Now that we have effectively de-supported CentOS 6, by removing support
for its OpenSSL version, I think we could also modernize the use of some
other libraries, such as zlib.
If we define ZLIB_CONST before including zlib.h, zlib augments some
interfaces with const decorations. By doing that we can keep our own
interfaces cleaner and can remove some unconstify calls.
ZLIB_CONST was introduced in zlib 1.2.5.2 (17 Dec 2011); CentOS 6 has
zlib-1.2.3-29.el6.x86_64.
Note that if you use this patch and compile on CentOS 6, it still works,
you just get a few compiler warnings about discarding qualifiers. Old
environments tend to produce more compiler warnings anyway, so this
doesn't seem so bad.From 324e37adff4c51f4f10807386c0c098cb8d21608 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pe...@eisentraut.org>
Date: Wed, 2 Aug 2023 11:01:27 +0200
Subject: [PATCH] Improve const use in zlib-using code
If we define ZLIB_CONST before including zlib.h, zlib augments some
interfaces with const decorations. By doing that we can keep our own
interfaces cleaner and can remove some unconstify calls.
ZLIB_CONST was introduced in zlib 1.2.5.2 (17 Dec 2011).
XXX CentOS 6 has zlib-1.2.3-29.el6.x86_64
---
contrib/pgcrypto/pgp-compress.c | 3 ++-
src/backend/backup/basebackup_gzip.c | 1 +
src/bin/pg_basebackup/bbstreamer_gzip.c | 3 ++-
src/bin/pg_basebackup/pg_basebackup.c | 1 +
src/bin/pg_basebackup/pg_receivewal.c | 1 +
src/bin/pg_basebackup/walmethods.c | 6 +++---
src/bin/pg_dump/compress_gzip.c | 1 +
src/common/compression.c | 1 +
8 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/contrib/pgcrypto/pgp-compress.c b/contrib/pgcrypto/pgp-compress.c
index 086bec31ae..5615f1acce 100644
--- a/contrib/pgcrypto/pgp-compress.c
+++ b/contrib/pgcrypto/pgp-compress.c
@@ -40,6 +40,7 @@
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include <zlib.h>
#define ZIP_OUT_BUF 8192
@@ -113,7 +114,7 @@ compress_process(PushFilter *next, void *priv, const uint8
*data, int len)
/*
* process data
*/
- st->stream.next_in = unconstify(uint8 *, data);
+ st->stream.next_in = data;
st->stream.avail_in = len;
while (st->stream.avail_in > 0)
{
diff --git a/src/backend/backup/basebackup_gzip.c
b/src/backend/backup/basebackup_gzip.c
index b2d5e19ad9..45210a2ff0 100644
--- a/src/backend/backup/basebackup_gzip.c
+++ b/src/backend/backup/basebackup_gzip.c
@@ -13,6 +13,7 @@
#include "postgres.h"
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include <zlib.h>
#endif
diff --git a/src/bin/pg_basebackup/bbstreamer_gzip.c
b/src/bin/pg_basebackup/bbstreamer_gzip.c
index 3bdbfa0bc4..fa52392a48 100644
--- a/src/bin/pg_basebackup/bbstreamer_gzip.c
+++ b/src/bin/pg_basebackup/bbstreamer_gzip.c
@@ -14,6 +14,7 @@
#include <unistd.h>
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include <zlib.h>
#endif
@@ -269,7 +270,7 @@ bbstreamer_gzip_decompressor_content(bbstreamer *streamer,
mystreamer = (bbstreamer_gzip_decompressor *) streamer;
zs = &mystreamer->zstream;
- zs->next_in = (uint8 *) data;
+ zs->next_in = (const uint8 *) data;
zs->avail_in = len;
/* Process the current chunk */
diff --git a/src/bin/pg_basebackup/pg_basebackup.c
b/src/bin/pg_basebackup/pg_basebackup.c
index 1dc8efe0cb..90fd044ec3 100644
--- a/src/bin/pg_basebackup/pg_basebackup.c
+++ b/src/bin/pg_basebackup/pg_basebackup.c
@@ -22,6 +22,7 @@
#include <signal.h>
#include <time.h>
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include <zlib.h>
#endif
diff --git a/src/bin/pg_basebackup/pg_receivewal.c
b/src/bin/pg_basebackup/pg_receivewal.c
index d0a4079d50..c0de77b5aa 100644
--- a/src/bin/pg_basebackup/pg_receivewal.c
+++ b/src/bin/pg_basebackup/pg_receivewal.c
@@ -24,6 +24,7 @@
#include <lz4frame.h>
#endif
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include <zlib.h>
#endif
diff --git a/src/bin/pg_basebackup/walmethods.c
b/src/bin/pg_basebackup/walmethods.c
index 376ddf72b7..b663a3d978 100644
--- a/src/bin/pg_basebackup/walmethods.c
+++ b/src/bin/pg_basebackup/walmethods.c
@@ -19,6 +19,7 @@
#include <lz4frame.h>
#endif
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include <zlib.h>
#endif
@@ -705,7 +706,7 @@ typedef struct TarMethodData
#ifdef HAVE_LIBZ
static bool
-tar_write_compressed_data(TarMethodData *tar_data, void *buf, size_t count,
+tar_write_compressed_data(TarMethodData *tar_data, const void *buf, size_t
count,
bool flush)
{
tar_data->zp->next_in = buf;
@@ -782,8 +783,7 @@ tar_write(Walfile *f, const void *buf, size_t count)
#ifdef HAVE_LIBZ
else if (f->wwmethod->compression_algorithm == PG_COMPRESSION_GZIP)
{
- if (!tar_write_compressed_data(tar_data, unconstify(void *,
buf),
-
count, false))
+ if (!tar_write_compressed_data(tar_data, buf, count, false))
return -1;
f->currpos += count;
return count;
diff --git a/src/bin/pg_dump/compress_gzip.c b/src/bin/pg_dump/compress_gzip.c
index 63dfd9668c..b536a527d7 100644
--- a/src/bin/pg_dump/compress_gzip.c
+++ b/src/bin/pg_dump/compress_gzip.c
@@ -18,6 +18,7 @@
#include "pg_backup_utils.h"
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include "zlib.h"
/*----------------------
diff --git a/src/common/compression.c b/src/common/compression.c
index ee937623f0..07a5d1b51d 100644
--- a/src/common/compression.c
+++ b/src/common/compression.c
@@ -31,6 +31,7 @@
#include <zstd.h>
#endif
#ifdef HAVE_LIBZ
+#define ZLIB_CONST
#include <zlib.h>
#endif
--
2.41.0
