validate linked-list updates with _XftValidateGlyphUsage

Signed-off-by: Thomas E. Dickey <dickey@invisible-island.net>

3 files changed, 92 insertions, 17 deletions

diff --git a/src/xftfreetype.c b/src/xftfreetype.c
index fd0c483..8504ce0 100644
--- a/src/xftfreetype.c
+++ b/src/xftfreetype.c
@@ -1052,7 +1052,7 @@ XftFontDestroy (Display *dpy, XftFont *public)
 {
     XftDisplayInfo  *info = _XftDisplayInfoGet (dpy, False);
     XftFontInt	    *font = (XftFontInt *) public;
-    int		    i;
+    FT_UInt	    i;
 
     /* note reduction in memory use */
     if (info)
diff --git a/src/xftglyphs.c b/src/xftglyphs.c
index de78918..7e238b3 100644
--- a/src/xftglyphs.c
+++ b/src/xftglyphs.c
@@ -52,6 +52,68 @@ _XftFontValidateMemory (Display *dpy _X_UNUSED, XftFont *public)
 		font->glyph_memory, glyph_memory);
 }
 
+/*
+ * Validate the glyph usage-links for a font.
+ */
+static void
+_XftValidateGlyphUsage(XftFontInt *font)
+{
+    if (font->newest != FT_UINT_MAX) {
+	FT_UInt forward;
+	FT_UInt reverse;
+	FT_UInt next;
+	XftGlyphUsage *x1st = (XftGlyphUsage *) font->glyphs[font->newest];
+	XftGlyphUsage *xuse = x1st;
+	for (forward = 1,
+	     next = x1st->newer;
+	     xuse != NULL &&
+	     next != font->newest;
+	     next = xuse->newer) {
+	    if (next >= font->num_glyphs) {
+		printf("Xft: out of range; %d\n", next);
+		break;
+	    }
+	    if (++forward > font->total_inuse) {
+		printf("Xft: too many in-use glyphs (%d vs %d)\n",
+		       forward, font->total_inuse);
+		if (forward > font->total_inuse + 10)
+		    break;
+	    }
+	    xuse = (XftGlyphUsage *) font->glyphs[next];
+	}
+	if (forward < font->total_inuse) {
+	    printf("Xft: too few in-use glyphs (%u vs %d)\n",
+		   forward, font->total_inuse);
+	}
+	for (reverse = 1,
+	     next = x1st->older;
+	     xuse != NULL &&
+	     next != font->newest;
+	     next = xuse->older) {
+	    if (next >= font->num_glyphs) {
+		printf("Xft out of range; %d\n", next);
+		break;
+	    }
+	    if (++reverse > font->total_inuse) {
+		printf("Xft: too many in-use glyphs (%d vs %d)\n",
+		       reverse, font->total_inuse);
+		if (reverse > font->total_inuse + 10)
+		    break;
+	    }
+	    xuse = (XftGlyphUsage *) font->glyphs[next];
+	}
+	if (reverse < font->total_inuse) {
+	    printf("Xft: too few in-use glyphs (%u vs %d)\n",
+		   reverse, font->total_inuse);
+	}
+	if (forward != reverse) {
+	    printf("Xft: forward %d vs reverse %d\n",
+		   forward, reverse);
+	    exit(1);
+	}
+    }
+}
+
 /* we sometimes need to convert the glyph bitmap in a FT_GlyphSlot
  * into a different format. For example, we want to convert a
  * FT_PIXEL_MODE_LCD or FT_PIXEL_MODE_LCD_V bitmap into a 32-bit
@@ -716,28 +778,37 @@ XftFontLoadGlyphs (Display	    *dpy,
 		    xftg->glyph_memory);
 
 	if (font->track_mem_usage) {
-	    XftGlyphUsage *xnew = (XftGlyphUsage *) xftg;
+	    XftGlyphUsage *xuse = (XftGlyphUsage *) xftg;
 
 	    if (font->newest == FT_UINT_MAX) {
-		xnew->older = glyphindex;
-	        xnew->newer = glyphindex;
+		xuse->older = glyphindex;
+	        xuse->newer = glyphindex;
+		if (XftDebug() & XFT_DBG_USAGE)
+		    printf("alloc %d: %p USE %d.%d\n", glyphindex,
+			    (void *) xuse, xuse->older, xuse->newer);
 	    } else {
+		XftGlyphUsage *xnew;
 		XftGlyphUsage *xold;
 
