Add exporters for CMake

CMake's older package finder, FindOpenSSL.cmake, does a best guess effort
and doesn't always get it right.

By CMake's own documentation, that's what such modules are (best effort
attempts), and package producers are (strongly) encouraged to help out by
producing and installing <PackageName>Config.cmake files to get a more
deterministic configuration.

The resulting OpenSSLConfig.cmake tries to mimic the result from CMake's
FindOpenSSL.cmake, by using the same variable and imported target names.
It also adds a few extra variables of its own, such as:

    OPENSSL_MODULES_DIR     Indicates the default installation directory
                            for OpenSSL loadable modules, such as providers.
    OPENSSL_RUNTIME_DIR     Indicates the default runtime directory, where
                            for example the openssl program is located.
    OPENSSL_PROGRAM         Is the full directory-and-filename of the
                            openssl program.

The imported targets OpenSSL::Crypto and OpenSSL::SSL are as precisely
specified as possible, so for example, they are specified with the both the
import library and the DLL on Windows, which should make life easier on that
platform.

For the moment, one of the following must be done in your CMake project for
this CMake configuration to take priority over CMake's FindOpenSSL.cmake:

-   The variable CMAKE_FIND_PACKAGE_PREFER_CONFIG must be set to true prior
    to the 'find_package(OpenSSL)' call.
-   The 'find_package' call itself must use the "Full Signature".  If you
    don't know any better, simply add the 'CONFIG' option, i.e. from this
    example:

        find_package(OpenSSL 3.0 REQUIRED)

    to this:

        find_package(OpenSSL 3.0 REQUIRED CONFIG)

Just as with the 'pkg-config' exporters, two variants of the .cmake files
are produced:

- Those in 'exporters/' are installed in the location that 'pkg-config'
  itself prefers for installed packages.
- Those in the top directory are to be used when it's desirable to build
  directly against an OpenSSL build tree.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20878)

