解决Node.js调用fs.renameSync报错的问题（Error: EXDEV, cross-device link not permitted）

在写一个文件上传的功能时候，调用fs.renameSync方法错误

出错 代码所在如下：

1 function upload(response,request){
2     console.log("upload called");
3     var form = new formidable.IncomingForm();
4     console.log("about to parse");
5     form.parse(request, function(error, fields, files) {
6         console.log("parsing done");
7         fs.renameSync(files.upload.path, "./tmp/test.jpg");
8         response.writeHead(200, {"Content-Type": "text/html"});
9         response.write("received image:<br/>");
10         response.write("<img src='/show' />");
11             response.end();
12     });
13 }

大致分析后，预计是因为 跨磁盘分区移动 或操作文件会有权限问题。

下面提供两种解决办法：

方法一：

主要利用fs的createReadStream、createWriteSream和unlinkSync方法

具体代码如下：

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

7 //      fs.renameSync(files.upload.path, "./tmp/test.jpg");
8         var readStream=fs.createReadStream(files.upload.path);
9         var writeStream=fs.createWriteStream("./tmp/test.jpg");
10         readStream.pipe(writeStream);
11         readStream.on('end',function(){
12             fs.unlinkSync(files.upload.path);
13         });

14         response.writeHead(200, {"Content-Type": "text/html"});
15         response.write("received image:<br/>");
16         response.write("<img src='/show' />");
17         response.end();
18     });
19 }

PS：我用的node版本是0.10.69,如果使用的是0.6以下的版本，可以使用util.pump

相应代码只需将上面的代码中readStream.on处改成：(注意引入util模块)

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

方法二：

这种就简洁很多了

添加一个 form.uploadDir='tmp' 即可（写一个临时路径）

1 function upload(response,request){
2     console.log("upload called");
3     var form = new formidable.IncomingForm();
4     form.uploadDir='tmp';
 5
6     console.log("about to parse");
7     form.parse(request, function(error, fields, files) {
8         console.log("parsing done");
9         fs.renameSync(files.upload.path, "./tmp/test.jpg");
10         response.writeHead(200, {"Content-Type": "text/html"});
11         response.write("received image:<br/>");
12         response.write("<img src='/show' />");
13         response.end();
14     });
15 }
16