Re: Libpq free bug? (Was: [ODBC] IIS Postgres ASP ADO - Problem)

Personally I cancelled this bug report:
The code contains a number of malloc() avoidance hacks for speedup, but
it seems to
be correct:

The speed optimizations confused me.

It seems, that only free(options[i].var) will be freed, if "var" is not
NULL.
Also free(options) will be freed. So this seems to work, because
PQconninfoOptions[i].val is NULL for every valid i.

Memory allocation debugger does not find any bugs here.
I was able to test that with my test.cpp.

Even though I could not find a bug in the case that Dave forwarded,
there is still a CONNECT problem that I can reproduce.

My CONNECT problem seems to be related with isql and self compiled
libdmalloc.so
enabled libpq and psqlodbc.so. It seems, that malloc() and free()
operations are correct,
but the libdmalloc internal memory structures are incorrect with isql.

I don't know the reason, but that seems to be the problem, that I have
found.

isql crashes under conninfo_parse() on line "free(buf)".
buf = malloc() and free(buf) seem to match each other (checked with gdb).
So it seems, that the problem relates with internal libdmalloc
implementation.

I had to modify libpq by inserting a header file into every C file and I
modified
Makefile to link libpq with libdmallocth.so. Even though libdmalloc crashes
often (at least dlclose() incompatibility), it seems to be a good tool
for searching memory
leaks even inside an ODBC driver: it tells the C file and the line of
the code, where the
memory leak happened.

Marko Ristola

Dave Page wrote:

