Access fish_history from $XDG_DATA_HOME

Add new functions path_get_data and path_create_data which parallel existing
functions path_get_config and path_create_data.  The new functions refer to
XDG_DATA_HOME, if it is defined, or ./local/share if not.

Modify history_filename to use the new function path_get_data.

As a consequence, fish_history will now be located in XDG_DATA_HOME,
not XDG_CONFIG_HOME.

Note that these changes mirror what is already used in
fish-shell/share/tools/create_manpage_completions.py, which stores the
completions in XDG_DATA_HOME

This change matches recommendations in the xdg basedir spec at
http://standards.freedesktop.org/basedir-spec/basedir-spec-0.7.html
($XDG_DATA_HOME defines the base directory relative to which user specific data
files should be stored. If $XDG_DATA_HOME is either not set or empty, a default
equal to $HOME/.local/share should be used.)

It addresses suggestions from the following issues:

1. Don't put history in $XDG_CONFIG_HOME (closes #744)
   https://github.com/fish-shell/fish-shell/issues/744

2. Fish is placing non-config files in $XDG_CONFIG_HOME #1257
   https://github.com/fish-shell/fish-shell/issues/1257

3. Move non-config data out of $XDG_CONFIG_HOME #1669
   https://github.com/fish-shell/fish-shell/issues/1669

1 files changed, 14 insertions, 1 deletions

diff --git a/src/path.h b/src/path.h
index eb79ee8a..973e8a3a 100644
--- a/src/path.h
+++ b/src/path.h
@@ -20,7 +20,7 @@
 
 /**
    Returns the user configuration directory for fish. If the directory
-   or one of it's parents doesn't exist, they are first created.
+   or one of its parents doesn't exist, they are first created.
 
    \param path The directory as an out param
    \return whether the directory was returned successfully
@@ -28,6 +28,19 @@
 bool path_get_config(wcstring &path);
 
 /**
+   Returns the user data directory for fish. If the directory
+   or one of its parents doesn't exist, they are first created.
+
+   Volatile files presumed to be local to the machine,
+   such as the fish_history and all the generated_completions,
+   will be stored in this directory.
+
+   \param path The directory as an out param
+   \return whether the directory was returned successfully
+*/
+bool path_get_data(wcstring &path);
+
+/**
    Finds the full path of an executable. Returns YES if successful.
 
    \param cmd The name of the executable.