CURLOPT_INFILESIZE_LARGE(3)

💅 CURLOPT_INFILESIZE_LARGE(3) — like, the libcurl manual, bestie edition 🎀

okay so real talk: this is a page from the Library Functions Manual, and today we're learning CURLOPT_INFILESIZE_LARGE — the glow-up sibling of the regular infilesize option, but for when your file is big big. Let's get into it ✨

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🌸 NAME 🌸

CURLOPT_INFILESIZE_LARGE — telling libcurl how big your input file is before you send it off. like a vibe check for your upload, but with bytes 📏

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🦋 SYNOPSIS 🦋

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_INFILESIZE_LARGE,
                          curl_off_t filesize);

that's it, that's the whole mood 💅

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💖 DESCRIPTION 💖

so when you're uploading a file to some remote site, you use filesize to tell libcurl what the expected size of the input file is. and bestie, this value has to be passed as a curl_off_t — no shortcuts, no "close enough" types, it's giving specific 💀

btw if you're uploading using SCP, this option or CURLOPT_INFILESIZE(3) is mandatory — like, not optional, not "maybe later", mandatory mandatory. main character requirement fr fr 👑

want to unset this value again? just set it to -1. that's the undo button, no cap 🙈

and oh! when you're sending emails using SMTP, this command can be used to specify the optional SIZE parameter for the MAIL FROM command. cute little bonus feature 🎀

ok here's the important caveat, listen up 🔥: this option does not limit how much data libcurl actually sends. that's controlled entirely by what the read callback returns — periodt. so if you tell it one value and then send a different amount, you may get errors. telling lies to libcurl = consequences, iykyk 😭

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⭐ DEFAULT ⭐

Unset — literally no value, it's a blank canvas, an empty group chat 💀

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🌈 PROTOCOLS 🌈

This functionality affects all supported protocols. every single one. universal slay 🫶

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🍓 EXAMPLE 🍓

ok here's a whole little program, isn't she precious:

#define FILE_SIZE 123456

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_off_t uploadsize = FILE_SIZE;

    curl_easy_setopt(curl, CURLOPT_URL,
                     "ftp://example.com/destination.tar.gz");

    curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

    curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, uploadsize);

    curl_easy_perform(curl);
  }
}

see how she sets the URL, turns on CURLOPT_UPLOAD with 1L, then drops in the big file size? that's the whole flow, ate and left no crumbs 🔥

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🧚 HISTORY 🧚

SMTP support was added in 7.23.0 — a lil throwback moment for the email girlies 💌

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👑 AVAILABILITY 👑

Added in curl 7.11.0. she's been iconic for a minute ⭐

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💜 RETURN VALUE 💜

curl_easy_setopt(3) returns a CURLcode indicating success or error.

• CURLE_OK (0) means everything was OK — like, we're so back 💖
• non-zero means an error occurred — check libcurl-errors(3) for the full tea 😭

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🎀 SEE ALSO 🎀

• CURLINFO_CONTENT_LENGTH_UPLOAD_T(3)
• CURLOPT_INFILESIZE(3)
• CURLOPT_UPLOAD(3)

go read those too, they're all connected bestie, it's a whole ecosystem 🦋

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okay that's the page!! this was libcurl, dated 2026-10-12, and the page is CURLOPT_INFILESIZE_LARGE(3) — go forth and upload responsibly, mwah 💋✨🌸