client_server_utils.c

/* File of shared functions between the server and the client
 * Author: YOUR NAME HERE */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "client_server_utils.h"


/* Function that finds the index at which the newline character exists in the
 * message. Returns -1 if no newline exists in the string. START is in the
 * index in the start at which the search should begin. */
int find_message_end (char *msg, int start) {
        int end = start;
        char *p = msg;
        for(int n = 0; n < start; n++)
                p++;
    
        while(*p != 0)
        {
                if(*p == '\n'){
                        return end;
                }
                end++;
                p++;
        }
        return -1;
}

/* Function that takes a char * which is a buffer of data received. This 
 * buffer contains 1 or MESSAGES where a message is defined as being a 
 * series of characters ending in a newline. Its other parameter, end,
 * is the length of the first message in the buffer. If MESSAGES contains more 
 * than one message then these messages WILL NOT be separated by a null
 * terminator. However, MESSAGES will always be terminated by a null 
 * terminator. The function should malloc and outputs a new char * consisting 
 * of the first message (which needs end + 1 Bytes). It should also update 
 * MESSAGES so that its contents are a string that contains any remaining 
 * messages and just a null terminator if no more messages remain. You may 
 * want to use some combination of strlen, strcpy, and strncpy. As an 
 * important note if you elect to attempt to use strcpy or strncpy for this 
 * function the dst pointer and the src pointer cannot contain addresses that 
 * will overlap. This means the address of any information from src cannot be 
 * the same as an address that gets written to in dst */
char *generate_message (char *messages, int end) {
    if(messages != NULL)
    {
        char *p;
        if((p = (char*) malloc(end+1)) == NULL){
                allocation_failed();
        }
        strncpy(p, messages, end);
        p[end] = '\0';
        
        char temp[1025];
        strcpy(temp, messages+end);
        strcpy(messages, temp);

        return p;
    }
    return NULL;
}

/* Function that terminates the program when a malloc fails. */
void allocation_failed () {
        fprintf (stderr, "Unable to allocate enough memory\n");
        exit (1);
}