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firebird-qa/tests/bugs/gh_8185_test.py

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#coding:utf-8
"""
ID: issue-8185
ISSUE: https://github.com/FirebirdSQL/firebird/issues/8185
TITLE: SIGSEGV in Firebird 5.0.0.1306 embedded during update on cursor
DESCRIPTION:
Test implements sequence of actions described by Dimitry Sibiryakov in the ticket,
see: https://github.com/FirebirdSQL/firebird/issues/8185#issuecomment-2258598579
NOTES:
[01.11.2024] pzotov
1. Bug was fixed on following commits:
5.x: 27.07.2024 11:48, 08dc25f8c45342a73c786bc60571c8a5f2c8c6e3
("Simplest fix for #8185: SIGSEGV in Firebird 5.0.0.1306 embedded during update on cursor - disallow caching for positioned updates/deletes")
6.x: 29.07.2024 00:53, a7d10a40147d326e56540498b50e40b2da0e5850
("Fix #8185 - SIGSEGV with WHERE CURRENT OF statement with statement cache turned on")
2. In current version of firebird-driver we can *not* set cursor name without executing it first.
But such execution leads to 'update conflict / deadlock' for subsequent UPDATE statement.
Kind of 'hack' is used to solve this problem: ps1._istmt.set_cursor_name(CURSOR_NAME)
3. GREAT thanks to:
* Vlad for providing workaround and explanation of problem with AV for code like this:
with connect(f'localhost:{DB_NAME}', user = DBA_USER, password = DBA_PSWD) as con:
cur1 = con.cursor()
ps1 = cur1.prepare('update test set id = -id rows 0 returning id')
cur1.execute(ps1)
ps1.free()
It is mandatory to store result of cur1.eecute in some variable, i.e. rs1 = cur1.execute(ps1),
and call then rs1.close() __BEFORE__ ps1.free().
Discussed 26.10.2024, subj:
"Oddities when using instance of selectable Statement // related to interfaces, VTable, iResultSet, iVersioned , CLOOP"
* Dimitry Sibiryakov for describe the 'step-by-step' algorithm for reproducing problem and providing working example in .cpp
Confirmed problem on 5.0.1.1452-b056f5b (last snapshot before it was fixed).
Checked on 5.0.1.1452-08dc25f (27.07.2024 11:50); 6.0.0.401-a7d10a4 (29.07.2024 01:33) -- all OK.
"""
import pytest
from firebird.qa import *
from firebird.driver import driver_config, connect, tpb, TraAccessMode, Isolation, DatabaseError
init_sql = """
set bail on;
recreate table test(id int, f01 int);
commit;
insert into test(id, f01) select row_number()over(), row_number()over() * 10 from rdb$types rows 3;
commit;
"""
db = db_factory(init = init_sql)
act = python_act('db')
@pytest.mark.version('>=5.0.0')
def test_1(act: Action, capsys):
srv_cfg = driver_config.register_server(name = 'test_srv_gh_8185', config = '')
db_cfg_name = f'db_cfg_8185'
db_cfg_object = driver_config.register_database(name = db_cfg_name)
db_cfg_object.server.value = srv_cfg.name
db_cfg_object.database.value = str(act.db.db_path)
db_cfg_object.config.value = f"""
MaxStatementCacheSize = 1M
"""
# Pre-check:
with connect(db_cfg_name, user = act.db.user, password = act.db.password) as con:
cur = con.cursor()
cur.execute("select a.mon$remote_protocol, g.rdb$config_value from mon$attachments a left join rdb$config g on g.rdb$config_name = 'MaxStatementCacheSize' where a.mon$attachment_id = current_connection")
for r in cur:
conn_protocol = r[0]
db_sttm_cache_size = int(r[1])
assert conn_protocol is None, "Test must use LOCAL protocol."
assert db_sttm_cache_size > 0, "Parameter 'MaxStatementCacheSize' (per-database) must be greater than zero for this test."
#---------------------------------------------
CURSOR_NAME = 'k1'
SELECT_STTM = 'select /* ps-1*/ id, f01 from test where id > 0 for update'
UPDATE_STTM = f'update /* ps-2 */ test set id = -id where current of {CURSOR_NAME} returning id'
update_tpb = tpb( access_mode = TraAccessMode.WRITE,
isolation = Isolation.READ_COMMITTED_RECORD_VERSION,
lock_timeout = 1)
with connect(db_cfg_name, user = act.db.user, password = act.db.password) as con:
tx2 = con.transaction_manager(update_tpb)
tx2.begin()
with con.cursor() as cur1, tx2.cursor() as cur2, con.cursor() as cur3:
ps1, rs1, ps2, rs2, ps3, rs3 = None, None, None, None, None, None
try:
ps1 = cur1.prepare(SELECT_STTM) # 1. [ticket, DS] Prepare statement 1 "select ... for update"
ps1._istmt.set_cursor_name(CURSOR_NAME) # 2. [ticket, DS] Set cursor name for statement 1 // ~hack.
