ERR_GET_ERROR(3ossl)

💖 ERR_GET_ERROR(3ossl) 💖

okay so bestie, welcome to the OpenSSL error-queue page — this is the 3ossl manual, and honestly it's giving "backstage pass to the error queue" energy. Let's get into it ✨

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🌸 NAME 🌸

ERR_get_error, ERR_peek_error, ERR_peek_last_error, ERR_get_error_line, ERR_peek_error_line, ERR_peek_last_error_line, ERR_peek_error_func, ERR_peek_last_error_func, ERR_peek_error_data, ERR_peek_last_error_data, ERR_get_error_all, ERR_peek_error_all, ERR_peek_last_error_all, ERR_get_error_line_data, ERR_peek_error_line_data, ERR_peek_last_error_line_data — all of these are about obtaining error code and data, periodt.

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🎀 SYNOPSIS 🎀

#include <openssl/err.h>

unsigned long ERR_get_error(void);
unsigned long ERR_peek_error(void);
unsigned long ERR_peek_last_error(void);

unsigned long ERR_peek_error_line(const char **file, int *line);
unsigned long ERR_peek_last_error_line(const char **file, int *line);

unsigned long ERR_peek_error_func(const char **func);
unsigned long ERR_peek_last_error_func(const char **func);

unsigned long ERR_peek_error_data(const char **data, int *flags);
unsigned long ERR_peek_last_error_data(const char **data, int *flags);

unsigned long ERR_get_error_all(const char **file, int *line,
                                const char **func,
                                const char **data, int *flags);
unsigned long ERR_peek_error_all(const char **file, int *line,
                                 const char **func,
                                 const char **data, int *flags);
unsigned long ERR_peek_last_error_all(const char **file, int *line,
                                      const char *func,
                                      const char **data, int *flags);

⚠️ the next batch is deprecated since OpenSSL 3.0 — you can hide them entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

unsigned long ERR_get_error_line(const char **file, int *line);
unsigned long ERR_get_error_line_data(const char **file, int *line,
                                      const char **data, int *flags);
unsigned long ERR_peek_error_line_data(const char **file, int *line,
                                       const char **data, int *flags);
unsigned long ERR_peek_last_error_line_data(const char **file, int *line,
                                            const char **data, int *flags);

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🦋 DESCRIPTION 🦋

ERR_get_error() grabs the earliest error code off the thread's error queue and removes the entry. like, it takes it out of the queue, no take-backs. you can call it over and over until there's literally nothing left to return 💅

ERR_peek_error() returns the earliest error code from the thread's error queue, but does not modify it. peek, don't touch, iykyk ✨

ERR_peek_last_error() returns the latest error code from the thread's error queue — again, without modifying it. newest one, still untouched.

fr fr, check out ERR_GET_LIB(3) if you want more specific info like the reason of the error, and ERR_error_string(3) for human-readable error messages 🫶

ERR_get_error_all() is the same as ERR_get_error(), but on success it additionally stores the filename, line number and function where the error happened in *file, *line and *func — plus extra text and flags in *data, *flags. If any of those parameters are NULL, it will not be changed. An unset filename is indicated as "", i.e. an empty string. An unset line number is indicated as 0. An unset function name is indicated as "", i.e. an empty string.

okay important detail: a pointer returned this way by these functions and the ones below is valid until the respective entry is overwritten in the error queue. so don't go holding onto it forever, bestie 😭

ERR_peek_error_line() and ERR_peek_last_error_line() are the same as ERR_peek_error() and ERR_peek_last_error(), but on success they additionally store the filename and line number where the error occurred in *file and *line, as far as they are not NULL. An unset filename is indicated as "", i.e., an empty string. An unset line number is indicated as 0.

ERR_peek_error_func() and ERR_peek_last_error_func() are the same as ERR_peek_error() and ERR_peek_last_error(), but on success they additionally store the name of the function where the error occurred in *func, unless it is NULL. An unset function name is indicated as "".

ERR_peek_error_data() and ERR_peek_last_error_data() are the same as ERR_peek_error() and ERR_peek_last_error(), but on success they additionally store additional data and flags associated with the error code in *data and *flags, as far as they are not NULL. Unset data is indicated as "". In this case the value given for the flag is irrelevant (and equals 0). *data contains a string if *flags&ERR_TXT_STRING is true.

ERR_peek_error_all() and ERR_peek_last_error_all() are combinations of all of the above. the whole package, the full combo meal 🍓

ERR_get_error_line(), ERR_get_error_line_data(), ERR_peek_error_line_data() and ERR_peek_last_error_line_data() are older variants of ERR_get_error_all(), ERR_peek_error_all() and ERR_peek_last_error_all(), and may give confusing results. They should no longer be used and are therefore deprecated. 🚩 not me telling you to stay away from these... but yeah, stay away from these.

🚨 BIG WARNING, NO CAP 🚨 An application MUST NOT free the *data pointer (or any other pointers returned by these functions) with OPENSSL_free() — freeing is handled automatically by the error library. do NOT double-free, that's not the vibe 💀

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⭐ RETURN VALUES ⭐

The error code, or 0 if there is no error in the queue. simple as that, slay.

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🌈 SEE ALSO 🌈

• ERR_error_string(3)
• ERR_GET_LIB(3)

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👑 HISTORY 👑

• ERR_peek_error_func(), ERR_peek_last_error_func(), ERR_peek_error_data(), ERR_peek_last_error_data(), ERR_peek_error_all() and ERR_peek_last_error_all() were added in OpenSSL 3.0 ✨
• ERR_get_error_line(), ERR_get_error_line_data(), ERR_peek_error_line_data() and ERR_peek_last_error_line_data() became deprecated in OpenSSL 3.0 🙈

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💜 COPYRIGHT 💜

Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

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🎀 that's the whole page, bestie — you ate that. this was 3.5.6, dated 2026-04-07, filed under ERR_GET_ERROR(3ossl). go forth and drain that error queue responsibly 💅💖