fix:add off_t conversion

[alexs-sh]

Hi,

1. Thanks for the perfect tool
2. I ran the bytehound on iMX6 board (ARM CPU). It works fine on a target device, but I faced light issues during the build. All of them are related to mixing 32/64 off_t types.

Here is an example:

error[E0308]: mismatched types
   --> preload/src/api.rs:79:55
    |
79  |     mmap_internal( addr, length, prot, flags, fildes, off, MapKind::Jemalloc )
    |     -------------                                     ^^^ expected `i64`, found `i32`
    |     |
    |     arguments to this function are incorrect
    |
note: function defined here
   --> preload/src/api.rs:895:11
    |
895 | unsafe fn mmap_internal( addr: *mut c_void, length: size_t, prot: c_int, flags: c_int, fildes: c_int, off: libc::off64_t, kind: MapKind )...
    |           ^^^^^^^^^^^^^                                                                               ------------------
help: you can convert an `i32` to an `i64`
    |
79  |     mmap_internal( addr, length, prot, flags, fildes, off.into(), MapKind::Jemalloc )
    |                                                          +++++++

error[E0308]: mismatched types
   --> preload/src/api.rs:881:97
    |
881 |             ptr = syscall::mmap( p0.add( 4096 ), length, prot, flags | libc::MAP_FIXED, fildes, off );
    |                   ------------- arguments to this function are incorrect                        ^^^ expected `i32`, found `i64`
    |
note: function defined here
   --> preload/src/syscall.rs:106:15

I added fixes to make everything buildable/runnable on the target device and prepared PR for discussion. I'm not sure that it's the correct or expected way to deal with problems.

The issue reproduced in 2 enviroments:

• Ubuntu 23 & rustc 1.66.0-nightly (c0983a9aa 2022-10-12)
• ArchLinux & rustc 1.68.0 (2c8cc3432 2023-03-06) or rustc 1.66.0-nightly (c0983a9aa 2022-10-12)

Build command:

• cargo build --target=armv7-unknown-linux-gnueabihf --release

[hardliner66]

I recently stumbled upon the same problem, but I think instead of using the bigger type and converting/truncating it, would be to use off_t instead of off64_t, which would make it the correct size for the platform it is compiled for.

e.g.: make_compilable_for_armv7.patch

[alexs-sh]

@hardliner66 Thanks for the information. I agree. The version with off_t looks better.

[alexs-sh]

@koute What do you think about that?