3 files changed, 265 insertions, 1 deletions

diff --git a/exporters/build.info b/exporters/build.info
index 503e15e8e8..86acf2df94 100644
--- a/exporters/build.info
+++ b/exporters/build.info
@@ -1,3 +1,12 @@
+# For installation: OpenSSLConfig.cmake, OpenSSLConfigVersion.cmake
+GENERATE[OpenSSLConfig.cmake]{exporter=cmake}=cmake/OpenSSLConfig.cmake.in
+DEPEND[OpenSSLConfig.cmake]=../installdata.pm
+GENERATE[OpenSSLConfigVersion.cmake]{exporter=cmake}=cmake/OpenSSLConfigVersion.cmake.in
+DEPEND[OpenSSLConfigVersion.cmake]=../installdata.pm
+DEPEND[OpenSSLConfigVersion.cmake]=OpenSSLConfig.cmake
+
+DEPEND[""]=OpenSSLConfigVersion.cmake
+
 # For installation: libcrypto.pc, libssl.pc, and openssl.pc
 GENERATE[libcrypto.pc]{exporter=pkg-config}=pkg-config/libcrypto.pc.in
 DEPEND[libcrypto.pc]=../installdata.pm
@@ -13,4 +22,5 @@ GENERATE[../installdata.pm]=../util/mkinstallvars.pl \
     "PREFIX=$(INSTALLTOP)" BINDIR=bin "LIBDIR=$(LIBDIR)" \
     INCLUDEDIR=include APPLINKDIR=include/openssl \
     "ENGINESDIR=$(ENGINESDIR)" "MODULESDIR=$(MODULESDIR)" \
-    "VERSION=$(VERSION)" "LDLIBS=$(LIB_EX_LIBS)"
+    "PKGCONFIGDIR=$(PKGCONFIGDIR)" "CMAKECONFIGDIR=$(CMAKECONFIGDIR)" \
+    "LDLIBS=$(LIB_EX_LIBS)" "VERSION=$(VERSION)"
diff --git a/exporters/cmake/OpenSSLConfig.cmake.in b/exporters/cmake/OpenSSLConfig.cmake.in
new file mode 100644
index 0000000000..606773ff27
--- /dev/null
+++ b/exporters/cmake/OpenSSLConfig.cmake.in
@@ -0,0 +1,237 @@
+# Generated by OpenSSL
+{-
+   use lib catdir($config{sourcedir}, 'Configurations');
+   use platform;
+   use Data::Dumper;
+
+   our %lib_info = (
+       map { my %x = ();
+             my $lib_static = platform->staticlib($_);
+             my $lib_shared =
+                 (platform->can("sharedlib_simple")
+                  ? platform->sharedlib_simple($_)
+                  : undef)
+                 // platform->sharedlib($_);
+             my $lib_shared_import = platform->sharedlib_import($_);
+             $x{static} = $lib_static if $lib_static;
+             $x{shared} = $lib_shared if $lib_shared;
+             $x{shared_import} = $lib_shared_import if $lib_shared_import;
+             %x ? ( $_ => \%x ) : () }
+       grep { !$unified_info{attributes}->{libraries}->{$_}->{noinst} }
+       @{$unified_info{libraries}}
+   );
+   our $no_static = !$disabled{shared} && !$lib_info{libcrypto}->{static};
+   our $no_shared = $disabled{shared};
+
+   # Unixifying of paths, because that's what CMake understands.
+   # This assumes that the given path is absolute.
+   sub unixify {
+       use File::Spec;
+       use File::Spec::Unix;
+
+       my $path = shift;
+       my $no_file = shift;
+       (my $volume, $directories, $file) = File::Spec->splitpath($path, $no_file // ());
+       $directories = File::Spec::Unix->catdir(File::Spec->splitdir($directories));
+
+       # We know that $volume is ignored by File::Spec::Unix, so we handle it specially
+       # according to the conventions of the platform.
+       $volume =~ s|^(.*?):$|/$1| if $^O eq "vms"; # On VMS, DEV: -> /DEV
+
+       return $volume . File::Spec::Unix->catpath('', $directories, $no_file ? () : $file);
+   }
+   ""
+-}
+# Commands may need to know the format version.
+set(CMAKE_IMPORT_FILE_VERSION 1)
+
+# Avoid duplicate find_package()
+set(_ossl_expected_targets OpenSSL::Crypto OpenSSL::SSL
