#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h> 
#include <sys/stat.h> 
#define MAXNAME 80
#define R_FLAGS O_RDONLY
#define W_FLAGS (O_WRONLY | O_CREAT)
#define W_PERMS (S_IRUSR | S_IWUSR)

typedef struct {
   int args[3];
   pthread_t tid;
} copy_t;

void *copyfilepass(void *arg);

int main(int argc, char *argv[]) {
   int *bytesp;
   copy_t *copies;
   int error;
   char filename[MAXNAME];
   int i;
   int numcopiers;  
   int totalbytes = 0;

   if (argc != 4) {
      fprintf(stderr, "Usage: %s infile outfile copies\n", argv[0]);
      return 1; 
   }   
   numcopiers = atoi(argv[3]);
   if ((copies = (copy_t *)calloc(numcopiers, sizeof(copy_t))) == NULL) {
      perror("Failed to allocate copier space");
      return 1;
   }  
              /* open the source and destination files and create the threads */
   for (i = 0; i < numcopiers; i++) {
      copies[i].tid = pthread_self();       /* cannot be value for new thread */
      if (snprintf(filename, MAXNAME, "%s.%d", argv[1], i+1) == MAXNAME) {
         fprintf(stderr, "Input filename %s.%d too long", argv[1], i + 1); 
         continue;
      }
      if ((copies[i].args[0] = open(filename, R_FLAGS)) == -1) {
         fprintf(stderr, "Failed to open source file %s: %s\n",
                         filename, strerror(errno));
         continue; 
      }
     if (snprintf(filename, MAXNAME, "%s.%d", argv[2], i+1) == MAXNAME) {
         fprintf(stderr, "Output filename %s.%d too long", argv[2], i + 1); 
         continue; 
      }
      if ((copies[i].args[1] = open(filename, W_FLAGS, W_PERMS)) == -1) {
         fprintf(stderr, "Failed to open destination file %s: %s\n",
                         filename, strerror(errno));
         continue;
      }
      if (error = pthread_create((&copies[i].tid), NULL, 
                                  copyfilepass, copies[i].args)) {
         fprintf(stderr, "Failed to create thread %d: %s\n", i + 1, 
                 strerror(error));
         copies[i].tid = pthread_self();    /* cannot be value for new thread */
      }
  
   }                                
                     /* wait for the threads to finish and report total bytes */
   for (i = 0; i < numcopiers; i++) {
      if (pthread_equal(copies[i].tid, pthread_self()))        /* not created */
         continue;
      if (error = pthread_join(copies[i].tid, (void**)&bytesp)) {
         fprintf(stderr, "Failed to join thread %d\n", i);
         continue;
      }
      if (bytesp == NULL) {
         fprintf(stderr, "Thread %d failed to return status\n", i);
         continue;
      }
      printf("Thread %d copied %d bytes from %s.%d to %s.%d\n",
             i, *bytesp, argv[1], i + 1, argv[2], i + 1);
      totalbytes += *bytesp;
   }
   printf("Total bytes copied = %d\n", totalbytes);
   return 0; 
}