possum-db 0.2.2

concurrent disk-backed cache supporting efficient direct file I/O, transactions, and snapshots using file cloning and sparse files
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

use std::io;
use std::io::Error;

use super::*;

pub fn punchfile(file: &File, offset: u64, length: u64) -> io::Result<()> {
    // TODO: On solaris we want fcntl(F_FREESP);
    let punchhole = libc::fpunchhole_t {
        fp_flags: 0,
        reserved: 0,
        fp_offset: offset.try_into().unwrap(),
        fp_length: length.try_into().unwrap(),
    };
    let first_arg = &punchhole;
    let fcntl_res = unsafe { libc::fcntl(file.as_fd().as_raw_fd(), libc::F_PUNCHHOLE, first_arg) };
    if fcntl_res == -1 {
        return Err(Error::last_os_error());
    }
    Ok(())
}