Another example

#include <stdio.h>
#include <string.h>
#include <cole/cole.h>

int
main (int argc, char **argv)
{
  pps_entry *stream_tree;
  U32 root_stream;
  U32 stream;
  FILE * f;
  unsigned char buff[6];

  if (argc != 2)
    {
      fprintf (stderr, "cole example 2. cole is a free C OLE library.\n");
      fprintf (stderr, "Usage: coleexample2 FILE.\n");
      return 1;
    }

  if (OLEdecode (argv[1], &stream_tree, &root_stream, 0)) {
      printf ("File is not a Microsoft Excel one.\n");
      return 1;
  }

  for (stream = stream_tree[root_stream].dir;
       stream != 0xffffffff;
       stream = stream_tree[stream].next) {
      if (stream_tree[stream].type != 1 && stream_tree[stream].level == 1)
	  if (!strcmp(stream_tree[stream].name, "Workbook") ||
	      !strcmp(stream_tree[stream].name, "Book")) {
	     /* Book stream found */
	     f = fopen (stream_tree[stream].filename, "rb");
	     if (f == NULL) {
		perror ("Error opening temporal file");
		freeOLEtree (stream_tree);
		return 1;
	     }
	     if (fread (buff, 1, 6, f) != 6) {
		perror ("Error reading temporal file");
		fclose (f);
		freeOLEtree (stream_tree);
		return 1;
	     }
	     /* the next is from the internal structure of a Excel stream */
	     if (buff[0] != 0x09 || buff[1] != 0x08) {
	        printf ("File is not a Microsoft Excel one.\n");
		fclose (f);
		freeOLEtree (stream_tree);
		return 1;
	     }
	     if (buff[4] != 0x00 || (buff[5] != 0x05 && buff[5] != 0x06)) {
	        printf ("File is from an unknown Microsoft Excel version.\n");
		fclose (f);
		freeOLEtree (stream_tree);
		return 1;
	     }
	     if (buff[5] == 0x05)
		printf ("File is from Microsoft Excel version 5 or 7.\n");
	     else
		printf ("File is from Microsoft Excel version 8.\n");

	     fclose (f);
	     freeOLEtree (stream_tree);
	     return 0;
	  }
  }

  printf ("File is not a Microsoft Excel one.\n");
  freeOLEtree (stream_tree);
  return 0;
}

$ coleexample2 examples/sprsheet.xls
File is from Microsoft Excel version 5 or 7.
$ coleexample2 examples/text.doc
File is not a Microsoft Excel one.
$ coleexample2 README
File is not a Microsoft Excel one.