Re: [PATCH] XDG base directory support (history and wxt)

diff --git a/src/gp_hist.h b/src/gp_hist.h
index 1a938a609..dc6b3d616 100644
--- a/src/gp_hist.h
+++ b/src/gp_hist.h
@@ -75,7 +75,7 @@ extern int history_base;
 void using_history(void);
 void clear_history(void);
 void add_history(char *line);
-void read_history(char *);
+int read_history(char *);
 int write_history(char *);
 int where_history(void);
 int history_set_pos(int offset);
diff --git a/src/history.c b/src/history.c
index 109018116..0c9999e5c 100644
--- a/src/history.c
+++ b/src/history.c
@@ -88,10 +88,10 @@ write_history(char *filename)
 
 /* routine to read history entries from a file
  */
-void
+int
 read_history(char *filename)
 {
-    gp_read_history(filename);
+    return gp_read_history(filename);
 }
 
 
diff --git a/src/plot.c b/src/plot.c
index 66fdb6e45..9770ff9b1 100644
--- a/src/plot.c
+++ b/src/plot.c
@@ -495,7 +495,19 @@ main(int argc_orig, char **argv)
 	    expanded_history_filename = gp_strdup(GNUPLOT_HISTORY_FILE);
 	    gp_expand_tilde(&expanded_history_filename);
 #endif
-	    read_history(expanded_history_filename);
+	    if (read_history(expanded_history_filename)) {
+#ifdef USE_XDG_BASEDIR
+		/* use $XDG_STATE_DIR/gnuplot_history only if
+		 * $XDG_STATE_DIR exists or can be created */
+		char *xdgpath = xdg_get_path(kXDGStateHome, "gnuplot_history",
+				FALSE /* no subdir */, TRUE /* create */);
+		if (xdgpath) {
+		    free(expanded_history_filename);
+		    expanded_history_filename = xdgpath;
+		    read_history(expanded_history_filename);
+		}
+#endif /* USE_XDG_BASEDIR */
+	    }
 
 	    /*
 	     * It is safe to ignore the return values of 'atexit()' and
@@ -790,13 +802,10 @@ load_rcfile(int where)
 	plotrc = fopen(rcfile, "r");
     } else if (where == 3) {
 #ifdef USE_XDG_BASEDIR
-	char * XDGConfigHome = xdg_get_var(kXDGConfigHome);
-	size_t len = strlen(XDGConfigHome);
-	rcfile = gp_alloc(len + 1 + sizeof("gnuplot/gnuplotrc"), "rcfile");
-	strcpy(rcfile, XDGConfigHome);
-	PATH_CONCAT(rcfile, "gnuplot/gnuplotrc");
-	plotrc = fopen(rcfile, "r");
-	free(XDGConfigHome);
+	rcfile = xdg_get_path(kXDGConfigHome, "gnuplotrc",
+			TRUE /* use subdir */, FALSE /* not create */);
+	if (rcfile)
+	    plotrc = fopen(rcfile, "r");
 #endif
     }
 
diff --git a/src/wxterminal/wxt_gui.cpp b/src/wxterminal/wxt_gui.cpp
index 7e59ee655..d79fd818b 100644
--- a/src/wxterminal/wxt_gui.cpp
+++ b/src/wxterminal/wxt_gui.cpp
@@ -120,6 +120,7 @@
 #include <wx/printdlg.h>
 
 extern "C" {
+#include "xdg.h"
 #ifdef HAVE_CONFIG_H
 # include "config.h"
 #endif
@@ -327,13 +328,28 @@ bool wxtApp::OnInit()
 	/* application and vendor name are used by wxConfig to construct the name
 	 * of the config file/registry key and must be set before the first call
 	 * to Get() */
-	SetVendorName(wxT("gnuplot"));
-	SetAppName(wxT("gnuplot-wxt"));
-	wxConfigBase *pConfig = wxConfigBase::Get();
+	const wxString vendorName(wxT("gnuplot"));
+	const wxString appName(wxT("gnuplot-wxt"));
+	SetVendorName(vendorName);
+	SetAppName(appName);
+
+#ifdef USE_XDG_BASEDIR
+	if (!wxFileConfig::GetLocalFile(appName).Exists()) {
+		// Traditional config file (~/.gnuplot-wxt) does not exist.
+		// We will use $XDG_CONFIG_HOME/gnuplot/gnuplot-wxt.conf only if
+		// $XDG_CONFIG_HOME/gnuplot/ exists or can be created.
+		char *configFile = xdg_get_path(kXDGConfigHome, "gnuplot-wxt.conf",
+									TRUE /* subdir */, TRUE /* create */);
+		if (configFile) {
+			wxConfig::Set(new wxFileConfig(appName, vendorName, configFile));
+			free(configFile);
+		}
+	}
+#endif
 	/* this will force writing back of the defaults for all values
 	 * if they're not present in the config - this can give the user an idea
 	 * of all possible settings */
-	pConfig->SetRecordDefaults();
+	wxConfig::Get()->SetRecordDefaults();
 
 	FPRINTF((stderr, "OnInit finished\n"));
 
diff --git a/src/xdg.c b/src/xdg.c
index e6652d329..513236a96 100644
--- a/src/xdg.c
+++ b/src/xdg.c
@@ -1,8 +1,9 @@
 #include "xdg.h"
+#ifdef USE_XDG_BASEDIR
+
 #include "plot.h"
 #include "util.h"
-
-#ifdef USE_XDG_BASEDIR
+#include "alloc.h"
 
