Add macos clonefile functions

libc-test/build.rs

@@ -217,6 +217,8 @@ fn test_apple(target: &str) {
         "stdio.h",
         "stdlib.h",
         "string.h",
+        "sys/attr.h",
+        "sys/clonefile.h",
         "sys/event.h",
         "sys/file.h",
         "sys/ioctl.h",

libc-test/semver/apple.txt

@@ -1514,6 +1514,8 @@ chflags
 chroot
 clearerr
 clock_getres
+clonefile
+clonefileat
 cmsghdr
 connectx
 cpu_subtype_t
@@ -1531,6 +1533,7 @@ exchangedata
 faccessat
 fchdir
 fchflags
+fclonefileat
 fdopendir
 fgetxattr
 flistxattr

src/unix/bsd/apple/mod.rs

@@ -3835,6 +3835,24 @@ extern "C" {
         outbytesleft: *mut ::size_t,
     ) -> ::size_t;
     pub fn iconv_close(cd: iconv_t) -> ::c_int;
+
+    // Copy-on-write functions.
+    // According to the man page `flags` is an `int` but in the header
+    // this is a `uint32_t`.
+    pub fn clonefile(src: *const ::c_char, dst: *const ::c_char, flags: u32) -> ::c_int;
+    pub fn clonefileat(
+        src_dirfd: ::c_int,
+        src: *const ::c_char,
+        dst_dirfd: ::c_int,
+        dst: *const ::c_char,
+        flags: u32,
+    ) -> ::c_int;
+    pub fn fclonefileat(
+        srcfd: ::c_int,
+        dst_dirfd: ::c_int,
+        dst: *const ::c_char,
+        flags: u32,
+    ) -> ::c_int;
 }
 
 cfg_if! {