From a9ceb6db7a8532f2aa8990e33a9228859f1d4902 Mon Sep 17 00:00:00 2001
From: Liang Chang <l-chang@users.sourceforge.net>
Date: Sat, 22 May 2021 00:10:48 +0800
Subject: [PATCH] DtHelp: Apply graceful degradation for font loading to avoid
 a segmentation fault.

---
 cde/include/DtI/FontI.h        |  1 +
 cde/lib/DtHelp/Font.c          | 25 +++++++++++++++++++++++++
 cde/lib/DtHelp/XInterface.c    | 11 +++++++++--
 cde/lib/DtHelp/libDtHelp.elist |  1 +
 4 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/cde/include/DtI/FontI.h b/cde/include/DtI/FontI.h
index e1477f1ee..e635baa63 100644
--- a/cde/include/DtI/FontI.h
+++ b/cde/include/DtI/FontI.h
@@ -78,6 +78,7 @@ extern "C" {
  *			Semi Public Routines
  ****************************************************************************/
 extern	void		 _DtHelpCopyDefaultList(XrmName *xrm_list);
+extern	void		 _DtHelpCopyCasualList(XrmName *xrm_list);
 extern	long		 __DtHelpDefaultFontIndexGet (
 				DtHelpDispAreaStruct	*pDAS);
 extern	void		 _DtHelpGetStringQuarks(XrmName *xrm_list);
diff --git a/cde/lib/DtHelp/Font.c b/cde/lib/DtHelp/Font.c
index 78bbfd978..eafeb8cd3 100644
--- a/cde/lib/DtHelp/Font.c
+++ b/cde/lib/DtHelp/Font.c
@@ -266,6 +266,7 @@ static  const char    *FontResources[] =
 static	Boolean		QuarksInited = FALSE;
 static	XrmQuark	StringFontQuark = 0;
 static	XrmName		DefaultFontQuarks[_DtHelpFontQuarkNumber];
+static	XrmName		CasualFontQuarks[_DtHelpFontQuarkNumber];
 static	XrmBinding	FontBindings[_DtHelpFontQuarkNumber] =
         { XrmBindLoosely, XrmBindLoosely, XrmBindLoosely, XrmBindLoosely,
           XrmBindLoosely, XrmBindLoosely, XrmBindLoosely };
@@ -673,6 +674,25 @@ _DtHelpCopyDefaultList (
         xrm_list[n] = DefaultFontQuarks[n];
 }
 
+/******************************************************************************
+ * Function:	void _DtHelpCopyCasualList (xrm_name)
+ *
+ * Parameters:	xrm_name	The quark list to fill out.
+ *
+ * Return Value: void
+ *
+ * Purpose:
+ *****************************************************************************/
+void
+_DtHelpCopyCasualList (
+    XrmName		 *xrm_list)
+{
+    int     n;
+
+    for (n = 0; n < _DT_HELP_FONT_END + 1; n++)
+        xrm_list[n] = CasualFontQuarks[n];
+}
+
 /******************************************************************************
  * Function:	void _DtHelpGetStringQuarks (xrm_name)
  *
@@ -744,6 +764,11 @@ __DtHelpFontDatabaseInit (
         DefaultFontQuarks[_DT_HELP_FONT_CHAR_SET] =
 						XrmStringToQuark ("ISO-8859-1");
         DefaultFontQuarks[_DT_HELP_FONT_END]      = 0;
+
+        for (n = 0; n < _DT_HELP_FONT_END; ++n)
+            CasualFontQuarks[n] = XrmStringToQuark("*");
+        CasualFontQuarks[_DT_HELP_FONT_END] = 0;
+
 	QuarksInited = True;
       }
     _DtHelpProcessUnlock();
diff --git a/cde/lib/DtHelp/XInterface.c b/cde/lib/DtHelp/XInterface.c
index 4f8346c27..20f9e6335 100644
--- a/cde/lib/DtHelp/XInterface.c
+++ b/cde/lib/DtHelp/XInterface.c
@@ -849,10 +849,17 @@ ResolveFont (
     if (charset != NULL)
         xrmList[_DT_HELP_FONT_CHAR_SET] = XrmStringToQuark(charset);
 
-    if (NULL == xlfdSpec ||
-		_DtHelpGetExactFontIndex(pDAS,lang,charset,xlfdSpec,ret_idx)!=0)
+    if (NULL != xlfdSpec)
+	result = _DtHelpGetExactFontIndex(pDAS,lang,charset,xlfdSpec,ret_idx);
+
+    if (result)
         result = __DtHelpFontIndexGet (pDAS, xrmList, ret_idx);
 
+    if (result) {
+	_DtHelpCopyCasualList(xrmList);
+	result = __DtHelpFontIndexGet(pDAS, xrmList, ret_idx);
+    }
+
     return result;
 }
 
diff --git a/cde/lib/DtHelp/libDtHelp.elist b/cde/lib/DtHelp/libDtHelp.elist
index 05e6621d0..c1cc930df 100644
--- a/cde/lib/DtHelp/libDtHelp.elist
+++ b/cde/lib/DtHelp/libDtHelp.elist
@@ -353,6 +353,7 @@ internal  _DtHelpCloseVolume
 internal  _DtHelpCommonHelpClean
 internal  _DtHelpCommonHelpInit
 internal  _DtHelpCopyDefaultList
+internal  _DtHelpCopyCasualList
 internal  _DtHelpDABuildSelection
 internal  _DtHelpDADestroyGraphic
 internal  _DtHelpDADestroyRegion