CURLOPT_FNMATCH_DATA(3)

💅 CURLOPT_FNMATCH_DATA(3) — bestie edition ✨

okay so this page lives in the Library Functions Manual and it's literally all about CURLOPT_FNMATCH_DATA(3), no cap. it's short, it's sweet, it's giving "small but crucial" 🎀

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🌸 NAME 🌸

CURLOPT_FNMATCH_DATA — the pointer you pass along to your fnmatch callback. that's it. that's the whole vibe 💖

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✨ SYNOPSIS ✨

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FNMATCH_DATA,
                          void *pointer);

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🦋 DESCRIPTION 🦋

so here's the tea ☕ — you hand libcurl a pointer, and libcurl is literally not going to touch it. like, zero touching. not even a little peek. instead it gets passed straight through as the ptr argument to whatever function you set with CURLOPT_FNMATCH_FUNCTION(3). 🫶

it's giving "you carry the bag, we do the wildcard matching" and honestly? iconic.

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🎀 DEFAULT 🎀

NULL

(yeah. nothing. empty. the void. very main-character-of-emptiness of it 💀)

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🌈 PROTOCOLS 🌈

this functionality affects ftp only. ftp girlies, this one's for you 🧚

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⭐ EXAMPLE ⭐

here's the whole thing, verbatim, because we respect the source:

extern int string_match(const char *s1, const char *s2);

struct local_stuff {
  void *custom;
};

static int my_fnmatch(void *clientp,
                      const char *pattern, const char *string)
{
  struct local_stuff *my = clientp;
  printf("my ptr: %p\n", my->custom);

  if(string_match(pattern, string))
    return CURL_FNMATCHFUNC_MATCH;
  else
    return CURL_FNMATCHFUNC_NOMATCH;
}

int main(void)
{
  struct local_stuff local_data;
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "ftp://ftp.example.com/file*");
    curl_easy_setopt(curl, CURLOPT_WILDCARDMATCH, 1L);
    curl_easy_setopt(curl, CURLOPT_FNMATCH_FUNCTION, my_fnmatch);
    curl_easy_setopt(curl, CURLOPT_FNMATCH_DATA, &local_data);

    curl_easy_perform(curl);
  }
}

see how &local_data slides right into CURLOPT_FNMATCH_DATA and then shows up as clientp in my_fnmatch? it's giving "the circle of life" 🦋✨

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👑 AVAILABILITY 👑

added in curl 7.21.0. vintage, but still slaying 💅

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🔥 RETURN VALUE 🔥

curl_easy_setopt(3) returns a CURLcode indicating success or error. very demure, very straightforward.

• CURLE_OK (0) means everything was OK — slay ✅
• non-zero means an error occurred 😭 — see libcurl-errors(3) for the full drama

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💜 SEE ALSO 💜

• CURLOPT_FNMATCH_FUNCTION(3)
• CURLOPT_WILDCARDMATCH(3)

lowkey go read both of these next, they're the other two-thirds of the wildcard-matching trifecta 🫶

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and that's the whole page bestie, hope it ate 💖 this one comes from libcurl, dated 2026-10-12, and it was originally titled CURLOPT_FNMATCH_DATA(3) in case the vibe check required receipts. mwah 😘🎀