Revert "Fix corner case with PGP decompression in pgcrypto"

michaelpq · michaelpq · commit e30a63f258f5 · 2020-07-23T08:29:18.000+09:00
This reverts commit 9e10898, after finding out that buildfarm members running SLES 15 on z390 complain on the compression and decompression logic of the new test: pipistrelles, barbthroat and steamerduck. Those hosts are visibly using hardware-specific changes to improve zlib performance, requiring more investigation. Thanks to Tom Lane for the discussion. Discussion: https://postgr.es/m/20200722093749.GA2564@paquier.xyz Backpatch-through: 9.5
diff --git a/contrib/pgcrypto/expected/pgp-compression.out b/contrib/pgcrypto/expected/pgp-compression.out
@@ -48,33 +48,3 @@ select pgp_sym_decrypt(
  Secret message
 (1 row)
 
--- check corner case involving an input string of 16kB, as per bug #16476.
-SELECT setseed(0);
- setseed 
----------
- 
-(1 row)
-
-WITH random_string AS
-(
-  -- This generates a random string of 16366 bytes.  This is chosen
-  -- as random so that it does not get compressed, and the decompression
-  -- would work on a string with the same length as the origin, making the
-  -- test behavior more predictible.  lpad() ensures that the generated
-  -- hexadecimal value is completed by extra zero characters if random()
-  -- has generated a value strictly lower than 16.
-  SELECT string_agg(decode(lpad(to_hex((random()*256)::int), 2, '0'), 'hex'), '') as bytes
-    FROM generate_series(0, 16365)
-)
-SELECT bytes =
-    pgp_sym_decrypt_bytea(
-      pgp_sym_encrypt_bytea(bytes, 'key',
-                            'compress-algo=1,compress-level=1'),
-                            'key', 'expect-compress-algo=1')
-    AS is_same
-  FROM random_string;
- is_same 
----------
- t
-(1 row)
-
diff --git a/contrib/pgcrypto/pgp-compress.c b/contrib/pgcrypto/pgp-compress.c
@@ -244,17 +244,6 @@ decompress_read(void *priv, PullFilter *src, int len,
 	struct DecomprData *dec = priv;
 
 restart:
-	if (dec->stream.avail_in == 0)
-	{
-		uint8	   *tmp;
-
-		res = pullf_read(src, 8192, &tmp);
-		if (res < 0)
-			return res;
-		dec->stream.next_in = tmp;
-		dec->stream.avail_in = res;
-	}
-
 	if (dec->buf_data > 0)
 	{
 		if (len > dec->buf_data)
@@ -268,6 +257,17 @@ decompress_read(void *priv, PullFilter *src, int len,
 	if (dec->eof)
 		return 0;
 
+	if (dec->stream.avail_in == 0)
+	{
+		uint8	   *tmp;
+
+		res = pullf_read(src, 8192, &tmp);
+		if (res < 0)
+			return res;
+		dec->stream.next_in = tmp;
+		dec->stream.avail_in = res;
+	}
+
 	dec->stream.next_out = dec->buf;
 	dec->stream.avail_out = dec->buf_len;
 	dec->pos = dec->buf;
diff --git a/contrib/pgcrypto/sql/pgp-compression.sql b/contrib/pgcrypto/sql/pgp-compression.sql
@@ -28,24 +28,3 @@ select pgp_sym_decrypt(
 	pgp_sym_encrypt('Secret message', 'key',
 			'compress-algo=2, compress-level=0'),
 	'key', 'expect-compress-algo=0');
-
--- check corner case involving an input string of 16kB, as per bug #16476.
-SELECT setseed(0);
-WITH random_string AS
-(
-  -- This generates a random string of 16366 bytes.  This is chosen
-  -- as random so that it does not get compressed, and the decompression
-  -- would work on a string with the same length as the origin, making the
-  -- test behavior more predictible.  lpad() ensures that the generated
-  -- hexadecimal value is completed by extra zero characters if random()
-  -- has generated a value strictly lower than 16.
-  SELECT string_agg(decode(lpad(to_hex((random()*256)::int), 2, '0'), 'hex'), '') as bytes
-    FROM generate_series(0, 16365)
-)
-SELECT bytes =
-    pgp_sym_decrypt_bytea(
-      pgp_sym_encrypt_bytea(bytes, 'key',
-                            'compress-algo=1,compress-level=1'),
-                            'key', 'expect-compress-algo=1')
-    AS is_same
-  FROM random_string;
