Fix a few goofs in new backup compression code.

When we try to set the zstd compression level either on the client
or on the server, check for errors.

For any algorithm, on the client side, don't try to set the compression
level unless the user specified one. This was visibly broken for
zstd, which managed to set -1 rather than 0 in this case, but tidy
up the code for the other methods, too.

On the client side, if we fail to create a ZSTD_CCtx, exit after
reporting the error. Otherwise we'll dereference a null pointer.

Patch by me, reviewed by Dipesh Pandit.

Discussion: http://postgr.es/m/CA+TgmoZK3zLQUCGi1h4XZw4jHiAWtcACc+GsdJR1_Mc19jUjXA@mail.gmail.com

4 files changed, 27 insertions, 6 deletions

diff --git a/src/backend/replication/basebackup_zstd.c b/src/backend/replication/basebackup_zstd.c
index bb5b668c2ab..5496eaa72b7 100644
--- a/src/backend/replication/basebackup_zstd.c
+++ b/src/backend/replication/basebackup_zstd.c
@@ -98,13 +98,17 @@ bbsink_zstd_begin_backup(bbsink *sink)
 {
 	bbsink_zstd *mysink = (bbsink_zstd *) sink;
 	size_t		output_buffer_bound;
+	size_t		ret;
 
 	mysink->cctx = ZSTD_createCCtx();
 	if (!mysink->cctx)
 		elog(ERROR, "could not create zstd compression context");
 
-	ZSTD_CCtx_setParameter(mysink->cctx, ZSTD_c_compressionLevel,
-						   mysink->compresslevel);
+	ret = ZSTD_CCtx_setParameter(mysink->cctx, ZSTD_c_compressionLevel,
+								 mysink->compresslevel);
+	if (ZSTD_isError(ret))
+		elog(ERROR, "could not set zstd compression level to %d: %s",
+			 mysink->compresslevel, ZSTD_getErrorName(ret));
 
 	/*
 	 * We need our own buffer, because we're going to pass different data to
diff --git a/src/bin/pg_basebackup/bbstreamer_gzip.c b/src/bin/pg_basebackup/bbstreamer_gzip.c
index 1979e956399..760619fcd74 100644
--- a/src/bin/pg_basebackup/bbstreamer_gzip.c
+++ b/src/bin/pg_basebackup/bbstreamer_gzip.c
@@ -116,7 +116,8 @@ bbstreamer_gzip_writer_new(char *pathname, FILE *file,
 		}
 	}
 
-	if (gzsetparams(streamer->gzfile, compress->level,
+	if ((compress->options & BACKUP_COMPRESSION_OPTION_LEVEL) != 0 &&
+		gzsetparams(streamer->gzfile, compress->level,
 					Z_DEFAULT_STRATEGY) != Z_OK)
 	{
 		pg_log_error("could not set compression level %d: %s",
diff --git a/src/bin/pg_basebackup/bbstreamer_lz4.c b/src/bin/pg_basebackup/bbstreamer_lz4.c
index a6ec317e2bd..67f841d96a9 100644
--- a/src/bin/pg_basebackup/bbstreamer_lz4.c
+++ b/src/bin/pg_basebackup/bbstreamer_lz4.c
@@ -89,7 +89,8 @@ bbstreamer_lz4_compressor_new(bbstreamer *next, bc_specification *compress)
 	prefs = &streamer->prefs;
 	memset(prefs, 0, sizeof(LZ4F_preferences_t));
 	prefs->frameInfo.blockSizeID = LZ4F_max256KB;
-	prefs->compressionLevel = compress->level;
+	if ((compress->options & BACKUP_COMPRESSION_OPTION_LEVEL) != 0)
+		prefs->compressionLevel = compress->level;
 
 	/*
 	 * Find out the compression bound, it specifies the minimum destination
diff --git a/src/bin/pg_basebackup/bbstreamer_zstd.c b/src/bin/pg_basebackup/bbstreamer_zstd.c
index caa5edcaf12..7946b6350b6 100644
--- a/src/bin/pg_basebackup/bbstreamer_zstd.c
+++ b/src/bin/pg_basebackup/bbstreamer_zstd.c
@@ -67,6 +67,8 @@ bbstreamer_zstd_compressor_new(bbstreamer *next, bc_specification *compress)
 {
 #ifdef USE_ZSTD
 	bbstreamer_zstd_frame *streamer;
+	int			compresslevel;
+	size_t		ret;
 
 	Assert(next != NULL);
 
@@ -81,11 +83,24 @@ bbstreamer_zstd_compressor_new(bbstreamer *next, bc_specification *compress)
 
 	streamer->cctx = ZSTD_createCCtx();
 	if (!streamer->cctx)
+	{
 		pg_log_error("could not create zstd compression context");
+		exit(1);
+	}
 
 	/* Initialize stream compression preferences */
-	ZSTD_CCtx_setParameter(streamer->cctx, ZSTD_c_compressionLevel,
-						   compress->level);
+	if ((compress->options & BACKUP_COMPRESSION_OPTION_LEVEL) == 0)
+		compresslevel = 0;
+	else
+		compresslevel = compress->level;
+	ret = ZSTD_CCtx_setParameter(streamer->cctx, ZSTD_c_compressionLevel,
+								 compresslevel);
+	if (ZSTD_isError(ret))
+	{
+		pg_log_error("could not set zstd compression level to %d: %s",
+					 compresslevel, ZSTD_getErrorName(ret));
+		exit(1);
+	}
 
 	/* Initialize the ZSTD output buffer. */
 	streamer->zstd_outBuf.dst = streamer->base.bbs_buffer.data;