[erlang-patches] Patch to add zlib:crc32_combine/4 and zlib:adler32_combine/4

[Matthew Dempsky]

Some further testing with the zipchunk module revealed that the
zlib_drv does not properly flush the zlib buffers.  In particular, a
call to zlib:deflate(Z, Binary, full) can leave part of Binary still
in Z's internal state.

The patch below properly follows the advice of zlib.h that ``If
deflate returns with avail_out == 0, this function must be called
again with the same value of the flush parameter and more output space
(updated avail_out).''

Also, Z_STREAM_END is only returned when Z_FINISH is given.

--- otp_src_R11B-5/erts/emulator/drivers/common/zlib_drv.c.orig	2007-11-06
11:44:12.000000000 -0800
+++ otp_src_R11B-5/erts/emulator/drivers/common/zlib_drv.c	2007-11-13
16:39:48.000000000 -0800
@@ -323,12 +323,15 @@
 		}
 	    }
 	} else {
-	    while (d->s.avail_out < d->binsz) {
+	    while (d->s.avail_out == 0) {
 		zlib_output(d);
-		if (res == Z_STREAM_END) {
-		    break;
+		if ((res = deflate(&d->s, flush)) < 0) {
+		    return res;
 		}
 	    }
+	    if (d->s.avail_out < d->binsz) {
+		zlib_output(d);
+	    }
 	}
     }
     return res;