curl tries to read from stdin when POSTing with -C

[Smackd0wn]

I did this

curl -v httpbin.org/post --data foobar -C 3

I expected the following

Not sure what to expect (POST data "bar", maybe?), but surely not the current behavior:

$ curl -v httpbin.org/post --data foobar -C3
*   Trying 34.235.32.249:80...
* Connected to httpbin.org (34.235.32.249) port 80 (#0)

and now it blocks forever, because it tries to read from stdin, seen from the strace log

lseek(0, 3, SEEK_SET)                   = -1 ESPIPE (Illegal seek)
read(0,

---

Now if I feed some data into stdin, say yes | curl -v httpbin.org/post --data foobar -C 3, curl will POST the string "foo", not "bar" or "y\ny".

$  yes|curl -v httpbin.org/post --data foobar -C3
*   Trying 34.235.32.249:80...
* Connected to httpbin.org (34.235.32.249) port 80 (#0)
> POST /post HTTP/1.1
> Host: httpbin.org
> Content-Range: bytes 3-5/6
> User-Agent: curl/8.0.1
> Accept: */*
> Content-Length: 3
> Content-Type: application/x-www-form-urlencoded
>
< HTTP/1.1 200 OK
< Date: Sun, 07 May 2023 17:05:37 GMT
< Content-Type: application/json
< Content-Length: 458
< Connection: keep-alive
< Server: gunicorn/19.9.0
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Credentials: true
<
{
  "args": {},
  "data": "",
  "files": {},
  "form": {
    "foo": ""
  },
  "headers": {
    "Accept": "*/*",
    "Content-Length": "3",
    "Content-Range": "bytes 3-5/6",
    "Content-Type": "application/x-www-form-urlencoded",
    "Host": "httpbin.org",
    "User-Agent": "curl/8.0.1",
    "X-Amzn-Trace-Id": "Root=1-XXX"
  },
  "json": null,
  "origin": "XXX",
  "url": "http://httpbin.org/post"
}
* Connection #0 to host httpbin.org left intact

curl/libcurl version

curl 8.0.1 (x86_64-pc-linux-gnu) libcurl/8.0.1 OpenSSL/3.0.7 zlib/1.2.13 brotli/1.0.9 zstd/1.5.2 libidn2/2.3.4 libpsl/0.21.2 (+libidn2/2.3.4) libssh2/1.10.0 nghttp2/1.51.0
Release-Date: [unreleased]
Protocols: dict file ftp ftps gopher gophers http https imap imaps mqtt pop3 pop3s rtsp scp sftp smb smbs smtp smtps telnet tftp
Features: alt-svc AsynchDNS brotli GSS-API HSTS HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz NTLM NTLM_WB PSL SPNEGO SSL threadsafe TLS-SRP UnixSockets zstd

operating system

Linux arch 5.15.86-1-lts #1 SMP Sun, 01 Jan 2023 16:03:00 +0000 x86_64 GNU/Linux

[Smackd0wn]

Actually it might be useful to PUT some partial data to a server, like
https://stackoverflow.com/questions/716680/difference-between-content-range-and-range-headers/6711496

[bagder]

Actually it might be useful to PUT some partial data to a server, like

There is no standard for doing "partial" uploads with HTTP PUT.

[bagder]

--data cannot be used with --continue-at. It should refuse to accept that combination.

[Smackd0wn]

I see. Thank you for the fix!