Edit: get-write-flag.js
// 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'
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