+    {- output_off() if $disabled{uplink}; "" -}OpenSSL::applink{- output_on() if $disabled{uplink}; "" -})
+set(_ossl_defined_targets)
+set(_ossl_undefined_targets)
+foreach(t IN LISTS _ossl_expected_targets)
+  if(TARGET "${t}")
+    LIST(APPEND _ossl_defined_targets "${t}")
+  else()
+    LIST(APPEND _ossl_undefined_targets "${t}")
+  endif()
+endforeach()
+message(DEBUG "_ossl_expected_targets = ${_ossl_expected_targets}")
+message(DEBUG "_ossl_defined_targets = ${_ossl_defined_targets}")
+message(DEBUG "_ossl_undefined_targets = ${_ossl_undefined_targets}")
+if(NOT _ossl_undefined_targets)
+  # All targets are defined, we're good, just undo everything and return
+  unset(_ossl_expected_targets)
+  unset(_ossl_defined_targets)
+  unset(_ossl_undefined_targets)
+  unset(CMAKE_IMPORT_FILE_VERSION)
+  return()
+endif()
+if(_ossl_defined_targets)
+  # We have a mix of defined and undefined targets.  This is hard to reconcile,
+  # and probably the result of another config, or FindOpenSSL.cmake having been
+  # called, or whatever.  Therefore, the best course of action is to quit with a
+  # hard error.
+  message(FATAL_ERROR "Some targets defined, others not:\nNot defined: ${_ossl_undefined_targets}\nDefined: ${_ossl_defined_targets}")
+endif()
+unset(_ossl_expected_targets)
+unset(_ossl_defined_targets)
+unset(_ossl_undefined_targets)
+
+{-
+  # It can be argued that 'cmake_path' would be the better choice here.  However,
+  # cmake_path is relatively new, while get_filename_component has been around
+  # since before CMake 3.0
+-}
+# Set up the import path, so all other import paths are made relative this file
+get_filename_component(_ossl_prefix "${CMAKE_CURRENT_LIST_FILE}" PATH)
+{-
+  # For each component in $OpenSSL::safe::installdata::CMAKECONFIGDIR_REL, have CMake
+  # out the parent directory.
+  my $d = unixify($OpenSSL::safe::installdata::CMAKECONFIGDIR_REL);
+  $OUT = '';
+  $OUT .= 'get_filename_component(_ossl_prefix "${_ossl_prefix}" PATH)' . "\n"
+      foreach (split '/', $d);
+-}
+if(_ossl_prefix STREQUAL "/")
+  set(_ossl_prefix "")
+endif()
+
+{- output_off() unless $disabled{shared}; "" -}
+set(_ossl_use_static_libs True)
+{- output_on() unless $disabled{shared}; "" -}
+if(OPENSSL_USE_STATIC_LIBS)
+  set(_ossl_use_static_libs True)
+elseif(DEFINED OPENSSL_USE_STATIC_LIBS)
+  # We know OPENSSL_USE_STATIC_LIBS is defined and False
+  if(_ossl_use_static_libs)
+    # OPENSSL_USE_STATIC_LIBS is explicitly false, indicating that shared libraries are
+    # required.  However, _ossl_use_static_libs indicates that no shared libraries are
+    # available.  The best course of action is to simply return and leave it to CMake to
+    # use another OpenSSL config.
+    unset(_ossl_use_static_libs)
+    unset(CMAKE_IMPORT_FILE_VERSION)
+    return()
+  endif()
+endif()
+
+# Version, copied from what find_package() gives, for compatibility with FindOpenSSL.cmake
+set(OPENSSL_VERSION "${OpenSSL_VERSION}")
+set(OPENSSL_VERSION_MAJOR "${OpenSSL_VERSION_MAJOR}")
+set(OPENSSL_VERSION_MINOR "${OpenSSL_VERSION_MINOR}")
+set(OPENSSL_VERSION_FIX "${OpenSSL_VERSION_PATCH}")
+set(OPENSSL_FOUND YES)
+
+# Directories and names
+set(OPENSSL_INCLUDE_DIR "${_ossl_prefix}/{- unixify($OpenSSL::safe::installdata::INCLUDEDIR_REL, 1); -}")
+set(OPENSSL_LIBRARY_DIR "${_ossl_prefix}/{- unixify($OpenSSL::safe::installdata::LIBDIR_REL, 1); -}")
