From d5d67b56f4a7ba8db25a595c03ba864b4d956d18 Mon Sep 17 00:00:00 2001
From: seafoodfry <99568361+seafoodfry@users.noreply.github.com>
Date: Fri, 12 Jul 2024 15:14:44 -0400
Subject: [PATCH] Documented the discrepancy in arguments for the clone sys
 call

Used
https://man7.org/linux/man-pages/man2/clone.2.html#VERSIONS
as reference

Signed-off-by: seafoodfry <99568361+seafoodfry@users.noreply.github.com>
---
 src/jailer/src/env.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/jailer/src/env.rs b/src/jailer/src/env.rs
index 5e5d5a66cdc..05e6235e5f6 100644
--- a/src/jailer/src/env.rs
+++ b/src/jailer/src/env.rs
@@ -83,6 +83,15 @@ fn clone(child_stack: *mut libc::c_void, flags: libc::c_int) -> Result<libc::c_i
     SyscallReturnCode(
         // SAFETY: This is safe because we are using a library function with valid parameters.
         libc::c_int::try_from(unsafe {
+            // Note: the order of arguments in the raw syscall differs between platforms.
+            // On x86-64, for example, the parameters passed are `flags`, `stack`, `parent_tid`,
+            // `child_tid`, and `tls`. But on On x86-32, and several other common architectures
+            // (including score, ARM, ARM 64) the order of the last two arguments is reversed,
+            // and instead we must pass `flags`, `stack`, `parent_tid`, `tls`, and `child_tid`.
+            // This difference in architecture currently doesn't matter because the last 2
+            // arguments are all 0 but if this were to change we should add an attribute such as
+            // #[cfg(target_arch = "x86_64")] or #[cfg(target_arch = "aarch64")] for each different
+            // call.
             libc::syscall(libc::SYS_clone, flags, child_stack, 0, 0, 0)
         })
         // Unwrap is needed because PIDs are 32-bit.