lib/crypto/MD5: add option to use libavutil instead of libgcrypt

src/lib/crypto/MD5.cxx

@@ -28,20 +28,38 @@
  */
 
 #include "MD5.hxx"
+#include "util/HexFormat.hxx"
+#include "config.h"
+
+#ifdef HAVE_LIBAVUTIL
+extern "C" {
+#include <libavutil/md5.h>
+}
+#else
 #include "lib/gcrypt/MD5.hxx"
 #include "lib/gcrypt/Init.hxx"
-#include "util/HexFormat.hxx"
+#endif
 
 void
 GlobalInitMD5() noexcept
 {
+#ifdef HAVE_LIBAVUTIL
+	/* no initialization necessary */
+#else
 	Gcrypt::Init();
+#endif
 }
 
 std::array<uint8_t, 16>
 MD5(ConstBuffer<void> input) noexcept
 {
+#ifdef HAVE_LIBAVUTIL
+	std::array<uint8_t, 16> result;
+	av_md5_sum(&result.front(), (const uint8_t *)input.data, input.size);
+	return result;
+#else
 	return Gcrypt::MD5(input);
+#endif
 }
 
 StringBuffer<33>

src/lib/crypto/meson.build

-if gcrypt_dep.found()
+if libavutil_dep.found() or gcrypt_dep.found()
   crypto_md5 = static_library(
     'crypto_md5',
     'MD5.cxx',
     include_directories: inc,
     dependencies: [
+      libavutil_dep,
       gcrypt_dep,
     ],
   )

src/lib/ffmpeg/meson.build

 libavformat_dep = dependency('libavformat', version: '>= 57.40', required: get_option('ffmpeg'))
 libavcodec_dep = dependency('libavcodec', version: '>= 57.48', required: get_option('ffmpeg'))
 libavutil_dep = dependency('libavutil', version: '>= 55.27', required: get_option('ffmpeg'))
+conf.set('HAVE_LIBAVUTIL', libavutil_dep.found())
 
 enable_ffmpeg = libavformat_dep.found() and libavcodec_dep.found() and libavutil_dep.found()
 conf.set('ENABLE_FFMPEG', enable_ffmpeg)

src/lib/gcrypt/meson.build

+if libavutil_dep.found()
+  # if we have FFmpeg, we can use its MD5 implementation and we don't
+  # need libgcrypt
+  gcrypt_dep = dependency('', required: false)
+  subdir_done()
+endif
+
 # Since version 0.49.0 Meson has native libgcrypt dependency support, which has
 # the advantage over find_library() as it uses libgcrypt-config to query the
 # required linker flags.