Fix incorrect value for "strategy" with deflateParams() in walmethods.c

michaelpq · michaelpq · commit b3c630cc9230 · 2022-09-14T14:52:26.000+09:00
The zlib documentation mentions the values supported for the compression strategy, but this code has been using a hardcoded value of 0 rather than Z_DEFAULT_STRATEGY. This commit adjusts the code to use Z_DEFAULT_STRATEGY. Backpatch down to where this code has been added to ease the backport of any future patch touching this area. Reported-by: Tom Lane Discussion: https://postgr.es/m/1400032.1662217889@sss.pgh.pa.us Backpatch-through: 10
diff --git a/src/bin/pg_basebackup/walmethods.c b/src/bin/pg_basebackup/walmethods.c
@@ -905,7 +905,7 @@ tar_open_for_write(const char *pathname, const char *temp_suffix, size_t pad_to_
 			return NULL;
 
 		/* Turn off compression for header */
-		if (deflateParams(tar_data->zp, 0, 0) != Z_OK)
+		if (deflateParams(tar_data->zp, 0, Z_DEFAULT_STRATEGY) != Z_OK)
 		{
 			tar_set_error("could not change compression parameters");
 			return NULL;
@@ -945,7 +945,8 @@ tar_open_for_write(const char *pathname, const char *temp_suffix, size_t pad_to_
 			return NULL;
 
 		/* Re-enable compression for the rest of the file */
-		if (deflateParams(tar_data->zp, tar_data->compression_level, 0) != Z_OK)
+		if (deflateParams(tar_data->zp, tar_data->compression_level,
+						  Z_DEFAULT_STRATEGY) != Z_OK)
 		{
 			tar_set_error("could not change compression parameters");
 			return NULL;
@@ -1164,7 +1165,7 @@ tar_close(Walfile f, WalCloseMethod method)
 	else if (tar_data->compression_algorithm == PG_COMPRESSION_GZIP)
 	{
 		/* Turn off compression */
-		if (deflateParams(tar_data->zp, 0, 0) != Z_OK)
+		if (deflateParams(tar_data->zp, 0, Z_DEFAULT_STRATEGY) != Z_OK)
 		{
 			tar_set_error("could not change compression parameters");
 			return -1;
@@ -1176,7 +1177,8 @@ tar_close(Walfile f, WalCloseMethod method)
 			return -1;
 
 		/* Turn compression back on */
-		if (deflateParams(tar_data->zp, tar_data->compression_level, 0) != Z_OK)
+		if (deflateParams(tar_data->zp, tar_data->compression_level,
+						  Z_DEFAULT_STRATEGY) != Z_OK)
 		{
 			tar_set_error("could not change compression parameters");
 			return -1;
