'use strict';
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const fs = require('fs');
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const shebangCommand = require('shebang-command');
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function readShebang(command) {
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// Read the first 150 bytes from the file
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const size = 150;
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let buffer;
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if (Buffer.alloc) {
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// Node.js v4.5+ / v5.10+
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buffer = Buffer.alloc(size);
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} else {
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// Old Node.js API
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buffer = new Buffer(size);
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buffer.fill(0); // zero-fill
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}
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let fd;
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try {
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fd = fs.openSync(command, 'r');
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fs.readSync(fd, buffer, 0, size, 0);
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fs.closeSync(fd);
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} catch (e) { /* Empty */ }
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// Attempt to extract shebang (null is returned if not a shebang)
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return shebangCommand(buffer.toString());
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}
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module.exports = readShebang;
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