From c50ee722a133ac2011242a888b533844c9400ad2 Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Wed, 10 Apr 2024 14:57:44 -0700
Subject: [PATCH] Use memmem for finding needle in haystack

---
 native/src/base/misc.rs | 31 ++++++++++++++++++++++++++++++-
 native/src/boot/cpio.rs |  6 +++---
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/native/src/base/misc.rs b/native/src/base/misc.rs
index ff9d1dfd0..5413ffe92 100644
--- a/native/src/base/misc.rs
+++ b/native/src/base/misc.rs
@@ -78,11 +78,40 @@ impl<T> LibcReturn for *mut T {
     }
 }
 
+pub trait BytesExt {
+    fn find(&self, needle: &[u8]) -> Option<usize>;
+    fn contains(&self, needle: &[u8]) -> bool {
+        self.find(needle).is_some()
+    }
+}
+
+impl<T: AsRef<[u8]> + ?Sized> BytesExt for T {
+    fn find(&self, needle: &[u8]) -> Option<usize> {
+        fn inner(haystack: &[u8], needle: &[u8]) -> Option<usize> {
+            unsafe {
+                let ptr: *const u8 = libc::memmem(
+                    haystack.as_ptr().cast(),
+                    haystack.len(),
+                    needle.as_ptr().cast(),
+                    needle.len(),
+                )
+                .cast();
+                if ptr.is_null() {
+                    None
+                } else {
+                    Some(ptr.offset_from(haystack.as_ptr()) as usize)
+                }
+            }
+        }
+        inner(self.as_ref(), needle)
+    }
+}
+
 pub trait MutBytesExt {
     fn patch(&mut self, from: &[u8], to: &[u8]) -> Vec<usize>;
 }
 
-impl<T: AsMut<[u8]>> MutBytesExt for T {
+impl<T: AsMut<[u8]> + ?Sized> MutBytesExt for T {
     fn patch(&mut self, from: &[u8], to: &[u8]) -> Vec<usize> {
         ffi::mut_u8_patch(self.as_mut(), from, to)
     }
diff --git a/native/src/boot/cpio.rs b/native/src/boot/cpio.rs
index d622e76b9..432161d38 100644
--- a/native/src/boot/cpio.rs
+++ b/native/src/boot/cpio.rs
@@ -21,8 +21,8 @@ use base::libc::{
     S_IWOTH, S_IWUSR, S_IXGRP, S_IXOTH, S_IXUSR,
 };
 use base::{
-    log_err, map_args, EarlyExitExt, FsPath, LoggedResult, MappedFile, ResultExt, Utf8CStr,
-    WriteExt,
+    log_err, map_args, BytesExt, EarlyExitExt, FsPath, LoggedResult, MappedFile, ResultExt,
+    Utf8CStr, WriteExt,
 };
 
 use crate::ffi::{unxz, xz};
@@ -246,7 +246,7 @@ impl Cpio {
                 continue;
             }
             if name == "TRAILER!!!" {
-                match data[pos..].windows(6).position(|x| x == b"070701") {
+                match data[pos..].find(b"070701") {
                     Some(x) => pos += x,
                     None => break,
                 }