1	/* fileCopy.c
   2	   This example shows how to do file copy, one block at a time.
   3	   System calls used in this program:
   4	    . write(), read(), open(), close(), exit().
   5	*/
     
   6	#include <stdio.h>
   7	#include <fcntl.h>
   8	#include <string.h> 
   9	#include <stdlib.h> 
  10	#include <unistd.h> 
  11	#include <sys/stat.h> 
     
  12	#define FMODE  (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
     
  13	main()
  14	{
  15	   char buf[BUFSIZ];
  16	   char PROMPT1[] = "Please enter source filename >> "; 
  17	   char PROMPT2[] = "Please enter target filename >> "; 
  18	   char ERR1[] = "Can't open source file\n";
  19	   char ERR2[] = "Can't open target file\n";
  20	   char ERR3[] = "Can't read source file\n";
  21	   int fd1, fd2;
  22	   ssize_t nread;
     
  23	   write(STDOUT_FILENO, PROMPT1, strlen(PROMPT1)); /* ask for input file */
  24	   nread = read(STDIN_FILENO, buf, BUFSIZ);        /* read from stdin */
  25	   buf[nread-1] = '\0';                   /* strip \n & NULL-terminate buf */
  26	   if ((fd1 = open(buf, O_RDONLY)) == -1) {         /* open for read */
  27	       write(STDERR_FILENO, ERR1, strlen(ERR1));    /* write to stderr */
  28	       return(1);
  29	   }
     
  30	   write(STDOUT_FILENO, PROMPT2, strlen(PROMPT2)); /* ask for output file */
  31	   nread = read(STDIN_FILENO, buf, BUFSIZ);        /* read from stdin */
  32	   buf[nread-1] = '\0';                   /* strip \n & NULL-terminate str */
  33	   if ((fd2 = open(buf, O_WRONLY | O_CREAT | O_TRUNC, FMODE)) == -1) {
  34	       write(STDERR_FILENO, ERR2, strlen(ERR2));    /* write to stderr */
  35	       return(2);
  36	   }
     
  37	   while ((nread = read(fd1, buf, BUFSIZ)) > 0) {    /* while not EOF */
  38	       write(fd2, buf, nread);                     /* save to file 2 */
  39	   }
  40	   if (nread < 0) {
  41	       write(STDERR_FILENO, ERR3, strlen(ERR3));   /* write to stderr */
  42	       return(3);
  43	   }
  44	   close(fd1);                            
  45	   close(fd2);
  46	   exit(0); 
  47	}