Ensure that g_settings.libretro is absolute path.

Avoid issues when relative libretro paths are stored in ROM history.

dynamic.c

@@ -290,6 +290,10 @@ static void load_symbols(bool is_dummy)
          strlcpy(g_settings.libretro, libretro_core_buffer, sizeof(g_settings.libretro));
       }
 
+      // Need to use absolute path for this setting. It can be saved to ROM history,
+      // and a relative path would break in that scenario.
+      path_resolve_realpath(g_settings.libretro, sizeof(g_settings.libretro));
+
       RARCH_LOG("Loading dynamic libretro from: \"%s\"\n", g_settings.libretro);
       lib_handle = dylib_load(g_settings.libretro);
       if (!lib_handle)

file.h

@@ -84,6 +84,10 @@ void path_basedir(char *path);
 // Assumes that path is a directory. Keeps trailing '/'.
 void path_parent_dir(char *path);
 
+// Turns relative paths into absolute path.
+// If relative, rebases on current working dir.
+void path_resolve_realpath(char *buf, size_t size);
+
 bool path_is_absolute(const char *path);
 
 // Path-name operations.

file_path.c

@@ -532,6 +532,30 @@ bool path_is_absolute(const char *path)
 #endif
 }
 
+void path_resolve_realpath(char *buf, size_t size)
+{
+#ifndef RARCH_CONSOLE
+   char tmp[PATH_MAX];
+   strlcpy(tmp, buf, sizeof(tmp));
+
+#ifdef _WIN32
+   if (!_fullpath(buf, tmp, size))
+      strlcpy(buf, tmp, size);
+#else
+   rarch_assert(size >= PATH_MAX);
+   // NOTE: realpath() expects at least PATH_MAX bytes in buf.
+   // Technically, PATH_MAX needn't be defined, but we rely on it anyways.
+   // POSIX 2008 can automatically allocate for you, but don't rely on that.
+   if (!realpath(tmp, buf))
+      strlcpy(buf, tmp, size);
+#endif
+
+#else
+   (void)buf;
+   (void)size;
+#endif
+}
+
 void fill_pathname_resolve_relative(char *out_path, const char *in_refpath, const char *in_path, size_t size)
 {
    if (path_is_absolute(in_path))