Expand '~/' to $HOME in session path.

src/globals.cc

@@ -2,6 +2,28 @@
 
 #include "globals.h"
 
+#include <torrent/exceptions.h>
+
 rpc::ip_table_list ip_tables;
 
 Control*           control{};
+
+std::string
+expand_path(const std::string& path) {
+  if (path.empty())
+    return std::string();
+
+  if (path[0] == '~') {
+    if (path.size() < 2 || path[1] != '/')
+      throw torrent::input_error("Could not expand ~ in session path, only ~/<path> is supported.");
+
+    const char* home = std::getenv("HOME");
+
+    if (home == nullptr || *home == '\0')
+      throw torrent::input_error("Could not expand ~ in session path, HOME environment variable not set.");
+
+    return home + path.substr(1);
+  }
+
+  return path;
+}