1 // This module defines safe wrappers around memchr (POSIX) and memrchr (GNU
2 // extension).
3
4 #![allow(dead_code)]
5
6 use libc::{c_int, c_void, size_t};
7
memchr(needle: u8, haystack: &[u8]) -> Option<usize>8 pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
9 // SAFETY: This is safe to call since all pointers are valid.
10 let p = unsafe {
11 libc::memchr(
12 haystack.as_ptr() as *const c_void,
13 needle as c_int,
14 haystack.len() as size_t,
15 )
16 };
17 if p.is_null() {
18 None
19 } else {
20 Some(p as usize - (haystack.as_ptr() as usize))
21 }
22 }
23
24 // memrchr is a GNU extension. We know it's available on Linux at least.
25 #[cfg(target_os = "linux")]
memrchr(needle: u8, haystack: &[u8]) -> Option<usize>26 pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {
27 // GNU's memrchr() will - unlike memchr() - error if haystack is empty.
28 if haystack.is_empty() {
29 return None;
30 }
31 // SAFETY: This is safe to call since all pointers are valid.
32 let p = unsafe {
33 libc::memrchr(
34 haystack.as_ptr() as *const c_void,
35 needle as c_int,
36 haystack.len() as size_t,
37 )
38 };
39 if p.is_null() {
40 None
41 } else {
42 Some(p as usize - (haystack.as_ptr() as usize))
43 }
44 }
45