# DO NOT use it because subsequent update statement will get 'deadlock / update conflict' and not able to start:
#rs1 = cur1.execute(ps1)
#cur1.set_cursor_name(CURSOR_NAME)
# DS example: "// Prepare positioned update statement"
ps2 = cur2.prepare(UPDATE_STTM) # 3. [ticket, DS] Prepare statement 2 "update ... where current of <cursor name from step 2>"
# DS .cpp: // fetch records from cursor and print them
rs1 = cur1.execute(ps1)
rs1.fetchall()
# DS .cpp: // IStatement* stmt2 = att->prepare(&status, tra, 0, "select * from pos where a > 1 for update",
ps3 = cur3.prepare(SELECT_STTM) # 4. [ticket, DS] Prepare statement 3 similar to statement 1
rs1.close() # 5. [ticket, DS] Release statement 1 // see hvlad recipe, 26.10.2024
ps1.free()
# DS .cpp: updStmt->free(&status);
ps2.free() # 6. [ticket, DS] Release statement 2 // see hvlad recipe, 26.10.2024
# DS .cpp: stmt = stmt2
ps3._istmt.set_cursor_name(CURSOR_NAME) # 7. [ticket, DS] Set cursor name to statement 3 as in step 2
ps2 = cur2.prepare(UPDATE_STTM) # 8. [ticket, DS] Prepare statement 2 again (it will be got from cache keeping reference to statement 1)
rs3 = cur3.execute(ps3)
rs3.fetchone() # 9. [ticket, DS] Run statement 3 and fetch one record
# At step 10 you can get "Invalid handle" error or a crash if you swap steps 5 and 6.
rs2 = cur2.execute(ps2) # 10. [ticket, DS] Execute statement 2
data2 = rs2.fetchone()
print('Changed ID:', data2[0])
# print(f'{rs2.rowcount=}')
except DatabaseError as e:
print(e.__str__())
print('gds codes:')
for i in e.gds_codes:
print(i)
finally:
if rs1:
rs1.close()
if ps1:
ps1.free()
if rs2:
rs2.close()
if ps2:
ps2.free()
if rs3:
rs3.close()
if ps3:
ps3.free()
#---------------------------------------------
act.expected_stdout = 'Changed ID: -1'
act.stdout = capsys.readouterr().out
assert act.clean_stdout == act.clean_expected_stdout
# Example in .cpp (provided by Dimitry Sibiryakov):
###################################################
#
# #include <memory>
# #include "ifaceExamples.h"
# static IMaster* master = fb_get_master_interface();
#
# int main()
# {
# int rc = 0;
#
# // status vector and main dispatcher
# ThrowStatusWrapper status(master->getStatus());
# IProvider* prov = master->getDispatcher();
# IUtil* utl = master->getUtilInterface();
#
# // declare pointers to required interfaces
# IAttachment* att = NULL;
# ITransaction* tra = NULL;
# IStatement* stmt = NULL;
# IMessageMetadata* meta = NULL;
# IMetadataBuilder* builder = NULL;
# IXpbBuilder* tpb = NULL;
#
# // Interface provides access to data returned by SELECT statement
# IResultSet* curs = NULL;
#
# try
# {
# // IXpbBuilder is used to access various parameters blocks used in API
# IXpbBuilder* dpb = NULL;
#
# // create DPB - use non-default page size 4Kb
# dpb = utl->getXpbBuilder(&status, IXpbBuilder::DPB, NULL, 0);
# dpb->insertString(&status, isc_dpb_user_name, "sysdba");
# dpb->insertString(&status, isc_dpb_password, "masterkey");
#
# // create empty database
# att = prov->attachDatabase(&status, "ctest", dpb->getBufferLength(&status),
# dpb->getBuffer(&status));
#
# dpb->dispose();
#
# printf("database attached.\n");
#
# att->execute(&status, nullptr, 0, "set debug option dsql_keep_blr = true", SAMPLES_DIALECT, nullptr, nullptr, nullptr, nullptr);
# // start read only transaction
# tpb = utl->getXpbBuilder(&status, IXpbBuilder::TPB, NULL, 0);
# tpb->insertTag(&status, isc_tpb_read_committed);
# tpb->insertTag(&status, isc_tpb_no_rec_version);
# tpb->insertTag(&status, isc_tpb_wait);
# tra = att->startTransaction(&status, tpb->getBufferLength(&status), tpb->getBuffer(&status));
#
# // prepare statement
# stmt = att->prepare(&status, tra, 0, "select * from pos where a > 1 for update",
# SAMPLES_DIALECT, IStatement::PREPARE_PREFETCH_METADATA);
#
# // get list of columns
# meta = stmt->getOutputMetadata(&status);
# unsigned cols = meta->getCount(&status);
# unsigned messageLength = meta->getMessageLength(&status);
#
# std::unique_ptr<char[]> buffer(new char[messageLength]);
#
# stmt->setCursorName(&status, "abc");
#
# // open cursor
# printf("Opening cursor...