On 11/19/2010 01:33 PM, Alan Bateman wrote:
Xueming Shen wrote:
:
I might not explain it clear enough. For Deflater.c we want to at
least keep the "malloc"
path for
if ((*env)->GetBooleanField(env, this, setParamsID)) {
....
}
so it will continue go down to deflateParams() to reset the params, with
a valid non-NULL ptr on most platforms, even for 0-length buf, this is
what it was before #6728376 and what it is now, We don't what to have
another "regression" (change the params, invoke the deflate() with
0-length
buffer, but now it returns 0 with change the setting, I have to
invoke it
again with...) here. And with the "len != 0" check, it will be no
behavior
change as well for that weird OS.
For other 2 paths (the Inflater.c and the
(*env)->GetBooleanField(env, this, setParamsID) == false
path, I believe/think/guess it should be safe to bypath the zlib by
checking len/in_len and returning 0 if any of them is zero. But this is
again a "change", probably:-) harmless giving my understand/reading of
zlib code and the existing regression tests.
So the "bit cleaner" webrev is
http://cr.openjdk.java.net/~sherman/6858865/webrev/
But it deal with the 0-length issue "differently" at different places.
This is why I proposed last night the "safe" and "simple: change.
Anyway, I'm fine with the "bit-cleaner" approach, so if you're OK with
it, throw it in:-)
The "old" webrev is at
http://cr.openjdk.java.net/~sherman/6858865/webrev.00/
-Sherman
The updated webrev looks better, but for the deflateParam path then
maybe you could do something like this:
if (this_len == 0) {
in_buf = NULL;
} else {
in_buf = (jbyte*) malloc(this_len);
if (in_buf == NULL) {
JNU_ThrowOutOfMemoryError(env, 0);
return 0;
}
}
and same thing for out_buf.
Would that be a bit cleaner?
Why do you want to feed the zlib with a null buffer? :-)
The zlib#deflate() does some null checks at the beginning as showed below.
I probably can do something tricky to make it work, but for me I don't see
the benefit of taking the risk. If it works don't break it:-)
-Sherman
int ZEXPORT deflate (strm, flush)
z_streamp strm;
int flush;
{
int old_flush; /* value of flush param for previous deflate call */
deflate_state *s;
if (strm == Z_NULL || strm->state == Z_NULL ||
flush > Z_FINISH || flush < 0) {
return Z_STREAM_ERROR;
}
s = strm->state;
if (strm->next_out == Z_NULL ||
(strm->next_in == Z_NULL && strm->avail_in != 0) ||
(s->status == FINISH_STATE && flush != Z_FINISH)) {
ERR_RETURN(strm, Z_STREAM_ERROR);
}
if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
....
-Alan
