
+        numReadonlySignedAccounts: 1,
+        numReadonlyUnsignedAccounts: 1,
+      },
+      recentBlockhash,
+      staticAccountKeys,
+      compiledInstructions: [],
+      addressTableLookups: [
+        {
+          accountKey: PublicKey.unique(),
+          writableIndexes: [0],
+          readonlyIndexes: [1],
+        },
+        {
+          accountKey: PublicKey.unique(),
+          writableIndexes: [0],
+          readonlyIndexes: [1],
+        },
+      ],
+    });
+
+    expect(message.isAccountWritable(0)).to.be.true;
+    expect(message.isAccountWritable(1)).to.be.false;
+    expect(message.isAccountWritable(2)).to.be.true;
+    expect(message.isAccountWritable(3)).to.be.false;
+
+    expect(message.isAccountWritable(4)).to.be.true;
+    expect(message.isAccountWritable(5)).to.be.true;
+
+    expect(message.isAccountWritable(6)).to.be.false;
+    expect(message.isAccountWritable(7)).to.be.false;
+  });
+
+  it('isAccountSigner', () => {
+    const staticAccountKeys = [
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+      PublicKey.unique(),
+    ];
+
+    const recentBlockhash = bs58.encode(sha256('test'));
+    const message = new MessageV0({
+      header: {
+        numRequiredSignatures: 2,
+        numReadonlySignedAccounts: 1,
+        numReadonlyUnsignedAccounts: 1,
+      },
+      recentBlockhash,
+      staticAccountKeys,
+      compiledInstructions: [],
+      addressTableLookups: [
+        {
+          accountKey: PublicKey.unique(),
+          writableIndexes: [0],
+          readonlyIndexes: [1],
+        },
+        {
+          accountKey: PublicKey.unique(),
+          writableIndexes: [0],
+          readonlyIndexes: [1],
+        },
+      ],
+    });
+
+    expect(message.isAccountSigner(0)).to.be.true;
+    expect(message.isAccountSigner(1)).to.be.true;
+    for (let i = 2; i < 8; i++) {
+      expect(message.isAccountSigner(i)).to.be.false;
+    }
+  });
 });