/* This will copy one or more files, as specified on the command-line
 * (using a separate thread to copy each one).
 */
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>

/* gcc ... -lpthread */
#include <pthread.h>

extern int errno;

#define BUFSIZE     256
#define MAXLEN      128
#define MAXTHREADS  100

void * copy_file( void * arg );

int main( int argc, char * argv[] )
{
 pthread_t tid[ MAXTHREADS ];

 int total_bytes_copied = 0;
 int * bytes_copied_p;
 int i;
 int rc;

 for ( i = 1 ; i < argc ; i++ ) {
   printf( "MAIN: Creating thread to copy %s\n", argv[i] );
   rc = pthread_create( &tid[i], NULL, copy_file, (void *)argv[i] );
   if ( rc != 0 ) {
     fprintf( stderr, "MAIN: Could not create thread %d: %s\n",
              i, strerror( errno ) );
     fprintf( stderr, "MAIN: rc is %d\n", rc );
   }
 }

 /* wait for the threads to complete */
 for ( i = 1 ; i < argc ; i++ ) {
   rc = pthread_join( tid[i], (void **)&( bytes_copied_p ) );
   if ( rc != 0 ) {
     fprintf( stderr, "MAIN: No thread %d to join: %s\n",
              i, strerror( errno ) );
   } else {
     printf( "MAIN: Thread %d copied %d bytes from %s\n",
             tid[i], *bytes_copied_p, argv[i] );
     total_bytes_copied += *bytes_copied_p;
   }
 }

 printf( "MAIN: Total bytes copied is %d\n", total_bytes_copied );

 return 0;
}

void * copy_file( void * arg )
{
 int infile, outfile;
 int bytes_read = 0;
 int bytes_written = 0;
 char buffer[ BUFSIZE ];
 char outfilename[ MAXLEN ];
 int * rc = (int *)malloc( sizeof ( int ) );
 *rc = 0;

 printf( "THREAD %d: Copying %s...\n", pthread_self(), (char *)arg );

 infile = open( arg, O_RDONLY );
 if ( infile < 0 ) {
   fprintf( stderr, "THREAD %d: Error opening file %s: ",
            pthread_self(), (char *)arg );
   fprintf( stderr, "THREAD %d: %s\n",
            pthread_self(), strerror( errno ) );
   pthread_exit( rc );
 }

 strcpy( outfilename, "backup_" );
 strcat( outfilename, arg );
 outfile = open( outfilename, O_WRONLY | O_CREAT | O_TRUNC,
                 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH );
 if ( outfile < 0 ) {
   fprintf( stderr, "THREAD %d: Error opening file %s",
            pthread_self(), outfilename );
   fprintf( stderr, "THREAD %d: %s\n",
            pthread_self(), strerror( errno ) );
   pthread_exit( rc );
 }

 while ( 1 ) {
   bytes_read = read( infile, buffer, BUFSIZE );
   if ( bytes_read == 0 )
     break;
   else if ( bytes_read < 0 ) {
     perror( "reading" );
     pthread_exit( rc );
   }
   bytes_written = write( outfile, buffer, bytes_read );
   if ( bytes_written != bytes_read ) {
     perror( "writing" );
     pthread_exit( rc );
   }
   *rc += bytes_written;
 }

 close( infile );
 close( outfile );
 pthread_exit( rc );
 return rc;  /* we never get here ... */
}