From ee59f90d0a7044ba9d0a146aefceb34e78891ab5 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 18 Nov 2021 15:54:46 +0300
Subject: Add openssl::info() overloads

---
 libbutl/openssl.hxx      | 33 ++++++++++++++++++++++++
 libbutl/openssl.ixx      |  9 +++++++
 libbutl/openssl.txx      | 66 ++++++++++++++++++++++++++++++++++++++++++++++++
 tests/openssl/driver.cxx | 24 +++++++++++++++---
 4 files changed, 128 insertions(+), 4 deletions(-)

diff --git a/libbutl/openssl.hxx b/libbutl/openssl.hxx
index 58e38f8..3bb70a2 100644
--- a/libbutl/openssl.hxx
+++ b/libbutl/openssl.hxx
@@ -8,8 +8,10 @@
 
 #include <libbutl/path.hxx>
 #include <libbutl/process.hxx>
+#include <libbutl/optional.hxx>
 #include <libbutl/fdstream.hxx>
 #include <libbutl/small-vector.hxx>
+#include <libbutl/semantic-version.hxx>
 
 #include <libbutl/export.hxx>
 
@@ -78,6 +80,21 @@ namespace butl
   //    department (that were apparently fixed in 1.0.2). To work around these
   //    bugs pass user-supplied options first.
   //
+  struct openssl_info
+  {
+    // Note that the program name can be used by the caller to properly
+    // interpret the version.
+    //
+    // The name/version examples:
+    //
+    // OpenSSL 3.0.0
+    // OpenSSL 1.1.1l
+    // LibreSSL 2.8.3
+    //
+    std::string name;
+    semantic_version version;
+  };
+
   class LIBBUTL_SYMEXPORT openssl: public process
   {
   public:
@@ -111,6 +128,22 @@ namespace butl
              const std::string& command,
              A&&... options);
 
+    // Run `openssl version` command and try to parse and return the
+    // information it prints to stdout. Return nullopt if the process hasn't
+    // terminated successfully or stdout parsing has failed. Throw
+    // process_error and io_error in case of errors.
+    //
+    template <typename E>
+    static optional<openssl_info>
+    info (E&& err, const process_env&);
+
+    template <typename C,
+              typename E>
+    static optional<openssl_info>
+    info (const C&,
+          E&& err,
+          const process_env&);
+
   private:
     template <typename T>
     struct is_other
diff --git a/libbutl/openssl.ixx b/libbutl/openssl.ixx
index 1435dcb..db2fbcd 100644
--- a/libbutl/openssl.ixx
+++ b/libbutl/openssl.ixx
@@ -26,4 +26,13 @@ namespace butl
                  std::forward<A> (options)...)
   {
   }
+
+  template <typename E>
+  inline optional<openssl_info> openssl::
+  info (E&& err, const process_env& env)
+  {
+    return info ([] (const char* [], std::size_t) {},
+                 std::forward<E> (err),
+                 env);
+  }
 }
diff --git a/libbutl/openssl.txx b/libbutl/openssl.txx
index f198c22..eebc332 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 +50,69 @@ 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 multiple
+    // lines.
+    //
+    string s;
+    getline (os.in, s);
+
+    bool eof (os.in.eof () ||
+              os.in.peek () == ifdstream::traits_type::eof ());
+
+    os.in.close ();
+
+    if (!(os.wait () && eof))
+      return nullopt;
+
+    // Parse the version string.
+    //
+    // 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)};
+  }
 }
diff --git a/tests/openssl/driver.cxx b/tests/openssl/driver.cxx
index d671c00..55f91dd 100644
--- a/tests/openssl/driver.cxx
+++ b/tests/openssl/driver.cxx
@@ -23,12 +23,28 @@ int
 main (int, const char* argv[])
 try
 {
-  openssl os (nullfd, path ("-"), 2, path ("openssl"), "rand", 128);
+  using butl::optional;
 
-  vector<char> r (os.in.read_binary ());
-  os.in.close ();
+  // Test openssl rand command.
+  //
+  {
+    openssl os (nullfd, path ("-"), 2, path ("openssl"), "rand", 128);
 
-  return os.wait () && r.size () == 128 ? 0 : 1;
+    vector<char> r (os.in.read_binary ());
+    os.in.close ();
+
+    assert (os.wait () && r.size () == 128);
+  }
+
+  // Test openssl info retrieval.
+  //
+  {
+    optional<openssl_info> v (openssl::info (2, path ("openssl")));
+
+    assert (v);
+  }
+
+  return 0;
 }
 catch (const system_error& e)
 {
-- 
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