/*
* === FUNCTION ======================================================================
* Name: main
* Description:
* =====================================================================================
*/
int main ( int argc, char *argv[] )
{
int pid = fork();
if( pid ){
if( fork() ){
executeParent();
printf("Parent waiting...\n");
int status = 0;
wait(&status); //wait for child process
if( shm_unlink(SEM_NAME) == -1 ){
perror( "sem unlink failed");
exit(1);
}
if( shm_unlink(SHM_NAME) == -1 ){
perror("shm unlink failed");
exit(1);
}
printf("Parent done\n");
} else {
executeChild();
}
}else{
executeChild();
}
return EXIT_SUCCESS;
}
void readAndExecute() {
int readStatus; /* An variable to hold the return value of the readStatus function. */
char input[COMMAND_MAX_LENGTH+2]; /* Array to be used for reading, with 2 extra char for newline and the '\0' char. */
/* Read a line of max COMMAND_MAX_LENGTH command chars from stdin. */
readStatus = readLine(input, COMMAND_MAX_LENGTH+2, stdin);
/* Check the read line status */
if(readStatus == 0) {
/* Read was successful. */
char *args[ARGUMENTS_MAX_LENGTH+2]; /* Array to hold all the arguments. 2 extra chars for command name and '\0' char. */
/* Parse the command line by exploding command string. Args will then contain all arguments of the command. */
explode(args, ARGUMENTS_MAX_LENGTH+2, input);
/* Check for built-in commands. */
if(executeCommand(args) != 0) {
/* The command is not a built in command. The command should be executed externally. */
struct timeval preExecute; /* Structure to hold time info from pre execution of the command. */
struct timeval postExecute; /* Structure to hold time info from post execution of the command. */
unsigned int elapsed; /* The number of milliseconds needed for executing the command. */
if(isBackgroundRequested(args, ARGUMENTS_MAX_LENGTH+2, BACKGROUND_REMOVE_CHAR) == 0) {
/* Command should be executed in foreground. */
/* Get the current time for command execution statistics. */
CHECK_SAFE(gettimeofday(&preExecute, NULL));
/* Execute the program with the executeChild function with foreground mode. */
executeChild(args, CHILD_FOREGROUND);
/* Get the current time for command executions statistics. */
CHECK_SAFE(gettimeofday(&postExecute, NULL));
/* Calculate the elapsed time. */
elapsed = postExecute.tv_usec - preExecute.tv_usec;
/* Print the statistics. */
printf("Command '%s' executed in %i milliseconds.\n", args[0], elapsed);
} else {
/* Command should be executed in background. */
/* Execute the program with the executeChild function with background mode. */
executeChild(args, CHILD_BACKGROUND);
}
}
} else if(readStatus == 1) {
/* Too many characters were read. */
/* Tell user to enter less number of characters. */
printLine("The character limit of a command is %i", COMMAND_MAX_LENGTH);
} else if(readStatus == -1) {
/* An error have occured. */
/* Check the error. */
if(errno == EINTR) {
/* Interrupted system call. */
/* Do not treat this like an error, just try again. */
} else {
/* Unhandled error. */
/* Force an error. */
CHECK_SAFE(-1);
}
}
}
