Cyril Brulebois <k...@debian.org> (08/02/2012):
> Playing on amd64:
> cbrulebois@Cygnus:/tmp/ppl-0.11.2$ cp ../ppl-pristine/{CREDITS,README} .
> cbrulebois@Cygnus:/tmp/ppl-0.11.2$ gzip -9nf CREDITS README
> cbrulebois@Cygnus:/tmp/ppl-0.11.2$ ls -l *gz
> -rw-r--r-- 1 cbrulebois cbrulebois 6343 Feb 8 12:34 CREDITS.gz
> -rw-r--r-- 1 cbrulebois cbrulebois 8745 Feb 8 12:34 README.gz
> cbrulebois@Cygnus:/tmp/ppl-0.11.2$ cp ../ppl-pristine/{CREDITS,README} .
> cbrulebois@Cygnus:/tmp/ppl-0.11.2$ gzip -9nf README CREDITS
> cbrulebois@Cygnus:/tmp/ppl-0.11.2$ ls -l *gz
> -rw-r--r-- 1 cbrulebois cbrulebois 6344 Feb 8 12:34 CREDITS.gz
> -rw-r--r-- 1 cbrulebois cbrulebois 8745 Feb 8 12:34 README.gz
>
> It looks to me like it shouldn't be hard to figure out what happens here
> given the few tests I performed with the above command lines. On a few
> iterations, reproducibility (with a given input command line) doesn't
> seem to be an issue.I think at least the attached patch won't hurt (when the DYN_ALLOC part is fixed; and possibly turning that into a MEMSET-like macro). And given dh_compress is passing files in an arbitrary order (it's using “find” to detect files which needs to be compressed), I think we have an explanation about the apparently-hard-to-reproduce issues. Mraw, KiBi.
diff --git a/gzip.c b/gzip.c
index b867350..1153bde 100644
--- a/gzip.c
+++ b/gzip.c
@@ -561,6 +561,19 @@ int main (int argc, char **argv)
SET_BINARY_MODE(fileno(stdout));
}
while (optind < argc) {
+
+ /* Make sure buffers are reset to 0 to ensure reproducibility when handling several files */
+ ZEROIFY(uch, inbuf, INBUFSIZ +INBUF_EXTRA);
+ ZEROIFY(uch, outbuf, OUTBUFSIZ+OUTBUF_EXTRA);
+ ZEROIFY(ush, d_buf, DIST_BUFSIZE);
+ ZEROIFY(uch, window, 2L*WSIZE);
+#ifndef MAXSEG_64K
+ ZEROIFY(ush, tab_prefix, 1L<<BITS);
+#else
+ ZEROIFY(ush, tab_prefix0, 1L<<(BITS-1));
+ ZEROIFY(ush, tab_prefix1, 1L<<(BITS-1));
+#endif
+
treat_file(argv[optind++]);
}
} else { /* Standard input */
diff --git a/gzip.h b/gzip.h
index 5270c56..7a1e84b 100644
--- a/gzip.h
+++ b/gzip.h
@@ -119,11 +119,13 @@ extern int method; /* compression method */
array = (type*)fcalloc((size_t)(((size)+1L)/2), 2*sizeof(type)); \
if (!array) xalloc_die (); \
}
+# error "ZEROIFY needs an implementation, KiBi is lazy"
# define FREE(array) {if (array != NULL) fcfree(array), array=NULL;}
#else
# define EXTERN(type, array) extern type array[]
# define DECLARE(type, array, size) type array[size]
# define ALLOC(type, array, size)
+# define ZEROIFY(type, array, size) { for (int i=0; i<size; i++) { array[i] = 0; } }
# define FREE(array)
#endif
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