Add "reproducible" deflate parameter

IBM Z DEFLATE CONVERSION CALL may produce different (but valid)
compressed data for the same uncompressed data. This behavior might be
unacceptable for certain use cases (e.g. reproducible builds). This
patch introduces Z_DEFLATE_REPRODUCIBLE parameter, which can be used to
indicate that this is the case, and turn off IBM Z DEFLATE CONVERSION
CALL.

1 files changed, 7 insertions, 0 deletions

diff --git a/zlib-ng.h b/zlib-ng.h
index 5662b27..a66b2af 100644
--- a/zlib-ng.h
+++ b/zlib-ng.h
@@ -1793,6 +1793,13 @@ ZEXTERN int ZEXPORT zng_gzgetc_(gzFile file);  /* backward compatibility */
 typedef enum {
     Z_DEFLATE_LEVEL = 0,         /* compression level, represented as an int */
     Z_DEFLATE_STRATEGY = 1,      /* compression strategy, represented as an int */
+    Z_DEFLATE_REPRODUCIBLE = 2,
+    /*
+         Whether reproducible compression results are required. Represented as an int, where 0 means that it is allowed
+       to trade reproducibility for e.g. improved performance or compression ratio, and non-0 means that
+       reproducibility is strictly required. Reproducibility is guaranteed only when using an identical zlib-ng build.
+       Default is 0.
+    */
 } zng_deflate_param;
 
 typedef struct {