| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * Copyright (c) 2017, Amjad Masad |
| 4 | * |
| 5 | * This source code is licensed under the MIT license found in the |
| 6 | * LICENSE file in the root directory of this source tree. |
| 7 | */ |
| 8 | |
| 9 | 'use strict'; |
| 10 | |
| 11 | // Based on https://repl.it/site/blog/infinite-loops. |
| 12 | |
| 13 | // This should be reasonable for all loops in the source. |
| 14 | // Note that if the numbers are too large, the tests will take too long to fail |
| 15 | // for this to be useful (each individual test case might hit an infinite loop). |
| 16 | const MAX_SOURCE_ITERATIONS = 6000; |
| 17 | // Code in tests themselves is permitted to run longer. |
| 18 | // For example, in the fuzz tester. |
| 19 | const MAX_TEST_ITERATIONS = 5000; |
| 20 | |
| 21 | module.exports = ({types: t, template}) => { |
| 22 | // We set a global so that we can later fail the test |
| 23 | // even if the error ends up being caught by the code. |
| 24 | const buildGuard = template(` |
| 25 | if (%%iterator%%++ > %%maxIterations%%) { |
| 26 | global.infiniteLoopError = new RangeError( |
| 27 | 'Potential infinite loop: exceeded ' + |
| 28 | %%maxIterations%% + |
| 29 | ' iterations.' |
| 30 | ); |
| 31 | throw global.infiniteLoopError; |
| 32 | } |
| 33 | `); |
| 34 | |
| 35 | return { |
| 36 | visitor: { |
| 37 | 'WhileStatement|ForStatement|DoWhileStatement': (path, file) => { |
| 38 | const filename = file.file.opts.filename; |
| 39 | const maxIterations = t.logicalExpression( |
| 40 | '||', |
| 41 | t.memberExpression( |
| 42 | t.identifier('global'), |
| 43 | t.identifier('__MAX_ITERATIONS__') |
| 44 | ), |
| 45 | t.numericLiteral( |
| 46 | filename.indexOf('__tests__') === -1 |
| 47 | ? MAX_SOURCE_ITERATIONS |
| 48 | : MAX_TEST_ITERATIONS |
| 49 | ) |
| 50 | ); |
| 51 | |
| 52 | // An iterator that is incremented with each iteration |
| 53 | const iterator = path.scope.parent.generateUidIdentifier('loopIt'); |
| 54 | const iteratorInit = t.numericLiteral(0); |
| 55 | path.scope.parent.push({ |
| 56 | id: iterator, |
| 57 | init: iteratorInit, |
| 58 | }); |
| 59 | // If statement and throw error if it matches our criteria |
| 60 | const guard = buildGuard({ |
| 61 | iterator, |
| 62 | maxIterations, |
| 63 | }); |
| 64 | // No block statement e.g. `while (1) 1;` |
| 65 | if (!path.get('body').isBlockStatement()) { |
| 66 | const statement = path.get('body').node; |
| 67 | path.get('body').replaceWith(t.blockStatement([guard, statement])); |
| 68 | } else { |
| 69 | path.get('body').unshiftContainer('body', guard); |
| 70 | } |
| 71 | }, |
| 72 | }, |
| 73 | }; |
| 74 | }; |