1.文件IO----COPY的实现

 《Makefile》 

***************

 CC=gcc
 TEXT=copy
 SVC=file_copy.c debug.h
 $(TEXT): $(SVC)
     $(CC) -o $@ $^
 clean:
     rm -rf $(TEXT) *.o
******************************

《头文件》

/*Comment/uncomment the following line to disable/enable debugging,
 OR define(or NOT) it in Makefile.
*/
//#define NDEBUG

#undef pr_debug             /* undef it, just in case */

#ifndef NDEBUG
 #ifdef __KERNEL__
      /* This one if debugging is on, and kernel space */
  #define pr_debug(fmt, args...) printk( KERN_ERR fmt, ## args)
 #else
      /* This one for user space */
  #define pr_debug(fmt, args...) fprintf(stderr, fmt, ## args)
 #endif
#else
 #define pr_debug(fmt, args...) /* not debugging: nothing */
#endif

******************************

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include "debug.h"

/*usage: ./file_copy file1 file2 */

void usage (const char *s)
{
 printf("usage:\n\t%s src_file dest_file\n", s);
}

int main(int argc, char **argv)
{
 FILE * src_fp, *dst_fp;
 if (argc != 3) {
  usage(argv[0]);
  exit(1);
 }

 src_fp = fopen(argv[1], "r");
 dst_fp = fopen(argv[2], "w+");
 
 assert( (src_fp !=NULL) && (dst_fp != NULL) );

 if (!src_fp || !dst_fp ) {
  usage(argv[0]);
  exit(1);
 }
 
 pr_debug("Hello, copying start!\n"); 
 
 while( !feof(src_fp)) {
  int c,d;
  c = fgetc(src_fp);
  d = fputc(c, dst_fp);
  if (d == EOF)  {
   pr_debug("fputc");
   continue;
  }  
 }
 
 pr_debug("OK, copying finished!\n");
 
 fclose(src_fp);
 fclose(dst_fp);
 return 0;
}