在s3上上传图像后，图像已上传但已损坏，我该怎么办？

Question

我已经创建了一个将图片上传到s3存储桶的api，但是目前我上传到s3的图片似乎无法读取，因此我猜测它们已损坏？

以下是我的代码：

const AWS = require('aws-sdk')
const s3= new AWS.S3()
const crypto = require("crypto")

const sha1 = data => {
    return crypto.createHash("sha1").update(data).digest("hex")
}

const getFile = (ext, buffer, type) => {
    let encryptedFileName = sha1(new Buffer(new Date().toString()))
    //let timeBasedFileName = new Date().valueOf()


    let fileName = encryptedFileName+'.'+ext
    let bucketPath = "bucketname/folder/"+type //eg: bucket1/animals/fish
    let fileFullPath = bucketPath+"/"+fileName //eg: bucket1/animals/fish/salmon.jpg

    let params = {
        Bucket: 'mybucket',
        Body: buffer,
        ContentType: ext==='jpg'||ext==='jpeg'?'image/jpeg':'image/'+ext,
        Key: fileName
    }

    let uploadFile = {
        size: buffer.toString('ascii').length,
        type: ext==='jpg'||ext==='jpeg'?'image/jpeg':'image/'+ext,
        name: fileName,
        full_path: fileFullPath
    }

    return {params,uploadFile}
}

exports.handler = (event, context, callback) => {
        let base64String = event.base64String
        let ext = base64String.substring("data:image/".length, base64String.indexOf(";base64"))
        if (ext===null || (ext!=='jpg' && ext!=='jpeg' && ext!=='gif' && ext!=='png')) {return context.fail('Base64 string is not a supported file type.')}

        //pass base64 string into buffer
        let buffer = new Buffer(base64String, 'base64')

        let file = getFile(ext, buffer, event.type)
        //callback(null, 'working fine')
        let params = file.params
        s3.putObject(params, function(err,data) {
            // example response: {"filename":"0242CCB0-CE2E-4C75-A02E-FC054DA9E743.png","status":1,"message":"save success"}
            let response = {"statusCode": 400, "filename": "", status: 0, message: "save fail"}
            if (err) {callback(err, null)}

            response.statusCode=200
            response.filename=file.uploadFile.name
            response.status=1
            response.message="save success"
            callback(null, response)
        })
}

我基本上是将base64图像字符串转换为缓冲区并上传。 我在这里做错了什么？