root/user/testbin/hash/hash.c

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DEFINITIONS

This source file includes following definitions.
  1. main

   1 /*
   2  * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
   3  *      The President and Fellows of Harvard College.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29 
  30 /*
  31  * hash: Takes a file and computes a "hash" value by adding together all
  32  * the values in the file mod some largish prime.
  33  *
  34  * Once the basic system calls are complete, this should work on any
  35  * file the system supports. However, it's probably of most use for
  36  * testing your file system code.
  37  *
  38  * This should really be replaced with a real hash, like MD5 or SHA-1.
  39  */
  40 
  41 #include <stdio.h>
  42 #include <unistd.h>
  43 #include <fcntl.h>
  44 #include <err.h>
  45 
  46 #ifdef HOST
  47 #include "hostcompat.h"
  48 #endif
  49 
  50 #define HASHP 104729
  51 
  52 int
  53 main(int argc, char *argv[])
  54 {
  55         int fd;
  56         char readbuf[1];
  57         int j = 0;
  58 
  59 #ifdef HOST
  60         hostcompat_init(argc, argv);
  61 #endif
  62 
  63         if (argc != 2) {
  64                 errx(1, "Usage: hash filename");
  65         }
  66         
  67         fd = open(argv[1], O_RDONLY, 0664);
  68         
  69         if (fd<0) { 
  70                 err(1, "%s", argv[1]);
  71         }
  72 
  73         for (;;) {
  74                 if (read(fd, readbuf, 1) <= 0) break;
  75                 j = ((j*8) + (int) readbuf[0]) % HASHP;
  76         }
  77 
  78         close(fd);
  79         
  80         printf("Hash : %d\n", j);
  81 
  82         return 0;
  83 }

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