OCI_Fetchnext crash on linux

[Nobody/Anonymous]

Hi Vincent,

My code work on window, but on linux "ubuntu 6.06 LTS".
It crash with below debug log .

Please Advice,
Alvin

Note: OCILIB 3.81 with WIDE char option

My source:
st = OCI_StatementCreate(Connection->cn);
OCI_SetFetchSize(st,500);
OCI_SetLongMaxSize(st, 1000000); // Long raw
if ( params.empty()) {
if (!OCI_Prepare(st,m_sql)) {
Connection->Lock.Post();
ThrowException();
}
} else {
if (!OCI_Prepare(st,OtlSqlToOciSQL(m_sql))) {
Connection->Lock.Post();
ThrowException();
}
bindParms(m_sql,params);

}
if (!OCI_Execute(st)) {
Connection->Lock.Post();
ThrowException();
}

m_stType = OCI_GetStatementType(st);
if ( m_stType == OCI_CST_SELECT {

rs = OCI_GetResultset(st);
if (!rs) {
Connection->Lock.Post();
ThrowException();
}
m_first_fetch = true;
m_first_fetch_eof = OCI_FetchNext(rs) == 0 ? true:false; // <========= crash
at here ..
}

Program received signal SIGSEGV, Segmentation fault.
0xb77418a0 in free () from /lib/tls/i686/cmov/libc.so.6
(gdb) info thread
* 1 Thread -1235036480 (LWP 3916) 0xb77418a0 in free () from /lib/tls/i686/cmov/libc.so.6
(gdb) backtrace

0 0xb77418a0 in free () from /lib/tls/i686/cmov/libc.so.6

1 0xb7743411 in malloc () from /lib/tls/i686/cmov/libc.so.6

2 0xb7949565 in OCI_MemAlloc (ptr_type=0, block_size=36, block_count=0,

zero_fill=1) at memory.c:56

3 0xb7942a8f in OCI_LongInit (stmt=0x0, plg=0x92bb2c0, def=0x91c3400, type=0)

at long.c:59

4 0xb7937cee in OCI_FetchPieces (rs=0x8fcd2a8) at resultset.c:238

5 0xb793803f in OCI_FetchData (rs=0x8fcd2a8, mode=2, offset=0,

err=0xbfba4838) at resultset.c:471

6 0xb7938a5d in OCI_FetchNext (rs=0x8fcd2a8) at resultset.c:1077

7 0x080937c8 in caQuery::Create (this=0xbfba499c, params=@0xbfba4a10) at

/home/tehbc/devl/oneora/src/caconnection.cpp:487

8 0x08093d7a in caQuery (this=0xbfba499c, conn=@0x8ff1080, sql=0x8a09308

"SELECT /+RULE/ v1.owner,v1.table_name,v1.column_id,v1.column_name,v1.data_t
ype,v1.data_precision,v1.data_scale,v1.data_length,v1.nullable,v1.data_default
,v2.comments, v1.character_set_name,v1.char_l"..., params=@0xbfba4a10) at
/home/tehbc/devl/oneora/src/caconnection.cpp:416

[Nobody/Anonymous]

Hi Vincent,

After test for few case, I found that the wchar_t* pointer for OCI_BindString
is main cause for crash on linux.
The below code work on window, by crash with invalid pointer for linux. ( some
time after a few time run the same code)

*** glic detected ** malloc(): memory corruption: 0x08f52928**

Please Help.
Alvin.