>Forwarded to -bugs in case it gets missed.
>
>This looks like it might be an issue to me, though I may well have
>overlooked something in my brief look at the code.
>
>Regards, Dave
>
>
>
>>-----Original Message-----
>>From: pgsql-odbc-owner(at)postgresql(dot)org
>>[mailto:pgsql-odbc-owner(at)postgresql(dot)org] On Behalf Of Marko Ristola
>>Sent: 01 August 2005 18:15
>>To: Joel Fradkin
>>Cc: 'James Dornan'; pgsql-odbc(at)postgresql(dot)org
>>Subject: Re: [ODBC] IIS Postgres ASP ADO - Problem
>>
>>
>>I found a crashing problem during CONNECT into a database.
>>
>>Here is the problem description:
>>
>>Used Environment:
>>libpq-API under PostgreSQL 8.0.3
>>CVS HEAD of psqlodbc
>>
>>libpq does have a problem with freeing memory, that has not
>>been alloced
>>with malloc()!
>>
>>Here is the problem (I don't know, wether the PostgreSQL CVS
>>HEAD has a
>>fix for this):
>>
>>postgresql-8.0.3/src/interfaces/libpq/fe-connect.c, function
>>conninfo_parse():
>>
>> /* Make a working copy of PQconninfoOptions */
>> options = malloc(sizeof(PQconninfoOptions));
>>...
>> memcpy(options, PQconninfoOptions,
>>sizeof(PQconninfoOptions));
>>
>>Unfortunately PQconninfoOptions[] contains only char*val
>>style pointers
>>instead of
>>char val[32] type character containers.
>>Because of this, the assumption, that memcpy() is enough to copy the
>>structure, is not
>>true anymore. You should NOT copy a static structure this way!
>>
>>Working code would be something like this:
>>
>>options = malloc(sizeof(PQconninfoOptions));
>>memcpy(options, PQconninfoOptions, sizeof(PQconninfoOptions));
>>for (i=0; PQconninfoOptions[i].val != NULL; i++) {
>> options[i].val = strdup(PQconninfoOptions[i].val);
>> ... same for all other values
>>}
>>NULL termination.
>>
>>
>>
>>Because of this, isql fails with me at the beginning, maybe because
>>dmalloc library, that I use for testing, discovered the problem.
>>
>>Marko Ristola
>>
>>
>>Joel Fradkin wrote:
>>
>>
>>
>>>James,
>>>
>>>The odbc is not working well for me (I can connect but get
>>>
>>>
>>intermittent
>>
>>
>>>issues of the IIS server locking up in regards to connectivity).
>>>My understanding is the snapshot version is the best odbc
>>>
>>>
>>out at this time.
>>
>>
>>>Also can you connect via pgadmin (IE have the hba and config
>>>
>>>
>>files set to
>>
>>
>>>allow external connections)?
>>>
>>>My conection is not using dsn, but I did get dsn to work in testing.
>>>My dsnless string is
>>>
>>>Session("StringConn") =
>>>"DRIVER={PostgreSQL};DATABASE=wazagua;SERVER=192.168.123.121;
>>>
>>>
>PORT=5432;UID=p
>
>
>>>ostgres;PWD=;ReadOnly=0;Protocol=6.4;FakeOidIndex=0;ShowOidCo
>>>
>>>
>lumn=0;RowVersi
>
>
>>>oning=0;ShowSystemTables=0;ConnSettings=;Fetch=100;Socket=409
>>>
>>>
>6;UnknownSizes=
>
>
>>>0;MaxVarcharSize=254;MaxLongVarcharSize=8190;Debug=0;CommLog=
>>>
>>>
>>0;Optimizer=1;K
>>
>>
>>>sqo=1;UseDeclareFetch=0;TextAsLongVarchar=1;UnknownsAsLongVar
>>>
>>>
>char=0;BoolsAsC
>
>
>>>har=1;Parse=0;CancelAsFreeStmt=0;ExtraSysTablePrefixes=dd_;LF
>>>
>>>
>Conversion=1;Up
>
>
>>>datableCursors=1;DisallowPremature=0;TrueIsMinus1=0;BI=0;Byte
>>>
>>>
>aAsLongVarBinar
>
>
>>>y=0;UseServerSidePrepare=0"
>>>
>>>My test using dsn used
>>>Session("StringConn") ="DSN=postgresql;" & _
>>> "UID=postgres;" & _
>>> "PWD=;" & _
>>> "Database=wazuni;"
>>>
>>>asp code to use connection is :
>>> dim Arec, Acmd, SQL ,AConn
>>> set Arec = server.CreateObject("ADODB.Recordset")
>>> Set AConn = Server.CreateObject("ADODB.CONNECTION")
>>> set Acmd = server.CreateObject("ADODB.Command")
>>> AConn.ConnectionTimeOut=30
>>> AConn.commandtimeout=30
>>> AConn.Open Session("StringConn")
>>>
>>>For .net I use the npgsql .net objects.
>>>
>>>Hope this helps you.
>>>
>>>Joel Fradkin
>>>
>>>
>>>
>>>
>>>-----Original Message-----
>>>From: James Dornan [mailto:james(at)catch22(dot)com]
>>>Sent: Sunday, July 31, 2005 4:44 PM
>>>To: jfradkin(at)wazagua(dot)com
>>>Subject: IIS Postgres ASP ADO - Problem
>>>
>>>
>>> I noticed more than a few post from you about trying to
>>>
>>>
>>get Postgres
>>
>>
>>>working with ODBC.
>>>I'm hoping that maybe you would share some of that information. I am
>>>running IIS under
>>>windos 2003 server, and the latest(8.0.3) Postgres server on
>>>
>>>
>>the same
>>
>>
>>>machine. I cannot
>>>connect no matter what I do. I have tried everything.
>>>
>>> The funny part is that I'm not new to ODBC, or windows.
>>>
>>>
>>I've worked
>>
>>
>>>with windows all
>>>the time, but just can't figure this one out. I've tried using a
>>>connection string, a DSN,
>>>reinstalling, IIS, Postgres, ODBC drivers, MDAC, Jet, and so
>>>
>>>
>>on. I still
>>
>>
>>>have the same problem.
>>>The odbc drive and it's dependant DDLs are in the path. The
>>>
>>>
>>permisions
>>
>>
>>>are wide open
>>>(for testing this specific problem).
>>>
>>> Is there any insight you could shed on the dark world of
>>>
>>>
>>windows and
>>
>>
>>>ODBC, where feed-
>>>back is rare.
>>>
>>> Thanks for any help you can provide.
>>>
>>>-- James
>>>
>>>
>>>---------------------------(end of
>>>
>>>
>>broadcast)---------------------------
>>
>>
>>>TIP 2: Don't 'kill -9' the postmaster
>>>
>>>
>>>
>>>
>>---------------------------(end of
>>broadcast)---------------------------
>>TIP 2: Don't 'kill -9' the postmaster
>>
>>
>>
>
>---------------------------(end of broadcast)---------------------------
>TIP 5: don't forget to increase your free space map settings
>
>