+set(OPENSSL_ENGINES_DIR "${_ossl_prefix}/{- unixify($OpenSSL::safe::installdata::ENGINESDIR_REL, 1); -}")
+set(OPENSSL_MODULES_DIR "${_ossl_prefix}/{- unixify($OpenSSL::safe::installdata::MODULESDIR_REL, 1); -}")
+set(OPENSSL_RUNTIME_DIR "${_ossl_prefix}/{- unixify($OpenSSL::safe::installdata::BINDIR_REL, 1); -}")
+{- output_off() if $disabled{uplink}; "" -}
+set(OPENSSL_APPLINK_SOURCE "${_ossl_prefix}/{- unixify($OpenSSL::safe::installdata::APPLINKDIR_REL, 1); -}/applink.c")
+{- output_on() if $disabled{uplink}; "" -}
+set(OPENSSL_PROGRAM "${OPENSSL_RUNTIME_DIR}/{- platform->bin('openssl') -}")
+
+# Set up the imported targets
+if(_ossl_use_static_libs)
+{- output_off() unless $no_static; "" -}
+  # Static libraries are UNSUPPORTED in this configuration
+{- output_on() unless $no_static; output_off() if $no_static; "" -}
+  add_library(OpenSSL::Crypto STATIC IMPORTED)
+  add_library(OpenSSL::SSL STATIC IMPORTED)
+
+  set(OPENSSL_LIBCRYPTO_STATIC "${OPENSSL_LIBRARY_DIR}/{- $lib_info{libcrypto}->{static} -}")
+  set(OPENSSL_LIBCRYPTO_DEPENDENCIES {- join(' ', @OpenSSL::safe::installdata::LDLIBS) -})
+  set_target_properties(OpenSSL::Crypto PROPERTIES
+    IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+    IMPORTED_LOCATION ${OPENSSL_LIBCRYPTO_STATIC})
+  set_property(TARGET OpenSSL::Crypto
+    PROPERTY INTERFACE_LINK_LIBRARIES ${OPENSSL_LIBCRYPTO_DEPENDENCIES})
+
+  set(OPENSSL_LIBSSL_STATIC "${OPENSSL_LIBRARY_DIR}/{- $lib_info{libssl}->{static} -}")
+  set(OPENSSL_LIBSSL_DEPENDENCIES OpenSSL::Crypto)
+  set_target_properties(OpenSSL::SSL PROPERTIES
+    IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+    IMPORTED_LOCATION ${OPENSSL_LIBSSL_STATIC})
+  set_property(TARGET OpenSSL::SSL
+    PROPERTY INTERFACE_LINK_LIBRARIES ${OPENSSL_LIBSSL_DEPENDENCIES})
+
+  # Directories and names compatible with CMake's FindOpenSSL.cmake
+  set(OPENSSL_CRYPTO_LIBRARY ${OPENSSL_LIBCRYPTO_STATIC})
+  set(OPENSSL_CRYPTO_LIBRARIES ${OPENSSL_CRYPTO_LIBRARY} ${OPENSSL_LIBCRYPTO_DEPENDENCIES})
+  set(OPENSSL_SSL_LIBRARY ${OPENSSL_LIBSSL_STATIC})
+  set(OPENSSL_SSL_LIBRARIES ${OPENSSL_SSL_LIBRARY} ${OPENSSL_LIBSSL_DEPENDENCIES})
+  set(OPENSSL_LIBRARIES ${OPENSSL_SSL_LIBRARY} ${OPENSSL_LIBSSL_DEPENDENCIES} ${OPENSSL_LIBCRYPTO_DEPENDENCIES})
+{- output_on(); "" -}
+else()
+{- output_off() unless $no_shared; "" -}
+  # Shared libraries are UNSUPPORTED in this configuration
+{- output_on() unless $no_shared;
+   output_off() if $no_shared; "" -}
+  add_library(OpenSSL::Crypto SHARED IMPORTED)
+  add_library(OpenSSL::SSL SHARED IMPORTED)
+{- output_off() unless $lib_info{libcrypto}->{shared_import}; "" -}
+  set(OPENSSL_LIBCRYPTO_SHARED "${OPENSSL_RUNTIME_DIR}/{- $lib_info{libcrypto}->{shared} -}")
+  set(OPENSSL_LIBCRYPTO_IMPORT "${OPENSSL_LIBRARY_DIR}/{- $lib_info{libcrypto}->{shared_import} -}")
+  set(OPENSSL_LIBCRYPTO_DEPENDENCIES {- join(' ', @LDLIBS) -})
+  set_target_properties(OpenSSL::Crypto PROPERTIES
+    IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+    IMPORTED_IMPLIB ${OPENSSL_LIBCRYPTO_IMPORT}
+    IMPORTED_LOCATION ${OPENSSL_LIBCRYPTO_SHARED})
+  set_property(TARGET OpenSSL::Crypto
+    PROPERTY INTERFACE_LINK_LIBRARIES ${OPENSSL_LIBCRYPTO_DEPENDENCIES})
+
+  set(OPENSSL_LIBSSL_SHARED "${OPENSSL_RUNTIME_DIR}/{- $lib_info{libssl}->{shared} -}")
+  set(OPENSSL_LIBSSL_IMPORT "${OPENSSL_LIBRARY_DIR}/{- $lib_info{libssl}->{shared_import} -}")
