Added fix for ptrace from PR nix-rust#566

Author: vincenthage

src/sys/ptrace.rs

@@ -58,6 +58,8 @@ pub mod ptrace {
     pub const PTRACE_O_TRACEVFORKDONE: PtraceOptions = (1 << PTRACE_EVENT_VFORK_DONE);
     pub const PTRACE_O_TRACEEXIT: PtraceOptions      = (1 << PTRACE_EVENT_EXIT);
     pub const PTRACE_O_TRACESECCOMP: PtraceOptions   = (1 << PTRACE_EVENT_SECCOMP);
+
+
 }
 
 mod ffi {

src/sys/wait.rs

@@ -47,6 +47,8 @@ pub enum WaitStatus {
     Stopped(Pid, Signal),
     #[cfg(any(target_os = "linux", target_os = "android"))]
     PtraceEvent(Pid, Signal, c_int),
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    PtraceSyscall(Pid),
     Continued(Pid),
     StillAlive
 }
@@ -56,6 +58,7 @@ pub enum WaitStatus {
 mod status {
     use sys::signal::Signal;
     use libc::c_int;
+    use libc::SIGTRAP;
 
     pub fn exited(status: i32) -> bool {
         (status & 0x7F) == 0
@@ -88,6 +91,9 @@ mod status {
     pub fn stop_additional(status: i32) -> c_int {
         (status >> 16) as c_int
     }
+    pub fn syscall_stop(status: i32) -> bool {
+        ((status & 0xFF00) >> 8) == SIGTRAP | 0x80
+    }
 
     pub fn continued(status: i32) -> bool {
         status == 0xFFFF
@@ -145,6 +151,7 @@ mod status {
           target_os = "netbsd"))]
 mod status {
     use sys::signal::Signal;
+    use libc::SIGTRAP;
 
     const WCOREFLAG: i32 = 0x80;
     const WSTOPPED: i32 = 0x7f;
@@ -196,7 +203,9 @@ fn decode(pid : Pid, status: i32) -> WaitStatus {
             if #[cfg(any(target_os = "linux", target_os = "android"))] {
                 fn decode_stopped(pid: Pid, status: i32) -> WaitStatus {
                     let status_additional = status::stop_additional(status);
-                    if status_additional == 0 {
+                    if status::syscall_stop(status) {
+                        WaitStatus::PtraceSyscall(pid)
+                    } else if status_additional == 0 {
                         WaitStatus::Stopped(pid, status::stop_signal(status))
                     } else {
                         WaitStatus::PtraceEvent(pid, status::stop_signal(status), status::stop_additional(status))