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Re: When CURLOPT_RANGE is specified in the FTP protocol, does it ever write out-of-range data?

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From: Daniel Stenberg via curl-library <curl-library_at_lists.haxx.se>
Date: Thu, 7 Aug 2025 17:27:03 +0200 (CEST)

On Thu, 7 Aug 2025, Yoshimasa Ohno via curl-library wrote:

> In the application, I am trying to specify the retrieval range in
> CURLOPT_RANGE and write incoming data through CURLOPT_WRITEFUNCTION.
>
> As far as I can tell, the callback to CURLOPT_WRITEFUNCTION doesn't seem to
> pass over data outside the range specified by CURLOPT_RANGE. Is this a
> coincidence? Or is it designed that way?

It is designed that way. You ask for a range, you get that range.

> Since the FTP protocol does not have a range specification (end-of-range
> specification) mechanism, we expect that the libcurl side is designed to
> ignore out-of-range data.

curl makes sure to deliver what the user asks for! FTP has a command to
instruct the server where to start reading from, and then curl stops reading
at the end of the range. Easy peacy!

-- 
  / daniel.haxx.se || https://rock-solid.curl.dev
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Received on 2025-08-07

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