zlib 1.2.1 inflate fix

Zack Winkles winkie at linuxfromscratch.org
Sat Mar 13 11:19:37 PST 2004


Extracted from test 1.2.1.1 release.
-------------- next part --------------
Submitted By: Zack Winkles <winkie at linuxfromscratch.org>
Date: 2004-03-13
Initial Package Version: 1.2.1
Upstream Status: Merged
Origin: http://xenon.nocdirect.com/pipermail/zlib-devel_madler.net/2004-January/000409.html
Description:

A zip file was found that zlib 1.2.1 could not properly inflate, but 
previous versions could (as well as various other versions of my 
inflate code).  Oops.

diff -Naur zlib-1.2.1/inftrees.c zlib-1.2.1.1/inftrees.c
--- zlib-1.2.1/inftrees.c	2003-11-08 21:38:38.000000000 -0500
+++ zlib-1.2.1.1/inftrees.c	2004-01-09 06:11:20.000000000 -0500
@@ -62,7 +62,7 @@
         35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
     static const unsigned short lext[31] = { /* Length codes 257..285 extra */
         16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18,
-        19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 76, 66};
+        19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 202, 196};
     static const unsigned short dbase[32] = { /* Distance codes 0..29 base */
         1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
         257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
@@ -114,7 +114,15 @@
     for (max = MAXBITS; max >= 1; max--)
         if (count[max] != 0) break;
     if (root > max) root = max;
-    if (max == 0) return -1;            /* no codes! */
+    if (max == 0) {                     /* no symbols to code at all */
+        this.op = (unsigned char)64;    /* invalid code marker */
+        this.bits = (unsigned char)1;
+        this.val = (unsigned short)0;
+        *(*table)++ = this;             /* make a table to force an error */
+        *(*table)++ = this;
+        *bits = 1;
+        return 0;     /* no symbols, but wait for decoding to report error */
+    }
     for (min = 1; min <= MAXBITS; min++)
         if (count[min] != 0) break;
     if (root < min) root = min;


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