Unable to create an empty file

[AndreKR]

Trying to create an empty file:

obj := bucket.Object("foo")
wc := obj.NewWriter(context.Background())
fmt.Println(wc.Write([]byte{}))
fmt.Println(wc.Close())

produces the error: b2_upload_file: 400: Missing header: Content-Length

[kurin]

I don't think this is me:

2018/09/12 10:53:43 >> b2_upload_file uri: https://pod-000-1039-13.backblaze.com/b2api/v1/b2_upload_file/72bdd680e4a7c5e76353081d/c001_v0001039_t0054 {X-Bz-Content-Sha1: da39a3ee5e6b4b0d3255bfef95601890afd80709;X-Blazer-Request-Id: 14;X-Bz-Test-Mode: fail_some_uploads,expire_some_account_authorization_tokens;X-Bz-File-Name: empty;Content-Type: application/octet-stream;Content-Length: 0;User-Agent: integration-test b2-test blazer/0.5.1} (no args)
2018/09/12 10:53:43 << b2_upload_file (14) 400  {Cache-Control: max-age=0, no-cache, no-store; Content-Type: application/json;charset=utf-8; Content-Length: 91; Date: Wed, 12 Sep 2018 17:53:43 GMT} ({
  "code": "bad_request",
  "message": "Missing header: Content-Length",
  "status": 400
})
2018/09/12 10:53:43 error writing empty: b2_upload_file: 400: Missing header: Content-Length

[kurin]

Although I think if you create a writer and immediately Close it, you should get an empty object as well, and right now you don't, with no error.

[kurin]

I couldn't open a bug on the backblaze site because the recaptcha form was broken, but I'll try again later.

[AndreKR]

It's not just B2 either, this works for uploading an empty file:

// Login
req, _ := http.NewRequest("GET", "https://api.backblazeb2.com/b2api/v1/b2_authorize_account", nil)
req.SetBasicAuth(username, password)
resp, err := http.DefaultClient.Do(req)
fmt.Println(err)
d := json.NewDecoder(resp.Body)
var auth struct {
	ApiUrl             string
	AuthorizationToken string
}
err = d.Decode(&auth)
resp.Body.Close()
fmt.Println(err)
fmt.Println(auth)

// Get upload URL
req, _ = http.NewRequest("POST", auth.ApiUrl+"/b2api/v1/b2_get_upload_url", bytes.NewReader([]byte(`{"bucketId": "`+bucket+`"}`)))
req.Header.Set("Authorization", auth.AuthorizationToken)
resp, err = http.DefaultClient.Do(req)
fmt.Println(err)
d = json.NewDecoder(resp.Body)
var upload struct {
	AuthorizationToken string
	UploadUrl          string
}
err = d.Decode(&upload)
resp.Body.Close()
fmt.Println(err)
fmt.Println(upload)

// Upload
req, _ = http.NewRequest("POST", upload.UploadUrl, bytes.NewReader([]byte(""))) // empty body
req.Header.Set("Authorization", upload.AuthorizationToken)
req.Header.Set("X-Bz-File-Name", "empty")
req.Header.Set("Content-Type", "application/octet-stream")
req.Header.Set("Content-Length", "0") // it works without this, probably Go sets it
req.Header.Set("X-Bz-Content-Sha1", "da39a3ee5e6b4b0d3255bfef95601890afd80709")
resp, err = http.DefaultClient.Do(req)
fmt.Println(err)
b, err := ioutil.ReadAll(resp.Body)
fmt.Println(err)
fmt.Println(string(b))

[kurin]

It looks like the http lib is setting the transfer encoding to "chunked" and then sending a non-empty body for reasons I don't yet understand.

[kurin]

POST /b2api/v1/b2_upload_file/22ed46e0b407c5f76353081d/c001_v0001105_t0039 HTTP/1.1
Host: pod-000-1105-00.backblaze.com
User-Agent: integration-test b2-test blazer/0.5.1
Transfer-Encoding: chunked
Authorization: boop
Content-Type: application/octet-stream
X-Blazer-Method: b2_upload_file
X-Blazer-Request-Id: 7
X-Bz-Content-Sha1: da39a3ee5e6b4b0d3255bfef95601890afd80709
X-Bz-File-Name: empty
X-Bz-Test-Mode: fail_some_uploads
X-Bz-Test-Mode: expire_some_account_authorization_tokens
Accept-Encoding: gzip

0

I think I want to explicitly set the encoding to "identity" but uh, that's not working.

[kurin]

// outgoingLength reports the Content-Length of this outgoing (Client) request.
// It maps 0 into -1 (unknown) when the Body is non-nil.
func (r *Request) outgoingLength() int64 {

Cool. Coolcoolcool.