Further fixes to universal variable server socket management

- Change fishd_path to std::string
- Warn, rather than exiting with an error, if the universal variable
  server path is not available, and provide more useful advice.
- Export the new __fishd_runtime_dir variable.

common.cpp

@@ -2268,10 +2268,11 @@ static int check_runtime_path(const char * path)
 }
 
 /** Return the path of an appropriate runtime data directory */
-const char* common_get_runtime_path(void)
+std::string common_get_runtime_path()
 {
     const char *dir = getenv("XDG_RUNTIME_DIR");
     const char *uname = getenv("USER");
+    std::string path;
 
     if (uname == NULL)
     {
@@ -2283,19 +2284,19 @@ const char* common_get_runtime_path(void)
     {
         // /tmp/fish.user
         dir = "/tmp/fish.";
-        std::string path;
         path.reserve(strlen(dir) + strlen(uname));
         path.append(dir);
         path.append(uname);
         if (check_runtime_path(path.c_str()) != 0)
         {
-            debug(0, L"Couldn't create secure runtime path: '%s'", path.c_str());
-            exit(EXIT_FAILURE);
+            debug(0, L"Runtime path not available. Try deleting the directory %s and restarting fish.", path.c_str());
+            path.clear();
         }
-        return strdup(path.c_str());
     }
     else
     {
-        return dir;
+        path.reserve(strlen(dir));
+        path.append(dir);
     }
+    return path;
 }

common.h

@@ -743,6 +743,6 @@ extern "C" {
 }
 
 /** Return the path of an appropriate runtime data directory */
-const char* common_get_runtime_path(void);
+std::string common_get_runtime_path();
 
 #endif

env.cpp

@@ -674,8 +674,8 @@ void env_init(const struct config_paths_t *paths /* or NULL */)
 
     const env_var_t user_dir_wstr = env_get_string(L"USER");
 
-    const char * fishd_dir = common_get_runtime_path();
-    env_set(L"__fish_runtime_dir", str2wcstring(fishd_dir).c_str(), ENV_GLOBAL);
+    std::string fishd_dir = common_get_runtime_path();
+    env_set(L"__fish_runtime_dir", str2wcstring(fishd_dir).c_str(), ENV_GLOBAL | ENV_EXPORT);
 
     wchar_t * user_dir = user_dir_wstr.missing()?NULL:const_cast<wchar_t*>(user_dir_wstr.c_str());
 

env_universal.cpp

@@ -242,16 +242,21 @@ static void reconnect()
 }
 
 
-void env_universal_init(const char * p,
+void env_universal_init(std::string p,
                         wchar_t *u,
                         void (*sf)(),
                         void (*cb)(fish_message_type_t type, const wchar_t *name, const wchar_t *val))
 {
-    path=p;
+    path=p.c_str();
     user=u;
     start_fishd=sf;
     external_callback = cb;
 
+    if (p == "") {
+        debug(1, L"Could not connect to universal variable server. You will not be able to share variable values between fish sessions.");
+    }
+    else
+    {
         env_universal_server.fd = get_socket();
         env_universal_common_init(&callback);
         env_universal_read_all();
@@ -261,6 +266,7 @@ void env_universal_init(const char * p,
             env_universal_barrier();
         }
     }
+}
 
 void env_universal_destroy()
 {

env_universal.h

@@ -17,7 +17,7 @@ extern connection_t env_universal_server;
 /**
    Initialize the envuni library
 */
-void env_universal_init(const char * p,
+void env_universal_init(std::string p,
                         wchar_t *u,
                         void (*sf)(),
                         void (*cb)(fish_message_type_t type, const wchar_t *name, const wchar_t *val));

fish_pager.cpp

@@ -1032,8 +1032,8 @@ static void init(int mangle_descriptors, int out)
         exit(1);
     }
 
-
-    env_universal_init("", 0, 0, 0);
+    std::string dir = common_get_runtime_path();
+    env_universal_init(dir, 0, 0, 0);
     input_common_init(&interrupt_handler);
     output_set_writer(&pager_buffered_writer);
 

fishd.cpp

@@ -159,10 +159,15 @@ static int quit=0;
 */
 static std::string get_socket_filename(void)
 {
-    const char *dir = common_get_runtime_path();
+    std::string dir = common_get_runtime_path();
+
+    if (dir == "") {
+        debug(0, L"Cannot access desired socket path.");
+        exit(EXIT_FAILURE);
+    }
 
     std::string name;
-    name.reserve(strlen(dir) + strlen(SOCK_FILENAME) + 1);
+    name.reserve(dir.length() + strlen(SOCK_FILENAME) + 1);
     name.append(dir);
     name.push_back('/');
     name.append(SOCK_FILENAME);