c++ byte array of chars - c++

Question

I'm having problems with byte array of chars.
I'm creating file transfer program, which transfers binary data over TCP socket.
So, when I'm getting data from chunks, I'm saving them to temporary container and then I have to add somewhere to hold whole data. I have tried std::vector but doesn't work well (or I'm using it wrong.)
size_t nbytes = 0;
char buffer[5]; //temporary container.
int result = 0;
std::vector<char> abc;
if (ioctl(sockfd, FIONREAD, (char*)&nbytes) < 0)
{
printf("[-] Error getting available data.\n");
return -1;
}
printf("[*] Bytes available: %lu\n", nbytes);
while(true)
{
if(nbytes > sizeof(buffer))
{
result = recv(sockfd, buffer, sizeof(buffer), 0);
for(int i = 0; i < result; i++)
{
abc.push_back(buffer[i]); //big data causes memory corruption.
}
nbytes -= result;
continue;
}
else if(nbytes <= sizeof(buffer) && nbytes != 0)
{
result = recv(sockfd, buffer, nbytes, 0);
for(int i = 0; i < result; i++)
{
abc.push_back(buffer[i]); //big data causes memory corruption.
}
break;
}
else
{
result = 0;
break;
}
}
printf("Data Received: %s", &abc[0]);

Answer 1

if recv fails it returns SOCKET_ERROR but you don't check it and instead use it as number of the bytes received. As SOCKET_ERROR is #defined to -1 you effectively read from address before buffer.
EDIT:
it turns out that original answer was wrong as in that case the loop would not execute at all.
However, the problem is that content of the vector is not null-terminated (as it is a plain buffer without any string semantics), so it looks like garbage, but it is actually OK.