PEM_read_bio_ex, PEM_FLAG_SECURE, PEM_FLAG_EAY_COMPATIBLE, PEM_FLAG_ONLY_B64 - read PEM format files with

       Copyright 2017 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>.

3.5.0                                              2025-06-04                              PEM_READ_BIO_EX(3SSL)

PEM_read_bio_ex() reads in PEM formatted data from an input BIO, outputting the name of the type of
       contained data, the header information regarding the possibly encrypted data, and the binary data payload
       (after base64 decoding).  It should generally only be used to implement PEM_read_bio_-family functions
       for specific data types or other usage, but is exposed to allow greater flexibility over how processing
       is performed, if needed.

       If PEM_FLAG_SECURE is set, the intermediate buffers used to read in lines of input are allocated from the
       secure heap.

       If PEM_FLAG_EAY_COMPATIBLE is set, a simple algorithm is used to remove whitespace and control characters
       from the end of each line, so as to be compatible with the historical behavior of PEM_read_bio().

       If PEM_FLAG_ONLY_B64 is set, all characters are required to be valid base64 characters (or newlines);
       non-base64 characters are treated as end of input.

       If neither PEM_FLAG_EAY_COMPATIBLE or PEM_FLAG_ONLY_B64 is set, control characters are ignored.

       If both PEM_FLAG_EAY_COMPATIBLE and PEM_FLAG_ONLY_B64 are set, an error is returned; these options are
       not compatible with each other.

       The PEM_read_bio_ex() function was added in OpenSSL 1.1.1.

       PEM_read_bio_ex, PEM_FLAG_SECURE, PEM_FLAG_EAY_COMPATIBLE, PEM_FLAG_ONLY_B64 - read PEM format files with
       custom processing

       The caller must release the storage allocated for *name, *header, and *data.  If PEM_FLAG_SECURE was set,
       use OPENSSL_secure_free(); otherwise, OPENSSL_free() is used.

PEM_read_bio_ex() returns 1 for success or 0 for failure.

PEM_bytes_read_bio(3)

        #include <openssl/pem.h>

        #define PEM_FLAG_SECURE             0x1
        #define PEM_FLAG_EAY_COMPATIBLE     0x2
        #define PEM_FLAG_ONLY_B64           0x4
        int PEM_read_bio_ex(BIO *in, char **name, char **header,
                            unsigned char **data, long *len, unsigned int flags);