glibc detected realloc(): invalid pointer - c

Question

Im constantly getting this when I build on Qtcreator.
*** glibc detected *** /home/Exxamples/EffectivCons: realloc(): invalid pointer: 0xb6fb5414 ***
======= Backtrace: =========
/lib/i386-linux-gnu/libc.so.6(+0x75ee2)[0xb6603ee2]
/lib/i386-linux-gnu/libc.so.6(realloc+0x25d)[0xb660856d]
/lib/i386-linux-gnu/libc.so.6(realloc+0x273)[0xb6608583]
/opt/Qt5.1.1/5.1.1/gcc/lib/libQt5Core.so.5(_ZN9QListData7reallocEi+0x37)[0xb6906e67]
/opt/Qt5.1.1/5.1.1/gcc/lib/libQt5Core.so.5(_ZN9QListData6appendEi+0x7c)[0xb6906f4c]
/opt/Qt5.1.1/5.1.1/gcc/lib/libQt5Core.so.5(_ZN9QListData6appendEv+0x23)[0xb6906fd3]
/opt/Qt5.1.1/5.1.1/gcc/lib/libQt5Core.so.5(+0x1afa3e)[0xb6a05a3e]
/opt/Qt5.1.1/5.1.1/gcc/lib/libQt5Core.so.5(_Z21qRegisterResourceDataiPKhS0_S0_+0x216)[
This is my code, through the other questions on the website, I saw some users using malloc or realloc, but Im not using it, why am i getting an error?
#include <termios.h>
#include <string.h>
#include <stdlib.h>
#define BUFLEN 512
std::string numberToString(const int n);
void sendExpressivAnimation(int,EmoStateHandle eState);
void handleExpressivEvent(std::ostream& os, EmoEngineEventHandle expressivEvent);
bool handleUserInput();
void promptUser();
void nonblocking();
int getch();
int kbhit();
int createSocket();
int startSendPort = 30000;
struct termios initial_settings, new_settings;
int kbhit (void)
{
struct timeval tv;
fd_set rdfs;
tv.tv_sec = 0;
tv.tv_usec = 0;
FD_ZERO(&rdfs);
FD_SET (STDIN_FILENO, &rdfs);
select(STDIN_FILENO+1, &rdfs, NULL, NULL, &tv);
return FD_ISSET(STDIN_FILENO, &rdfs);
}
int main(int argc, char **argv)
{
EmoEngineEventHandle eEvent = EE_EmoEngineEventCreate();
EmoStateHandle eState = EE_EmoStateCreate();
unsigned int userID = 0;
const int CONTROL_PANEL_PORT = 3008;
bool connected = false;
if(EE_EngineRemoteConnect("127.0.0.1", CONTROL_PANEL_PORT)== EDK_OK)
{
std::cout <<"Emotiv Engine started" << std::endl;
connected = true;
}
else
{
std::cout <<"Emotiv Engine failed !"<< std::endl;
connected = false;
}
std::cout << "Type \"exit\" to quit, \"help\" to list available commands..." << std::endl;
promptUser();
int _socket;
_socket = createSocket();
if(connected)
{
nonblocking();
fflush(stdin);
while (true) {
// Handle the user input
//if (_kbhit()) {
if (!handleUserInput()) {
break;
}
//}
int state = EE_EngineGetNextEvent(eEvent);
// New event needs to be handled
if (state == EDK_OK) {
EE_Event_t eventType = EE_EmoEngineEventGetType(eEvent);
EE_EmoEngineEventGetUserId(eEvent, &userID);
switch (eventType) {
// New headset connected, create a new socket to send the animation
case EE_UserAdded:
{
std::cout << std::endl << "New user " << userID << " added, sending Expressiv animation to ";
std::cout << "127.0.0.1" << ":" << startSendPort << "..." << std::endl;
promptUser();
break;
}
// Headset disconnected, remove the existing socket
case EE_UserRemoved:
{
std::cout << std::endl << "User " << userID << " has been removed." << std::endl;
promptUser();
break;
}
// Send the Expressiv animation if EmoState has been updated
case EE_EmoStateUpdated:
{
//std::cout << "New EmoState from user " << userID << "..." << std::endl;
EE_EmoEngineEventGetEmoState(eEvent, eState);
sendExpressivAnimation(_socket,eState);
break;
}
// Handle Expressiv training event
case EE_ExpressivEvent:
{
handleExpressivEvent(std::cout, eEvent);
break;
}
default:
break;
}
}
else if (state != EDK_NO_EVENT) {
std::cout << std::endl << "Internal error in Emotiv Engine!" << std::endl;
break;
}
}
}
EE_EngineDisconnect();
EE_EmoStateFree(eState);
EE_EmoEngineEventFree(eEvent);
return 0;
}
std::string numberToString(const int n) {
char* buf;
//_itoa(n, buf, 10);
QString nStr = QString::number(n);
buf = nStr.toLocal8Bit().data();
return std::string(buf);
}
void sendExpressivAnimation(int _socket,EmoStateHandle eState) {
std::ostringstream output;
EE_ExpressivAlgo_t upperFaceType = ES_ExpressivGetUpperFaceAction(eState);
EE_ExpressivAlgo_t lowerFaceType = ES_ExpressivGetLowerFaceAction(eState);
float upperFaceAmp = ES_ExpressivGetUpperFaceActionPower(eState);
float lowerFaceAmp = ES_ExpressivGetLowerFaceActionPower(eState);
if (ES_ExpressivIsBlink(eState)) {
output << "B,";
}
if (ES_ExpressivIsLeftWink(eState)) {
output << "l,";
}
if (ES_ExpressivIsRightWink(eState)) {
output << "r,";
}
if (ES_ExpressivIsLookingRight(eState)) {
output << "R,";
}
if (ES_ExpressivIsLookingLeft(eState)) {
output << "L,";
}
if (upperFaceAmp > 0.0) {
switch (upperFaceType) {
case EXP_EYEBROW: output << "b"; break;
case EXP_FURROW: output << "f"; break;
default: break;
}
