unix-ffi/sqlite3: Fix bytes to accommodate for different pointer sizes.

Currently, the bytes object used to store the sqlite3 database pointer is always 4 bytes, which causes segfaults on 64 bit platforms with 8 byte pointers. To address this, the size is now dynamically determined using the uctypes modules pointer size. Signed-off-by: Robert Klink <rhermanklink@ripe.net>

Author: rhermanklink

unix-ffi/sqlite3/sqlite3.py

@@ -1,5 +1,6 @@
 import sys
 import ffilib
+import uctypes
 
 
 sq3 = ffilib.open("libsqlite3")
@@ -61,6 +62,10 @@ def check_error(db, s):
  raise Error(s, sqlite3_errmsg(db))
 
 
+def get_ptr_size():
+ return uctypes.sizeof({"ptr": (0 | uctypes.PTR, uctypes.PTR)})
+
+
 class Connections:
  def __init__(self, h):
  self.h = h
@@ -83,13 +88,13 @@ def execute(self, sql, params=None):
  params = [quote(v) for v in params]
  sql = sql % tuple(params)
  print(sql)
- b = bytearray(4)
- s = sqlite3_prepare(self.h, sql, -1, b, None)
- check_error(self.h, s)
- self.stmnt = int.from_bytes(b, sys.byteorder)
- # print("stmnt", self.stmnt)
+
+ stmnt_ptr = bytes(get_ptr_size())
+ res = sqlite3_prepare(self.h, sql, -1, stmnt_ptr, None)
+ check_error(self.h, res)
+ self.stmnt = int.from_bytes(stmnt_ptr, sys.byteorder)
  self.num_cols = sqlite3_column_count(self.stmnt)
- # print("num_cols", self.num_cols)
+
  # If it's not select, actually execute it here
  # num_cols == 0 for statements which don't return data (=> modify it)
  if not self.num_cols:
@@ -127,10 +132,9 @@ def fetchone(self):
 
 
 def connect(fname):
- b = bytearray(4)
- sqlite3_open(fname, b)
- h = int.from_bytes(b, sys.byteorder)
- return Connections(h)
+ sqlite_ptr = bytes(get_ptr_size())
+ sqlite3_open(fname, sqlite_ptr)
+ return Connections(int.from_bytes(sqlite_ptr, sys.byteorder))
 
 
 def quote(val):