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[WIP] gh-81040: use sqlite3_stmt_readonly() to detect DML statements #24492

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[WIP] gh-81040: use sqlite3_stmt_readonly() to detect DML statements #24492

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11e9829
Use sqlite3_stmt_readonly API to determine is statement is DML.
coleifer May 9, 2019
29a7e20
Skip dml detection + sql comment for old sqlite.
coleifer May 9, 2019
f20d41b
Add news item.
coleifer May 9, 2019
868b97a
Address review comments, additional regression test.
coleifer May 9, 2019
a13fb71
Fix rest markup
berkerpeksag May 9, 2019
6e1cf06
cosmetic fixes
berkerpeksag May 9, 2019
013e43b
Ensure all non-DML statements that write are covered.
coleifer May 9, 2019
6e6f2a0
Move DML detection tests into transactions test module.
coleifer May 10, 2019
09cac6c
Fix version-check for sqlite3_stmt_readonly availability.
coleifer May 11, 2019
d1efa55
Sync with GH-24106
Feb 9, 2021
3645ccc
Merge branch 'main' into bpo-36859
Jun 5, 2021
dce7ada
PEP 7
Jun 5, 2021
7c01d5a
Merge branch 'main' into bpo-36859
Jun 8, 2021
6eb6ec9
Improve namespace
Jun 8, 2021
1bdefdd
Merge branch 'main' into bpo-36859
Jun 15, 2021
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cosmetic fixes
  • Loading branch information
@berkerpeksag
berkerpeksag authored and Erlend E. Aasland committed Mar 2, 2021
commit 6e1cf0669400420c3b7db393e3534e689b4654c1
42 changes: 23 additions & 19 deletions Lib/sqlite3/test/regression.py
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Original file line number Diff line number Diff line change
Expand Up @@ -416,61 +416,65 @@ class DMLStatementDetectionTestCase(unittest.TestCase):
Test behavior of sqlite3_stmt_readonly() in determining if a statement is
DML or not.
"""
@unittest.skipIf(sqlite.sqlite_version_info < (3, 8, 3),
'needs sqlite 3.8.3 or newer')
@unittest.skipIf(sqlite.sqlite_version_info < (3, 8, 3), 'needs sqlite 3.8.3 or newer')
def test_dml_detection_cte(self):
conn = sqlite.connect(':memory:')
conn.execute('create table kv ("key" text, "val" integer)')
conn.execute('CREATE TABLE kv ("key" TEXT, "val" INTEGER)')
self.assertFalse(conn.in_transaction)
conn.execute('insert into kv (key, val) values (?, ?), (?, ?)',
conn.execute('INSERT INTO kv (key, val) VALUES (?, ?), (?, ?)',
('k1', 1, 'k2', 2))
self.assertTrue(conn.in_transaction)

conn.commit()
self.assertFalse(conn.in_transaction)

rc = conn.execute('update kv set val=val + ?', (10,))
rc = conn.execute('UPDATE kv SET val=val + ?', (10,))
self.assertEqual(rc.rowcount, 2)
self.assertTrue(conn.in_transaction)
conn.commit()
self.assertFalse(conn.in_transaction)

rc = conn.execute('with c(k, v) as (select key, val + ? from kv) '
'update kv set val=(select v from c where k=kv.key)',
(100,))
rc = conn.execute(
'WITH c(k, v) AS (SELECT key, val + ? FROM kv) '
'UPDATE kv SET val=(SELECT v FROM c WHERE k=kv.key)',
(100,)
)
self.assertEqual(rc.rowcount, 2)
self.assertTrue(conn.in_transaction)

curs = conn.execute('select key, val from kv order by key')
curs = conn.execute('SELECT key, val FROM kv ORDER BY key')
self.assertEqual(curs.fetchall(), [('k1', 111), ('k2', 112)])

@unittest.skipIf(sqlite.sqlite_version_info < (3, 7, 11),
'needs sqlite 3.7.11 or newer')
@unittest.skipIf(sqlite.sqlite_version_info < (3, 7, 11), 'needs sqlite 3.7.11 or newer')
def test_dml_detection_sql_comment(self):
conn = sqlite.connect(':memory:')
conn.execute('create table kv ("key" text, "val" integer)')
conn.execute('insert into kv (key, val) values (?, ?), (?, ?)',
conn.execute('CREATE TABLE kv ("key" TEXT, "val" INTEGER)')
self.assertFalse(conn.in_transaction)
conn.execute('INSERT INTO kv (key, val) VALUES (?, ?), (?, ?)',
('k1', 1, 'k2', 2))
conn.commit()

self.assertFalse(conn.in_transaction)
rc = conn.execute('-- a comment\nupdate kv set val=val + ?', (10,))

rc = conn.execute('-- a comment\nUPDATE kv SET val=val + ?', (10,))
self.assertEqual(rc.rowcount, 2)
self.assertTrue(conn.in_transaction)

curs = conn.execute('select key, val from kv order by key')
curs = conn.execute('SELECT key, val FROM kv ORDER BY key')
self.assertEqual(curs.fetchall(), [('k1', 11), ('k2', 12)])
conn.rollback()
self.assertFalse(conn.in_transaction)
# Fetch again after rollback.
curs = conn.execute('SELECT key, val FROM kv ORDER BY key')
self.assertEqual(curs.fetchall(), [('k1', 1), ('k2', 2)])

def test_dml_detection_begin_exclusive(self):
# sqlite3_stmt_readonly() reports BEGIN EXCLUSIVE as being a
# non-read-only statement. To retain compatibility with the
# transactional behavior, we add a special exclusion for these
# statements.
conn = sqlite.connect(':memory:')
conn.execute('begin exclusive')
conn.execute('BEGIN EXCLUSIVE')
self.assertTrue(conn.in_transaction)
conn.execute('rollback')
conn.execute('ROLLBACK')
self.assertFalse(conn.in_transaction)


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10 changes: 4 additions & 6 deletions Modules/_sqlite/statement.c
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Expand Up @@ -52,17 +52,16 @@ typedef enum {
TYPE_UNKNOWN
} parameter_type;

int pysqlite_statement_is_dml(sqlite3_stmt *st, const char *sql)
static int pysqlite_statement_is_dml(sqlite3_stmt *statement, const char *sql)
{
const char* p;
int is_dml = 0;

#ifdef HAVE_SQLITE3_STMT_READONLY
is_dml = !sqlite3_stmt_readonly(st);
is_dml = !sqlite3_stmt_readonly(statement);
if (is_dml) {
/* Retain backwards-compatibility, as sqlite3_stmt_readonly will return
* false for BEGIN [IMMEDIATE|EXCLUSIVE] or DDL statements.
*/
* false for BEGIN [IMMEDIATE|EXCLUSIVE] or DDL statements. */
for (p = sql; *p != 0; p++) {
switch (*p) {
case ' ':
Expand All @@ -81,8 +80,7 @@ int pysqlite_statement_is_dml(sqlite3_stmt *st, const char *sql)
#else
/* Determine if the statement is a DML statement. SELECT is the only
* exception. This is a fallback for older versions of SQLite which do not
* support the sqlite3_stmt_readonly() API.
*/
* support the sqlite3_stmt_readonly() API. */
for (p = sql; *p != 0; p++) {
switch (*p) {
case ' ':
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