vendor/memchr/src/memchr/c.rs

   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
   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")]
  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 }