output << numberToString(static_cast<int>(upperFaceAmp*100.0f)) << ",";
}
if (lowerFaceAmp > 0.0) {
switch (lowerFaceType) {
case EXP_CLENCH: output << "G"; break;
case EXP_SMILE: output << "S"; break;
case EXP_LAUGH: output << "H"; break;
case EXP_SMIRK_LEFT: output << "sl"; break;
case EXP_SMIRK_RIGHT: output << "sr"; break;
default: break;
}
output << numberToString(static_cast<int>(lowerFaceAmp*100.0f)) << ",";
}
std::string outString = output.str();
// Remove the last comma
if (outString.length()) {
outString.resize(outString.length()-1);
}
if (!outString.length()) {
outString = std::string("neutral");
}
if(send(_socket, outString.c_str(), BUFLEN, 0)==-1)
{
std::cout<<"sending error"<<std::endl;
//exit(1);
}
}
void handleExpressivEvent(std::ostream& os, EmoEngineEventHandle expressivEvent) {
unsigned int userID = 0;
EE_EmoEngineEventGetUserId(expressivEvent, &userID);
EE_ExpressivEvent_t eventType = EE_ExpressivEventGetType(expressivEvent);
switch (eventType) {
case EE_ExpressivTrainingStarted:
{
os << std::endl << "Expressiv training for user " << userID << " STARTED!" << std::endl;
break;
}
case EE_ExpressivTrainingSucceeded:
{
os << std::endl << "Expressiv training for user " << userID << " SUCCEEDED!" << std::endl;
break;
}
case EE_ExpressivTrainingFailed:
{
os << std::endl << "Expressiv training for user " << userID << " FAILED!" << std::endl;
break;
}
case EE_ExpressivTrainingCompleted:
{
os << std::endl << "Expressiv training for user " << userID << " COMPLETED!" << std::endl;
break;
}
case EE_ExpressivTrainingDataErased:
{
os << std::endl << "Expressiv training data for user " << userID << " ERASED!" << std::endl;
break;
}
case EE_ExpressivTrainingRejected:
{
os << std::endl << "Expressiv training for user " << userID << " REJECTED!" << std::endl;
break;
}
case EE_ExpressivTrainingReset:
{
os << std::endl << "Expressiv training for user " << userID << " RESET!" << std::endl;
break;
}
case EE_ExpressivNoEvent:
default:
//## unhandled case
assert(0);
return;
}
promptUser();
}
bool handleUserInput() {
static std::string inputBuffer;
char c = getch();
if ((int)c == 10) {
std::cout << std::endl;
std::string command;
const size_t len = inputBuffer.length();
command.reserve(len);
// Convert the input to lower case first
for (size_t i=0; i < len; i++) {
command.append(1, tolower(inputBuffer.at(i)));
}
inputBuffer.clear();
bool success = parseCommand(command, std::cout);
promptUser();
return success;
}
else {
if ((int)c == 127) { // Backspace key
if (inputBuffer.length()) {
putchar('\b');
putchar(' ');
putchar('\b');
inputBuffer.erase(inputBuffer.end()-1);
}
}
else {
std::cout << c;
if(((int) c == 32) || ((int)c == 95) || (((int)c >= 97 && (int)c <=122)) || (((int)c >=48 && (int)c <= 57)))
inputBuffer.append(1,c);
}
}
return true;
}
void promptUser()
{
std::cout << "ExpressivDemo> "<<std::endl;
}
void nonblocking()
{
tcgetattr(0, &initial_settings);
new_settings = initial_settings;
new_settings.c_lflag &= ~ICANON;
new_settings.c_lflag &= ~ECHO;
//new_settings.c_lflag &= ~ISIG;
new_settings.c_cc[VMIN] = 0;
new_settings.c_cc[VTIME] = 0;
tcsetattr(0, TCSANOW, &new_settings);
}
int getch()
{
int r;
unsigned char c=0;
if((r = read(0, &c, sizeof(c))) < 0 )
{
return r;
}
else
{
return c;
}
}
int createSocket()
{
struct sockaddr_in si_other;
int s, slen = sizeof(si_other);
if ((s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1)
std::cout<<"socket"<<std::endl;
memset((char *) &si_other, 0, sizeof(si_other));
si_other.sin_family = AF_INET;
si_other.sin_port = htons(startSendPort);
if (inet_aton("127.0.0.1", &si_other.sin_addr)==0)
{
std::cout<<"intet_aton failed !"<<std::endl;
//exit(1);
}
if(connect(s,(sockaddr*)&si_other,slen)==-1)
{
std::cout<<"connect failed !"<<std::endl;
// exit(1);
}
return s;
}

Answer 1

Your code is too big to be checked wholly. If you can reduce it to a SSCCE it will be easier for everybody.
Anyway, skimming over your code, only one thing catched my eye:
char *buf;
QString nStr = QString::number(n);
buf = nStr.toLocal8Bit().data();
return std::string(buf);
The call to toLocal8Bit() returns a temporary QByteArray and then you call its data() member function. The returned pointer is only valid during the lifetime of that temporary, that is, until the ending ;. After that the buf pointer is invalid and the next line renders undefined behavior.
You should do something like:
QString nStr = QString::number(n);
QByteArray a(nStr.toLocal8Bit());
char *buf = a.data();
return std::string(buf);
Or even better:
QString nStr = QString::number(n);
return std::string(nStr.toLocal8Bit().data());
Or just for show:
return std::string(QString::number(n).toLocal8Bit().data());