document additional stack push error code

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17351)

diff --git a/doc/man3/DEFINE_STACK_OF.pod b/doc/man3/DEFINE_STACK_OF.pod
index 43a3214d584a98a262391667b3c13d13453e4cb8..6f4ac7ec0ef059f9d9fd058953a8601a9e946b84 100644 (file)
--- a/doc/man3/DEFINE_STACK_OF.pod
+++ b/doc/man3/DEFINE_STACK_OF.pod
@@ -238,7 +238,8 @@ sk_TYPE_pop(), sk_TYPE_shift(), sk_TYPE_delete() and sk_TYPE_delete_ptr()
 return a pointer to the deleted element or B<NULL> on error.
 
 sk_TYPE_insert(), sk_TYPE_push() and sk_TYPE_unshift() return the total
-number of elements in the stack and 0 if an error occurred.
+number of elements in the stack and 0 if an error occurred. sk_TYPE_push()
+further returns -1 if B<sk> is B<NULL>.
 
 sk_TYPE_set() returns a pointer to the replacement element or B<NULL> on
 error.