Implement findLinkReferences in linker.js

Author: axic

linker.js

@@ -31,6 +31,40 @@ var linkBytecode = function (bytecode, libraries) {
   return bytecode;
 };
 
+var findLinkReferences = function (bytecode) {
+  // find 40 bytes in the pattern of __...<36 digits>...__
+  // e.g. __Lib.sol:L_____________________________
+  var linkReferences = {};
+  var offset = 0;
+  while (true) {
+    var found = bytecode.match(/__(.{36})__/);
+    if (!found) {
+      break;
+    }
+
+    var start = found.index;
+    // trim trailing underscores
+    // NOTE: this has no way of knowing if the trailing underscore was part of the name
+    var libraryName = found[1].replace(/_+$/gm, '');
+
+    if (!linkReferences[libraryName]) {
+      linkReferences[libraryName] = [];
+    }
+
+    linkReferences[libraryName].push({
+      // offsets are in bytes in binary representation (and not hex)
+      start: (offset + start) / 2,
+      length: 20
+    });
+
+    offset += start + 20;
+
+    bytecode = bytecode.slice(start + 20);
+  }
+  return linkReferences;
+};
+
 module.exports = {
-  linkBytecode: linkBytecode
+  linkBytecode: linkBytecode,
+  findLinkReferences: findLinkReferences
 };

test/index.js

@@ -1,3 +1,4 @@
+require('./linker.js');
 require('./translate.js');
 require('./package.js');
 require('./abi.js');

