FlashFS: Bug in fcheck (fs_fcheck.c)

   for (bl = 0; bl < fcb->NumSect; bl++) {
      /* Check all File Blocks for invalid FID and check file pointers for */
      /* reasonable values in ascending order.                             */
      adr = fs_adr_sig (bl, fcb);
      adr = fs_rd_sig (adr, &fa.end);
      if (fa.end != fcb->InitVal) {
         sa = ((DEVCONF *)fcb->DevCfg)[bl].bStart;
         for (prev = 0; ; prev = fa.end) {
            adr = fs_rd_alloc (adr, &fa);

            if (fa.end == fcb->InitVal) break;    // << this line has to be here!!

            if (fa.fileID == 0x8000) {
               /* Error, not existing file ID. */
               return (1);
            }
            if (fa.end < prev) {
               /* Error, not ascending allocation pointers. */
               return (1);
            }
            if ((sa + fa.end) > (adr & ~1)) {
               /* Error, overlapping file allocation record. */
               return (1);
            }

            // if (fa.end == fcb->InitVal) break;   // << originally, the line was here.

            // but if 'sa' == 0 (first file on SPI-Flash Drive is at origin '0'), the
            // check above "if ((sa + fa.end) > (adr & ~1))" fails already, because fa.end == 0xFFFFFFFF!!!
         }
      }
   }