Fix for issue where history file would be read immediately on launch

history.cpp

@@ -1468,14 +1468,35 @@ void history_t::clear(void)
 
 bool history_t::is_empty(void)
 {
-    bool result = false;
     scoped_lock locker(lock);
-    if (new_items.empty())
+    
+    /* If we have new items, we're not empty */
+    if (! new_items.empty())
+        return false;
+
+    bool empty = false;
+    if (loaded_old)
     {
-        load_old_if_needed();
+        /* If we've loaded old items, see if we have any offsets */
-        result = old_item_offsets.empty();
+        empty = old_item_offsets.empty();
     }
-    return result;
+    else
+    {
+        /* If we have not loaded old items, don't actually load them (which may be expensive); just stat the file and see if it exists and is nonempty */
+        const wcstring where = history_filename(name, L"");
+        struct stat buf = {};
+        if (wstat(where, &buf) != 0)
+        {
+            /* Access failed, assume missing */
+            empty = true;
+        }
+        else
+        {
+            /* We're empty if the file is empty */
+            empty = (buf.st_size == 0);
+        }
+    }
+    return empty;
 }
 
 /* Indicate whether we ought to import the bash history file into fish */

history.h

@@ -159,6 +159,9 @@ private:
 
     /** Loads old if necessary */
     bool load_old_if_needed(void);
+    
+    /** Memory maps the history file if necessary */
+    bool mmap_if_needed(void);
 
     /** Deletes duplicates in new_items. */
     void compact_new_items();

signal.cpp

@@ -694,7 +694,7 @@ void signal_unblock()
 //	debug( 0, L"signal block level decreased to %d", block_count );
 }
 
-int signal_is_blocked()
+bool signal_is_blocked()
 {
     return !!block_count;
 }

signal.h

@@ -55,7 +55,7 @@ void signal_unblock();
 /**
    Returns true if signals are being blocked
 */
-int signal_is_blocked();
+bool signal_is_blocked();
 
 /**
   Returns signals with non-default handlers