Fix for https://github.com/fish-shell/fish-shell/issues/66

Make fish import .bash_history if regular history is not found

history.cpp

@@ -373,7 +373,6 @@ static size_t offset_of_next_item_fish_1_x(const char *begin, size_t mmap_length
 				else
 				{
                     /* Note: pos will be left pointing just after this newline, because of the ++ in the loop */
-                    
                     all_done = true;
 				}
 				break;
@@ -1143,6 +1142,18 @@ void history_t::clear(void)
     
 }
 
+bool history_t::is_empty(void)
+{
+    bool result = false;
+    scoped_lock locker(lock);
+    if (new_items.empty())
+    {
+        load_old_if_needed();
+        result = old_item_offsets.empty();
+    }
+    return result;
+}
+
 /* Indicate whether we ought to import the bash history file into fish */
 static bool should_import_bash_history_line(const std::string &line)
 {
@@ -1161,7 +1172,11 @@ static bool should_import_bash_history_line(const std::string &line)
             return false;
         }
     }
-    printf("Importing %s\n", line.c_str());
+    
+    /* Skip lines with backticks */
+    if (line.find('`') != std::string::npos)
+        return false;
+    
     return true;
 }
 

history.h

@@ -146,6 +146,9 @@ public:
     /** Returns history with the given name, creating it if necessary */
     static history_t & history_with_name(const wcstring &name);
     
+    /** Determines whether the history is empty. Unfortunately this cannot be const, since it may require populating the history. */
+    bool is_empty(void);
+    
     /** Add a new history item to the end */
     void add(const wcstring &str, const path_list_t &valid_paths = path_list_t());
 

reader.cpp

@@ -2093,7 +2093,7 @@ static int default_test( const wchar_t *b )
 void reader_push( const wchar_t *name )
 {
     // use something nasty which guarantees value initialization (that is, all fields zero)
-    reader_data_t zerod = {};
+    const reader_data_t zerod = {};
     reader_data_t *n = new reader_data_t(zerod);
     
     n->history = & history_t::history_with_name(name);
@@ -2113,7 +2113,6 @@ void reader_push( const wchar_t *name )
 	reader_set_highlight_function( &highlight_universal );
 	reader_set_test_function( &default_test );
 	reader_set_prompt( L"" );
-	//history_set_mode( name );
 }
 
 void reader_pop()
@@ -2164,6 +2163,24 @@ void reader_set_test_function( int (*f)( const wchar_t * ) )
 	data->test_func = f;
 }
 
+void reader_import_history_if_necessary(void)
+{
+    /* Import history from bash, etc. if our current history is empty */
+    if (data->history && data->history->is_empty())
+    {
+        /* Try opening a bash file. We make an effort to respect $HISTFILE; this isn't very complete (AFAIK it doesn't have to be exported), and to really get this right we ought to ask bash itself. But this is better than nothing.
+        */
+        const env_var_t var = env_get_string(L"HISTFILE");
+        wcstring path = (var.missing() ? L"~/.bash_history" : var);
+        expand_tilde(path);
+        FILE *f = wfopen(path, "r");
+        if (f)
+        {
+            data->history->populate_from_bash(f);
+            fclose(f);
+        }
+    }
+}
 
 /** A class as the context pointer for a background (threaded) highlight operation. */
 class background_highlight_context_t {
@@ -2376,6 +2393,8 @@ static int read_i()
 	reader_set_complete_function( &complete );
 	reader_set_highlight_function( &highlight_shell );
 	reader_set_test_function( &reader_shell_test );
+    reader_import_history_if_necessary();
+    
 	parser_t &parser = parser_t::principal_parser();
     
 	data->prev_end_loop=0;