+  set(OPENSSL_LIBSSL_DEPENDENCIES OpenSSL::Crypto {- join(' ', @LDLIBS) -})
+  set_target_properties(OpenSSL::SSL PROPERTIES
+    IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+    IMPORTED_IMPLIB ${OPENSSL_LIBSSL_IMPORT}
+    IMPORTED_LOCATION ${OPENSSL_LIBSSL_SHARED})
+  set_property(TARGET OpenSSL::SSL
+    PROPERTY INTERFACE_LINK_LIBRARIES ${OPENSSL_LIBSSL_DEPENDENCIES})
+
+  # Directories and names compatible with CMake's FindOpenSSL.cmake
+  set(OPENSSL_CRYPTO_LIBRARY ${OPENSSL_LIBCRYPTO_IMPORT})
+  set(OPENSSL_CRYPTO_LIBRARIES ${OPENSSL_CRYPTO_LIBRARY} ${OPENSSL_LIBCRYPTO_DEPENDENCIES})
+  set(OPENSSL_SSL_LIBRARY ${OPENSSL_LIBSSL_IMPORT})
+  set(OPENSSL_SSL_LIBRARIES ${OPENSSL_SSL_LIBRARY} ${OPENSSL_LIBSSL_DEPENDENCIES})
+  set(OPENSSL_LIBRARIES ${OPENSSL_SSL_LIBRARY} ${OPENSSL_LIBSSL_DEPENDENCIES} ${OPENSSL_LIBCRYPTO_DEPENDENCIES})
+{- output_on() unless $lib_info{libcrypto}->{shared_import};
+   output_off() if $lib_info{libcrypto}->{shared_import}; "" -}
+  # Dependencies are assumed to be implied in the shared libraries
+  set(OPENSSL_LIBCRYPTO_SHARED "${OPENSSL_LIBRARY_DIR}/{- $lib_info{libcrypto}->{shared} -}")
+  set_target_properties(OpenSSL::Crypto PROPERTIES
+    IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+    IMPORTED_LOCATION ${OPENSSL_LIBCRYPTO_SHARED})
+
+  set(OPENSSL_LIBSSL_SHARED "${OPENSSL_LIBRARY_DIR}/{- $lib_info{libssl}->{shared} -}")
+  set_target_properties(OpenSSL::SSL PROPERTIES
+    IMPORTED_LINK_INTERFACE_LANGUAGES "C"
+    IMPORTED_LOCATION ${OPENSSL_LIBSSL_SHARED})
+
+  # Directories and names compatible with CMake's FindOpenSSL.cmake
+  set(OPENSSL_CRYPTO_LIBRARY ${OPENSSL_LIBCRYPTO_SHARED})
+  set(OPENSSL_CRYPTO_LIBRARIES ${OPENSSL_CRYPTO_LIBRARY})
+  set(OPENSSL_SSL_LIBRARY ${OPENSSL_LIBSSL_SHARED})
+  set(OPENSSL_SSL_LIBRARIES ${OPENSSL_SSL_LIBRARY})
+  set(OPENSSL_LIBRARIES ${OPENSSL_SSL_LIBRARIES})
+{- output_on() if $lib_info{libcrypto}->{shared_import}; "" -}
+{- output_on() if $no_shared; "" -}
+endif()
+
+set_target_properties(OpenSSL::Crypto PROPERTIES
+  INTERFACE_INCLUDE_DIRECTORIES "${OPENSSL_INCLUDE_DIR}")
+set_target_properties(OpenSSL::SSL PROPERTIES
+  INTERFACE_INCLUDE_DIRECTORIES "${OPENSSL_INCLUDE_DIR}")
+
+{- output_off() if $disabled{uplink}; "" -}
+add_library(OpenSSL::applink INTERFACE IMPORTED)
+set_property(TARGET OpenSSL::applink PROPERTY
+  INTERFACE_SOURCES "${OPENSSL_APPLINK_SOURCE}")
+{- output_on() if $disabled{uplink}; "" -}
+
+unset(_ossl_prefix)
+unset(_ossl_use_static_libs)
diff --git a/exporters/cmake/OpenSSLConfigVersion.cmake.in b/exporters/cmake/OpenSSLConfigVersion.cmake.in
new file mode 100644
index 0000000000..b1290a9eec
--- /dev/null
+++ b/exporters/cmake/OpenSSLConfigVersion.cmake.in
@@ -0,0 +1,17 @@
+# Generated by OpenSSL
+
+set(PACKAGE_VERSION {- $config{version} -})
+
+if(NOT PACKAGE_FIND_VERSION)
+  # find_package() was called without any version information.  This is assumed to
+  # mean that the caller accepts whatever they get.
+  set(PACKAGE_VERSION_COMPATIBLE 1)
+elseif(PACKAGE_FIND_VERSION_MAJOR LESS {- my $x = $config{version}; $x =~ s/\..*//; $x -}
+   OR PACKAGE_FIND_VERSION VERSION_GREATER {- $config{version} -})
+  set(PACKAGE_VERSION_UNSUITABLE 1)
+else()
+  set(PACKAGE_VERSION_COMPATIBLE 1)
+  if(PACKAGE_FIND_VERSION VERSION_EQUAL {- $config{version} -})
+    set(PACKAGE_VERSION_EXACT 1)
+  endif()
+endif()