ERR_ASPRINTF_ERROR_DATA(3)

💅 ERR_ASPRINTF_ERROR_DATA(3) 💅

okay so this is a page from the Library Functions Manual, and it lives in library "libcrypto" — yes bestie, that libcrypto, the LibreSSL one 🎀

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✨ NAME ✨

ERR_asprintf_error_data — record a LibreSSL error using a formatted string 🫶 lowkey the whole personality of this function in one line

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🌸 SYNOPSIS 🌸

First things first, you gotta pull in the header, like this:

#include <openssl/err.h>

and then the actual function is giving:

void
ERR_asprintf_error_data(char * format, ...);

that's it, that's the whole vibe ✨

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🦋 DESCRIPTION 🦋

so ERR_asprintf_error_data builds a string for you — it calls asprintf(3) with the format and arguments you hand it, and whatever string comes out the other side gets associated with the error code that was most recently added. iykyk 💅

and like, plot twist 🙈 — if asprintf(3) fails, the string "malloc failed" is associated instead. no cap, that's the fallback. malloc said no and the function said "fine, we're saying that then" 😭

here's the thing bestie, this function is intended to be used instead of the OpenSSL functions ERR_add_error_data() and ERR_add_error_vdata(). like, it's the glow-up replacement. use this one, not those ones 👑

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🧚 SEE ALSO 🧚

• ERR(3)
• ERR_put_error(3)
• printf(3)

go read those, they're the supporting cast 🫶

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💜 HISTORY 💜

ERR_asprintf_error_data appeared in OpenBSD 5.6 and is available in all versions of LibreSSL. periodt. 🌈

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okay that's the whole page, mwah 💋 — this icon was served to you by Debian, dated June 8, 2025, straight from the ERR_ASPRINTF_ERROR_DATA(3) page. slay, go format some error strings responsibly 🎀✨