Add reset-dirs element

This element removes all of fonts directories where added by
dir elements. it is useful to override fonts dirs from system
to their own dirs only.

conf.d/05-reset-dirs-sample.conf

@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
+<fontconfig>
+  <description>Re-define fonts dirs sample</description>
+
+  <reset-dirs />
+  <dir prefix="xdg">fonts</dir>
+
+</fontconfig>

conf.d/Makefile.am

@@ -52,6 +52,7 @@ config_DATA = $(DOC_FILES)
 
 templatedir = $(TEMPLATEDIR)
 template_DATA =				\
+	05-reset-dirs-sample.conf	\
 	10-autohint.conf		\
 	10-hinting-full.conf		\
 	10-hinting-medium.conf		\

doc/fontconfig-user.sgml

@@ -358,6 +358,10 @@ as the path 'as-path' in cached information.
 This is useful if the directory name is an alias
 (via a bind mount or symlink) to another directory in the system for
 which cached font information is likely to exist.
+  </para></refsect2>
+  <refsect2><title><literal>&lt;reset-dirs /&gt;</literal></title><para>
+This element removes all of fonts directories where added by <literal>&lt;dir&gt;</literal> elements.
+This is useful to override fonts directories from system to own fonts directories only.
   </para></refsect2>
   <refsect2><title><literal>&lt;rescan&gt;</literal></title><para>
 The <literal>&lt;rescan&gt;</literal> element holds an <literal>&lt;int&gt;</literal> element which indicates the default

fonts.dtd

@@ -8,6 +8,7 @@
 		      include |
 		      match |
 		      remap-dir |
+		      reset-dirs |
 		      selectfont)* >
 
 <!-- 
@@ -120,6 +121,11 @@
           prefix    (default|xdg|relative|cwd)  "default"
 	  xml:space (default|preserve)          "preserve">
 
+<!--
+    Reset the list of fonts directories
+-->
+<!ELEMENT reset-dirs >
+
 <!--
     Periodically rescan the font configuration and
     directories to synch internal state with filesystem

src/fccfg.c

@@ -545,6 +545,12 @@ FcConfigAddFontDir (FcConfig	    *config,
     return FcStrSetAddFilenamePair (config->fontDirs, d, m);
 }
 
+FcBool
+FcConfigResetFontDirs (FcConfig *config)
+{
+    return FcStrSetDeleteAll (config->fontDirs);
+}
+
 FcStrList *
 FcConfigGetFontDirs (FcConfig	*config)
 {

src/fcint.h

@@ -662,6 +662,9 @@ FcConfigAddFontDir (FcConfig	    *config,
 		    const FcChar8   *d,
 		    const FcChar8   *m);
 
+FcPrivate FcBool
+FcConfigResetFontDirs (FcConfig *config);
+
 FcPrivate FcChar8 *
 FcConfigMapFontPath(FcConfig		*config,
 		    const FcChar8	*path);
@@ -1250,6 +1253,9 @@ FcStrPairSecond (FcChar8 *s);
 FcPrivate FcBool
 FcStrSetAddFilenamePair (FcStrSet *strs, const FcChar8 *d, const FcChar8 *m);
 
+FcPrivate FcBool
+FcStrSetDeleteAll (FcStrSet *set);
+
 FcPrivate void
 FcStrBufInit (FcStrBuf *buf, FcChar8 *init, int size);
 

src/fcstr.c

@@ -1388,6 +1388,22 @@ FcStrSetDel (FcStrSet *set, const FcChar8 *s)
     return FcFalse;
 }
 
+FcBool
+FcStrSetDeleteAll (FcStrSet *set)
+{
+    int i;
+
+    if (FcRefIsConst (&set->ref))
+	return FcFalse;
+
+    for (i = set->num; i > 0; i--)
+    {
+	FcStrFree (set->strs[i - 1]);
+	set->num--;
+    }
+    return FcTrue;
+}
+
 /* TODO Make public */
 static FcStrSet *
 FcStrSetReference (FcStrSet *set)

src/fcxml.c

@@ -359,6 +359,7 @@ typedef enum _FcElement {
     FcElementAlias,
     FcElementDescription,
     FcElementRemapDir,
+    FcElementResetDirs,
 	
     FcElementRescan,
 
@@ -423,6 +424,7 @@ static const struct {
     { "alias",		FcElementAlias },
     { "description",	FcElementDescription },
     { "remap-dir",	FcElementRemapDir },
+    { "reset-dirs",	FcElementResetDirs },
 
     { "rescan",		FcElementRescan },
 
@@ -2085,6 +2087,16 @@ FcParseRemapDir (FcConfigParse *parse)
 	FcStrFree (prefix);
 }
 
+static void
+FcParseResetDirs (FcConfigParse *parse)
+{
+    if (!parse->scanOnly)
+    {
+	if (!FcConfigResetFontDirs (parse->config))
+	    FcConfigMessage (parse, FcSevereError, "Unable to reset fonts dirs");
+    }
+}
+
 static FcExpr *
 FcPopExpr (FcConfigParse *parse)
 {
@@ -3065,6 +3077,9 @@ FcEndElement(void *userData, const XML_Char *name FC_UNUSED)
     case FcElementRemapDir:
 	FcParseRemapDir (parse);
 	break;
+    case FcElementResetDirs:
+	FcParseResetDirs (parse);
+	break;
 
     case FcElementRescan:
 	FcParseRescan (parse);