1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43

// Original implementation taken from rust-memchr.
// Copyright 2015 Andrew Gallant, bluss and Nicolas Koch

pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
    let p = unsafe {
        libc::memchr(
            haystack.as_ptr() as *const libc::c_void,
            needle as libc::c_int,
            haystack.len())
    };
    if p.is_null() {
        None
    } else {
        Some(p as usize - (haystack.as_ptr() as usize))
    }
}

pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {

    #[cfg(target_os = "linux")]
    fn memrchr_specific(needle: u8, haystack: &[u8]) -> Option<usize> {
        // GNU's memrchr() will - unlike memchr() - error if haystack is empty.
        if haystack.is_empty() {return None}
        let p = unsafe {
            libc::memrchr(
                haystack.as_ptr() as *const libc::c_void,
                needle as libc::c_int,
                haystack.len())
        };
        if p.is_null() {
            None
        } else {
            Some(p as usize - (haystack.as_ptr() as usize))
        }
    }

    #[cfg(not(target_os = "linux"))]
    fn memrchr_specific(needle: u8, haystack: &[u8]) -> Option<usize> {
        core::slice::memchr::memrchr(needle, haystack)
    }

    memrchr_specific(needle, haystack)
}