[FFmpeg-devel] [PATCH v2] avformat/tls_openssl: fix warnings when openssl is lower version

[Jack Lau]

> On Jun 8, 2025, at 08:25, Jack Lau via ffmpeg-devel <ffmpeg-devel at ffmpeg.org> wrote:
> 
> api doc: https://docs.openssl.org/1.0.2/man3/BIO_s_mem
> 
> In higher versions (openssl 1.0.2 and higher),
> the function signature is BIO *BIO_new_mem_buf(const void *buf, int len),
> so passing a const string doesn't cause an warnings.
> However, in lower versions of OpenSSL,
> the function signature becomes BIO *BIO_new_mem_buf(void *buf, int len),
> which leads to warnings.
> 
> OpenSSL guarantees that it will not modify the string,
> so it's safe to cast the pem_str to (void *) to avoid this warning.
> 
> Signed-off-by: Jack Lau <jacklau1222 at qq.com>
> ---
> libavformat/tls_openssl.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/libavformat/tls_openssl.c b/libavformat/tls_openssl.c
> index 86e8935fee..0a6e5680f4 100644
> --- a/libavformat/tls_openssl.c
> +++ b/libavformat/tls_openssl.c
> @@ -415,7 +415,12 @@ error:
>  */
> static EVP_PKEY *pkey_from_pem_string(const char *pem_str, int is_priv)
> {
> -    BIO *mem = BIO_new_mem_buf(pem_str, -1);
> +    BIO *mem = NULL;
> +#if OPENSSL_VERSION_NUMBER < 0x10002000L /* OpenSSL 1.0.2 */
> +    mem = BIO_new_mem_buf((void *)pem_str, -1);
> +#else
> +    mem = BIO_new_mem_buf(pem_str, -1);
> +#endif
>     if (!mem) {
>         av_log(NULL, AV_LOG_ERROR, "BIO_new_mem_buf failed\n");
>         return NULL;
> @@ -445,7 +450,12 @@ static EVP_PKEY *pkey_from_pem_string(const char *pem_str, int is_priv)
>  */
> static X509 *cert_from_pem_string(const char *pem_str)
> {
> -    BIO *mem = BIO_new_mem_buf(pem_str, -1);
> +    BIO *mem = NULL;
> +#if OPENSSL_VERSION_NUMBER < 0x10002000L /* OpenSSL 1.0.2 */
> +    mem = BIO_new_mem_buf((void *)pem_str, -1);
> +#else
> +    mem = BIO_new_mem_buf(pem_str, -1);
> +#endif
>     if (!mem) {
>         av_log(NULL, AV_LOG_ERROR, "BIO_new_mem_buf failed\n");
>         return NULL;
> -- 
> 2.49.0
> 
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