[gs-cvs] rev 8776 - trunk/gs/src

[leonardo at ghostscript.com]

Author: leonardo
Date: 2008-05-25 00:23:38 -0700 (Sun, 25 May 2008)
New Revision: 8776

Modified:
   trunk/gs/src/gstype42.c
   trunk/gs/src/ttfmain.c
Log:
Fix (True Type font loader) : Work around incorrect numGlyphs.

DETAILS :

Bug 689516 "problem reading PDF: Failed to interpret TT instructions (ref 7814)".

The bug report supplies a PDF document, which embeds a TT font
with a too small numGlyphs. The loca table contains more glyphs and 
they are referenced in a text. The font is incorrect, but Acrobat handles the document.

This patch checks whether there are glyphs behind numGlyphs and 
extends numGlyphs to cover them. Also improved error handling in ttfmain.c .

Besides that, now we print a warning about an incorrect numGlyphs
in release build. The olkd code did with debug buil only.
I believe that users need to know whether a font is broken, and that
its rendering is hewristic.
 
EXPECTED DIFFERENCES :

None.


Modified: trunk/gs/src/gstype42.c
===================================================================
--- trunk/gs/src/gstype42.c	2008-05-25 05:45:15 UTC (rev 8775)
+++ trunk/gs/src/gstype42.c	2008-05-25 07:23:38 UTC (rev 8776)
@@ -243,11 +243,23 @@
 	   Continue using trueNumGlyphs since the document of
 	   the bug 688467 fails otherwise.
 	 */
-#	ifdef DEBUG
-	    /* pfont->key_name.chars is ASCIIZ due to copy_font_name. */
+	/* pfont->key_name.chars is ASCIIZ due to copy_font_name. */
 	eprintf3("Warning: 'loca' length %d is greater than numGlyphs %d in the font %s.\n", 
 		pfont->data.numGlyphs + 1, pfont->data.trueNumGlyphs, pfont->key_name.chars);
-#	endif
+	if (loca_size > pfont->data.trueNumGlyphs + 1) {
+	    /* Bug 689516 demonstrates a font, in which numGlyps is smaller than loca size,
+	       and there are useful glyphs behind maxp.numGlyphs. */
+	    for (i = loca_size - 1;  i > pfont->data.trueNumGlyphs; i--) {
+		glyph_offset = get_glyph_offset(pfont, i);
+		if (glyph_offset < glyph_size)
+		    break;
+	    }
+	    if (i > pfont->data.trueNumGlyphs) {
+		/* loca contains more good offsets, fix maxp.numGlyphs. 
+		   Note a code below will fix bad offsets if any. */
+		 pfont->data.numGlyphs = pfont->data.trueNumGlyphs = loca_size - 1;
+	    }
+	}
 	pfont->data.numGlyphs = pfont->data.trueNumGlyphs;
 	loca_size = pfont->data.numGlyphs + 1;
     }
@@ -279,7 +291,10 @@
 	glyph_offset = get_glyph_offset(pfont, i);
 	glyph_length = glyph_offset - glyph_start;
 	if (glyph_length > 0x80000000)
-	    break;				/* out of order loca */
+	    break;
+	if (glyph_offset > glyph_size)
+	    break;
+	/* out of order loca */
 	pfont->data.len_glyphs[i - 1] = glyph_length;
 	glyph_start = glyph_offset;
     }

Modified: trunk/gs/src/ttfmain.c
===================================================================
--- trunk/gs/src/ttfmain.c	2008-05-25 05:45:15 UTC (rev 8775)
+++ trunk/gs/src/ttfmain.c	2008-05-25 07:23:38 UTC (rev 8776)
@@ -220,7 +220,7 @@
 {   char sVersion[4], sVersion1[4] = {0, 1, 0, 0};
     char sVersion2[4] = {0, 2, 0, 0};
     unsigned int nNumTables, i;
-    TT_Error code;
+    TT_Error code, code1 = 0;
     int k;
     TT_Instance I;
     ttfMemory *mem = tti->ttf_memory;
@@ -328,8 +328,8 @@
     if (code == TT_Err_Out_Of_Memory)
 	return fMemoryError;
     if (code >= TT_Err_Invalid_Opcode && code <= TT_Err_Invalid_Displacement)
-	return fBadInstruction;
-    if (code)
+	code1 = fBadInstruction;
+    else if (code)
 	return fBadFontData;
     I.z = this->inst;
     if (design_grid)
@@ -349,6 +349,8 @@
 	return fBadInstruction;
     if (code)
 	return fBadFontData;
+    if (code1)
+	return code1;
     return code;
 }