From 8ef8072ba151dc06214ee70985a7fb03ebc2932f Mon Sep 17 00:00:00 2001
From: Werner Lemberg <wl@gnu.org>
Date: Tue, 19 Oct 2021 22:59:46 +0200
Subject: [PATCH] [bdf, cid, pfr, winfonts] Improve rejection of other font
 formats.

This is mainly for better diagnostics of malformed fonts.

* src/bdf/bdflib.c (_bfd_readstream): Stop font format testing if the first
input line is too long or doesn't end with `\r` or `\n`.

* src/cid/cidparse.c (cid_parser_new): Don't handle too short input as an
error but as an unknown format.

* src/pfr/pfrobjs.c (pfr_face_init): Ditto.

* src/winfonts/winfnt.c (fnt_font_load, fnt_face_get_dll_font): Ditto.
---
 src/bdf/bdflib.c      | 21 ++++++++++++++++-----
 src/cid/cidparse.c    |  4 ++++
 src/pfr/pfrobjs.c     |  4 ++++
 src/winfonts/winfnt.c |  7 +++++++
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/src/bdf/bdflib.c b/src/bdf/bdflib.c
index 82272ced6..b65c8a2f3 100644
--- a/src/bdf/bdflib.c
+++ b/src/bdf/bdflib.c
@@ -581,8 +581,14 @@
       /* or even resizing it                                       */
       if ( end >= avail )
       {
-        if ( bytes == 0 )  /* last line in file doesn't end in \r or \n */
-          break;           /* ignore it then exit                       */
+        if ( bytes == 0 )
+        {
+          /* last line in file doesn't end in \r or \n; */
+          /* ignore it then exit                        */
+          if ( lineno == 1 )
+            error = FT_THROW( Missing_Startfont_Field );
+          break;
+        }
 
         if ( start == 0 )
         {
@@ -593,8 +599,13 @@
 
           if ( buf_size >= 65536UL )  /* limit ourselves to 64KByte */
           {
-            FT_ERROR(( "_bdf_readstream: " ERRMSG6, lineno ));
-            error = FT_THROW( Invalid_Argument );
+            if ( lineno == 1 )
+              error = FT_THROW( Missing_Startfont_Field );
+            else
+            {
+              FT_ERROR(( "_bdf_readstream: " ERRMSG6, lineno ));
+              error = FT_THROW( Invalid_Argument );
+            }
             goto Exit;
           }
 
@@ -2169,7 +2180,7 @@
     unsigned long  lineno = 0; /* make compiler happy */
     _bdf_parse_t   *p     = NULL;
 
-    FT_Error   error  = FT_Err_Ok;
+    FT_Error  error = FT_Err_Ok;
 
 
     if ( FT_NEW( p ) )
diff --git a/src/cid/cidparse.c b/src/cid/cidparse.c
index 96ca1c350..852c9b6b9 100644
--- a/src/cid/cidparse.c
+++ b/src/cid/cidparse.c
@@ -73,7 +73,11 @@
 
     /* first of all, check the font format in the header */
     if ( FT_FRAME_ENTER( 31 ) )
+    {
+      FT_TRACE2(( "  not a CID-keyed font\n" ));
+      error = FT_THROW( Unknown_File_Format );
       goto Exit;
+    }
 
     if ( ft_strncmp( (char *)stream->cursor,
                      "%!PS-Adobe-3.0 Resource-CIDFont", 31 ) )
diff --git a/src/pfr/pfrobjs.c b/src/pfr/pfrobjs.c
index 5302fac4c..3080cb650 100644
--- a/src/pfr/pfrobjs.c
+++ b/src/pfr/pfrobjs.c
@@ -83,7 +83,11 @@
     /* load the header and check it */
     error = pfr_header_load( &face->header, stream );
     if ( error )
+    {
+      FT_TRACE2(( "  not a PFR font\n" ));
+      error = FT_THROW( Unknown_File_Format );
       goto Exit;
+    }
 
     if ( !pfr_header_check( &face->header ) )
     {
diff --git a/src/winfonts/winfnt.c b/src/winfonts/winfnt.c
index 9c4b13ed9..b4fabad28 100644
--- a/src/winfonts/winfnt.c
+++ b/src/winfonts/winfnt.c
@@ -217,7 +217,11 @@
     /* first of all, read the FNT header */
     if ( FT_STREAM_SEEK( font->offset )                        ||
          FT_STREAM_READ_FIELDS( winfnt_header_fields, header ) )
+    {
+      FT_TRACE2(( "  not a Windows FNT file\n" ));
+      error = FT_THROW( Unknown_File_Format );
       goto Exit;
+    }
 
     /* check header */
     if ( header->version != 0x200 &&
@@ -284,7 +288,10 @@
     /* does it begin with an MZ header? */
     if ( FT_STREAM_SEEK( 0 )                                      ||
          FT_STREAM_READ_FIELDS( winmz_header_fields, &mz_header ) )
+    {
+      error = FT_ERR( Unknown_File_Format );
       goto Exit;
+    }
 
     error = FT_ERR( Unknown_File_Format );
     if ( mz_header.magic == WINFNT_MZ_MAGIC )