tools/dtdesc/c_iff/checkiff.c

   1 /*
   2  *  c_iff - a portable IFF-parser
   3  *
   4  *  Copyright (C) 2000, 2001 Joerg Dietrich
   5  *
   6  *  This is the AROS-version of c_iff.
   7  *  It is distributed under the AROS Public License.
   8  *  But I reserve the right to distribute
   9  *  my own version under other licenses.
  10  */
  11
  12 /*
  13  *  checkiff.c - check if it's a valid IFF
  14  */
  15
  16 #include "c_iff.h"
  17
  18 /****** c_iff/CheckIFF ******************************************************
  19 *
  20 *   NAME
  21 *       CheckIFF -- Check the file, if it's a valid IFF
  22 *
  23 *   SYNOPSIS
  24 *       Success = CheckIFF( TheHandle )
  25 *
  26 *       int CheckIFF( struct IFFHandle * )
  27 *
  28 *   FUNCTION
  29 *       This internal function scans a file freshly opened with OpenIFF(),
  30 *       if it is a valid IFF-file.
  31 *
  32 *   INPUTS
  33 *       TheHandle   - IFFHandle to scan
  34 *
  35 *   RESULT
  36 *       Success     - TRUE when it's a valid IFF, otherwise FALSE
  37 *
  38 *   EXAMPLE
  39 *
  40 *   NOTES
  41 *       Sets TheHandle->IFFType to the value found in the IFF-file.
  42 *       This function only recognises 'FORM'-IFFs.
  43 *       The "EA IFF 85" standard  specifies several other IFFs.
  44 *       But these are very rarly used.
  45 *       The file-position-indicator  must point to offset 0 when entering
  46 *       this function. It points to offset 12 after leaving the function.
  47 *
  48 *   BUGS
  49 *
  50 *   SEE ALSO
  51 *       OpenIFF()
  52 *
  53 *****************************************************************************
  54 *
  55 *       Private notes:
  56 */
  57
  58 int CheckIFF(struct IFFHandle *TheHandle)
  59 {
  60  uint32_t Buffer[3];
  61
  62  if(!TheHandle)
  63  {
  64   return(FALSE);
  65  }
  66
  67  if(!(fread((void *) Buffer, sizeof(uint32_t), 3, TheHandle->TheFile)==3))
  68  {
  69   return(FALSE);
  70  }
  71
  72  Buffer[0]=Swap32IfLE(Buffer[0]);
  73  Buffer[1]=Swap32IfLE(Buffer[1]);
  74  Buffer[2]=Swap32IfLE(Buffer[2]);
  75
  76  if(!(Buffer[0]==ID_FORM))
  77  {
  78   return(FALSE);
  79  }
  80
  81  if(!((Buffer[1] + 2*sizeof(uint32_t))==FileSize(TheHandle->TheFile)))
  82  {
  83   return(FALSE);
  84  }
  85
  86  TheHandle->IFFType=Buffer[2];
  87
  88  return(TRUE);
  89 }
  90
  91