How to deal with the error reported when Node.js calls fs.renameSync (Error: EXDEV, cross-device link not permitted)

This article mainly introduces the error reported when Node.js calls fs.renameSync (Error: EXDEV, cross-device link not permitted). It is of great practical value. Friends who need it can refer to it. I hope it can help everyone.

When writing a file upload function, there is an error in calling the fs.renameSync method

The error code is as follows:

 function upload(response,request){
 console.log("upload called");
 var form = new formidable.IncomingForm();
 console.log("about to parse");
 form.parse(request, function(error, fields, files) {
  console.log("parsing done");
  fs.renameSync(files.upload.path, "./tmp/test.jpg");
  response.writeHead(200, {"Content-Type": "text/html"});
  response.write("received image:<br/>");
  response.write("<img src=&#39;/show&#39; />");
  response.end();
 });
 }

Brief analysis Finally, it is expected that there will be permission issues when moving or operating files across disk partitions.

Two solutions are provided below:

Method 1:

Mainly use the createReadStream, createWriteSream and unlinkSync methods of fs

The specific code is as follows:

 function upload(response,request){
 console.log("upload called");
 var form = new formidable.IncomingForm();
 console.log("about to parse");
 form.parse(request, function(error, fields, files) {
  console.log("parsing done");

 // fs.renameSync(files.upload.path, "./tmp/test.jpg");
  var readStream=fs.createReadStream(files.upload.path);
  var writeStream=fs.createWriteStream("./tmp/test.jpg");
  readStream.pipe(writeStream);
  readStream.on('end',function(){
  fs.unlinkSync(files.upload.path);
  });

  response.writeHead(200, {"Content-Type": "text/html"});
  response.write("received image:<br/>");
  response.write("<img src=&#39;/show&#39; />");
  response.end();
 });
 }

PS: The node version I use is 0.10.69. If you are using a version below 0.6, you can use util .pump

The corresponding code only needs to change the readStream.on in the above code to: (note the introduction of the util module)

util.pump(readStream,writeStream, function() {
 fs.unlinkSync('files.upload.path');
});

method Two:

This is much simpler

Just add a form.uploadDir='tmp' (write a temporary path)

 function upload(response,request){
 console.log("upload called");
 var form = new formidable.IncomingForm();
 form.uploadDir='tmp';
 console.log("about to parse");
 form.parse(request, function(error, fields, files) {
  console.log("parsing done");
  fs.renameSync(files.upload.path, "./tmp/test.jpg");
  response.writeHead(, {"Content-Type": "text/html"});
  response.write("received image:<br/>");
  response.write("<img src=&#39;/show&#39; />");
  response.end();
 });
 }

Related recommendations:

Instructions for using the fs.renameSync method in node.js_node.js

Detailed explanation of node .js uses websocket based on express

How to use the async function in Node.js

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