Question

this is part of my code which reads an http response. It’s supposed to increase the buffer size if it runs out of room. But i keep getting access violations. It happens when copying the data to the new buffer: memcpy(tmp_alloc, rec, ResponseLength); Any help/suggestions are appreciated.

#define SERVER_CHUNK 1024

char *rec = new char[10000];
char in_buff[SERVER_CHUNK];
int in_sz, 
    ResponseLength = 0, 
    rec_len = 10000;

in_sz = recv(ss,in_buff,SERVER_CHUNK,0);//get the response  

while(in_sz > 0)
{           

    memcpy(rec + ResponseLength,in_buff,in_sz);
    ResponseLength += in_sz;

    if((ResponseLength + SERVER_CHUNK) > rec_len)
    {
        char *tmp_alloc = (char*) malloc (ResponseLength + SERVER_CHUNK); 
        if(!tmp_alloc)
        {   
            printf("failed to alocate memory!\n");
            break;
        }
        memcpy(tmp_alloc, rec, ResponseLength);
        free(rec);
        rec = tmp_alloc;
        rec_len = ResponseLength + SERVER_CHUNK; 
    }

    in_sz = recv(ss,in_buff,SERVER_CHUNK,0);    
}   

Answer 1

It’s possible that you’re corrupting the heap by mixing new[] with free(), which is not supported.

Change:

char *rec = new char[10000];

To:

char *rec = (char*) malloc( 10000);

and see if it makes any difference.