Hello !
I did something similar to your sugestion (sqlite3_next_stmt(db, NULL))? and
it still segfaults.
What you mention about fts3/4 having prepared statemtns that and somehow I'm
doing a double free a good point.
And will be sad to not be able to use sqlite3_next_stmt(db, NULL) to finalize
any open preapred statemnt, because it's very handy when using "exceptions"
and having a single point to do the cleanup.
Can somehow sqlite3_prepare somehow have any extra parameter to indicated
that we are using it from an extension and somehow sqlite3_next_stmt detect
it and skip it ?
Or any way to safely have a central point to do a cleanup ?
Cheers !
> Fri Sep 04 2015 4:44:02 pm CEST CEST from "Dan Kennedy"
><danielk1977 at gmail.com> Subject: Re: [sqlite] SQLite3 trunk error with old
>database with fts3/4
>
> On 09/04/2015 09:29 PM, Domingo Alvarez Duarte wrote:
>
>>Hello again !
>>
>> On mac os x some time ago I was getting segfaults here and tought that it
>>was
>> caused by the way os x manage memory but it doesn't seem correct.
>>
>> The error happens on this code that is called before call sqlite3_close:
>>
>> sqlite3 *db = sdb->db;
>> sqlite3_stmt* statement = NULL;
>> int count = 0;
>> while ((statement = sqlite3_next_stmt(db, statement)))
>> {
>> //do no close statements because garbage collector will
>> do it
>> //on MacOSX we get segfaults finalizing statements here
>> printf("sq_sqlite3_close_release:stmt:%s\n",
>> sqlite3_sql(statement));
>> sqlite3_finalize(statement);
>> count++;
>> }
>> if (count) return sq_throwerror(v, _SC("closing database with
>> %d statements not closed."), count);
>>
> Hi,
>
> Two problems:
>
> After you have finalized a statement handle, it may not be passed to
> sqlite3_next_stmt(). Change the while() line to:
>
> while( (statement = sqlite3_next_stmt(db, NULL)) ){ ...
>
> Another reason not to do this before calling sqlite3_close() is that the
> FTS module may be managing some of these statement handles. So if you
> finalize() them before sqlite3_close() is called, then when the FTS
> module is shut down as part of the eventual sqlite3_close() call, it may
> pass the same statement handle pointers to sqlite3_finalize() - similar
> to a double-free of any other object or memory allocation. SQLite
> includes checks to try to return SQLITE_MISUSE instead of crashing when
> this happens, but they only work some of the time - this scenario can
> still cause crashes or heap corruption.
>
> A workaround is to call sqlite3_close() on the db, then do the above
> only if it returns SQLITE_BUSY. This works because, even though it
> fails, the first sqlite3_close() shuts down the FTS module -
> guaranteeing that it is no longer holding pointers to statement handles.
>
> Even better is not to leak statement handle pointers. The
> sqlite3_next_stmt() API should really only be used to help track down
> leaks, not to do cleanup.
>
> Dan.
>
>
>
>
>
>
>
>
>
>
>>
>>>Fri Sep 04 2015 4:18:01 pm CEST CEST from "Domingo Alvarez Duarte"
>>> <sqlite-mail at dev.dadbiz.es> Subject: Re: [sqlite] SQLite3 trunk error
>>>with
>>> old database with fts3/4
>>>
>>> Hello !
>>>
>>> I'm not sure where the problem is but this code worked without any
>>>problem
>>> with previous sqlite3.
>>>
>>> Here is a backtrace of a segfault using gdb (the line numbers will not
>>> match
>>> standard sqlite3.c because I have some custom extensions):
>>>
>>> enter mutex 0x7fffe405f570 (1213663847) with nRef=1919906927
>>>
>>> Program received signal SIGSEGV, Segmentation fault.
>>> [Switching to Thread 0x7ffff3c70700 (LWP 22336)]
>>> 0x0000000000479d85 in freeEphemeralFunction (db=0x7fffe4000078,
>>> pDef=0xaaaaaaaaaaaaaaaa)
>>> at sqlite3.c:66869
>>> 66869 if( ALWAYS(pDef) && (pDef->funcFlags & SQLITE_FUNC_EPHEM)!=0
>>> ){
>>> (gdb) bt
>>> #0 0x0000000000479d85 in freeEphemeralFunction (db=0x7fffe4000078,
>>> pDef=0xaaaaaaaaaaaaaaaa)
>>> at sqlite3.c:66869
>>> #1 0x0000000000479e39 in freeP4 (db=db at entry=0x7fffe4000078,
>>> p4type=-1431655766, p4=0x7fffe4181588)
>>> at sqlite3.c:66884
>>> #2 0x0000000000479f14 in vdbeFreeOpArray (db=0x7fffe4000078,
>>> aOp=0x7fffe40df508, nOp=<optimised out>)
>>> at sqlite3.c:66933
>>> #3 0x000000000047a01c in sqlite3VdbeClearObject (db=0x7fffe4000078,
>>> p=0x7fffe408ac88) at sqlite3.c:68920
>>> #4 0x000000000047a0c3 in sqlite3VdbeDelete (p=0x7fffe408ac88)
>>> at sqlite3.c:68941
>>> #5 0x00000000004e6044 in sqlite3VdbeFinalize (p=0x7fffe408ac88)
>>> at sqlite3.c:68861
>>> #6 0x00000000004e60cd in sqlite3_finalize (pStmt=0x7fffe408ac88)
>>> at sqlite3.c:70500
>>>
>>>
>>>
>>>
>>>>Fri Sep 04 2015 4:05:12 pm CEST CEST from "Dan Kennedy"
>>>> <danielk1977 at gmail.com> Subject: Re: [sqlite] SQLite3 trunk error with
>>>>old
>>>> database with fts3/4
>>>>
>>>> On 09/04/2015 07:35 PM, Domingo Alvarez Duarte wrote:
>>>>
>>>>
>>>>
>>>>>Hello !
>>>>>
>>>>> After fix the index issues using an old sqlite3 executable (the trunk
>>>>> refuse
>>>>> to work on indexes created with single quotes on field names) I'm
>>>>>getting
>>>>> ocasionaly memory errors when using fts3/4 searches, see error below:
>>>>>
>>>>> free(): corrupted unsorted chunks: 0x00007fa3a01073a0
>>>>>
>>>>>
>>>> Is this error on the trunk or with the old version?
>>>>
>>>> If it's on the trunk, is the error reproducible using the sqlite3 shell
>>>> tool?
>>>>
>>>> If not, what does valgrind have to say about the app?
>>>>
>>>> Thanks,
>>>> Dan.
>>>>
>>>> _______________________________________________
>>>> sqlite-users mailing list
>>>> sqlite-users at mailinglists.sqlite.org
>>>> http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>>
>>>
>>>
>>>
>>>
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