Fix BIO_get_mem_data(3) return value documentation

pointed out by/ok dlg

1 files changed, 18 insertions, 3 deletions

diff --git a/src/lib/libcrypto/man/BIO_s_mem.3 b/src/lib/libcrypto/man/BIO_s_mem.3
index e43be66e2f..61b9a9c70f 100644
--- a/src/lib/libcrypto/man/BIO_s_mem.3
+++ b/src/lib/libcrypto/man/BIO_s_mem.3
@@ -1,4 +1,4 @@
-.\" $OpenBSD: BIO_s_mem.3,v 1.20 2025/06/08 22:40:29 schwarze Exp $
+.\" $OpenBSD: BIO_s_mem.3,v 1.21 2026/03/10 05:50:11 tb Exp $
 .\" full merge up to: OpenSSL 8711efb4 Mon Apr 20 11:33:12 2009 +0000
 .\" selective merge up to: OpenSSL 36359cec Mar 7 14:37:23 2018 +0100
 .\"
@@ -49,7 +49,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 .\" OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: June 8 2025 $
+.Dd $Mdocdate: March 10 2026 $
 .Dt BIO_S_MEM 3
 .Os
 .Sh NAME
@@ -231,12 +231,27 @@ returns a pointer to the static string
 .Qq memory buffer .
 .Pp
 .Fn BIO_set_mem_eof_return ,
-.Fn BIO_get_mem_data ,
 .Fn BIO_set_mem_buf ,
 and
 .Fn BIO_get_mem_ptr
 return 1 on success or a value less than or equal to 0 if an error occurred.
 .Pp
+.Fn BIO_get_mem_data
+returns the number of bytes available for reading at
+.Pf * Fa ptr
+on success, or a value less than or equal to zero if an error occurs.
+Error conditions include that
+.Fa b
+is
+.Dv NULL ,
+no data is available, or any error of
+.Xr BIO_ctrl 3 ,
+including error returns of a callback called with a
+.Dv BIO_CB_CTRL
+or
+.Dv BIO_CB_CTRL Ns | Ns BIO_CB_RETURN
+operation.
+.Pp
 .Fn BIO_new_mem_buf
 returns a newly allocated
 .Vt BIO