Re: gzip --force bug

[Mark Adler]

Jim,

Below is a patch to the patch.

A test case will be forthcoming (I need to create a case that delicately 
crosses a buffer boundary).  Once I get a test case working, you can push it.

By the way, I found an even more serious incarnation of the original bug shown 
by this test case:

$ echo -n x | gzip124 -cdf | wc -c
       0
$ echo -n x | gzip14 -cdf | wc -c
       0

It should be the same as cat:

$ echo -n x | cat | wc -c
       1
$ echo -n x | ./gzip -cdf | wc -c
       1

Test cases to add for completeness are:

$ echo -n | ./gzip -cdf | wc -c
$ echo -n x | ./gzip -cdf | wc -c
$ echo -n xy | ./gzip -cdf | wc -c
$ echo -n xyz | ./gzip -cdf | wc -c

Those should return 0, 1, 2, and 3 respectively.

Mark


--- gzip-1.4p1.c        2010-02-02 23:11:45.000000000 -0800
+++ gzip.c      2010-02-03 07:39:18.000000000 -0800
@@ -1398,7 +1398,8 @@
     } else if (force && to_stdout && !list) { /* pass input unchanged */
         method = STORED;
         work = copy;
-        inptr--;
+        if (imagic1 != EOF)
+            inptr--;
         last_member = 1;
         if (imagic0 != EOF) {
             write_buf(fileno(stdout), magic, 1);