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bpo-44329: Refactor sqlite3 statement creation (GH-26566) 

Call SQLite API's first, and return early in case of error. At the end,
allocate the object and initialise members. We now avoid unneeded
alloc/dealloc's in case the statement creation fails.
This commit is contained in:
Erlend Egeberg Aasland 2021-06-08 17:00:56 +02:00 committed by GitHub
parent 3fe921cd49
commit 1c02655fb0
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 37 additions and 45 deletions
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82
Modules/_sqlite/statement.c
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@ -51,15 +51,9 @@ typedef enum {
pysqlite_Statement *
pysqlite_statement_create(pysqlite_Connection *connection, PyObject *sql)
{
const char* tail;
int rc;
const char* sql_cstr;
Py_ssize_t sql_cstr_len;
const char* p;
assert(PyUnicode_Check(sql));
sql_cstr = PyUnicode_AsUTF8AndSize(sql, &sql_cstr_len);
Py_ssize_t size;
const char *sql_cstr = PyUnicode_AsUTF8AndSize(sql, &size);
if (sql_cstr == NULL) {
PyErr_Format(pysqlite_Warning,
"SQL is of wrong type ('%s'). Must be string.",
@ -67,31 +61,40 @@ pysqlite_statement_create(pysqlite_Connection *connection, PyObject *sql)
return NULL;
}
int max_length = sqlite3_limit(connection->db, SQLITE_LIMIT_LENGTH, -1);
if (sql_cstr_len >= max_length) {
sqlite3 *db = connection->db;
int max_length = sqlite3_limit(db, SQLITE_LIMIT_LENGTH, -1);
if (size >= max_length) {
PyErr_SetString(pysqlite_DataError, "query string is too large");
return NULL;
}
if (strlen(sql_cstr) != (size_t)sql_cstr_len) {
if (strlen(sql_cstr) != (size_t)size) {
PyErr_SetString(PyExc_ValueError,
"the query contains a null character");
return NULL;
}
pysqlite_Statement *self = PyObject_GC_New(pysqlite_Statement,
pysqlite_StatementType);
if (self == NULL) {
sqlite3_stmt *stmt;
const char *tail;
int rc;
Py_BEGIN_ALLOW_THREADS
rc = sqlite3_prepare_v2(db, sql_cstr, (int)size + 1, &stmt, &tail);
Py_END_ALLOW_THREADS
if (rc != SQLITE_OK) {
_pysqlite_seterror(db);
return NULL;
}
self->st = NULL;
self->in_use = 0;
self->is_dml = 0;
self->in_weakreflist = NULL;
if (pysqlite_check_remaining_sql(tail)) {
PyErr_SetString(pysqlite_Warning,
"You can only execute one statement at a time.");
goto error;
}
/* Determine if the statement is a DML statement.
SELECT is the only exception. See #9924. */
for (p = sql_cstr; *p != 0; p++) {
int is_dml = 0;
for (const char *p = sql_cstr; *p != 0; p++) {
switch (*p) {
case ' ':
case '\r':
@ -100,40 +103,29 @@ pysqlite_statement_create(pysqlite_Connection *connection, PyObject *sql)
continue;
}
self->is_dml = (PyOS_strnicmp(p, "insert", 6) == 0)
|| (PyOS_strnicmp(p, "update", 6) == 0)
|| (PyOS_strnicmp(p, "delete", 6) == 0)
|| (PyOS_strnicmp(p, "replace", 7) == 0);
is_dml = (PyOS_strnicmp(p, "insert", 6) == 0)
|| (PyOS_strnicmp(p, "update", 6) == 0)
|| (PyOS_strnicmp(p, "delete", 6) == 0)
|| (PyOS_strnicmp(p, "replace", 7) == 0);
break;
}
Py_BEGIN_ALLOW_THREADS
rc = sqlite3_prepare_v2(connection->db,
sql_cstr,
(int)sql_cstr_len + 1,
&self->st,
&tail);
Py_END_ALLOW_THREADS
pysqlite_Statement *self = PyObject_GC_New(pysqlite_Statement,
pysqlite_StatementType);
if (self == NULL) {
goto error;
}
self->st = stmt;
self->in_use = 0;
self->is_dml = is_dml;
self->in_weakreflist = NULL;
PyObject_GC_Track(self);
if (rc != SQLITE_OK) {
_pysqlite_seterror(connection->db);
goto error;
}
if (rc == SQLITE_OK && pysqlite_check_remaining_sql(tail)) {
(void)sqlite3_finalize(self->st);
self->st = NULL;
PyErr_SetString(pysqlite_Warning,
"You can only execute one statement at a time.");
goto error;
}
return self;
error:
Py_DECREF(self);
(void)sqlite3_finalize(stmt);
return NULL;
}