numpy fromfile(count = -1) returns array of zeros on Mac OS for huge filesize

Question

I am reading a file using numpy.fromfile:

mat1=numpy.fromfile("path/to/file", numpy.uint8, 40000, "")

this reads the file as I expect.

but when I read the entire file:

mat1=numpy.fromfile("path/to/file", numpy.uint8, -1, "")

this gives me an array of zeros. [0,0,0,...,0,0,0]

I tired: numpy.count_nonzeros(mat1) which gives 0

size(mat1) gives the exact size of the file in bytes. So it makes an array of the expected size, but its full of zeros.

Answer 1

This was apparently mitigated by OS X upgrades. The original issue pointed out by @MichaelJCox was closed, but a patch was never applied:

Closing. The fix is to upgrade to Mavericks.