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1 files changed, 37 insertions, 0 deletions

diff --git a/node_modules/cross-spawn/lib/util/readShebang.js b/node_modules/cross-spawn/lib/util/readShebang.js
new file mode 100644
index 00000000..2cf3541c
--- /dev/null
+++ b/node_modules/cross-spawn/lib/util/readShebang.js
@@ -0,0 +1,37 @@
+'use strict';
+
+var fs = require('fs');
+var LRU = require('lru-cache');
+var shebangCommand = require('shebang-command');
+
+var shebangCache = new LRU({ max: 50, maxAge: 30 * 1000 });  // Cache just for 30sec
+
+function readShebang(command) {
+    var buffer;
+    var fd;
+    var shebang;
+
+    // Check if it is in the cache first
+    if (shebangCache.has(command)) {
+        return shebangCache.get(command);
+    }
+
+    // Read the first 150 bytes from the file
+    buffer = new Buffer(150);
+
+    try {
+        fd = fs.openSync(command, 'r');
+        fs.readSync(fd, buffer, 0, 150, 0);
+        fs.closeSync(fd);
+    } catch (e) { /* empty */ }
+
+    // Attempt to extract shebang (null is returned if not a shebang)
+    shebang = shebangCommand(buffer.toString());
+
+    // Store the shebang in the cache
+    shebangCache.set(command, shebang);
+
+    return shebang;
+}
+
+module.exports = readShebang;