From 1e48b13948a2d5c6459d0d57f3fdb5395a4d2b4d Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Sun, 4 May 2025 09:32:10 -0600
Subject: [PATCH] Debug recvmsg on redox

---
 src/header/sys_socket/mod.rs | 61 ++++++++++++++++++++++++++++++++++++
 src/platform/redox/socket.rs | 20 ++++++++++--
 2 files changed, 79 insertions(+), 2 deletions(-)

diff --git a/src/header/sys_socket/mod.rs b/src/header/sys_socket/mod.rs
index 58f9e5912a..527afa03ba 100644
--- a/src/header/sys_socket/mod.rs
+++ b/src/header/sys_socket/mod.rs
@@ -24,6 +24,7 @@ pub struct linger {
 pub extern "C" fn _cbindgen_export_linger(linger: linger) {}
 
 #[repr(C)]
+#[derive(Debug)]
 pub struct msghdr {
     pub msg_name: *mut c_void,
     pub msg_namelen: socklen_t,
@@ -35,6 +36,7 @@ pub struct msghdr {
 }
 
 #[repr(C)]
+#[derive(Debug)]
 pub struct cmsghdr {
     pub cmsg_len: size_t,
     pub cmsg_level: c_int,
@@ -71,6 +73,65 @@ pub struct sockaddr_storage {
     __ss_align: usize,
 }
 
+// These must match C macros in include/bits/sys/socket.h {
+pub unsafe extern "C" fn __CMSG_LEN(cmsg: *const cmsghdr) -> ssize_t {
+    ((unsafe { (*cmsg).cmsg_len as size_t } + mem::size_of::<c_long>() - 1)
+        & !(mem::size_of::<c_long>() - 1)) as ssize_t
+}
+
+pub unsafe extern "C" fn __CMSG_NEXT(cmsg: *const cmsghdr) -> *mut c_uchar {
+    unsafe { (cmsg as *mut c_uchar).offset(__CMSG_LEN(cmsg)) }
+}
+
+pub unsafe extern "C" fn __MHDR_END(mhdr: *const msghdr) -> *mut c_uchar {
+    unsafe { ((*mhdr).msg_control as *mut c_uchar).offset((*mhdr).msg_controllen as isize) }
+}
+
+pub unsafe extern "C" fn CMSG_DATA(cmsg: *const cmsghdr) -> *mut c_uchar {
+    unsafe { (cmsg as *mut c_uchar).offset(CMSG_ALIGN(mem::size_of::<cmsghdr>()) as isize) }
+}
+
+pub unsafe extern "C" fn CMSG_NXTHDR(mhdr: *const msghdr, cmsg: *const cmsghdr) -> *mut cmsghdr {
+    if cmsg.is_null() {
+        return CMSG_FIRSTHDR(mhdr);
+    };
+
+    unsafe {
+        let next = cmsg as usize
+            + CMSG_ALIGN((*cmsg).cmsg_len as usize)
+            + CMSG_ALIGN(mem::size_of::<cmsghdr>());
+        let max = (*mhdr).msg_control as usize + (*mhdr).msg_controllen as usize;
+        if next > max {
+            0 as *mut cmsghdr
+        } else {
+            (cmsg as usize + CMSG_ALIGN((*cmsg).cmsg_len as usize)) as *mut cmsghdr
+        }
+    }
+}
+
+pub unsafe extern "C" fn CMSG_FIRSTHDR(mhdr: *const msghdr) -> *mut cmsghdr {
+    unsafe {
+        if (*mhdr).msg_controllen as usize >= mem::size_of::<cmsghdr>() {
+            (*mhdr).msg_control as *mut cmsghdr
+        } else {
+            0 as *mut cmsghdr
+        }
+    }
+}
+
+pub unsafe extern "C" fn CMSG_ALIGN(len: size_t) -> size_t {
+    (len + mem::size_of::<size_t>() - 1) & !(mem::size_of::<size_t>() - 1)
+}
+
+pub unsafe extern "C" fn CMSG_SPACE(len: c_uint) -> c_uint {
+    (CMSG_ALIGN(len as size_t) + CMSG_ALIGN(mem::size_of::<cmsghdr>())) as c_uint
+}
+
+pub unsafe extern "C" fn CMSG_LEN(length: c_uint) -> c_uint {
+    (CMSG_ALIGN(mem::size_of::<cmsghdr>()) + length as usize) as c_uint
+}
+// } These must match C macros in include/bits/sys/socket.h
+
 #[no_mangle]
 pub unsafe extern "C" fn accept(
     socket: c_int,
diff --git a/src/platform/redox/socket.rs b/src/platform/redox/socket.rs
index f28f23fea5..1e571f4bfb 100644
--- a/src/platform/redox/socket.rs
+++ b/src/platform/redox/socket.rs
@@ -14,7 +14,9 @@ use crate::{
         errno::{EAFNOSUPPORT, EDOM, EFAULT, EINVAL, ENOSYS, EOPNOTSUPP, EPROTONOSUPPORT},
         netinet_in::{in_addr, in_port_t, sockaddr_in},
         string::strnlen,
-        sys_socket::{constants::*, msghdr, sa_family_t, sockaddr, socklen_t},
+        sys_socket::{
+            constants::*, msghdr, sa_family_t, sockaddr, socklen_t, CMSG_FIRSTHDR, CMSG_NXTHDR,
+        },
         sys_time::timeval,
         sys_un::sockaddr_un,
     },
@@ -310,7 +312,21 @@ impl PalSocket for Sys {
 
     unsafe fn recvmsg(socket: c_int, msg: *mut msghdr, flags: c_int) -> Result<usize> {
         //TODO: implement recvfrom with recvmsg
-        eprintln!("recvmsg not implemented on redox");
+        eprintln!(
+            "recvmsg({}, {:p}, {:#x}) not implemented on redox",
+            socket, msg, flags
+        );
+        if !msg.is_null() {
+            let msg = &*msg;
+            eprintln!("{:#x?}", msg);
+            if !msg.msg_control.is_null() {
+                let mut cmsg = CMSG_FIRSTHDR(msg);
+                while !cmsg.is_null() {
+                    eprintln!("{:#x?}", *cmsg);
+                    cmsg = CMSG_NXTHDR(msg, cmsg);
+                }
+            }
+        }
         Err(Errno(ENOSYS))
     }