When the download file is less than the limit speed, it cannot be limited

[liupeidong0620]

I did this

Download file size:

[root@california src]# du -sh curl-7.58.0.tar.gz
3.8M	curl-7.58.0.tar.gz

Problems with the new version：

[root@california src]# ./curl -V
curl 7.57.0 (x86_64-pc-linux-gnu) libcurl/7.57.0 OpenSSL/1.0.2h
Release-Date: 2017-11-29
Protocols: dict file ftp ftps gopher http https imap imaps pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
Features: AsynchDNS IPv6 Largefile NTLM NTLM_WB SSL TLS-SRP UnixSockets HTTPS-proxy

[root@california src]# time ./curl https://curl.haxx.se/download/curl-7.58.0.tar.gz -O --limit-rate 4M
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 3788k  100 3788k    0     0  3788k      0  0:00:01 --:--:--  0:00:01 28.6M

real	0m0.145s
user	0m0.033s
sys	0m0.021s

Real download time: real 0m0.145s

I expected the following

Correct performance

[root@california src]# ./curl -V
curl 7.36.0 (x86_64-unknown-linux-gnu) libcurl/7.36.0 OpenSSL/1.0.2h
Protocols: dict file ftp ftps gopher http https imap imaps pop3 pop3s rtsp smtp smtps telnet tftp
Features: IPv6 Largefile NTLM NTLM_WB SSL TLS-SRP

[root@california src]# time ./curl https://curl.haxx.se/download/curl-7.58.0.tar.gz -O --limit-rate 4M
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 3788k  100 3788k    0     0  4110k      0 --:--:-- --:--:-- --:--:-- 4113k

real	0m0.936s
user	0m0.027s
sys	0m0.013s

Real download time: real 0m0.936s

The reason for the problem is here

long Curl_pgrsLimitWaitTime(curl_off_t cursize,
                            curl_off_t startsize,
                            curl_off_t limit,
                            struct curltime start,
                            struct curltime now)
{
  ...........

  /* not enough data yet */
  if(size < limit)
    return -1;

  ..........
}

When the download file is less than the limit speed, it cannot be limited

After this code comment, execute the program:

[root@california src]# ./curl -V
curl 7.57.0 (x86_64-pc-linux-gnu) libcurl/7.57.0 OpenSSL/1.0.2h
Release-Date: 2017-11-29
Protocols: dict file ftp ftps gopher http https imap imaps pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
Features: AsynchDNS IPv6 Largefile NTLM NTLM_WB SSL TLS-SRP UnixSockets HTTPS-proxy

[root@california src]# time ./curl https://curl.haxx.se/download/curl-7.58.0.tar.gz -O --limit-rate 4M
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 3788k  100 3788k    0     0  3788k      0  0:00:01 --:--:--  0:00:01 4052k

real	0m0.950s
user	0m0.026s
sys	0m0.015s

Real download time: real 0m0.950s

operating system

Linux california 4.13.2-1.el7.elrepo.x86_64 #1 SMP Wed Sep 13 18:48:00 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux

[bagder]

Maybe we should just make it

  /* not enough data yet */
  if(!limit)
    return -1;

What do you think?

[liupeidong0620]

Good idea！

[bagder]

@liupeidong0620 give #2373 a try if you can