*** Error in `./text_buffer': corrupted double-linked list: 0x089cbd98 ** - sql

Question

I'm trying to make the app using FreeTDS. Following are my code
/*
* Purpose: Test to see if row buffering and blobs works correctly.
* Functions: dbbind dbnextrow dbopen dbresults dbsqlexec dbgetrow
*/
#include "common.h"
#include "stdio.h"
#include<stdlib.h>
#include "readline/readline.h"
#include "readline/history.h"
#include "string.h"
int
main(int argc, char **argv)
{
char failed;
int hasil;
char ch;
char* r = malloc(30);
LOGINREC *login;
DBPROCESS *dbproc;
int i;
int p = 0;
char teststr[1024];
DBINT testint;
read_login_info(argc, argv);
fprintf(stdout, "Starting %s\n", argv[0]);
/* Fortify_EnterScope(); */
while(1)
{
char qrcode[50];
char perintahsql[100] = "select * from REF_COBA where id=";
char *alokasi="";
while(ch != '\n') // terminates if user hit enter
{
ch = getchar();
qrcode[p] = ch;
p++;
}
qrcode[p]='\0';
strcpy(r,qrcode);
alokasi = strsep(&r, ",");
strcpy(r,"");
p=0;
ch = "";
dbinit();
dberrhandle(syb_err_handler);
dbmsghandle(syb_msg_handler);
fprintf(stdout, "About to logon\n");
login = dblogin();
DBSETLPWD(login, PASSWORD);
DBSETLUSER(login, USER);
DBSETLAPP(login, "text_buffer");
//DBSETLHOST(login, "ntbox.dntis.ro");
DBSETLHOST(login, "192.168.1.9");
fprintf(stdout, "About to open\n");
dbproc = dbopen(login, SERVER);
if (strlen(DATABASE))
dbuse(dbproc, DATABASE);
dbloginfree(login);
#ifdef MICROSOFT_DBLIB
dbsetopt(dbproc, DBBUFFER, "100");
#else
dbsetopt(dbproc, DBBUFFER, "100", 0);
#endif
dbcmd(dbproc, strcat(perintahsql,alokasi));
dbsqlexec(dbproc);
if (dbresults(dbproc) != SUCCEED)
{
failed = 1;
fprintf(stdout, "Was expecting a result set.");
exit(1);
}
fprintf(stdout, "select\n");
for (i = 1; i <= dbnumcols(dbproc); i++)
printf("col %d is %s\n", i, dbcolname(dbproc, i));
fprintf(stdout, "setelah for\n");
dbbind(dbproc, 1, INTBIND, 0, (BYTE *) & testint);
dbbind(dbproc, 2, CHARBIND, 0, (BYTE *) teststr);
for (i = 1; i < 2; i++)
{
char expected[1024];
sprintf(expected, "row %03d", i);
if (i % 100 == 0)
{
dbclrbuf(dbproc, 100);
}
if (REG_ROW != dbnextrow(dbproc))
{
failed = 1;
fprintf(stderr, "Failed. Expected a row\n");
//exit(1);
}
else
{
fprintf(stdout, "jalanin usb\n");
printf("Read a row of data -> %d %s\n", (int) testint, teststr);
hasil = system("/opt/usb1rc_linux USB1REL-172 R");
sleep(2);
hasil = system("/opt/usb1rc_linux USB1REL-172 r");
}
}
dbfreebuf(dbproc);
dbexit();
}
return 0;
}
I modified the source from FreeTDS, after compilation there are some warning
bash-4.2# make text_buffer
CC text_buffer.o
text_buffer.c: In function 'main':
text_buffer.c:54:8: warning: assignment makes integer from pointer without a cast [enabled by default]
ch = "";
^
text_buffer.c:18:7: warning: variable 'hasil' set but not used [-Wunused-but-set-variable]
int hasil;
^
text_buffer.c:17:8: warning: variable 'failed' set but not used [-Wunused-but-set-variable]
char failed;
^
CC common.o
CCLD text_buffer
I execute the program without error. This program will check input from user then run the sql command. The format of input shall be , e.g 123456,john doe then press enter. After 50-60 times of input, the double-linked list error will happen.
could anybody help why the error happen?