Backwards-compatibility subject to OPENSSL_API_COMPAT

Provide backwards-compatiblity for functions, macros and include
files if OPENSSL_API_COMPAT is either not defined or defined less
than the version number of the release in which the feature was
deprecated.

Reviewed-by: Richard Levitte <levitte@openssl.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/CHANGES b/CHANGES
index 31fe88a9ab..b5a9e1e967 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,35 @@
 
  Changes between 1.0.2e and 1.1.0  [xx XXX xxxx]
 
+  *) Revert default OPENSSL_NO_DEPRECATED setting.  Instead OpenSSL
+     continues to support deprecated interfaces in default builds.
+     However, applications are strongly advised to compile their
+     source files with -DOPENSSL_API_COMPAT=0x10100000L, which hides
+     the declarations of all interfaces deprecated in 0.9.8, 1.0.0
+     or the 1.1.0 releases.
+
+     In environments in which all applications have been ported to
+     not use any deprecated interfaces OpenSSL's Configure script
+     should be used with the --api=1.1.0 option to entirely remove
+     support for the deprecated features from the library and
+     unconditionally disable them in the installed headers.
+     Essentially the same effect can be achieved with the "no-deprecated"
+     argument to Configure, except that this will always restrict
+     the build to just the latest API, rather than a fixed API
+     version.
+
+     As applications are ported to future revisions of the API,
+     they should update their compile-time OPENSSL_API_COMPAT define
+     accordingly, but in most cases should be able to continue to
+     compile with later releases.
+
+     The OPENSSL_API_COMPAT versions for 1.0.0, and 0.9.8 are
+     0x10000000L and 0x00908000L, respectively.  However those
+     versions did not support the OPENSSL_API_COMPAT feature, and
+     so applications are not typically tested for explicit support
+     of just the undeprecated features of either release.
+     [Viktor Dukhovni]
+
   *) Add support for setting the minimum and maximum supported protocol.
      It can bet set via the SSL_set_min_proto_version() and
      SSL_set_max_proto_version(), or via the SSL_CONF's MinProtocol and