library/std/src/sys/unix/memchr.rs

   1 // Original implementation taken from rust-memchr.
   2 // Copyright 2015 Andrew Gallant, bluss and Nicolas Koch
   3
   4 pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
   5     let p = unsafe {
   6         libc::memchr(
   7             haystack.as_ptr() as *const libc::c_void,
   8             needle as libc::c_int,
   9             haystack.len(),
  10         )
  11     };
  12     if p.is_null() { None } else { Some(p as usize - (haystack.as_ptr() as usize)) }
  13 }
  14
  15 pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {
  16     #[cfg(target_os = "linux")]
  17     fn memrchr_specific(needle: u8, haystack: &[u8]) -> Option<usize> {
  18         // GNU's memrchr() will - unlike memchr() - error if haystack is empty.
  19         if haystack.is_empty() {
  20             return None;
  21         }
  22         let p = unsafe {
  23             libc::memrchr(
  24                 haystack.as_ptr() as *const libc::c_void,
  25                 needle as libc::c_int,
  26                 haystack.len(),
  27             )
  28         };
  29         if p.is_null() { None } else { Some(p as usize - (haystack.as_ptr() as usize)) }
  30     }
  31
  32     #[cfg(not(target_os = "linux"))]
  33     fn memrchr_specific(needle: u8, haystack: &[u8]) -> Option<usize> {
  34         core::slice::memchr::memrchr(needle, haystack)
  35     }
  36
  37     memrchr_specific(needle, haystack)
  38 }