Attachment 52152 Details for Bug 41628 – Proposed patch

[patch] Proposed patch

libXfont-compress-maxbits12.diff (text/plain), 2.55 KB, created by Tomas Hoger on 2011-10-09 11:20:44 UTC

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Creator: Tomas Hoger

Created: 2011-10-09 11:20:44 UTC

Size: 2.55 KB

patch

obsolete

>commit 033492720c88a064b134f6851ee0f4a876cd4d6c
>Author: Tomas Hoger <thoger@redhat.com>
>Date:   Sun Oct 9 19:51:50 2011 +0200
>
>    Support compress files with maxbits < 12
>    
>    The compress decompression code used by libXfont rejects valid archives
>    with maxbits less than 12 (compress allows values 9 - 16, 16 is the
>    default).  This is because maxbits-12 is used as index to hsize_table[].
>    
>    That looks like an incorrect port of the original compress code, where:
>    - hsize depended on BITS, the maximum maxbits value supported by particular
>      build, rather than on maxbits value from the particular input file
>    - the same hsize was used for all BITS <= 12
>    
>    The quick way to verify the problem is:
>      compress -b 11 fontfile.bdf
>      bdftopcf -o /dev/null fontfile.bdf.Z
>    which fails, while 12-16 works correctly.
>    
>    This fix removes hsize_table and uses 1 << maxbits (aka maxmaxcode) as
>    tab_prefix size.  As decompression code does not use hashing as compression
>    code, there does not seem to be a reason to allocate any extra space.
>    
>    Note: In this fix, maxbits == 9 is still rejected early.  AFAICS compress
>    is able to generate such files (unknown how correct such output is), but is
>    unable to uncompress them correctly.
>
>diff --git a/src/fontfile/decompress.c b/src/fontfile/decompress.c
>index 6405d76..20971df 100644
>--- a/src/fontfile/decompress.c
>+++ b/src/fontfile/decompress.c
>@@ -124,14 +124,6 @@ typedef struct _compressedFILE {
> } CompressedFile;
> 
> 
>-static int hsize_table[] = {
>-    5003,	/* 12 bits - 80% occupancy */
>-    9001,	/* 13 bits - 91% occupancy */
>-    18013,	/* 14 bits - 91% occupancy */
>-    35023,	/* 15 bits - 94% occupancy */
>-    69001	/* 16 bits - 95% occupancy */
>-};
>-
> static int BufCompressedClose ( BufFilePtr f, int doClose );
> static int BufCompressedFill ( BufFilePtr f );
> static code_int getcode ( CompressedFile *file );
>@@ -142,7 +134,6 @@ BufFilePushCompressed (BufFilePtr f)
> {
>     int		    code;
>     int		    maxbits;
>-    int		    hsize;
>     CompressedFile  *file;
>     int		    extra;
> 
>@@ -155,11 +146,10 @@ BufFilePushCompressed (BufFilePtr f)
>     if (code == BUFFILEEOF) return 0;
> 
>     maxbits = code & BIT_MASK;
>-    if (maxbits > BITS || maxbits < 12)
>+    if (maxbits > BITS || maxbits <= INIT_BITS)
> 	return 0;
>-    hsize = hsize_table[maxbits - 12];
>     extra = (1 << maxbits) * sizeof (char_type) +
>-	    hsize * sizeof (unsigned short);
>+	    (1 << maxbits) * sizeof (unsigned short);
>     file = malloc (sizeof (CompressedFile) + extra);
>     if (!file)
> 	return 0;

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