| // Get the appropriate flag to use for creating files |
| // We use fmap on Windows platforms for files less than |
| // 512kb. This is a fairly low limit, but avoids making |
| // things slower in some cases. Since most of what this |
| // library is used for is extracting tarballs of many |
| // relatively small files in npm packages and the like, |
| // it can be a big boost on Windows platforms. |
| // Only supported in Node v12.9.0 and above. |
| const platform = process.env.__FAKE_PLATFORM__ || process.platform |
| const isWindows = platform === 'win32' |
| const fs = global.__FAKE_TESTING_FS__ || require('fs') |
| |
| /* istanbul ignore next */ |
| const { O_CREAT, O_TRUNC, O_WRONLY, UV_FS_O_FILEMAP = 0 } = fs.constants |
| |
| const fMapEnabled = isWindows && !!UV_FS_O_FILEMAP |
| const fMapLimit = 512 * 1024 |
| const fMapFlag = UV_FS_O_FILEMAP | O_TRUNC | O_CREAT | O_WRONLY |
| module.exports = !fMapEnabled ? () => 'w' |
| : size => size < fMapLimit ? fMapFlag : 'w' |