 #include <assert.h>
 #include <stdio.h>
@@ -13,6 +14,7 @@
 static const char *xdg_env_vars[] = {
     [kXDGConfigHome] = "XDG_CONFIG_HOME",
     [kXDGDataHome] = "XDG_DATA_HOME",
+    [kXDGStateHome] = "XDG_STATE_HOME",
     [kXDGCacheHome] = "XDG_CACHE_HOME",
     [kXDGRuntimeDir] = "XDG_RUNTIME_DIR",
     [kXDGConfigDirs] = "XDG_CONFIG_DIRS",
@@ -25,36 +27,69 @@ static const char *xdg_env_vars[] = {
 static const char *const xdg_defaults[] = {
     [kXDGConfigHome] = "~/.config",
     [kXDGDataHome] = "~/.local/share",
+    [kXDGStateHome] = "~/.local/state",
     [kXDGCacheHome] = "~/.cache",
     [kXDGRuntimeDir] = "",
     [kXDGConfigDirs] = "/etc/xdg/",
     [kXDGDataDirs] = "/usr/local/share/:/usr/share/",
 };
 
+/* helper function: return TRUE if dirname exists or can be created */
+
+static TBOOLEAN check_dir(const char *dirname) {
+#ifdef HAVE_SYS_STAT_H
+     return existdir(dirname) || !mkdir(dirname, 00700);
+#else	/* I believe this does not happen */
+     return FALSE;
+#endif
+}
+
+/* name used for subdirectory */
+static const char *appname = "gnuplot";
 
-/* Return XDG variable value
+/* Return pathname of XDG base directory or a file in it
  *
- * First query the environement variable and if that does not exist fall back
- * to the defaults. Further reading:
+ * XDG base directory specification:
  * https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
  *
- * @param[in]  idx  XDG variable to use.
+ * @param[in]  idx     XDG variable to use.
+ * @param[in]  fname   if not NULL, name of a file in the base directory
+ * @param[in]  subdir  if TRUE, append "/gnuplot" to the base directory
+ * @param[in]  create  if TRUE, try to create the directory
  *
- * @return [allocated] variable value.
+ * @return [allocated] pathname of the base directory if fname is NULL,
+ *                     else of the file in the directory. Returns NULL if
+ *                     create is TURE but the directory can't be created.
  */
-char *xdg_get_var(const XDGVarType idx) {
-    /* Check the environment variable. If it is there, we are done. */
-    char *XDGVar;
-    if ((XDGVar = getenv(xdg_env_vars[idx])) != NULL) {
-        return gp_strdup(XDGVar);
+char *xdg_get_path(XDGVarType idx, const char* fname,
+		    TBOOLEAN subdir, TBOOLEAN create) {
+    char *pathname;
+    if ((pathname = getenv(xdg_env_vars[idx]))) {
+        pathname = gp_strdup(pathname);	/* use the environment variable */
     }
-
-    /* Looks like the environment variable is not there.
-     * Load the default and run word expansion on it.
-     */
-    XDGVar = gp_strdup(xdg_defaults[idx]);
-    gp_expand_tilde(&XDGVar);
-    return XDGVar;
+    else {
+	pathname = gp_strdup(xdg_defaults[idx]);    /* use the default */
+	gp_expand_tilde(&pathname);
+    }
+    if (create && !check_dir(pathname)) {
+	free(pathname);
+	return NULL;
+    }
+    if (subdir) {
+	pathname = gp_realloc(pathname,
+			    strlen(pathname) + strlen(appname) + 2, "XDG");
+	PATH_CONCAT(pathname, appname);
+	if (create && !check_dir(pathname)) {
+	    free(pathname);
+	    return NULL;
+	}
+    }
+    if (fname) {
+	pathname = gp_realloc(pathname,
+			    strlen(pathname) + strlen(fname) + 2, "XDG");
+	PATH_CONCAT(pathname, fname);
+    }
+    return pathname;
 }
 
 #endif /* USE_XDG_BASEDIR */
diff --git a/src/xdg.h b/src/xdg.h
index cab5e1415..7510444ee 100644
--- a/src/xdg.h
+++ b/src/xdg.h
@@ -5,18 +5,22 @@
 
 #define USE_XDG_BASEDIR
 
+#include "syscfg.h" /* for TBOOLEAN */
+
 /* List of possible XDG variables */
 typedef enum {
   kXDGNone = -1,
   kXDGConfigHome,  /* XDG_CONFIG_HOME */
   kXDGDataHome,    /* XDG_DATA_HOME */
+  kXDGStateHome,   /* XDG_STATE_HOME */
   kXDGCacheHome,   /* XDG_CACHE_HOME */
   kXDGRuntimeDir,  /* XDG_RUNTIME_DIR */
   kXDGConfigDirs,  /* XDG_CONFIG_DIRS */
   kXDGDataDirs,    /* XDG_DATA_DIRS */
 } XDGVarType;
 
-char *xdg_get_var(const XDGVarType idx);
+char *xdg_get_path(XDGVarType idx, const char *fname,
+		    TBOOLEAN subdir, TBOOLEAN create);
 
 #endif /* USE_XDG_BASEDIR */