\n");
# curs = stmt->openCursor(&status, tra, NULL, NULL, meta, 0);
#
# // Prepare positioned update statement
# printf("Preparing update statement...\n");
# IStatement* updStmt = att->prepare(&status, tra, 0, "update pos set b=b+1 where current of abc",
# SAMPLES_DIALECT, 0);
#
# const unsigned char items[] = {isc_info_sql_exec_path_blr_text, isc_info_sql_explain_plan};
# unsigned char infoBuffer[32000];
# updStmt->getInfo(&status, sizeof items, items, sizeof infoBuffer, infoBuffer);
#
# IXpbBuilder* pb = utl->getXpbBuilder(&status, IXpbBuilder::INFO_RESPONSE, infoBuffer, sizeof infoBuffer);
# for (pb->rewind(&status); !pb->isEof(&status); pb->moveNext(&status))
# {
# switch (pb->getTag(&status))
# {
# case isc_info_sql_exec_path_blr_text:
# printf("BLR:\n%s\n", pb->getString(&status));
# break;
# case isc_info_sql_explain_plan:
# printf("Plan:\n%s\n", pb->getString(&status));
# break;
# case isc_info_truncated:
# printf(" truncated\n");
# // fall down...
# case isc_info_end:
# break;
# default:
# printf("Unexpected item %d\n", pb->getTag(&status));
# }
# }
# pb->dispose();
#
# // fetch records from cursor and print them
# for (int line = 0; curs->fetchNext(&status, buffer.get()) == IStatus::RESULT_OK; ++line)
# {
# printf("Fetched record %d\n", line);
# updStmt->execute(&status, tra, nullptr, nullptr, nullptr, nullptr);
# printf("Update executed\n");
# }
#
# IStatement* stmt2 = att->prepare(&status, tra, 0, "select * from pos where a > 1 for update",
# SAMPLES_DIALECT, IStatement::PREPARE_PREFETCH_METADATA);
#
# // close interfaces
# curs->close(&status);
# curs = NULL;
#
# stmt->free(&status);
# stmt = NULL;
#
# updStmt->free(&status);
#
# stmt = stmt2;
# stmt->setCursorName(&status, "abc");
#
# // open cursor
# printf("Opening cursor2...\n");
# curs = stmt->openCursor(&status, tra, NULL, NULL, meta, 0);
#
# // Prepare positioned update statement
# printf("Preparing update statement again...\n");
# updStmt = att->prepare(&status, tra, 0, "update pos set b=b+1 where current of abc",
# SAMPLES_DIALECT, 0);
#
# // fetch records from cursor and print them
# for (int line = 0; curs->fetchNext(&status, buffer.get()) == IStatus::RESULT_OK; ++line)
# {
# printf("Fetched record %d\n", line);
# updStmt->execute(&status, tra, nullptr, nullptr, nullptr, nullptr);
# printf("Update executed\n");
# }
#
# curs->close(&status);
# curs = NULL;
#
# stmt->free(&status);
# stmt = NULL;
#
# updStmt->free(&status);
#
# meta->release();
# meta = NULL;
#
# tra->commit(&status);
# tra = NULL;
#
# att->detach(&status);
# att = NULL;
# }
# catch (const FbException& error)
# {
# // handle error
# rc = 1;
#
# char buf[256];
# master->getUtilInterface()->formatStatus(buf, sizeof(buf), error.getStatus());
# fprintf(stderr, "%s\n", buf);
# }
#
# // release interfaces after error caught
# if (meta)
# meta->release();
# if (builder)
# builder->release();
# if (curs)
# curs->release();
# if (stmt)
# stmt->release();
# if (tra)
# tra->release();
# if (att)
# att->release();
# if (tpb)
# tpb->dispose();
#
# prov->release();
# status.dispose();
#
# return rc;
# }
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