1 files changed, 40 insertions, 0 deletions
diff --git a/library/std/src/sys/unix/memchr.rs b/library/std/src/sys/unix/memchr.rs
new file mode 100644
index 000000000..73ba604ec
--- /dev/null
+++ b/library/std/src/sys/unix/memchr.rs
@@ -0,0 +1,40 @@
+// 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.addr() - haystack.as_ptr().addr()) }
+}
+
+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(),
+            )
+        };
+        // FIXME: this should *likely* use `offset_from`, but more
+        // investigation is needed (including running tests in miri).
+        if p.is_null() { None } else { Some(p.addr() - haystack.as_ptr().addr()) }
+    }
+
+    #[cfg(not(target_os = "linux"))]
+    fn memrchr_specific(needle: u8, haystack: &[u8]) -> Option<usize> {
+        core::slice::memchr::memrchr(needle, haystack)
+    }
+
+    memrchr_specific(needle, haystack)
+}