/***
 *	Using multiple threads to copy files
 *	Compile:  gcc -o copyc.exe exmutex.c  -pthread
 ***/
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#define  MAX 5
#define	BLOCK 1024

void * read_file( void *);

/***       This is global ***/
pthread_mutex_t lock_it  = PTHREAD_MUTEX_INITIALIZER;

int main(int argc, char *argv[]) {
  int             i;
  int	  save_status = 0;
  pthread_t       thread_id[MAX];
  void *result;  //Need a place to store the return value from each thread

  if ( argc < 2 || argc > MAX+1 )           /* check arg list       */
    fprintf(stderr,"%s arg1, arg2, ... arg%d\n", *argv, MAX ), exit( 1 );
  
  printf("Copying the files named on the command line\n\n");

  for (i = 0; i < argc - 1; ++i) {              /* generate threads     */
    if( pthread_create(&thread_id[i], NULL, read_file, (void *) argv[i + 1]) != 0)
      fprintf(stderr, "pthread_create failure\n"), exit( 2 );
  }

  for (i = 0; i < argc - 1; ++i){               /* wait for each thread */
    if ( pthread_join(thread_id[i], &result) > 0 ) {
      printf("pthread_join failure\n");
      exit(3);
    }
    if ((*(int*)result) > save_status) {
      save_status = *((int*)result);
      printf("Thread %d returns %d\n", i,*((int*)result));
    }
    free((int*)result);  //Have to free memory allocated in the thread
  }

  pthread_mutex_destroy(&lock_it);  //The mutex is no longer needed

  if (save_status == 0 )
    printf("\nAll files copied\n");
  exit (0);
}
/***
 *      Open and copy to stdout the contents of the file
 ***/
void  *read_file(void *filename) {
  char buffer[BLOCK];
  FILE* fp;
  int *ip = (int*)malloc(sizeof(int));  //This pointer will point at the return value
  pthread_t	tid;
  ssize_t bytes_read;

  *ip = 0; //Initialize the return value to zero
  tid = pthread_self(); //What is the thread ID?

  if((fp = fopen((char *)filename,"r")) == NULL ) { //Try to open the external file
//  open was unsuccessful, so return a value of 1
        *ip = 1;
	pthread_exit((void *)ip);
  }

  pthread_mutex_lock(&lock_it);   /*lock stdout */
  printf("Thread %2d copying file %s\n",(int)tid,(char *)filename);
  pthread_mutex_unlock(&lock_it);   /*unlock stdout */

//This loop uses fgets() to read a line into the array buffer
  pthread_mutex_lock(&lock_it);   /*lock stdout */
  while ((fgets(buffer,BLOCK,fp)) != NULL)
	printf("%s",buffer);
  pthread_mutex_unlock(&lock_it);   /*unlock stdout */

  fclose(fp);  //The file has been read
// The value of ip should still be 0
  return (void *)ip;
}