test/linker.js

@@ -0,0 +1,84 @@
+const tape = require('tape');
+const linker = require('../linker.js');
+
+tape('Link references', function (t) {
+  t.test('Empty bytecode', function (st) {
+    st.deepEqual(linker.findLinkReferences(''), {});
+    st.end();
+  });
+
+  t.test('No references', function (st) {
+    st.deepEqual(linker.findLinkReferences('6060604052341561000f57600080fd'), {});
+    st.end();
+  });
+
+  t.test('One reference', function (st) {
+    var bytecode = '6060604052341561000f57600080fd5b60f48061001d6000396000f300606060405260043610603e5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166326121ff081146043575b600080fd5b3415604d57600080fd5b60536055565b005b73__lib2.sol:L____________________________6326121ff06040518163ffffffff167c010000000000000000000000000000000000000000000000000000000002815260040160006040518083038186803b151560b357600080fd5b6102c65a03f4151560c357600080fd5b5050505600a165627a7a723058207979b30bd4a07c77b02774a511f2a1dd04d7e5d65b5c2735b5fc96ad61d43ae40029';
+    st.deepEqual(linker.findLinkReferences(bytecode), { 'lib2.sol:L': [ { start: 116, length: 20 } ] });
+    st.end();
+  });
+
+  t.test('Two references', function (st) {
+    var bytecode = '6060604052341561000f57600080fd5b61011a8061001e6000396000f30060606040526004361060255763ffffffff60e060020a60003504166326121ff08114602a575b600080fd5b3415603457600080fd5b603a603c565b005b73__lib2.sol:L____________________________6326121ff06040518163ffffffff1660e060020a02815260040160006040518083038186803b1515608157600080fd5b6102c65a03f41515609157600080fd5b50505073__linkref.sol:Lx________________________6326121ff06040518163ffffffff1660e060020a02815260040160006040518083038186803b151560d957600080fd5b6102c65a03f4151560e957600080fd5b5050505600a165627a7a72305820fdfb8eab411d7bc86d7dfbb0c985c30bebf1cc105dc5b807291551b3d5aa29d90029';
+    st.deepEqual(
+      linker.findLinkReferences(bytecode),
+      { 'lib2.sol:L': [ { start: 92, length: 20 } ], 'linkref.sol:Lx': [ { start: 180, length: 20 } ] }
+    );
+    st.end();
+  });
+
+  t.test('Library name with leading underscore', function (st) {
+    var bytecode = '6060604052341561000f57600080fd5b60f48061001d6000396000f300606060405260043610603e5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166326121ff081146043575b600080fd5b3415604d57600080fd5b60536055565b005b73__lib2.sol:_L___________________________6326121ff06040518163ffffffff167c010000000000000000000000000000000000000000000000000000000002815260040160006040518083038186803b151560b357600080fd5b6102c65a03f4151560c357600080fd5b5050505600a165627a7a7230582089689827bbf0b7dc385ffcb4b1deb9f9e61741f61f89b4af65f806ff2b0d73470029';
+    st.deepEqual(
+      linker.findLinkReferences(bytecode),
+      { 'lib2.sol:_L': [ { start: 116, length: 20 } ] }
+    );
+    st.end();
+  });
+
+  t.test('Library name with leading underscore (without fqdn)', function (st) {
+    var bytecode = '6060604052341561000f57600080fd5b60f48061001d6000396000f300606060405260043610603e5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166326121ff081146043575b600080fd5b3415604d57600080fd5b60536055565b005b73___L____________________________________6326121ff06040518163ffffffff167c010000000000000000000000000000000000000000000000000000000002815260040160006040518083038186803b151560b357600080fd5b6102c65a03f4151560c357600080fd5b5050505600a165627a7a7230582089689827bbf0b7dc385ffcb4b1deb9f9e61741f61f89b4af65f806ff2b0d73470029';
+    st.deepEqual(
+      linker.findLinkReferences(bytecode),
+      { '_L': [ { start: 116, length: 20 } ] }
+    );
+    st.end();
+  });
+
+  t.test('Library name with underscore in the name', function (st) {
+    var bytecode = '6060604052341561000f57600080fd5b60f48061001d6000396000f300606060405260043610603e5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166326121ff081146043575b600080fd5b3415604d57600080fd5b60536055565b005b73__lib2.sol:L_L__________________________6326121ff06040518163ffffffff167c010000000000000000000000000000000000000000000000000000000002815260040160006040518083038186803b151560b357600080fd5b6102c65a03f4151560c357600080fd5b5050505600a165627a7a723058205cb324a27452cc7f8894a57cb0e3ddce2dce0c423e4fc993a3dd51287abd49110029';
+    st.deepEqual(
+      linker.findLinkReferences(bytecode),
+      { 'lib2.sol:L_L': [ { start: 116, length: 20 } ] }
+    );
+    st.end();
+  });
+
+  // Note: this is a case the reference finder cannot properly handle as there's no way to tell
+  t.test('Library name with trailing underscore', function (st) {
+    var bytecode = '6060604052341561000f57600080fd5b60f48061001d6000396000f300606060405260043610603e5763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166326121ff081146043575b600080fd5b3415604d57600080fd5b60536055565b005b73__lib2.sol:L____________________________6326121ff06040518163ffffffff167c010000000000000000000000000000000000000000000000000000000002815260040160006040518083038186803b151560b357600080fd5b6102c65a03f4151560c357600080fd5b5050505600a165627a7a7230582058e61511a603707222cfa83fd3ae4269f94eb86513cb9042cf0b44877403d85c0029';
+    st.deepEqual(
+      linker.findLinkReferences(bytecode),
+      { 'lib2.sol:L': [ { start: 116, length: 20 } ] }
+    );
+    st.end();
+  });
+
+  t.test('Invalid input (too short)', function (st) {
+    var bytecode = '6060604052341561000____66606060606060';
+    st.deepEqual(
+      linker.findLinkReferences(bytecode),
+      {}
+    );
+    st.end();
+  });
+
+  t.test('Invalid input (1 byte short)', function (st) {
+    var bytecode = '6060604052341561000__lib2.sol:L___________________________66606060606060';
+    st.deepEqual(
+      linker.findLinkReferences(bytecode),
+      {}
+    );
+    st.end();
+  });
+});