[pcf] Quickly exit if font index < 0.

Similar to other font formats, this commit makes the parser no
longer check the whole PCF file but only the header and the TOC if
we just want to get the number of available faces (and a proper
recognition of the font format).

* src/pcf/pcfdrivr.c (PCF_Face_Init): Updated.
Exit quickly if face_index < 0.

* src/pcfread.c (pcf_load_font): Add `face_index' argument.
Exit quickly if face_index < 0.

* src/pcf/pcf.h: Updated.

ChangeLog

@@ -1,3 +1,20 @@
+2015-10-13  Werner Lemberg  <wl@gnu.org>
+
+	[pcf] Quickly exit if font index < 0.
+
+	Similar to other font formats, this commit makes the parser no
+	longer check the whole PCF file but only the header and the TOC if
+	we just want to get the number of available faces (and a proper
+	recognition of the font format).
+
+	* src/pcf/pcfdrivr.c (PCF_Face_Init): Updated.
+	Exit quickly if face_index < 0.
+
+	* src/pcfread.c (pcf_load_font): Add `face_index' argument.
+	Exit quickly if face_index < 0.
+
+	* src/pcf/pcf.h: Updated.
+
 2015-10-13  Werner Lemberg  <wl@gnu.org>
 
 	[ftfuzzer] Handle TTCs and MM/GX variations.

src/pcf/pcf.h

@@ -226,8 +226,9 @@ FT_BEGIN_HEADER
 #define GLYPHPADOPTIONS  4 /* I'm not sure about this */
 
   FT_LOCAL( FT_Error )
-  pcf_load_font( FT_Stream,
-                 PCF_Face );
+  pcf_load_font( FT_Stream  stream,
+                 PCF_Face   face,
+                 FT_Long    face_index );
 
 FT_END_HEADER
 

src/pcf/pcfdrivr.c

@@ -271,7 +271,7 @@ THE SOFTWARE.
 
     FT_TRACE2(( "PCF driver\n" ));
 
-    error = pcf_load_font( stream, face );
+    error = pcf_load_font( stream, face, face_index );
     if ( error )
     {
       PCF_Face_Done( pcfface );
@@ -332,7 +332,7 @@ THE SOFTWARE.
 
       stream = pcfface->stream;
 
-      error = pcf_load_font( stream, face );
+      error = pcf_load_font( stream, face, face_index );
       if ( error )
         goto Fail;
 
@@ -351,7 +351,9 @@ THE SOFTWARE.
      *      an invalid argument error when the font could be
      *      opened by the specified driver.
      */
-    if ( face_index > 0 && ( face_index & 0xFFFF ) > 0 )
+    if ( face_index < 0 )
+      goto Exit;
+    else if ( face_index > 0 && ( face_index & 0xFFFF ) > 0 )
     {
       FT_ERROR(( "PCF_Face_Init: invalid face index\n" ));
       PCF_Face_Done( pcfface );

src/pcf/pcfread.c

@@ -1184,8 +1184,10 @@ THE SOFTWARE.
 
   FT_LOCAL_DEF( FT_Error )
   pcf_load_font( FT_Stream  stream,
-                 PCF_Face   face )
+                 PCF_Face   face,
+                 FT_Long    face_index )
   {
+    FT_Face    root   = FT_FACE( face );
     FT_Error   error;
     FT_Memory  memory = FT_FACE( face )->memory;
     FT_Bool    hasBDFAccelerators;
@@ -1195,6 +1197,13 @@ THE SOFTWARE.
     if ( error )
       goto Exit;
 
+    root->num_faces  = 1;
+    root->face_index = 0;
+
+    /* If we are performing a simple font format check, exit immediately. */
+    if ( face_index < 0 )
+      return FT_Err_Ok;
+
     error = pcf_get_properties( stream, face );
     if ( error )
       goto Exit;
@@ -1237,13 +1246,9 @@ THE SOFTWARE.
 
     /* now construct the face object */
     {
-      FT_Face       root = FT_FACE( face );
       PCF_Property  prop;
 
 
-      root->num_faces  = 1;
-      root->face_index = 0;
-
       root->face_flags |= FT_FACE_FLAG_FIXED_SIZES |
                           FT_FACE_FLAG_HORIZONTAL  |
                           FT_FACE_FLAG_FAST_GLYPHS;