1 files changed, 63 insertions, 0 deletions
diff --git a/libbutl/openssl.txx b/libbutl/openssl.txx
index f198c22..01e854c 100644
--- a/libbutl/openssl.txx
+++ b/libbutl/openssl.txx
@@ -1,6 +1,7 @@
 // file      : libbutl/openssl.txx -*- C++ -*-
 // license   : MIT; see accompanying LICENSE file
 
+#include <cstddef> // size_t
 #include <utility> // forward()
 
 namespace butl
@@ -49,4 +50,66 @@ namespace butl
 
     // Note: leaving this scope closes any open ends of the pipes in io_data.
   }
+
+  template <typename C,
+            typename E>
+  optional<openssl_info> openssl::
+  info (const C& cmdc, E&& err, const process_env& env)
+  {
+    using namespace std;
+
+    // Run the `openssl version` command.
+    //
+    openssl os (cmdc,
+                nullfd, fdstream_mode::text, forward<E> (err),
+                env,
+                "version");
+
+    // Read the command's stdout and wait for its completion. Bail out if the
+    // command didn't terminate successfully or stdout contains no data.
+    //
+    string s;
+    if (!getline (os.in, s))
+      return nullopt;
+
+    os.in.close ();
+
+    if (!os.wait ())
+      return nullopt;
+
+    // Parse the version string.
+    //
+    // Note that there is some variety in the version representations:
+    //
+    // OpenSSL 3.0.0 7 sep 2021 (Library: OpenSSL 3.0.0 7 sep 2021)
+    // OpenSSL 1.1.1l  FIPS 24 Aug 2021
+    // LibreSSL 2.8.3
+    //
+    // We will only consider the first two space separated components as the
+    // program name and version. We will also assume that there are no leading
+    // spaces and the version is delimited from the program name with a single
+    // space character.
+    //
+    size_t e (s.find (' '));
+
+    // Bail out if there is no version present in the string or the program
+    // name is empty.
+    //
+    if (e == string::npos || e == 0)
+      return nullopt;
+
+    string nm (s, 0, e);
+
+    size_t b (e + 1);    // The beginning of the version.
+    e = s.find (' ', b); // The end of the version.
+
+    optional<semantic_version> ver (
+      parse_semantic_version (string (s, b, e != string::npos ? e - b : e),
+                              "" /* build_separators */));
+
+    if (!ver)
+      return nullopt;
+
+    return openssl_info {move (nm), move (*ver)};
+  }
 }