Add BpfLoader (#34)

feat: Add BpfLoader

web3.js/src/bpf-loader.js

@@ -0,0 +1,55 @@
+// @flow
+
+import fs from 'mz/fs';
+import elfy from 'elfy';
+
+import {Account, PublicKey, Loader, SystemProgram} from '.';
+import {sendAndConfirmTransaction} from './util/send-and-confirm-transaction';
+import type {Connection} from '.';
+
+/**
+ * Factory class for transactions to interact with a program loader
+ */
+export class BpfLoader {
+  /**
+   * Public key that identifies the NativeLoader
+   */
+  static get programId(): PublicKey {
+    return new PublicKey('0x0606060606060606060606060606060606060606060606060606060606060606');
+  }
+
+  /**
+   * Loads a BPF program
+   *
+   * @param connection The connection to use
+   * @param owner User account to load the program with
+   * @param programName Name of the BPF program
+   */
+  static async load(
+    connection: Connection,
+    owner: Account,
+    programName: string,
+  ): Promise<PublicKey> {
+    const programAccount = new Account();
+
+    const data = await fs.readFile(programName);
+    const elf = elfy.parse(data);
+    const section = elf.body.sections.find(section => section.name === '.text.entrypoint');
+
+    // Allocate memory for the program account
+    const transaction = SystemProgram.createAccount(
+      owner.publicKey,
+      programAccount.publicKey,
+      1,
+      section.data.length,
+      BpfLoader.programId,
+    );
+    await sendAndConfirmTransaction(connection, owner, transaction);
+
+    const loader = new Loader(connection, BpfLoader.programId);
+    await loader.load(programAccount, section.data);
+    await loader.finalize(programAccount);
+
+    return programAccount.publicKey;
+  }
+}