On 06/07/12 10:14, Jan Urbański wrote:
On 06/07/12 10:05, Heikki Linnakangas wrote:
In the backend elog routines, there is a global variable
'recursion_depth', which is incremented when an error-handling routine
is entered, and decremented afterwards. Can we use a similar mechinism
in PLy_elog() to detect and stop recursion?
I guess we can, I'll try to do some tests in order to see if there's an
easy user-triggereable way of causing PLy_elog to recurse and if not
then a guard like this should be enough as a safety measure against as
yet unknown conditions (as opposed to something we expect to happen
regularly).
Attached is a patch that stores the recursion level of PLy_traceback and
prevents it from running if it's too deep (PLy_traceback is the one
doing heavy lifting, that's why I chose to put the logic to skip running
there).
I tried a few things and was not able to easily invoke the infinite
recursion condition, but I did notice that there are two more encodings
that have different names in Postgres and in Python (KOI8-R and KOI8-U)
and added them to the switch.
There's still trouble with EUC_TW and MULE_INTERNAL which don't have
Python equivalents. EUC-TW has been discussed in
http://bugs.python.org/issue2066 and rejected (see
http://bugs.python.org/issue2066#msg113731).
If you use any of these encodings, you *will* get into the recursion
trouble described eariler, just as before the path you'd get into it
with CP1252 as your encoding.
What shall we do about those? Ignore them? Document that if you're sing
one of these encodings then PL/Python with Python 2 will be crippled and
with Python 3 just won't work?
Cheers,
Jan
diff --git a/src/pl/plpython/plpy_elog.c b/src/pl/plpython/plpy_elog.c
new file mode 100644
index c375ac0..c2b3cb8
*** a/src/pl/plpython/plpy_elog.c
--- b/src/pl/plpython/plpy_elog.c
*************** static char *get_source_line(const char
*** 28,33 ****
--- 28,41 ----
/*
+ * Guard agains re-entrant calls to PLy_traceback, which can happen if
+ * traceback formatting functions raise Python errors.
+ */
+ #define TRACEBACK_RECURSION_LIMIT 2
+ static int recursion_depth = 0;
+
+
+ /*
* Emit a PG error or notice, together with any available info about
* the current Python error, previously set by PLy_exception_set().
* This should be used to propagate Python errors into PG. If fmt is
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 147,166 ****
StringInfoData xstr;
StringInfoData tbstr;
/*
* get the current exception
*/
PyErr_Fetch(&e, &v, &tb);
/*
! * oops, no exception, return
*/
! if (e == NULL)
{
*xmsg = NULL;
*tbmsg = NULL;
*tb_depth = 0;
return;
}
--- 155,177 ----
StringInfoData xstr;
StringInfoData tbstr;
+ recursion_depth++;
+
/*
* get the current exception
*/
PyErr_Fetch(&e, &v, &tb);
/*
! * oops, no exception or recursion depth exceeded, return
*/
! if (e == NULL || recursion_depth > TRACEBACK_RECURSION_LIMIT)
{
*xmsg = NULL;
*tbmsg = NULL;
*tb_depth = 0;
+ recursion_depth--;
return;
}
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 326,331 ****
--- 337,344 ----
(*tb_depth)++;
}
+ recursion_depth--;
+
/* Return the traceback. */
*tbmsg = tbstr.data;
diff --git a/src/pl/plpython/plpy_util.c b/src/pl/plpython/plpy_util.c
new file mode 100644
index bf29532..ea4ecdf
*** a/src/pl/plpython/plpy_util.c
--- b/src/pl/plpython/plpy_util.c
*************** PLyUnicode_Bytes(PyObject *unicode)
*** 112,117 ****
--- 112,123 ----
case PG_WIN874:
serverenc = "cp874";
break;
+ case PG_KOI8R:
+ serverenc = "koi8-r";
+ break;
+ case PG_KOI8U:
+ serverenc = "koi8-u";
+ break;
default:
/* Other encodings have the same name in Python. */
serverenc = GetDatabaseEncodingName();
*************** PLyUnicode_Bytes(PyObject *unicode)
*** 120,135 ****
rv = PyUnicode_AsEncodedString(unicode, serverenc, "strict");
if (rv == NULL)
! {
! /*
! * Use a plain ereport instead of PLy_elog to avoid recursion, if
! * the traceback formatting functions try to do unicode to bytes
! * conversion again.
! */
! ereport(ERROR,
! (errcode(ERRCODE_INTERNAL_ERROR),
! errmsg("could not convert Python Unicode object to PostgreSQL server encoding")));
! }
return rv;
}
--- 126,132 ----
rv = PyUnicode_AsEncodedString(unicode, serverenc, "strict");
if (rv == NULL)
! PLy_elog(ERROR, "could not convert Python Unicode object to PostgreSQL server encoding");
return rv;
}
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
