feat: add keepTimes option

Refs webpack-contrib#396

README.md

@@ -505,6 +505,7 @@ module.exports = {
 |         [`ignore`](#ignore)         |  `{Array}`  |            `[]`            | Array of globs to ignore (applied to `from`)                                                                                                      |
 |        [`context`](#context)        | `{String}`  | `compiler.options.context` | A path that determines how to interpret the `from` path, shared for all patterns                                                                  |
 | [`copyUnmodified`](#copyunmodified) | `{Boolean}` |          `false`           | Copies files, regardless of modification when using watch or `webpack-dev-server`. All files are copied on first build, regardless of this option |
+|      [`keepTimes`](#keeptimes)      | `{Boolean}` |          `false`           | Copy the original access and modification over to the destination files, when possible                                                            |
 
 #### `logLevel`
 
@@ -568,6 +569,18 @@ module.exports = {
 };
 ```
 
+#### `keepTimes`
+
+Attempt to copy source files' access and modification times over to the destination files.
+
+**webpack.config.js**
+
+```js
+module.exports = {
+  plugins: [new CopyPlugin([...patterns], { keepTimes: true })],
+};
+```
+
 ## Contributing
 
 Please take a moment to read our contributing guidelines if you haven't yet done so.

src/index.js

@@ -7,6 +7,7 @@ import schema from './options.json';
 import preProcessPattern from './preProcessPattern';
 import processPattern from './processPattern';
 import postProcessPattern from './postProcessPattern';
+import updateTimes from './updateTimes';
 
 class CopyPlugin {
   constructor(patterns = [], options = {}) {
@@ -52,6 +53,7 @@ class CopyPlugin {
         output: compiler.options.output.path,
         ignore: this.options.ignore || [],
         copyUnmodified: this.options.copyUnmodified,
+        keepTimes: this.options.keepTimes,
         concurrency: this.options.concurrency,
       };
 
@@ -117,6 +119,10 @@ class CopyPlugin {
         }
       }
 
+      if (this.options.keepTimes) {
+        updateTimes(compiler, compilation, logger);
+      }
+
       logger.debug('finishing after-emit');
 
       callback();

src/options.json

@@ -67,6 +67,9 @@
         },
         "transformPath": {
           "instanceof": "Function"
+        },
+        "keepTimes": {
+          "type": "boolean"
         }
       },
       "required": ["from"]

src/postProcessPattern.js

@@ -197,6 +197,10 @@ export default function postProcessPattern(globalRef, pattern, file) {
           source() {
             return content;
           },
+          copyPluginTimes: {
+            atime: stats.atime,
+            mtime: stats.mtime,
+          },
         };
       });
   });

src/updateTimes.js

@@ -0,0 +1,57 @@
+/**
+ * Attempt to get an Utimes function for the compiler's output filesystem.
+ */
+function getUtimesFunction(compiler) {
+  if (compiler.outputFileSystem.utimes) {
+    // Webpack 5+ on Node will use graceful-fs for outputFileSystem so utimes is always there.
+    // Other custom outputFileSystems could also have utimes.
+    return compiler.outputFileSystem.utimes.bind(compiler.outputFileSystem);
+  } else if (
+    compiler.outputFileSystem.constructor &&
+    compiler.outputFileSystem.constructor.name === 'NodeOutputFileSystem'
+  ) {
+    // Default NodeOutputFileSystem can just use fs.utimes, but we need to late-import it in case
+    // we're running in a web context and statically importing `fs` might be a bad idea.
+    // eslint-disable-next-line global-require
+    return require('fs').utimes;
+  }
+  return null;
+}
+
+/**
+ * Update the times of disk files for which we have recorded a source time
+ * @param compiler
+ * @param compilation
+ * @param logger
+ */
+function updateTimes(compiler, compilation, logger) {
+  const utimes = getUtimesFunction(compiler);
+  let nUpdated = 0;
+  for (const [name, asset] of Object.entries(compilation.assets)) {
+    // eslint-disable-next-line no-underscore-dangle
+    const times = asset.copyPluginTimes;
+    if (times) {
+      const targetPath =
+        asset.existsAt ||
+        compiler.outputFileSystem.join(compiler.outputPath, name);
+      if (!utimes) {
+        logger.warn(
+          `unable to update time for ${targetPath} using current file system`
+        );
+      } else {
+        // TODO: process these errors in a better way and/or wait for completion?
+        utimes(targetPath, times.atime, times.mtime, (err) => {
+          if (err) {
+            logger.warn(`${targetPath}: utimes: ${err}`);
+          }
+        });
+        nUpdated += 1;
+      }
+    }
+  }
+  if (nUpdated > 0) {
+    logger.info(`times updated for ${nUpdated} copied files`);
+  }
+}
+
+export default updateTimes;

test/CopyPlugin.test.js

@@ -1,4 +1,5 @@
 import path from 'path';
+import fs from 'fs';
 
 import { MockCompiler } from './helpers/mocks';
 import { run, runEmit, runChange } from './helpers/run';
@@ -250,6 +251,38 @@ describe('apply function', () => {
         .then(done)
         .catch(done);
     });
+
+    it('should copy file modification times when told to', (done) => {
+      const origStat = fs.statSync(path.join(FIXTURES_DIR, 'file.txt'));
+      const utimeCalls = {};
+      const compiler = new MockCompiler();
+      // Patch in some things that are missing by default...
+      compiler.outputFileSystem.join = (a, b) => path.join(a || '', b);
+      compiler.outputFileSystem.utimes = (pth, atime, mtime, callback) => {
+        utimeCalls[pth] = { atime, mtime };
+        callback(null);
+      };
+
+      runEmit({
+        compiler,
+        expectedAssetKeys: ['file.txt'],
+        options: {
+          keepTimes: true,
+        },
+        patterns: [
+          {
+            from: 'file.txt',
+          },
+        ],
+      })
+        .then(() => {
+          const { atime, mtime } = utimeCalls['file.txt'];
+          expect(atime).toEqual(origStat.atime);
+          expect(mtime).toEqual(origStat.mtime);
+        })
+        .then(done)
+        .catch(done);
+    });
   });
 
   describe('difference path segment separation', () => {