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