Items overriden in list from keyboard thread - c

Question

[1]I'm having a problem with my keyboard input thread. I'm currently using fgets to read input from the keyboard and then store it to a list using List_add. Problem is, my program seems to just print the last character that I inputted instead of the different strings of messages.
UPDATE:
Code in keyboardinput Thread
#define MAX_LEN 258
static pthread_t keyboardThread;
static pthread_mutex_t *psharedMutex;
static List* pList;
void* inputFunction(void* unused){
printf("Enter message:\n");
while (1) {
char* messageAllocated;
messageAllocated = malloc(MAX_LEN);
if(messageAllocated != NULL) {
//Wait for user input
fgets(messageAllocated, MAX_LEN, stdin); // This is how C read something from keyboard
pthread_mutex_lock(psharedMutex);
{
List_add(pList, messageAllocated); // Add message to list for FCFS
}
pthread_mutex_unlock(psharedMutex);
if (messageAllocated[0] == '!' && messageAllocated[2] == '\0') {
break;
}
memset(messageAllocated, 0, MAX_LEN);
}
else {
printf("Malloc Failed.\n");
}
};
return NULL;
}
void KeyboardInput_init(List* myList, pthread_mutex_t *sharedMutex) {
psharedMutex = sharedMutex;
pList = myList;
pthread_create(&keyboardThread, NULL, inputFunction, NULL);
}
void KeyboardInput_shutdown() {
pthread_join(keyboardThread, NULL);
}
Code in main.c
int main(int argc, char** args) {
// Create 2 Lists for transmit and receive
//List listPool;
List* outboundList; // Used in keyboard and UDP sendto threads
List* inboundList; // Used in screen and UDP recvfrom threads
outboundList = List_create();
inboundList = List_create();
// Receive information for s-talk transmission (ports, machine names)
setUpSTalkApplication();
Printer_init();
Signaller_init();
Printer_waitForShutdown();
Signaller_shutdown();
// Startup Modules
Receiver_init("Message received on Port ", &sharedMutex, remoteMachineName, hostPort); // goes before keyboard
KeyboardInput_init(outboundList, &sharedMutex);
Sender_init(outboundList, &sharedMutex, &condVar, remoteMachineName, targetPort);
//ScreenOutput_init(inboundList, &condVar, &sharedMutex);
// Shutdown Modules
//ScreenOutput_shutdown();
KeyboardInput_shutdown();
Receiver_shutdown();
Sender_shutdown();
printf("Done.\n");
while(List_count(outboundList) != 0) {
char* x = List_trim(outboundList);
printf("%s", x);
};
return 0;
}

Answer 1

Firstly, You should validate the pointer messageAllocated after malloc and the sizeof(messageAllocated) is only 4 or 8 bytes, you should use MAX_LEN instead of sizeof(messageAllocated)
while (1) {
char * messageAllocated;
messageAllocated = malloc(MAX_LEN);
if(messageAllocated != NULL)
{
fgets(messageAllocated, MAX_LEN, stdin);
List_add(pList, messageAllocated)
if (messageAllocated[0] == '!') {
break;
}
//hope you are doing this before reading another string, or else there will be memory leak
free(messageAllocated); messageAllocated = NULL;
}
else
{
printf("malloc failed\n");
}
}