SERIALIZER: add functions for serialization to file

These functions are added:

- OSSL_SERIALIZER_to_bio()
- OSSL_SERIALIZER_to_fp() (unless 'no-stdio')

OSSL_SERIALIZER_to_bio() and OSSL_SERIALIZER_to_fp() work as wrapper
functions, and call an internal "do_output" function with the given
serializer context and a BIO to output the serialized result to.

The internal "do_output" function must have intimate knowledge of the
object being output.  This will defined independently with context
creators for specific OpenSSL types.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10394)

2 files changed, 61 insertions, 1 deletions

diff --git a/doc/man3/OSSL_SERIALIZER.pod b/doc/man3/OSSL_SERIALIZER.pod
index 34767734f7..bf6ef3431c 100644
--- a/doc/man3/OSSL_SERIALIZER.pod
+++ b/doc/man3/OSSL_SERIALIZER.pod
@@ -110,7 +110,8 @@ OSSL_SERIALIZER_number() returns an integer.
 
 =head1 SEE ALSO
 
-L<provider(7)>, L<OSSL_SERIALIZER_CTX(3)>, L<OPENSSL_CTX(3)>
+L<provider(7)>, L<OSSL_SERIALIZER_CTX(3)>, L<OSSL_SERIALIZER_to_bio(3)>,
+L<OPENSSL_CTX(3)>
 
 =head1 HISTORY
 
diff --git a/doc/man3/OSSL_SERIALIZER_to_bio.pod b/doc/man3/OSSL_SERIALIZER_to_bio.pod
new file mode 100644
index 0000000000..3ed68a17ed
--- /dev/null
+++ b/doc/man3/OSSL_SERIALIZER_to_bio.pod
@@ -0,0 +1,59 @@
+=pod
+
+=head1 NAME
+
+OSSL_SERIALIZER_to_bio,
+OSSL_SERIALIZER_to_fp
+- Serializer file output routines
+
+=head1 SYNOPSIS
+
+ #include <openssl/serializer.h>
+
+ int OSSL_SERIALIZER_to_bio(OSSL_SERIALIZER_CTX *ctx, BIO *out);
+ int OSSL_SERIALIZER_to_fp(OSSL_SERIALIZER_CTX *ctx, FILE *fp);
+
+Feature availability macros:
+
+=over 4
+
+=item OSSL_SERIALIZER_to_fp() is only available when B<OPENSSL_NO_STDIO>
+is undefined.
+
+=back
+
+=head1 DESCRIPTION
+
+OSSL_SERIALIZER_to_bio() runs the serialization process for the
+context I<ctx>, with the output going to the B<BIO> I<out>.  The
+application is required to set up the B<BIO> properly, for example to
+have it in text or binary mode if that's appropriate.
+
+=for comment Know your serializer!
+
+OSSL_SERIALIZER_to_fp() does the same thing as OSSL_SERIALIZER_to_bio(),
+except that the output is going to the B<FILE> I<fp>.
+
+=head1 RETURN VALUES
+
+OSSL_SERIALIZER_to_bio() and OSSL_SERIALIZER_to_fp() return 1 on
+success, or 0 on failure.
+
+=head1 SEE ALSO
+
+L<provider(7)>, L<OSSL_SERIALIZER_CTX(3)>
+
+=head1 HISTORY
+
+The functions described here were added in OpenSSL 3.0.
+
+=head1 COPYRIGHT
+
+Copyright 2019 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
+L<https://www.openssl.org/source/license.html>.
+
+=cut