Copy openssl library finder for ext/digest from OpenSSL extention.

  * ext/digest/digest_conf.rb: Support to search variaous filenames of
    OpenSSL/LibreSSL libraries.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59362 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/digest/digest_conf.rb

@@ -1,4 +1,56 @@
 # frozen_string_literal: false
+
+# Copy from ext/openssl/extconf.rb
+def find_openssl_library
+  if $mswin || $mingw
+    # required for static OpenSSL libraries
+    have_library("gdi32") # OpenSSL <= 1.0.2 (for RAND_screen())
+    have_library("crypt32")
+  end
+
+  return false unless have_header("openssl/ssl.h")
+
+  ret = have_library("crypto", "CRYPTO_malloc") &&
+    have_library("ssl", "SSL_new")
+  return ret if ret
+
+  if $mswin
+    # OpenSSL >= 1.1.0: libcrypto.lib and libssl.lib.
+    if have_library("libcrypto", "CRYPTO_malloc") &&
+        have_library("libssl", "SSL_new")
+      return true
+    end
+
+    # OpenSSL <= 1.0.2: libeay32.lib and ssleay32.lib.
+    if have_library("libeay32", "CRYPTO_malloc") &&
+        have_library("ssleay32", "SSL_new")
+      return true
+    end
+
+    # LibreSSL: libcrypto-##.lib and libssl-##.lib, where ## is the ABI version
+    # number. We have to find the version number out by scanning libpath.
+    libpath = $LIBPATH.dup
+    libpath |= ENV["LIB"].split(File::PATH_SEPARATOR)
+    libpath.map! { |d| d.tr(File::ALT_SEPARATOR, File::SEPARATOR) }
+
+    ret = [
+      ["crypto", "CRYPTO_malloc"],
+      ["ssl", "SSL_new"]
+    ].all? do |base, func|
+      result = false
+      libs = ["lib#{base}-[0-9][0-9]", "lib#{base}-[0-9][0-9][0-9]"]
+      libs = Dir.glob(libs.map{|l| libpath.map{|d| File.join(d, l + ".*")}}.flatten).map{|path| File.basename(path, ".*")}.uniq
+      libs.each do |lib|
+        result = have_library(lib, func)
+        break if result
+      end
+      result
+    end
+    return ret if ret
+  end
+  return false
+end
+
 def digest_conf(name, hdr = name, funcs = nil, types = nil)
   unless with_config("bundled-#{name}")
     cc = with_config("common-digest")
@@ -14,7 +66,7 @@ def digest_conf(name, hdr = name, funcs = nil, types = nil)
     dir_config("openssl")
     pkg_config("openssl")
     require File.expand_path('../../openssl/deprecation', __FILE__)
-    if have_library("crypto")
+    if find_openssl_library
       funcs ||= name.upcase
       funcs = Array(funcs)
       types ||= funcs