ccdfits fails on very large fits files

[teuben]

example of failure:

  ccdgen  cube1 noise 0,1 1024,1024,1024
  ccdfits cube1 cube1.fits
  fitshead cube1.fits 

fitshead will then spit out garbage. The header appears incomplete.

[teuben]

The cause was some important variables in fitsio.c - offset and length related - that needed to be off_t instead of int. Old code (from miriad) that was never fully converted to 64bit.
Fixed now.