-		xold = (XftGlyphUsage *) font->glyphs[font->newest];
-
-		xnew->older = font->newest;
-		xnew->newer = xold->newer;
-		xold->newer = glyphindex;
-		if (XftDebug() & XFT_DBG_CACHEV)
-		    printf("alloc %p NEW %d.%d, OLD %d.%d\n", xnew,
-			    xnew->older, xnew->newer,
-			    xold->older, xold->newer);
+		xnew = (XftGlyphUsage *) font->glyphs[font->newest];
+		xold = (XftGlyphUsage *) font->glyphs[xnew->newer];
+
+		xuse->older = font->newest;
+		xuse->newer = xnew->newer;
+		xnew->newer = glyphindex;
+		xold->older = glyphindex;
+		if (XftDebug() & XFT_DBG_USAGE)
+		    printf("alloc %d: %p USE %d.%d, %p NEW %d.%d %p OLD %d.%d\n",
+			    glyphindex,
+			    (void *) xuse, xuse->older, xuse->newer,
+			    (void *) xnew, xnew->older, xnew->newer,
+			    (void *) xold, xold->older, xold->newer);
 	    }
 
 	    font->newest = glyphindex;
 	    font->total_inuse++;
-	    // FIXME - validate
+	    if (XftDebug() & XFT_DBG_USAGE)
+		_XftValidateGlyphUsage(font);
 	}
     }
     if (bufBitmap != bufLocal)
@@ -794,7 +865,8 @@ XftFontUnloadGlyphs (Display		*dpy,
 	    XftGlyphUsage *xtmp;
 
 	    if (XftDebug() & XFT_DBG_CACHEV)
-		printf("free %p USE %d.%d\n", xuse, xuse->older, xuse->newer);
+		printf("free %p USE %d.%d\n",
+		       (void *) xuse, xuse->older, xuse->newer);
 
 	    if (xuse->older != FT_UINT_MAX) {
 		xtmp = (XftGlyphUsage *) font->glyphs[xuse->older];
@@ -802,8 +874,9 @@ XftFontUnloadGlyphs (Display		*dpy,
 		    /* update link around to oldest glyph */
 		    xtmp->newer = xuse->newer;
 		}
-		if (font->newest == glyphindex)
+		if (font->newest == glyphindex) {
 		    font->newest = xuse->older;
+		}
 	    }
 	    if (xuse->newer != FT_UINT_MAX) {
 		xtmp = (XftGlyphUsage *) font->glyphs[xuse->newer];
@@ -817,7 +890,8 @@ XftFontUnloadGlyphs (Display		*dpy,
 	    } else {
 		fprintf (stderr, "Xft: glyph count error\n");
 	    }
-	    // FIXME - validate
+	    if (XftDebug() & XFT_DBG_USAGE)
+		_XftValidateGlyphUsage(font);
 	}
 
 	free (xftg);
diff --git a/src/xftint.h b/src/xftint.h
index 3304217..1e292d7 100644
--- a/src/xftint.h
+++ b/src/xftint.h
@@ -301,6 +301,7 @@ extern XftDisplayInfo	*_XftDisplayInfo;
 #define XFT_DBG_CACHE	128
 #define XFT_DBG_CACHEV	256
 #define XFT_DBG_MEMORY	512
+#define XFT_DBG_USAGE	1024
 
 /*
  * Categories for memory allocation.