file - The essential steps in verifying a file upload

Question

What would you say are the essential steps in verifying a file upload?

I'd tend to check the MIME type, give it a new (random) name, make sure its got an allowed file extension, and then I'd check the contents of the file. How do you go about it?

Answer 1

检查（按此顺序）：文件 MIME 类型（并注意某些浏览器存在 MIME 类型检测问题...）；文件路径存在；不存在具有相同名称的文件的先前版本，否则，请修改它；文件不是太大；成功后，在服务器上运行病毒检查。

Answer 2

Check the file type, check the file size, the image dimension.

These are the 3 I always check to be sure to have good result.

Answer 3

取决于预期的文件内容...对文件运行病毒扫描可能是个好主意。

Answer 4

例如，如果您收到个人资料照片的 gif 文件，则应检查 mime 类型是否为 gif。
这样您就可以避免上传坏文件。
这里有一个使用 php 的示例。