Added/Updated tests\bugs\gh_7772_test.py: Confirmed bug on 4.0.4.2997: restored database contains blob with size = 4464 which is less than initial size. Checked on 4.0.4.2998 -- all fine.

tests/bugs/gh_7772_test.py

@@ -0,0 +1,115 @@
+#coding:utf-8
+
+"""
+ID:          issue-7772
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/7772
+TITLE:       Blob corruption in FB4.0.3 (embedded)
+DESCRIPTION: 
+    Problem appears when we use big streamed blobs with size 64K ... 128K.
+    Test creates table and fills it using BLOB_APPEND() function.
+    Then we do b/backup and make restore using embedded (local) mode.
+    Values of octet_length and hash for blob in restored DB must be unchanged.
+NOTES:
+    [01.10.2023] pzotov
+    Thanks to Vlad for provided example for test.
+    Confirmed bug on 4.0.4.2997: restored database contains blob with size = 4464 which is less than initial size.
+
+    Checked on 4.0.4.2998 -- all fine.
+    ::: NB :::
+    Currently FB 5.x and 6.x are also affected, so this test will FAIL on them.
+    Sent report to Vlad, 01.10.2023 09:50. Waiting for reply / fix in FB 5.x and 6.x
+"""
+from io import BytesIO
+from pathlib import Path
+
+import pytest
+from firebird.qa import *
+from firebird.driver import SrvRestoreFlag
+
+BLOB_DATA_LEN = 70000
+init_sql = f"""
+    set term ^;
+    create table t_blb
+    (
+        id int
+       ,blb blob sub_type text
+    ) ^
+    commit ^
+    create or alter function gen_blb(asize int)
+       returns blob
+    as
+        declare b blob;
+        declare str varchar(36);
+    begin
+        str = uuid_to_char(gen_uuid());
+        while (asize > 0) do
+        begin
+            if (asize < 36) then
+                begin
+                    str = substring(str from 1 for asize);
+                    asize = 0;
+                end
+            else
+                asize = asize - 36;
+            
+            b = blob_append(b, str);
+        end
+        return b;
+    end ^
+    commit ^
+    insert into t_blb values (1, gen_blb({BLOB_DATA_LEN})) ^
+    commit ^
+"""
+
+db = db_factory(init = init_sql)
+act = python_act('db')
+
+#-------------------------------------------------------------------------------------
+
+def get_blob_octets_hash(act: Action):
+    blob_octets_len, blob_hash = -1, -1
+    with act.db.connect() as con:
+        cur = con.cursor()
+        #cur.execute('select octet_length(blb) from t_blb')
+        cur.execute('select octet_length(blb), crypt_hash(blb using sha512) from t_blb')
+        for r in cur:
+            blob_octets_len = r[0]
+            blob_hash = r[1]
+            # Convert binary to more readable view:
+            blob_hash = format(int.from_bytes(blob_hash,  'big'), 'x')
+            blob_hash = blob_hash.upper().rjust(128, '0')
+    
+    return blob_octets_len, blob_hash
+
+#-------------------------------------------------------------------------------------
+
+@pytest.mark.version('>=4.0.4')
+def test_1(act: Action, capsys):
+
+    init_len, init_hash = get_blob_octets_hash(act)
+
+    # backup + restore without creating .fbk:
+    #
+    bkp_data = BytesIO()
+    with act.connect_server() as srv:
+        srv.database.local_backup(database = act.db.db_path, backup_stream = bkp_data)
+        bkp_data.seek(0)
+        srv.database.local_restore(backup_stream = bkp_data, database = act.db.db_path, flags = SrvRestoreFlag.REPLACE)
+
+    curr_len, curr_hash = get_blob_octets_hash(act)
+
+    expected_stdout = "EXPECTED: blob data did not changed after backup-restore"
+
+    if init_len == curr_len and init_hash == curr_hash:
+        print(expected_stdout)
+    else:
+        print('UNEXPECTED: blob data CHANGED after backup-restore!')
+        print(f'Initial len: {init_len}')
+        print(f'Initial hash: {init_hash}')
+        print(f'Current len: {curr_len}')
+        print(f'Current hash: {curr_hash}')
+
+    act.expected_stdout = expected_stdout
+    act.stdout = capsys.readouterr().out
+    assert act.clean_stdout == act.clean_expected_stdout
+    act.reset()