Mail Archives: cygwin/2002/06/04/07:12:10
Thanks for answering at first, Pavel.
I have been trying to detail the problem preparing several tests.
I've tested the following c program:
odbc.c:
#include <windows.h>
#include <sql.h>
#include <sqlext.h>
int main()
{
SQLHENV henv;
SQLHDBC hdbc;
SQLHSTMT hstmt;
SQLRETURN retcode;
char buf[1024];
char CamposConsulta[256];
unsigned char sqlstate[15];
short ncol, cont = 0, i;
long buflen, nrow;
UWORD Functions[100];
retcode = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION,
(SQLPOINTER)SQL_OV_ODBC2, 0);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
//retcode = SQLGetFunctions(hdbc, SQL_API_SQLCONNECT,
Functions);
retcode = SQLConnect(hdbc, (SQLCHAR*) "sample-MCODBC",
SQL_NTS, NULL, 0, NULL, 0);
/*
* Obtener errores de conexión
*/
if (retcode)
{
if (SQLError (henv, hdbc, SQL_NULL_HSTMT, sqlstate,
NULL, buf, sizeof(buf), NULL) == SQL_SUCCESS)
{
printf ("%s, SQLSTATE=%s\n", buf, sqlstate);
}
}
else printf ("\nConexión establecida\n");
if (retcode == SQL_SUCCESS || retcode == SQL_SUCCESS_WITH_INFO)
{
retcode = SQLAllocHandle(SQL_HANDLE_STMT, hdbc, &hstmt);
if (retcode == SQL_SUCCESS || retcode ==
SQL_SUCCESS_WITH_INFO)
{
retcode = SQLAllocStmt(hdbc, &hstmt);
sprintf(CamposConsulta,
"PRENUMORD,PRETAR,PREPROD,PREFEC,PREHOR,PREDENS,PREVOLTOT,PREDES1,PREDES2,PREDES3,PRECANSEC1,PRECANSEC2,PRECANSEC3,PRECANSEC4,PRECANSEC5,PRECANSEC6");
sprintf(buf, "SELECT %s FROM preconfiguraciones
WHERE PRECLI > 0", CamposConsulta);
retcode = SQLExecDirect(hstmt, (UCHAR *)buf,
strlen(buf));
if (!retcode)
printf ("\nEjecución de frase correcta\n");
retcode = SQLNumResultCols(hstmt, &ncol);
while(!retcode)
{
retcode = SQLFetch(hstmt);
if (retcode)
{
if (SQLError (henv, hdbc, SQL_NULL_HSTMT,
sqlstate, NULL, buf, sizeof(buf), NULL) == SQL_SUCCESS)
{
printf ( "%s, SQLSTATE=%s\n", buf,
sqlstate);
}
}
else
{
printf ("\nRecuperado registro\n");
for (i = 1; i <= ncol; i++)
{
retcode = SQLGetData(hstmt, i,
SQL_C_DEFAULT, buf, 100, &buflen);
printf ("\nCampo %d: %s\n", i, buf);
}
}
cont++;
}
SQLFreeHandle(SQL_HANDLE_STMT, hstmt);
}
SQLDisconnect(hdbc);
printf ("\nDesconexión realizada\n");
}
SQLFreeHandle(SQL_HANDLE_DBC, hdbc);
}
}
}
SQLFreeHandle(SQL_HANDLE_ENV, henv);
}
1) First test
The first compilation is as follows:
gcc -o odbc.exe odbc.c -lmcodbcnt
Previously I generated a libmcodbcnt.a file using following line:
DLLTOOL --dllname mcodbcnt.dll --def libmcodbcnt.def --output-lib
libmcodbcnt.a
mcodbcnt.dll is the odbc driver I'm testing and libmcodbcnt.def contents
are:
DESCRIPTION 'MCASE ODBC Driver'
EXPORTS
SQLAllocHandle AT 12
SQLSetEnvAttr AT 16
SQLError AT 32
SQLFetch AT 4
SQLGetData AT 24
SQLConnect AT 28
SQLAllocStmt AT 8
SQLExecDirect AT 12
SQLNumResultCols AT 8
SQLFreeHandle AT 8
SQLDisconnect AT 4
SQLFreeStmt AT 8
Aditionally, I included a message Box as the first instruction of
SqlConnect to check that dll is working properly.
When I run odbc.exe I get the proper messageBox telling me the program
is running SqlConnect function.
2) Second test
When I try to test dll file as an odbc driver:
- I install mcodbcnt.dll as an odbc driver. I have installation routines
for the driver and sample-data sources. After this process I can see
mcodbc driver an data source in Windows ODBC Administration tool. (Or in
Windows Register).
- I run 'gcc -o odbc.exe odbc.c -lodbc32' linking to odbc32 instead of
mcodbcnt .
Then I get when calling SqlConnect:
0 [main] odbc 868 handle_exceptions: Exception: STATUS_ACCESS_VIOLATION
4934 [main] odbc 868 open_stackdumpfile: Dumping stack trace to
odbc.exe.stackdump
And odbc.exe.stackdump is:
Exception: STATUS_ACCESS_VIOLATION at eip=1A4599A2
eax=00000000 ebx=000003E9 ecx=00000000 edx=00000000 esi=00911748
edi=00911764
ebp=0022F5D8 esp=0022F5A4 program=S:\MC\BPAA\odbc.exe
cs=001B ds=0023 es=0023 fs=003B gs=0000 ss=0023
Stack trace:
Frame Function Args
0022F5D8 1A4599A2 (1A459E11, 00000000, 1A456E50, 784629C0)
0022F618 1A459E96 (00000000, 0022F648, 1A45BDAC, 009117F0)
0022F658 1A45BDDE (00911764, 009112F8, 00911748, 00911250)
0022F6B4 1A45BE59 (00911764, 009112F8, 009112F8, 0022F6F8)
009112F8 1F7E3D0E (00000000, 00000000, 00000000, 00000000)
47443 [main] odbc 868 handle_exceptions: Exception:
STATUS_ACCESS_VIOLATION
48345 [main] odbc 868 handle_exceptions: Error while dumping state
(probably corrupted stack)
It finds SqlConnect (The message I sent last week didn't and a IM001
message appeared). It didn't find SqlConnect because .def was wrong. It
was my mistake. Now it finds the function but fails. It doesn't arrive
at MessageBox. And that's the first instruccion into the driver.
Obviously I suppose is not a problem to run MessageBox into my odbc driver.
3) Third test.
I try the to compile odbc.c against MySql 2.5 odbc driver. I change the
data source to be attached.
I call
retcode = SQLConnect(hdbc, (SQLCHAR*) "test", SQL_NTS, NULL, 0,
NULL, 0);
instead of
retcode = SQLConnect(hdbc, (SQLCHAR*) "sample-MCODBC", SQL_NTS,
NULL, 0, NULL, 0);
and test is a data source for MySql odbc driver.
I compile gcc -o odbc.exe odbc.c -lodbc32
I test it and it works properly.
-----------------------------------------------------------------------------------------------------------------------------------
So there's something I'm going wrong using mcodbcnt.dll as a odbc driver.
There's no odbc syntax problem in odbc.c because gcc compiles it and it
works fine using MySql.
The dll is properly built because the program finds the entry points
when directly attached. So there's a problem when using odbc32.dll
between odbc.exe and mcodbcnt.dll. I don't know if it's a compile
options issue or if it's a necesary odbc step I'm not following.
Could anyone help me ?
Thanks in advance. Ignasi Villagrasa.
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