1 files changed, 53 insertions, 0 deletions
diff --git a/compat/zlib-compat.h b/compat/zlib-compat.h
new file mode 100644
index 0000000000..ac08276622
--- /dev/null
+++ b/compat/zlib-compat.h
@@ -0,0 +1,53 @@
+#ifndef COMPAT_ZLIB_H
+#define COMPAT_ZLIB_H
+
+#ifdef HAVE_ZLIB_NG
+# include <zlib-ng.h>
+
+# define z_stream_s zng_stream_s
+# define gz_header_s zng_gz_header_s
+
+# define crc32(crc, buf, len) zng_crc32(crc, buf, len)
+
+# define inflate(strm, bits) zng_inflate(strm, bits)
+# define inflateEnd(strm) zng_inflateEnd(strm)
+# define inflateInit(strm) zng_inflateInit(strm)
+# define inflateInit2(strm, bits) zng_inflateInit2(strm, bits)
+# define inflateReset(strm) zng_inflateReset(strm)
+
+# define deflate(strm, flush) zng_deflate(strm, flush)
+# define deflateBound(strm, source_len) zng_deflateBound(strm, source_len)
+# define deflateEnd(strm) zng_deflateEnd(strm)
+# define deflateInit(strm, level) zng_deflateInit(strm, level)
+# define deflateInit2(stream, level, method, window_bits, mem_level, strategy) zng_deflateInit2(stream, level, method, window_bits, mem_level, strategy)
+# define deflateReset(strm) zng_deflateReset(strm)
+# define deflateSetHeader(strm, head) zng_deflateSetHeader(strm, head)
+
+#else
+# include <zlib.h>
+
+# if defined(NO_DEFLATE_BOUND) || ZLIB_VERNUM < 0x1200
+#  define deflateBound(c,s)  ((s) + (((s) + 7) >> 3) + (((s) + 63) >> 6) + 11)
+# endif
+
+/*
+ * zlib only gained support for setting up the gzip header in v1.2.2.1. In
+ * Git we only set the header to make archives reproducible across different
+ * operating systems, so it's fine to simply make this a no-op when using a
+ * zlib version that doesn't support this yet.
+ */
+# if ZLIB_VERNUM < 0x1221
+struct gz_header_s {
+	int os;
+};
+
+static int deflateSetHeader(z_streamp strm, struct gz_header_s *head)
+{
+	(void)(strm);
+	(void)(head);
+	return Z_OK;
+}
+# endif
+#endif /* HAVE_ZLIB_NG */
+
+#endif /* COMPAT_ZLIB_H */