From e75a23602aed74595cfeeb9d26e5faf3011a9244 Mon Sep 17 00:00:00 2001
From: Mackenzie Clark <mackenzie.a.z.c@gmail.com>
Date: Fri, 22 Mar 2019 16:57:29 -0700
Subject: [PATCH] wip

---
 lib/emscripten/src/syscalls/emscripten_vfs.rs | 10 +++++++-
 lib/emscripten/src/syscalls/unix/select.rs    | 23 ++++++++++++++++++-
 lib/emscripten/src/syscalls/unix/vfs.rs       | 11 +++++++--
 3 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/lib/emscripten/src/syscalls/emscripten_vfs.rs b/lib/emscripten/src/syscalls/emscripten_vfs.rs
index a8c9f54a8..a34a42e68 100644
--- a/lib/emscripten/src/syscalls/emscripten_vfs.rs
+++ b/lib/emscripten/src/syscalls/emscripten_vfs.rs
@@ -97,7 +97,12 @@ impl EmscriptenVfs {
 
     pub fn get_host_socket_fd(&self, vfd: &VirtualFd) -> Option<Fd> {
         match self.fd_map.get(&vfd) {
-            Some(FileHandle::Socket(fd)) => Some(*fd),
+            Some(FileHandle::Socket(fd)) => {
+                if *fd < 0 {
+                    panic!()
+                }
+                Some(*fd)
+            },
             _ => None,
         }
     }
@@ -119,6 +124,9 @@ impl EmscriptenVfs {
 
     pub fn new_socket_fd(&mut self, host_fd: Fd) -> VirtualFd {
         let vfd = self.next_lowest_fd();
+        if host_fd < 0 {
+            panic!()
+        }
         self.fd_map.insert(vfd.clone(), FileHandle::Socket(host_fd));
         vfd
     }
diff --git a/lib/emscripten/src/syscalls/unix/select.rs b/lib/emscripten/src/syscalls/unix/select.rs
index 6f77708e8..315154988 100644
--- a/lib/emscripten/src/syscalls/unix/select.rs
+++ b/lib/emscripten/src/syscalls/unix/select.rs
@@ -194,6 +194,27 @@ pub fn ___syscall142(ctx: &mut Ctx, _which: libc::c_int, mut varargs: VarArgs) -
             .map(|pair| pair.host_fd)
             .collect::<Vec<_>>()
     );
+
+    unsafe {
+        use libc::FD_ISSET;
+        let s = 3;
+        let x = [
+            FD_ISSET(s, readfds_set_ptr),
+            FD_ISSET(s + 1, readfds_set_ptr),
+            FD_ISSET(s + 2, readfds_set_ptr),
+            FD_ISSET(s + 3, readfds_set_ptr),
+            FD_ISSET(s + 4, readfds_set_ptr),
+            FD_ISSET(s + 5, readfds_set_ptr),
+            FD_ISSET(s + 6, readfds_set_ptr),
+            FD_ISSET(s + 7, readfds_set_ptr),
+            FD_ISSET(s + 8, readfds_set_ptr),
+            FD_ISSET(s + 9, readfds_set_ptr),
+            FD_ISSET(s + 10, readfds_set_ptr),
+            FD_ISSET(s + 11, readfds_set_ptr),
+        ];
+        debug!("BEFORE sets start with fd #{}: {:?}", s, x);
+    }
+
     let fds_slice = unsafe { slice::from_raw_parts(readfds_set_ptr as *const u8, 4) } as &[u8];
     debug!("host read set before: {:?}", fds_slice);
     let mut result = unsafe { libc::select(sz, readfds_set_ptr, writefds_set_ptr, 0 as _, 0 as _) };
@@ -216,7 +237,7 @@ pub fn ___syscall142(ctx: &mut Ctx, _which: libc::c_int, mut varargs: VarArgs) -
             FD_ISSET(s + 10, readfds_set_ptr),
             FD_ISSET(s + 11, readfds_set_ptr),
         ];
-        debug!("sets (start with fd #{}: {:?}", s, x);
+        debug!("AFTER sets (start with fd #{}: {:?}", s, x);
     }
 
     if result == -1 {
diff --git a/lib/emscripten/src/syscalls/unix/vfs.rs b/lib/emscripten/src/syscalls/unix/vfs.rs
index 9f1bf729c..d00cc5879 100644
--- a/lib/emscripten/src/syscalls/unix/vfs.rs
+++ b/lib/emscripten/src/syscalls/unix/vfs.rs
@@ -264,7 +264,7 @@ pub fn ___syscall63(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_int
         Some(FileHandle::Socket(src_host_fd)) => unsafe {
             // get a dst file descriptor, or just use the underlying dup syscall
             let dst_host_fd = libc::dup(*src_host_fd);
-            if dst_host_fd == -1 {
+            if dst_host_fd < 0 {
                 panic!()
             }
             FileHandle::Socket(dst_host_fd)
@@ -440,6 +440,10 @@ pub fn ___syscall102(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_in
             let new_accept_host_fd =
                 unsafe { libc::accept(host_socket_fd, address, address_len_addr) };
 
+            if new_accept_host_fd < 0 {
+                panic!("accept file descriptor should not be negative.");
+            }
+
             unsafe {
                 let address_linux =
                     emscripten_memory_pointer!(ctx.memory(0), address_addr) as *mut LinuxSockAddr;
@@ -548,6 +552,9 @@ pub fn ___syscall102(ctx: &mut Ctx, _which: c_int, mut varargs: VarArgs) -> c_in
                 "recvfrom: socket: {}, flags: {}, len: {}, result: {}",
                 socket, flags, len, recv_result
             );
+            if recv_result < 0 {
+                panic!("recvfrom result was less than zero. Errno: {}", errno::errno());
+            }
             recv_result
         }
         14 => {
@@ -691,7 +698,7 @@ pub fn ___syscall146(ctx: &mut Ctx, _which: i32, mut varargs: VarArgs) -> i32 {
                 Some(FileHandle::Socket(host_fd)) => unsafe {
                     let count = libc::write(*host_fd, iov_buf_ptr, count);
                     if count < 0 {
-                        panic!()
+                        panic!("the count from write was less than zero. errno: {}", errno::errno());
                     }
                     count as usize
                 },