From: Michael M Slusarz <michael.slusarz@open-xchange.com>
Date: Sat, 4 Oct 2025 18:04:31 +0000 (-0600)
Subject: lib-compression: Don't calculate crc32 if using zlib in deflate mode
X-Git-Tag: 2.4.2~72
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cac140a9e4e12485bde4348b8a8c94a7a96a6e5e;p=thirdparty%2Fdovecot%2Fcore.git

lib-compression: Don't calculate crc32 if using zlib in deflate mode
---

diff --git a/src/lib-compression/istream-zlib.c b/src/lib-compression/istream-zlib.c
index f551374724..93b3473071 100644
--- a/src/lib-compression/istream-zlib.c
+++ b/src/lib-compression/istream-zlib.c
@@ -264,9 +264,11 @@ static ssize_t i_stream_zlib_read(struct istream_private *stream)
 	ret = inflate(&zstream->zs, Z_SYNC_FLUSH);
 
 	out_size -= zstream->zs.avail_out;
-	zstream->crc32 = crc32_data_more(zstream->crc32,
-					 stream->w_buffer + stream->pos,
-					 out_size);
+	/* CRC32 is only needed for GZ trailer. */
+	if (zstream->gz)
+		zstream->crc32 = crc32_data_more(zstream->crc32,
+						 stream->w_buffer + stream->pos,
+						 out_size);
 	stream->pos += out_size;
 
 	size_t bytes_consumed = size - zstream->zs.avail_in;
diff --git a/src/lib-compression/ostream-zlib.c b/src/lib-compression/ostream-zlib.c
index 5cc2215737..ed41f5054f 100644
--- a/src/lib-compression/ostream-zlib.c
+++ b/src/lib-compression/ostream-zlib.c
@@ -228,7 +228,9 @@ o_stream_zlib_send_chunk(struct zlib_ostream *zstream,
 	}
 	size -= zs->avail_in;
 
-	zstream->crc = crc32_data_more(zstream->crc, data, size);
+	/* CRC32 is only needed for GZ trailer. */
+	if (zstream->gz)
+		zstream->crc = crc32_data_more(zstream->crc, data, size);
 	zstream->bytes32 += size;
 	zstream->flushed = FALSE;
 	return size;