mdw@git.distorted.org.uk Git - ssr/blob - StraySrc/Libraries/Steel/c/crc

   1 /*
   2  * crc
   3  *  Checks CRC values for resource files
   4  *
   5  * v. 1.00 (24 August 1993)
   6  *
   7  * © 1993-1998 Straylight
   8  */
   9
  10 /*----- Licensing note ----------------------------------------------------*
  11  *
  12  * This file is part of Straylight's Steel library.
  13  *
  14  * Steel is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2, or (at your option)
  17  * any later version.
  18  *
  19  * Steel is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with Steel.  If not, write to the Free Software Foundation,
  26  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 #include "crc.h"
  30 #include "crc32.h"
  31 #include "os.h"
  32 #include "res.h"
  33 #include "msgs.h"
  34 #include "werr.h"
  35 #include "wimpt.h"
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38
  39 /*
  40  * long crc__doCRC(char *filename,int offset)
  41  *
  42  * Use
  43  *  Returns the CRC value for a file starting from a certain offset.
  44  *
  45  * Parameters
  46  *  char *filename == the resource filename to use
  47  *  int offset == the offset to start from
  48  *
  49  * Returns
  50  *  A 4-byte CRC value.
  51  */
  52
  53 static long crc__doCRC(char *filename,int offset)
  54 {
  55   FILE *fp;
  56   char buffer[1024];
  57   int read;
  58   long c=0;
  59   fp=res_openfile(filename,"rb");
  60   if (!fp)
  61   {
  62     werr(FALSE,msgs_lookup("crcFNF:Couldn't open file '%s'."),filename);
  63     exit(0);
  64   }
  65   fseek(fp,offset,SEEK_SET);
  66   do
  67   {
  68     read=fread(buffer,1,1024,fp);
  69     c=crc32(c,buffer,read,1);
  70   }
  71   while (read==1024);
  72   fclose(fp);
  73   return (c);
  74 }
  75
  76 /*
  77  * long crc(char *filename)
  78  *
  79  * Use
  80  *  Calculates the CRC value for the file specified.  Uses the same method
  81  *  as WindowEd etc.
  82  *
  83  * Parameters
  84  *  char *filename == the filename of the file to check (leaf only - it's
  85  *    passed through res_findname()).  Note that CRC-checking the
  86  *    '!RunImage' file is rather silly.
  87  *
  88  * Returns
  89  *  A 4-byte CRC value
  90  */
  91
  92 long crc(char *filename)
  93 {
  94   return (crc__doCRC(filename,0));
  95 }
  96
  97 /*
  98  * void crc_check(char *filename,int check)
  99  *
 100  * Use
 101  *  Checks a CRC value for a file and reports a fatal error if the check
 102  *  fails.
 103  *
 104  * Parameters
 105  *  char *filename == the leafname of the file
 106  *  long check == the CRC number to check with
 107  */
 108
 109 void crc_check(char *filename,long check)
 110 {
 111   if (check==-1)
 112     return;
 113   if (crc__doCRC(filename,0)!=check)
 114   {
 115     werr
 116     (
 117       FALSE,
 118       msgs_lookup("crcFC:%s resource file '%s' has been corrupted.  "
 119                   "Please restore this file from the distribution disk."),
 120       wimpt_programname(),
 121       filename
 122     );
 123     exit(0);
 124   }
 125 }
 126
 127 /*
 128  * void crc_checkRunImage(void)
 129  *
 130  * Use
 131  *  Corruption-checks the main !RunImage file.  It must have been passed
 132  *  through CodeScr first, to install the CRC into the code.
 133  */
 134
 135 void crc_checkRunImage(void)
 136 {
 137   FILE *fp=res_openfile("!RunImage","r");
 138   long c;
 139   if (!fp)
 140     werr(TRUE,msgs_lookup("crcFNF:Couldn't open file '%s'."),"!RunImage");
 141   fseek(fp,8,SEEK_SET);
 142   fread(&c,4,1,fp);
 143   fclose(fp);
 144   if (c!=crc__doCRC("!RunImage",12))
 145   {
 146     werr
 147     (
 148       FALSE,
 149       msgs_lookup("crcFC:%s resource file '%s' has been corrupted.  "
 150                   "Please restore this file from the distribution disk."),
 151       wimpt_programname(),
 152       "!RunImage"
 153     );
 154     exit(0);
 155   }
 156 }