Programming

You don't need to use lseek64 explicitly. Applications are made large file aware with

Code:

-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64

or

Code:

-D_LARGEFILE64_SOURCE

when compiling.

Searching for largefile should yield more info.

If you're running a 64-bit install, just compile your code as a 64-bit binary and don't worry about special handling for files greater than 2 GB in size.

Unless your code makes incorrect and unsupported assumptions that pointers and sizes are integer or unsigned integer values, that is. Pointers are pointers, sizes are size_t/ssize_t, differences in pointers are ptrdiff_t, etc. Putting those values into an int or unsigned is wrong. Sun's latest C++ compiler has an "-xport64" argument you can pass to have it look for improper usages such as putting size_t values into unsigned ints. I don't know offhand if GCC does anything similar.

And FWIW, the effective limit is 2 GB and not 4 GB, or at least should be - because failed calls return -1, which translates to 0xFFFFFFFF in a 32-bit value, making that byte effectively unreachable via lseek(). I'm pretty sure the kernel implementation enforces this.