void test_bind_bug(void)
{

    OCI_Statement *st1  = OCI_StatementCreate(Connection()->cn);
    OCI_Resultset  *rs1;
    //OCI_SetFetchSize(st1,500);
    //OCI_SetLongMaxSize(st1, 1000000);  // Long raw    
/* execute query in three steps */
    bool result = OCI_Prepare(st1,MT("select owner,index_name from sys.all_indexes ")
              MT("where table_owner = :owner AND table_name = :name"));;
        wxString owner = wxT("HR");
        wxString name = wxT("DEPARTMENTS");
        wchar_t* wowner = new wchar_t[31]; // = (wchar_t*)owner.c_str();
        wchar_t* wname =  new wchar_t[31];  //(wchar_t*)name.c_str();
        wcscpy(wowner,owner.c_str());
        wcscpy(wname,name.c_str());
        result = OCI_BindString(st1,MT(":owner"),wowner,31);
        OCI_BindString(st1,MT(":name"),wname,31);
        int ret1 = OCI_Execute(st1);
        if (ret1 != 1) {
            wxLogDebug(wxT("Error Execute"));
        }
        rs1 = OCI_GetResultset(st1);
        int ret = OCI_FetchNext(rs1);
        while (ret ==1 )
        {
        ret = OCI_FetchNext(rs1);
        }
//      delete [] wowner;     --> can delete the pointer on window, crash on linux if uncomment it
//      delete [] wname;
//  OCI_StatementFree(st1);

}

[Vincent Rogier]

Hi,

It's normal. A bind pointer must stay valid until the statement is re prepared
or freed.

vincent

[Vincent Rogier]

because on linux, the binded pointer is accessed in OCI_CHARSET_WIDE after
execution to perform conversion if needed between internal oracle Unicode
encoding and wchar_t

[Nobody/Anonymous]

Hi Vincent,

From the above code,
How to modify it to prevent crash on *** glic detected ** malloc(): memory
corruption: 0x08f52928** ?
I try for so many time but still can't find the way . please help

Regards
Teh

[Nobody/Anonymous]

Hi Vincent,

Should I report this as bug ?
Or
The version of gcc i use is too old ?

gcc (GCC) 4.0.3 (Ubuntu 4.0.3-1ubuntu5)
Copyright (C) 2006 Free Software Foundation, Inc.

Regards
Alvin Teh

[Vincent Rogier]

I'll run your piece of code on my linux box and try to investigate any issues
before the end of the week.

[Nobody/Anonymous]

Hi vincent,

Thank for investigate.

That is addition info discovered.
If move the OCI_Statement *st1 = OCI_StatementCreate(Connection()->cn);
for procedure. ( Create one time and reuse it ), The program will not crash
for above code.

But when run whole my application. it also crash randomly .

After i change all SQL to not using String Binding (OCI_BindString) , It work
without any problem.

For my existing program, the part of program use PL/SQL code. For PL/SQL code,
i didn't have an idea to change
it without use OCI_BindString.

Hope u can reproduce it and solve my trouble :(
Thank
Alvin

[Nobody/Anonymous]

Hi Vencent,

Any new about this issue ? Do you able to get this error ?

Recently, Test on Mac Os, The source code "test_bind_bug" work correctly.
But it also crash randomly by running my application.
After took out OCI_BindString, the program work without problem.

Regards
Alvin

[Nobody/Anonymous]

Hi Vincent,

After try on error for few days, Now i am able to call PL/SQL code and sql
binding from string for linux and mac.
For output bind :
wchar_t f2;
f2 = '\0'; // add this.
CHECK_ERR(OCI_BindString(m_conn->st,MT(":f2"),(wchar_t)f2,201));
For input bind:
CHECK_ERR(OCI_BindString(m_conn->st,MT(":name"),(wchar_t)name.c_str(),0)); //
Change the len to zero.

For sql, change the len to 0.

Regards
Alvin

[Vincent Rogier]

string binds must always initialized a.nd valid before being passed to Oracle.

But the len parameter mustn't set to zero. It's not imposed by OCI nor OCILIB.

[Nobody/Anonymous]

Hi Vincent,

"Len parameter mustn't set to zero"

That is a bit strange on linux/mac , if i put in a len > 0 same as Ms Window.
My application on linux/mac will crash.

I use wxWidget, with below syntax,

wxString value = wxT("TEST");
OCI_BindString(st,name,(wchar_t*)value.c_str(), 31);

Do you have idea, what is going on ?

Regards
Alvin