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// This module defines safe wrappers around memchr (POSIX) and memrchr (GNU
// extension).
#![allow(dead_code)]
use libc::{c_int, c_void, size_t};
pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
// SAFETY: This is safe to call since all pointers are valid.
let p = unsafe {
libc::memchr(
haystack.as_ptr() as *const c_void,
needle as c_int,
haystack.len() as size_t,
)
};
if p.is_null() {
None
} else {
Some(p as usize - (haystack.as_ptr() as usize))
}
}
// memrchr is a GNU extension. We know it's available on Linux at least.
#[cfg(target_os = "linux")]
pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {
// GNU's memrchr() will - unlike memchr() - error if haystack is empty.
if haystack.is_empty() {
return None;
}
// SAFETY: This is safe to call since all pointers are valid.
let p = unsafe {
libc::memrchr(
haystack.as_ptr() as *const c_void,
needle as c_int,
haystack.len() as size_t,
)
};
if p.is_null() {
None
} else {
Some(p as usize - (haystack.as_ptr() as usize))
}
}